// Copyright © 2025-2026 rustmailer.com
// Licensed under RustMailer License Agreement v1.0
// Unauthorized use, distribution, or modification is prohibited.

syntax = "proto3";

package rustmailer.grpc;

import "google/protobuf/struct.proto";

// An empty message used for requests or responses that do not require a payload.
message Empty {}

// AccountInfo represents a basic overview of an account.
message AccountInfo {
  // The unique identifier of the account.
  uint64 id = 1;
  // The primary email address associated with the account.
  string email = 2;
}

// Encryption defines the supported encryption protocols for server connections.
enum Encryption {
  // Secure Sockets Layer/Transport Layer Security.
  SSL = 0;
  // Opportunistic TLS, typically used after an unencrypted connection is established.
  START_TLS = 1;
  // No encryption.
  NONE = 2;
}

// AuthType specifies the authentication mechanisms available for email servers.
enum AuthType {
  // Password-based authentication.
  PASSWORD = 0;
  // OAuth2 authentication.
  OAUTH2 = 1;
}

// Unit specifies the time unit for relative date calculations.
enum Unit {
  // Represents a period in days.
  DAYS = 0;
  // Represents a period in months.
  MONTHS = 1;
  // Represents a period in years.
  YEARS = 2;
}

// AuthConfig defines the authentication settings for an email server.
message AuthConfig {
  // The type of authentication to use (e.g., PASSWORD, OAUTH2).
  AuthType auth_type = 1;
  // Optional: The password for password-based authentication. This field should be omitted if auth_type is OAUTH2.
  optional string password = 2;
}

// ImapConfig defines the configuration for an IMAP server connection.
message ImapConfig {
  // The hostname or IP address of the IMAP server.
  string host = 1;
  // The port number for the IMAP server.
  uint32 port = 2;
  // The encryption method to use for the IMAP connection.
  Encryption encryption = 3;
  // The authentication configuration for the IMAP server.
  AuthConfig auth = 4;
  // Optional: The ID of a proxy to use for the IMAP connection.
  optional uint64 use_proxy = 5;
}

// SmtpConfig defines the configuration for an SMTP server connection.
message SmtpConfig {
  // The hostname or IP address of the SMTP server.
  string host = 1;
  // The port number for the SMTP server.
  uint32 port = 2;
  // The encryption method to use for the SMTP connection.
  Encryption encryption = 3;
  // The authentication configuration for the SMTP server.
  AuthConfig auth = 4;
  // Optional: The ID of a proxy to use for the SMTP connection.
  optional uint64 use_proxy = 5;
}

// RelativeDate specifies a date relative to the current time.
message RelativeDate {
  // The unit of time (e.g., DAYS, MONTHS, YEARS).
  Unit unit = 1;
  // The numeric value for the specified unit.
  uint32 value = 2;
}

// DateSince defines a point in time from which to start synchronization.
message DateSince {
  // Optional: A fixed date in "YYYY-MM-DD" format.
  optional string fixed = 1;
  // Optional: A date relative to the current time.
  optional RelativeDate relative = 2;
}

// Account represents a full email account configuration.
message Account {
  // The unique identifier of the account.
  uint64 id = 1;
  // The IMAP server configuration for the account.
  optional ImapConfig imap = 2;
  // The SMTP server configuration for the account.
  optional SmtpConfig smtp = 3;
  // Indicates whether the account is enabled for synchronization.
  bool enabled = 4;
  // The email address of the account.
  string email = 5;
  // Optional: A display name for the account.
  optional string name = 6;
  // If true, only minimal metadata will be synced initially (e.g., no full message bodies).
  optional bool minimal_sync = 7;
  // A list of capabilities supported by the account (e.g., "IMAP4REV1", "AUTH=PLAIN").
  repeated string capabilities = 8;
  // Optional: Indicates if the account is capable of Delivery Status Notifications (DSN).
  optional bool dsn_capable = 9;
  // Optional: The date from which to start syncing emails for this account.
  optional DateSince date_since = 10;
  // A list of folders to synchronize. If empty, all folders might be synced based on `minimal_sync`.
  repeated string sync_folders = 11;
  // A list of known folders (e.g., "INBOX", "Sent Items").
  repeated string known_folders = 12;
  // The interval (in minutes) for a full synchronization pass.
  optional int64 full_sync_interval_min = 13;
  // The interval (in seconds) for incremental synchronization updates.
  int64 incremental_sync_interval_sec = 14;
  // The timestamp when the account was created.
  int64 created_at = 15;
  // The timestamp when the account was last updated.
  int64 updated_at = 16;
  // Method used to access and manage emails.
  MailerType mailer_type = 17;
  // Optional proxy ID for establishing the connection to external APIs (e.g., Gmail, Outlook).
  // - If `None` or not provided, the client will connect directly to the API server.
  // - If `Some(proxy_id)`, the client will use the pre-configured proxy with the given ID for API requests.
  optional uint64 use_proxy = 18;
  // Max emails to sync for this folder.  
  // If not set, sync all emails.  
  // otherwise sync up to `n` most recent emails (min 10).
  optional uint32 folder_limit = 19; 
}

// PagedAccount represents a paginated list of Account messages.
message PagedAccount {
  // Optional: The current page number being returned.
  optional uint64 current_page = 1;
  // Optional: The number of items per page.
  optional uint64 page_size = 2;
  // The total number of items available across all pages.
  uint64 total_items = 3;
  // The list of Account items for the current page.
  repeated Account items = 4;
  // Optional: The total number of pages available.
  optional uint64 total_pages = 5;
}

// AccountCreateRequest defines the parameters for creating a new email account.
message AccountCreateRequest {
  // The email address for the new account.
  string email = 1;
  // Optional: A display name for the new account.
  optional string name = 2;
  // The IMAP configuration for the new account.
  optional ImapConfig imap = 3;
  // The SMTP configuration for the new account.
  optional SmtpConfig smtp = 4;
  // Indicates whether the new account should be enabled immediately.
  bool enabled = 5;
  // Optional: The date from which to start syncing emails for this account.
  optional DateSince date_since = 6;
  // If true, only minimal metadata will be synced initially for the new account.
  optional bool minimal_sync = 7;
  // Optional: The interval (in minutes) for a full synchronization pass.
  optional int64 full_sync_interval_min = 8;
  // Optional: The interval (in seconds) for incremental synchronization updates.
  int64 incremental_sync_interval_sec = 9;
  // Method used to access and manage emails.
  MailerType mailer_type = 10;
  // Optional proxy ID for establishing the connection to external APIs (e.g., Gmail, Outlook).
  // - If `None` or not provided, the client will connect directly to the API server.
  // - If `Some(proxy_id)`, the client will use the pre-configured proxy with the given ID for API requests.
  optional uint64 use_proxy = 11;
  // Max emails to sync for this folder.  
  // If not set, sync all emails.  
  // otherwise sync up to `n` most recent emails (min 10).
  optional uint32 folder_limit = 12;
}

// AccountUpdateRequest defines the parameters for updating an existing email account.
message AccountUpdateRequest {
  // The ID of the account to update.
  uint64 account_id = 1;
  // Optional: Update the enabled status of the account.
  optional bool enabled = 2;
  // Optional: Update the IMAP server configuration.
  optional ImapConfig imap = 3;
  // Optional: Update the SMTP server configuration.
  optional SmtpConfig smtp = 4;
  // Optional: Update the display name of the account.
  optional string name = 5;
  // Optional: Update the date from which to start syncing emails.
  optional DateSince date_since = 6;
  // A list of folders to synchronize. This will overwrite existing sync folders.
  repeated string sync_folders = 7;
  // Optional: Update the interval (in minutes) for a full synchronization pass.
  optional int64 full_sync_interval_min = 8;
  // Optional: Update the interval (in seconds) for incremental synchronization updates.
  optional int64 incremental_sync_interval_sec = 9;
  // Optional proxy ID for establishing the connection to external APIs (e.g., Gmail, Outlook).
  // - If `None` or not provided, the client will connect directly to the API server.
  // - If `Some(proxy_id)`, the client will use the pre-configured proxy with the given ID for API requests.
  optional uint64 use_proxy = 10;
  // Max emails to sync for this folder.  
  // If not set, sync all emails.  
  // otherwise sync up to `n` most recent emails (min 10).
  optional uint32 folder_limit = 11;
}

// AccountError represents an error encountered during account processing.
message AccountError {
  // The error message.
  string error = 1;
  // The timestamp when the error occurred.
  int64 at = 2;
}

// AccountRunningState provides real-time information about an account's synchronization status.
message AccountRunningState {
  // The ID of the account.
  uint64 account_id = 1;
  // The timestamp when the last full synchronization started.
  int64 last_full_sync_start = 2;
  // Optional: The timestamp when the last full synchronization ended.
  optional int64 last_full_sync_end = 3;
  // The timestamp when the last incremental synchronization started.
  int64 last_incremental_sync_start = 4;
  // Optional: The timestamp when the last incremental synchronization ended.
  optional int64 last_incremental_sync_end = 5;
  // A list of errors encountered during synchronization.
  repeated AccountError errors = 6;
  // Indicates if the initial synchronization for the account is completed.
  bool is_initial_sync_completed = 7;
  // A list of folders that were part of the initial synchronization.
  repeated string initial_sync_folders = 8;
  // Optional: The name of the folder currently being synchronized.
  optional string current_syncing_folder = 9;
  // Optional: The current batch number within the current folder sync.
  optional uint32 current_batch_number = 10;
  // Optional: The total number of batches for the current folder sync.
  optional uint32 current_total_batches = 11;
  // Optional: The timestamp when the initial synchronization started.
  optional int64 initial_sync_start_time = 12;
  // Optional: The timestamp when the initial synchronization ended.
  optional int64 initial_sync_end_time = 13;
}

// PaginateRequest defines parameters for paginating lists of items.
message PaginateRequest {
  // Optional: The requested page number (1-based).
  optional uint64 page = 1;
  // Optional: The number of items to return per page.
  optional uint64 page_size = 2;
  // Optional: If true, results will be returned in descending order.
  optional bool desc = 3;
}

// AccountId is a simple message to specify an account by its ID.
message AccountId {
  // The unique identifier of the account.
  uint64 account_id = 1;
}

// MinimalAccount provides a reduced set of account information.
message MinimalAccount {
  // The unique identifier of the account.
  uint64 id = 1;
  // The email address associated with the account.
  string email = 2;
  // The type of the mailer (e.g., IMAP, Gmail API, etc.).
  MailerType mailer_type = 3;
}

// ListMinimalAccountsResponse contains a list of minimal account information.
message ListMinimalAccountsResponse {
  // A list of minimal account details.
  repeated MinimalAccount accounts = 1;
}

// Represents the method used to access/manage emails.
enum MailerType {
    // Default value: use IMAP/SMTP protocol
    IMAP_SMTP = 0;
    // Use Gmail API
    GMAIL_API = 1;
    // Use Graph API
    GRAPH_API = 2;
}

// AccountService provides APIs for managing email accounts.
service AccountService {
  // Retrieves a specific email account by its ID.
  rpc GetAccount(AccountId) returns (Account);
  // Removes an email account.
  rpc RemoveAccount(AccountId) returns (Empty);
  // Creates a new email account.
  rpc CreateAccount(AccountCreateRequest) returns (Account);
  // Updates an existing email account.
  rpc UpdateAccount(AccountUpdateRequest) returns (Empty);
  // Lists email accounts with pagination.
  rpc ListAccounts(PaginateRequest) returns (PagedAccount);
  // Retrieves the current running state and synchronization status of an account.
  rpc GetAccountState(AccountId) returns (AccountRunningState);
  // Lists minimal details for all accounts.
  rpc ListMinimalAccounts (Empty) returns (ListMinimalAccountsResponse);
}

// MailServerConfig aggregates IMAP, SMTP, and optional OAuth2 configurations for a mail server.
message MailServerConfig {
  // The IMAP server configuration.
  ServerConfig imap = 1;
  // The SMTP server configuration.
  ServerConfig smtp = 2;
  // Optional: OAuth2 configuration if supported by the mail server.
  optional OAuth2Config oauth2 = 3;
}

// ServerConfig defines the basic connection details for a mail server.
message ServerConfig {
  // The hostname or IP address of the server.
  string host = 1;
  // The port number for the server.
  uint32 port = 2;
  // The encryption method to use for the connection.
  Encryption encryption = 3;
}

// OAuth2Config defines the necessary parameters for OAuth2 authentication.
message OAuth2Config {
  // The OAuth2 issuer URL.
  string issuer = 1;
  // A list of OAuth2 scopes required.
  repeated string scope = 2;
  // The OAuth2 authorization endpoint URL.
  string auth_url = 3;
  // The OAuth2 token endpoint URL.
  string token_url = 4;
}

// AutoconfigRequest is used to request mail server configurations based on an email address.
message AutoconfigRequest {
  // The email address for which to retrieve autoconfiguration.
  string email_address = 1;
}

// AutoConfigService provides a mechanism to automatically discover mail server configurations.
service AutoConfigService {
  // Retrieves mail server configurations (IMAP, SMTP, OAuth2) for a given email address.
  rpc GetAutoconfig (AutoconfigRequest) returns (MailServerConfig);
}

// MailBox represents a mail folder on an IMAP server.
message MailBox {
  // The unique hash of the mailbox, serving as a primary key.
  uint64 mailbox_id = 1;
  // The hash of the account to which this mailbox belongs, serving as a secondary key.
  uint64 account_hash = 2;
  // The unique name of the mailbox (e.g., "INBOX", "Sent Items").
  string name = 3;
  // Optional: The delimiter used for hierarchy within the mailbox name (e.g., "/").
  optional string delimiter = 4;
  // A list of attributes (e.g., "\Noinferiors", "\Noselect") for the mailbox.
  repeated Attribute attributes = 5;
  // A list of flags currently applicable to messages in this mailbox.
  repeated EnvelopeFlag flags = 6;
  // The number of messages currently in the mailbox.
  uint32 exists = 7;
  // Optional: The number of unseen messages in the mailbox.
  optional uint32 unseen = 8;
  // A list of permanent flags that can be set on messages in this mailbox.
  repeated EnvelopeFlag permanent_flags = 9;
  // Optional: The next unique identifier (UID) that will be assigned to a new message in this mailbox.
  optional uint32 uid_next = 10;
  // Optional: The UID validity value for this mailbox. Changes indicate old UIDs are invalid.
  optional uint32 uid_validity = 11;
  // Optional: The highest modification sequence value for messages in this mailbox (for CONDSTORE).
  optional uint64 highest_modseq = 12;
}

// EnvelopeFlag represents a single IMAP message flag, which can be standard or custom.
message EnvelopeFlag {
  // The standard email flag type.
  EmailFlag flag = 1;
  // Optional: Custom flag string if `flag` is CUSTOM.
  optional string custom = 2;
}

// EmailFlag enumerates standard IMAP message flags.
enum EmailFlag {
  // Message has been read.
  SEEN = 0;
  // Message has been answered.
  ANSWERED = 1;
  // Message is flagged for special attention.
  EMAIL_FLAGGED = 2;
  // Message is marked for deletion.
  DELETED = 3;
  // Message is a draft.
  DRAFT = 4;
  // Message has been recently arrived.
  RECENT = 5;
  // The client may create new messages in this mailbox.
  MAY_CREATE = 6;
  // A custom flag, requiring the `custom` field to be set.
  CUSTOM = 7;
}

// Attribute represents a single IMAP mailbox attribute.
message Attribute {
  // The enumerated attribute type.
  AttributeEnum attr = 1;
  // Optional: Extension string for custom attributes.
  optional string extension = 2;
}

// AttributeEnum enumerates standard IMAP mailbox attributes.
enum AttributeEnum {
  // No inferior hierarchical names exist.
  NO_INFERIORS = 0;
  // Mailbox cannot be selected.
  NO_SELECT = 1;
  // Mailbox is marked (implementation-defined).
  MARKED = 2;
  // Mailbox is unmarked (implementation-defined).
  UNMARKED = 3;
  // Generic attribute for all mailboxes.
  ALL = 4;
  // Mailbox for archive messages.
  ARCHIVE = 5;
  // Mailbox for draft messages.
  DRAFTS = 6;
  // Mailbox for flagged messages.
  FLAGGED = 7;
  // Mailbox for junk/spam messages.
  JUNK = 8;
  // Mailbox for sent messages.
  SENT = 9;
  // Mailbox for trash/deleted messages.
  TRASH = 10;
  // An extension attribute, requiring the `extension` field to be set.
  EXTENSION = 11;
  // An unknown attribute.
  UNKNOWN = 12;
}

// ListMailboxesRequest is used to request a list of mailboxes for a given account.
message ListMailboxesRequest {
  // The ID of the account.
  uint64 account_id = 1;
  // If true, fetches mailboxes directly from the remote server.
  bool remote = 2;
}

// ListSubscribedRequest is used to request a list of subscribed mailboxes for a given account.
message ListSubscribedRequest {
  // The ID of the account.
  uint64 account_id = 1;
}

// ListMailboxesResponse contains a list of MailBox messages.
message ListMailboxesResponse {
  // The list of mailboxes.
  repeated MailBox mailboxes = 1;
}

// SubscribeRequest is used to subscribe to a mailbox.
message SubscribeRequest {
  // The ID of the account.
  uint64 account_id = 1;
  // The name of the mailbox to subscribe to.
  string mailbox_name = 2;
}

// UnsubscribeRequest is used to unsubscribe from a mailbox.
message UnsubscribeRequest {
  // The ID of the account.
  uint64 account_id = 1;
  // The name of the mailbox to unsubscribe from.
  string mailbox_name = 2;
}

// Label color settings, only applicable for Gmail API accounts.
message LabelColor {
    // Text color of the label.
    // Allowed values include:
    // "#000000", "#434343", "#666666", "#999999", "#cccccc", "#efefef", "#f3f3f3", "#ffffff",
    // "#fb4c2f", "#ffad47", "#fad165", "#16a766", "#43d692", "#4a86e8", "#a479e2", "#f691b3",
    // "#f6c5be", "#ffe6c7", "#fef1d1", "#b9e4d0", "#c6f3de", "#c9daf8", "#e4d7f5", "#fcdee8",
    // "#efa093", "#ffd6a2", "#fce8b3", "#89d3b2", "#a0eac9", "#a4c2f4", "#d0bcf1", "#fbc8d9",
    // "#e66550", "#ffbc6b", "#fcda83", "#44b984", "#68dfa9", "#6d9eeb", "#b694e8", "#f7a7c0",
    // "#cc3a21", "#eaa041", "#f2c960", "#149e60", "#3dc789", "#3c78d8", "#8e63ce", "#e07798",
    // "#ac2b16", "#cf8933", "#d5ae49", "#0b804b", "#2a9c68", "#285bac", "#653e9b", "#b65775",
    // "#822111", "#a46a21", "#aa8831", "#076239", "#1a764d", "#1c4587", "#41236d", "#83334c",
    // "#464646", "#e7e7e7", "#0d3472", "#b6cff5", "#0d3b44", "#98d7e4", "#3d188e", "#e3d7ff",
    // "#711a36", "#fbd3e0", "#8a1c0a", "#f2b2a8", "#7a2e0b", "#ffc8af", "#7a4706", "#ffdeb5",
    // "#594c05", "#fbe983", "#684e07", "#fdedc1", "#0b4f30", "#b3efd3", "#04502e", "#a2dcc1",
    // "#c2c2c2", "#4986e7", "#2da2bb", "#b99aff", "#994a64", "#f691b2", "#ff7537", "#ffad46",
    // "#662e37", "#ebdbde", "#cca6ac", "#094228", "#42d692", "#16a765"
    string text_color = 1;

    // Background color of the label.
    // Allowed values include the same set as text_color.
    string background_color = 2;
}

// CreateMailboxRequest is used to create a new mailbox.
message CreateMailboxRequest {
  // The ID of the account.
  uint64 account_id = 1;
  // - For IMAP accounts, this is the name of the mailbox to create.  
  //   Supports hierarchical paths using `/` as a separator.  
  //   For example, `"a/b"` creates mailbox `b` under parent mailbox `a`.  
  //   **Note:** The parent mailbox (`a`) must already exist.
  // - For Gmail API accounts, this corresponds to the label's name.  
  //   Gmail labels do not require the parent to exist beforehand; nested labels are created automatically.
  string mailbox_name = 2;
  /// Parent mailbox ID.
  ///
  /// Only applicable for **Graph API** accounts.  
  /// For IMAP or Gmail API accounts, this field is always `None`.  
  /// The ID can be retrieved via the **`/list-mailboxes?remote=true`** endpoint.
  optional string parent_name = 3;
  // Optional color settings for the label (Gmail API only).
  // Only applicable to Gmail API accounts. See [`LabelColor`] for the allowed
  // `text_color` and `background_color` values.
  optional LabelColor label_color = 4;
}

// DeleteMailboxRequest is used to delete a mailbox.
message DeleteMailboxRequest {
  // The ID of the account.
  uint64 account_id = 1;
  // The name of the mailbox to delete.
  string mailbox_name = 2;
}

// MailboxUpdateRequest is used to rename an existing mailbox.
message MailboxUpdateRequest {
  // The ID of the account.
  uint64 account_id = 1;
  // Current name of the mailbox or label.
  // - For IMAP accounts, this is the existing mailbox name.  
  // - For Gmail API accounts, this is the existing label name.
  string current_name = 2;
  // New name for the mailbox or label (optional).
  optional string new_name = 3;
  // Optional color settings for the label (Gmail API only).
  // Only applicable to Gmail API accounts. See [`LabelColor`] for allowed
  // `text_color` and `background_color` values.
  optional LabelColor label_color = 4;
}

// MailboxService provides APIs for managing mailboxes (folders) on an email server.
service MailboxService {
  // Lists all mailboxes for a given account.
  rpc ListMailboxes(ListMailboxesRequest) returns (ListMailboxesResponse);
  // Lists mailboxes to which the account is subscribed.
  rpc ListSubscribedMailboxes(ListSubscribedRequest) returns (ListMailboxesResponse);
  // Subscribes the account to a specific mailbox.
  rpc SubscribeMailbox(SubscribeRequest) returns (Empty);
  // Unsubscribes the account from a specific mailbox.
  rpc UnsubscribeMailbox(UnsubscribeRequest) returns (Empty);
  // Creates a new mailbox for the account.
  rpc CreateMailbox(CreateMailboxRequest) returns (Empty);
  // Removes (deletes) a mailbox from the account.
  rpc RemoveMailbox(DeleteMailboxRequest) returns (Empty);
  // Update an existing mailbox for the account.
  rpc UpdateMailbox(MailboxUpdateRequest) returns (Empty);
}

// MailboxTransferRequest is used to move or copy messages between mailboxes or labels.
message MailboxTransferRequest {
  // The ID of the account.
  uint64 account_id = 1;
  // A list of unique message identifiers as strings.
  // - For IMAP accounts, each UID is converted to a numeric string (parseable back to `u32`).
  // - For Gmail API accounts, each element is a message ID (`mid`) returned by the API.
  // Unifying them as strings simplifies handling across different backends.
  repeated string ids = 2;
  // The name of the mailbox or label from which to transfer messages.
  // For IMAP: decoded human-readable mailbox name (e.g., "INBOX").
  // For Gmail API: the label name.
  // For Graph API: the folder name.
  optional string current_mailbox = 3;
  // The name of the target mailbox or label to which messages will be transferred.
  // For IMAP: decoded human-readable mailbox name (e.g., "INBOX").
  // For Gmail API: the label name.
  string target_mailbox = 4;
}

// MessageDeleteRequest is used to delete messages from a mailbox.
message MessageDeleteRequest {
  // The ID of the account.
  uint64 account_id = 1;
  // A list of unique message identifiers as strings.
  // - For IMAP accounts, each UID is converted to a numeric string (parseable back to `u32`).
  // - For Gmail API accounts, each element is a message ID (`mid`) returned by the API.
  // Unifying them as strings simplifies handling across different backends.
  repeated string ids = 2;
  /// The decoded, human-readable name of the mailbox containing the email (e.g., "INBOX").  (IMAP only)
  /// This name is presented as it appears to users, with any encoding (e.g., UTF-7) automatically handled by the system,
  /// so no manual decoding is required.
  /// In Gmail API, this field is not required and can be set to `None`.
  optional string mailbox_name = 3;
}

// FlagMessageRequest is used to update flags on messages within a mailbox.
message FlagMessageRequest {
  // The ID of the account.
  uint64 account_id = 1;
  // A list of unique identifiers (UIDs) of the messages to flag.
  repeated uint32 uids = 2;
  // The name of the mailbox containing the messages.
  string mailbox_name = 3;
  // The flag actions to perform (add, remove, overwrite).
  FlagAction action = 4;
}

// FlagAction defines how message flags should be modified.
message FlagAction {
  // Flags to add to the messages.
  repeated EnvelopeFlag add = 1;
  // Flags to remove from the messages.
  repeated EnvelopeFlag remove = 2;
  // Flags to set, replacing all existing flags on the messages.
  repeated EnvelopeFlag overwrite = 3;
}

// Addr represents an email address, including an optional display name.
message Addr {
  // Optional: The display name associated with the email address (e.g., "John Doe").
  optional string name = 1;
  // Optional: The email address (e.g., "john.doe@example.com").
  optional string address = 2;
}

// Received provides details from a "Received" header in an email.
message Received {
  // Optional: The host from which the message was received.
  optional string from = 1;
  // Optional: The host by which the message was received.
  optional string by = 2;
  // Optional: The protocol used (e.g., "ESMTP").
  optional string with = 3;
  // Optional: The date the message was received (Unix timestamp).
  optional int64 date = 4;
}

// EmailBodyPart represents a specific part of an email's body, typically a text or HTML section.
message EmailBodyPart {
  // A unique identifier for this body part.
  string id = 1;
  // The type of content in this body part (e.g., PLAIN, HTML).
  PartType part_type = 2;
  // The path (segment numbers) within the MIME structure to locate this part.
  SegmentPath path = 3;
  // A list of parameters associated with this body part (e.g., charset).
  repeated Param params = 4;
  // The size of the body part in bytes.
  uint64 size = 5;
  // The content transfer encoding of this body part (e.g., QUOTED_PRINTABLE).
  Encoding transfer_encoding = 6;
}

// PartType defines the content type of an email body part.
enum PartType {
  // Plain text content.
  PLAIN = 0;
  // HTML content.
  HTML = 1;
}

// SegmentPath represents a numerical path to a specific MIME part within an email.
message SegmentPath {
  // A sequence of segment numbers to navigate the MIME tree.
  repeated uint64 segments = 1;
}

// Param represents a key-value pair for MIME parameters.
message Param {
  // The key of the parameter.
  string key = 1;
  // The value of the parameter.
  string value = 2;
}

// Encoding defines common content transfer encodings.
enum Encoding {
  // No specific encoding applied.
  NONE_CODING = 0;
  // Quoted-Printable encoding.
  QUOTED_PRINTABLE = 1;
  // Base64 encoding.
  BASE64 = 2;
}

// ImapAttachment represents an attachment parsed from an IMAP message.
message ImapAttachment {
  // A unique identifier for this attachment.
  string id = 1;
  // The path (segment numbers) within the MIME structure to locate this attachment.
  SegmentPath path = 2;
  // Optional: The filename of the attachment.
  optional string filename = 3;
  // Indicates if the attachment should be displayed inline with the message.
  bool inline = 4;
  // Optional: The Content-ID header value for inline attachments.
  optional string content_id = 5;
  // The size of the attachment in bytes.
  uint64 size = 6;
  // The MIME type of the attachment (e.g., "image/jpeg", "application/pdf").
  string file_type = 7;
  // The content transfer encoding of this attachment.
  Encoding transfer_encoding = 8;
}

// EmailEnvelope contains summary information about an email message, similar to IMAP ENVELOPE data.
message EmailEnvelope {
  // The ID of the account this email belongs to.
  uint64 account_id = 1;
  // The hash of the mailbox this email is in.
  uint64 mailbox_id = 2;
  // The name of the mailbox this email is in.
  string mailbox_name = 3;
  // The unique ID of the message, either IMAP UID or Gmail API MID.
  // - For IMAP accounts, this is the UID converted to a string.
  // - For Gmail API accounts, this is the message ID returned by the API.
  string id = 4;
  // Optional: The internal date and time of the message on the server (Unix timestamp).
  optional int64 internal_date = 5;
  // The size of the message in bytes.
  uint32 size = 6;
  // A list of flags currently set on the message (e.g., \Seen, \Answered).
  repeated EnvelopeFlag flags = 7;
  // A hash of the message flags for quick comparison.
  optional uint64 flags_hash = 8;
  // A list of blind carbon copy (BCC) recipients.
  repeated Addr bcc = 9;
  // A list of carbon copy (CC) recipients.
  repeated Addr cc = 10;
  // Optional: The date from the message's "Date" header (Unix timestamp).
  optional int64 date = 11;
  // The sender's address.
  Addr from = 12;
  // Optional: The Message-ID of the message this one is a reply to.
  optional string in_reply_to = 13;
  // The actual sender's address (distinct from 'from' if delegated).
  Addr sender = 14;
  // Optional: The return address for bounces (Return-Path).
  optional string return_address = 15;
  // Optional: The unique message identifier (Message-ID).
  optional string message_id = 16;
  // Optional: The subject line of the email.
  optional string subject = 17;
  // Optional: The name of the thread this message belongs to.
  optional string thread_name = 18;
  // Optional: The MIME-Version header.
  optional string mime_version = 19;
  // A list of Message-IDs that this message references.
  repeated string references = 20;
  // A list of reply-to addresses.
  repeated Addr reply_to = 21;
  // A list of primary recipients (To).
  repeated Addr to = 22;
  // A list of attachments found in the message.
  repeated ImapAttachment attachments = 23;
  // Metadata about the body parts (e.g., plain text, HTML).
  repeated EmailBodyPart body_meta = 24;
  // Information from the "Received" header.
  Received received = 25;
  // The identifier of the thread this email belongs to.
  // This is computed based on `in_reply_to` / `references` / `message_id`.
  string thread_id = 26;
  // A list of labels applied to the message.
  // Each element is a string representing a Gmail label name (e.g., "INBOX", "UNREAD").
  // This field reflects the current labels associated with the email.
  // **Note:** This field is populated only for Gmail API accounts. For other account types, it will be empty.
  repeated string labels = 27;
}

// FetchMessageContentRequest is used to fetch specific content sections of an email message.
message FetchMessageContentRequest {
  // The ID of the account.
  uint64 account_id = 1;
  // The name of the mailbox containing the message.
  optional string mailbox_name = 2;
  // The unique ID of the message, either IMAP UID or Gmail API MID.
  // - For IMAP accounts, this is the UID converted to a string. It must be a valid numeric string
  //   that can be parsed back to a `u32`.
  // - For Gmail API accounts, this is the message ID (`mid`) returned by the API.
  string id = 3;
  // Optional: The maximum length of content to fetch.
  optional uint64 max_length = 4;
  // A list of specific body sections to fetch.
  repeated EmailBodyPart sections = 5;
  // A list of inline attachments to fetch.
  repeated ImapAttachment inline = 6;
}

// FetchMessageAttachmentRequest is used to fetch a specific attachment from an email message.
message FetchMessageAttachmentRequest {
  // The ID of the account.
  uint64 account_id = 1;
  // The unique ID of the message, either IMAP UID or Gmail API MID.
  // - For IMAP accounts, this is the UID converted to a string. It must be a valid numeric string
  //   that can be parsed back to a `u32`.
  // - For Gmail/Graph API accounts, this is the message ID (`mid`) returned by the API.
  string id = 2;
  // The name of the mailbox containing the message.
  optional string mailbox_name = 3;
  // The attachment to fetch, identified by its data.
  optional ImapAttachment attachment = 4;
  // Gmail API only: attachment info used to fetch it via Gmail API.
  optional AttachmentInfo attachment_info = 5;
  // Optional: The filename of the attachment.  
  // - Gmail API only.  
  optional string filename = 6;
  // Optional: The id of the attachment.  
  // - Graph API only.  
  optional string attachment_id = 7;
}

// FetchRawMessageRequest is used to fetch the complete raw content of an email message.
message FetchRawMessageRequest {
  // The ID of the account.
  uint64 account_id = 1;
  // The name of the mailbox containing the message. (IMAP only)
  optional string mailbox_name = 2;
  // The unique ID of the message, either IMAP UID or Gmail API MID.
  // - For IMAP accounts, this is the UID converted to a string. It must be a valid numeric string
  //   that can be parsed back to a `u32`.
  // - For Gmail API accounts, this is the message ID (`mid`) returned by the API.
  string id = 3;
}

// MessageSearch represents a search query for email messages, which can be a single condition or a logical combination of conditions.
message MessageSearch {
  // A search can be either a single condition or a logical combination of conditions.
  oneof search_type {
    // A single search condition.
    Condition condition = 1;
    // A logical combination of multiple search conditions.
    Logic logic = 2;
  }
}

// Condition represents a single search criterion for email messages.
message Condition {
  // The type of condition to apply (e.g., SUBJECT, FROM).
  Conditions condition = 1;
  // Optional: The value to match for the condition.
  optional string value = 2;
}

// Conditions enumerates various IMAP search criteria.
enum Conditions {
  // All messages in the mailbox.
  ALL_C = 0;
  // Messages with the \Answered flag set.
  ANSWERED_C = 1;
  // Messages with a BCC header containing the value.
  BCC = 2;
  // Messages with an internal date earlier than the specified date.
  BEFORE = 3;
  // Messages with a body containing the value.
  BODY = 4;
  // Messages with a CC header containing the value.
  CC = 5;
  // Messages with the \Deleted flag set.
  DELETED_C = 6;
  // Messages with the \Draft flag set.
  DRAFT_C = 7;
  // Messages with the \Flagged flag set.
  FLAGGED_C = 8;
  // Messages with a FROM header containing the value.
  FROM = 9;
  // Messages with a specific header containing the value.
  HEADER = 10;
  // Messages with a specific keyword flag set.
  KEYWORD = 11;
  // Messages larger than the specified size in bytes.
  LARGER = 12;
  // Messages with the \Recent flag set and not \Seen.
  NEW = 13;
  // Messages that do not have the \Recent flag set.
  OLD = 14;
  // Messages with an internal date equal to the specified date.
  ON = 15;
  // Messages with the \Recent flag set.
  RECENT_C = 16;
  // Messages with the \Seen flag set.
  SEEN_C = 17;
  // Messages with a SENT date earlier than the specified date.
  SENT_BEFORE = 18;
  // Messages with a SENT date equal to the specified date.
  SENT_ON = 19;
  // Messages with a SENT date later than or equal to the specified date.
  SENT_SINCE = 20;
  // Messages with an internal date later than or equal to the specified date.
  SINCE = 21;
  // Messages smaller than the specified size in bytes.
  SMALLER = 22;
  // Messages with a SUBJECT header containing the value.
  SUBJECT = 23;
  // Messages with text in the header or body containing the value.
  TEXT = 24;
  // Messages with a TO header containing the value.
  TO = 25;
  // Messages with a UID matching the value.
  UID = 26;
  // Messages that do not have the \Answered flag set.
  UNANSWERED = 27;
  // Messages that do not have the \Deleted flag set.
  UNDELETED = 28;
  // Messages that do not have the \Draft flag set.
  UNDRAFT = 29;
  // Messages that do not have the \Flagged flag set.
  UNFLAGGED = 30;
  // Messages that do not have a specific keyword flag set.
  UNKEYWORD = 31;
  // Messages that do not have the \Seen flag set.
  UNSEEN = 32;
  // This is a full Gmail search expression, only available for Gmail API accounts.
  // Messages with a specific header containing the specified text  
  GMAIL_SEARCH = 33;
}

// Logic defines a logical operator (AND, OR, NOT) applied to child search conditions.
message Logic {
  // The logical operator to apply.
  Operator operator = 1;
  // A list of nested MessageSearch components.
  repeated MessageSearch children = 2;
}

// Operator enumerates logical operators for message searches.
enum Operator {
  // Logical AND.
  AND = 0;
  // Logical OR.
  OR = 1;
  // Logical NOT.
  NOT = 2;
}

// MessageSearchRequest is used to search for messages within a mailbox.
message MessageSearchRequest {
  // The ID of the account.
  uint64 account_id = 1;
  // The name of the mailbox to search in
  // - For **IMAP accounts**, this field is **required** and specifies which mailbox
  //   (e.g. `INBOX`, `Sent`, or a custom folder) the search will run against.
  // - For **Gmail API accounts**, this field is **optional**. If provided, it is treated
  //   as a label name and will override any label filter specified in the `query` string.
  optional string mailbox_name = 2;
  // The search query.
  MessageSearch search = 3;
  // The token for fetching the next page of results in pagination.
  // - If `None`, this indicates that the first page should be returned.
  // - If `Some(token)`, the page corresponding to this token will be fetched.
  optional string next_page_token = 4;
  // The number of messages to return per page.
  uint64 page_size = 5;
  // If true, results will be returned in descending order. imap account only
  optional bool desc = 6;
}

/// Request structure for unified message search across accounts.
message UnifiedSearchRequest {
  // Optional list of account IDs to search within.
  // If omitted, search across all accessible accounts.
  repeated uint64 accounts = 1;
  // Customer email address to search for.
  // This will match fields like from, to, cc, and bcc.
  string email = 2;
  // Optional start timestamp in UTC milliseconds.
  // Filters messages received/sent after this time.
  optional int64 after = 3;
  // Optional end timestamp in UTC milliseconds.
  // Filters messages received/sent before this time.
  optional int64 before = 4;
  // The page number to retrieve, starting from 1.
  // Defaults to 1 if not specified.
  uint64 page = 5;
  // Number of messages to return per page.
  // Defaults to a reasonable value (e.g., 50).
  uint64 page_size = 6;
  // If true, sort messages in descending order (newest first).
  // If false or unset, sort in ascending order (oldest first).
  bool desc = 7;
}



// ListMessagesRequest is used to retrieve a list of messages from a mailbox with pagination.
message ListMessagesRequest {
  // The ID of the account.
  uint64 account_id = 1;
  // The name of the mailbox to list messages from.
  string mailbox_name = 2;
  // The token for fetching the next page of results in pagination.
  // - If `None`, this indicates that the first page should be returned.
  // - If `Some(token)`, the page corresponding to this token will be fetched.
  optional string next_page_token = 3;
  // The number of messages to return per page. max 500
  uint64 page_size = 4;
  // If true, fetches messages directly from the remote server.
  bool remote = 5;
  // If true, results will be returned in descending order.
  bool desc = 6;
}


// ListThreadsRequest is used to retrieve a list of threads from a mailbox with pagination.
message ListThreadsRequest {
  // The ID of the account.
  uint64 account_id = 1;
  // The name of the mailbox to list messages from.
  string mailbox_name = 2;
  // The requested page number (1-based).
  optional string next_page_token = 3;
  // The number of messages to return per page.
  uint64 page_size = 4;
  // If true, results will be returned in descending order.
  bool desc = 5;
  bool remote = 6;
}


// GetThreadMessagesRequest is used to retrieve a list of envelopes of a thread.
message GetThreadMessagesRequest {
  // The ID of the account.
  uint64 account_id = 1;
  // thread id.
  string thread_id = 2;
  optional bool remote = 3;
}

// PagedMessages represents a paginated list of EmailEnvelope messages.
message PagedMessages {
  // Optional: The current page number being returned.
  optional uint64 current_page = 1;
  // Optional: The number of items per page.
  optional uint64 page_size = 2;
  // The total number of items available across all pages.
  uint64 total_items = 3;
  // The list of EmailEnvelope items for the current page.
  repeated EmailEnvelope items = 4;
  // Optional: The total number of pages available.
  optional uint64 total_pages = 5;
}

// CursorDataPage represents a collection of EmailEnvelope messages
// returned using cursor-based pagination rather than numeric page numbers.
message CursorDataPage {
  // A cursor used for pagination (returned by the previous response).
  // Pass this token to retrieve the next page of results.
  // If `None`, there are no more pages available.
  optional string next_page_token = 1;
  // Optional: The number of items per page.
  optional uint64 page_size = 2;
  // The total number of items available across all pages.
  uint64 total_items = 3;
  // The list of EmailEnvelope items for the current page.
  repeated EmailEnvelope items = 4;
  // Optional: The total number of pages available.
  optional uint64 total_pages = 5;
}

// A list of email envelopes.
// corresponding to an EmailEnvelope array.
message EmailEnvelopeList {
    repeated EmailEnvelope items = 1;
}


// PlainText represents plain text content, potentially truncated.
message PlainText {
  // The plain text content.
  string content = 1;
  // Indicates if the content has been truncated.
  bool truncated = 2;
}

// Represents information about an email attachment, including both regular files and inline attachments
message AttachmentInfo {
  // MIME content type of the attachment (e.g., "image/png", "application/pdf").
  string file_type = 1;
  // Content transfer encoding (usually "base64").
  optional string transfer_encoding = 2;
  // Content-ID, used for inline attachments (referenced in HTML by `cid:` URLs).
  optional string content_id = 3;
  // Whether the attachment is marked as inline (true) or a regular file (false).
  bool inline = 4;
  // Original filename of the attachment, if provided.
  string filename = 5;
  // Gmail-specific attachment ID, used to fetch the attachment via Gmail API.
  string id = 6;
  // Size of the attachment in bytes.
  uint32 size = 7;
}


// MessageContentResponse contains the parsed content of an email message.
message MessageContentResponse {
  // The plain text version of the email content.
  PlainText plain = 1;
  // Optional: The HTML version of the email content.
  optional string html = 2;
  // - Gmail API accounts: Always present. If the message has no attachments,
  //   this will be an empty list.
  // - IMAP accounts: Always absent (empty), since attachment metadata is already
  //   included in the envelope.
  repeated AttachmentInfo attachments = 3;
}

// ByteResponse is a generic message for returning raw byte data.
message ByteResponse {
  // The raw byte data.
  bytes data = 1;
}

// Request message to create a reply draft email linked to an existing message thread.
message AppendReplyToDraftRequest {
    // The ID of the email account
    uint64 account_id = 1;
    // The name of the mailbox or label containing the original message
    // - For IMAP accounts, this is the mailbox name where the source message resides.
    // - For Gmail API accounts, this refers to the label name associated with the source message.
    optional string mailbox_name = 2;
    // The unique ID of the message, either IMAP UID or Gmail API MID.
    // - For IMAP accounts, this is the UID converted to a string. It must be a valid numeric string
    //   that can be parsed back to a `u32`.
    // - For Gmail API accounts, this is the message ID (`mid`) returned by the API.
    string id = 3;
    // Optional preview text for the reply email
    optional string preview = 4;
    // Optional plain text body of the reply email
    optional string text = 5;
    // Optional HTML body of the reply email
    optional string html = 6;
    // The path of the folder used to store drafts (IMAP accounts only)
    // For example: "[Gmail]/Drafts".
    // For Gmail API accounts, this field is ignored.
    optional string draft_folder_path = 7;
    // Whether to create a reply-all message.
    // Defaults to false when not set.
    optional bool reply_all = 8;
}

// Represents a tag (Label/Category/Flag) and its associated color
message TagAndColor {
  // Name of the label, category, or IMAP custom flag
  string name = 1;

  // Predefined Outlook category presets (e.g., "preset0", "preset1")
  // Only used for Microsoft Graph API
  optional string graph_color = 2;

  // Custom hex colors for Gmail API
  optional LabelColor gmail_color = 3;
}

// Defines the type of operation to be performed
enum TagAction {
  // Adds tags to the specified messages
  ADD = 0;
  // Removes tags from the specified messages
  REMOVE = 1;
  // Overwrites the entire list of tags
  SET = 2;
}

// The main request for batch tagging operations
message BatchTagRequest {
  // The ID of the email account
  uint64 account_id = 1;
  // A list of unique message identifiers
  repeated string message_ids = 2;

  // The list of tags/categories with their optional color info
  repeated TagAndColor tags = 3;

  // The action to perform (Add, Remove, or Set)
  TagAction action = 4;

  // Required for IMAP context (e.g., "INBOX")
  optional string mailbox_name = 5;

  // Whether to create tags if they don't exist (Gmail/Graph only)
  optional bool auto_create_tags = 6;
}

// MessageService provides APIs for interacting with email messages.
service MessageService {
  // Moves messages from one mailbox to another.
  rpc MoveMessages(MailboxTransferRequest) returns (Empty);
  // Copies messages from one mailbox to another.
  rpc CopyMessages(MailboxTransferRequest) returns (Empty);
  // Deletes messages from a mailbox.
  rpc DeleteMessages(MessageDeleteRequest) returns (Empty);
  // Updates flags on messages within a mailbox.
  rpc UpdateMessageFlags(FlagMessageRequest) returns (Empty);
  // Lists messages within a mailbox with pagination.
  rpc ListMessages(ListMessagesRequest) returns (CursorDataPage);
  // Lists threads within a mailbox with pagination.
  rpc ListThreads(ListThreadsRequest) returns (CursorDataPage);
  // Get thread's envelopes within a mailbox.
  rpc GetThreadMessages(GetThreadMessagesRequest) returns (EmailEnvelopeList);
  // Fetches specific content parts (e.g., plain text, HTML) of an email message.
  rpc FetchMessageContent(FetchMessageContentRequest) returns (MessageContentResponse);
  // Fetches the raw content of a specific attachment from an email message.
  rpc FetchMessageAttachment(FetchMessageAttachmentRequest) returns (ByteResponse);
  // Fetches the complete raw EML content of an email message.
  rpc FetchRawMessage(FetchRawMessageRequest) returns (ByteResponse);
  // Searches for messages within a mailbox based on specified criteria.
  rpc MessageSearch(MessageSearchRequest) returns (CursorDataPage);
  // Performs a unified search across mail accounts and messages.
  rpc UnifiedSearch(UnifiedSearchRequest) returns (PagedMessages);
  // Creates a reply draft email linked to an existing message thread.
  rpc AppendReplyToDraft(AppendReplyToDraftRequest) returns (Empty);
  // Batch modifies the custom tags, categories, or keywords on messages.
  // This interface is dedicated to operating on **user-defined labels** and is separate
  // from standard system status flags (like Read/Unread).
  // It unifies tagging across different email services:
  // - **Gmail/Graph API:** Operates on user-defined Label IDs or Category Names.
  // - **IMAP/SMTP:** Operates on custom IMAP Keywords (Custom Flags).
  // **Note:** This is a high-level operation designed for user tag management.
  rpc TagMessages(BatchTagRequest) returns (Empty);
}

// Mta represents a Mail Transfer Agent configuration.
message Mta {
  // The unique identifier for the MTA.
  uint64 id = 1;
  // Optional: A description for the MTA.
  optional string description = 2;
  // The credentials used for authenticating with the MTA.
  MTACredentials credentials = 3;
  // The SMTP server configuration for the MTA.
  SmtpServerConfig server = 4;
  // The timestamp when the MTA was created.
  int64 created_at = 5;
  // Indicates if the MTA supports Delivery Status Notifications (DSN).
  bool dsn_capable = 6;
  // The timestamp when the MTA was last updated.
  int64 updated_at = 7;
  // The timestamp of the last time this MTA was accessed or used.
  int64 last_access_at = 8;
  // Optional: The ID of a proxy to use for the MTA connection.
  optional uint64 use_proxy = 9;
}

// MTACredentials defines the username and optional password for MTA authentication.
message MTACredentials {
  // The username for authentication.
  string username = 1;
  // Optional: The password for authentication.
  optional string password = 2;
}

// SmtpServerConfig defines the basic connection details for an SMTP server.
message SmtpServerConfig {
  // The hostname or IP address of the SMTP server.
  string host = 1;
  // The port number for the SMTP server.
  uint32 port = 2;
  // The encryption method to use for the SMTP connection.
  Encryption encryption = 3;
}

// GetMtaRequest is used to retrieve a specific MTA by its ID.
message GetMtaRequest {
  // The ID of the MTA to retrieve.
  uint64 id = 1;
}

// DeleteMtaRequest is used to delete a specific MTA by its ID.
message DeleteMtaRequest {
  // The ID of the MTA to delete.
  uint64 id = 1;
}

// MTACreateRequest defines the parameters for creating a new MTA.
message MTACreateRequest {
  // Optional: A description for the new MTA.
  optional string description = 1;
  // The credentials for the new MTA.
  MTACredentials credentials = 2;
  // The SMTP server configuration for the new MTA.
  SmtpServerConfig server = 3;
  // Indicates if the new MTA should be DSN capable.
  bool dsn_capable = 4;
  // Optional: The ID of a proxy to use for the MTA connection.
  optional uint64 use_proxy = 5;
}

// MTAUpdateRequest defines the parameters for updating an existing MTA.
message MTAUpdateRequest {
  // The ID of the MTA to update.
  uint64 id = 1;
  // Optional: Update the description of the MTA.
  optional string description = 2;
  // Optional: Update the credentials for the MTA.
  optional MTACredentials credentials = 3;
  // Optional: Update the SMTP server configuration for the MTA.
  optional SmtpServerConfig server = 4;
  // Optional: Update the DSN capability of the MTA.
  optional bool dsn_capable = 5;
  // Optional: The ID of a proxy to use for the MTA connection.
  optional uint64 use_proxy = 6;
}

// ListMtaRequest defines parameters for paginating lists of MTAs.
message ListMtaRequest {
  // Optional: The requested page number (1-based).
  optional uint64 page = 1;
  // Optional: The number of items to return per page.
  optional uint64 page_size = 2;
  // Optional: If true, results will be returned in descending order.
  optional bool desc = 3;
}

// PagedMta represents a paginated list of Mta messages.
message PagedMta {
  // Optional: The current page number being returned.
  optional uint64 current_page = 1;
  // Optional: The number of items per page.
  optional uint64 page_size = 2;
  // The total number of items available across all pages.
  uint64 total_items = 3;
  // The list of Mta items for the current page.
  repeated Mta items = 4;
  // Optional: The total number of pages available.
  optional uint64 total_pages = 5;
}

// Message representing a request to send a test email.
message SendTestEmailRequest {
  // The email address of the sender (e.g., "no-reply@yourdomain.com").
  string from = 1;
  // The email address of a single recipient (e.g., "user@example.com").
  string to = 2;
  // The subject line of the email.
  // Must be between 1 and 256 characters.
  string subject = 3;
  // The plain text body content of the email, sent as the text/plain part.
  // Must be between 1 and 1024 characters.
  string message = 4;
  // The ID of the MTA (Mail Transfer Agent) to use for sending the email.
  uint64 mta_id = 5;
}

// MtaService provides APIs for managing Mail Transfer Agents.
service MtaService {
  // Retrieves a specific MTA by its ID.
  rpc GetMta(GetMtaRequest) returns (Mta);
  // Removes an MTA.
  rpc RemoveMta(DeleteMtaRequest) returns (Empty);
  // Creates a new MTA.
  rpc CreateMta(MTACreateRequest) returns (Empty);
  // Updates an existing MTA.
  rpc UpdateMta(MTAUpdateRequest) returns (Empty);
  // Lists MTAs with pagination.
  rpc ListMta(ListMtaRequest) returns (PagedMta);
  // Sends a test email using a specified MTA.
  rpc SendTestEmail(SendTestEmailRequest) returns (Empty);
}

// OAuth2GrantType defines the type of OAuth2 grant flow.
enum OAuth2GrantType {
  // Authorization Code Flow with PKCE — requires user interaction.
  AUTHORIZATION_CODE = 0;
  // Client Credentials Flow — no user interaction, suitable for service-to-service auth.
  CLIENT_CREDENTIALS = 1;
}

// OAuth2 represents an OAuth2 client configuration.
message OAuth2 {
  // The unique identifier for the OAuth2 configuration.
  uint64 id = 1;
  // Optional: A description for the OAuth2 configuration.
  optional string description = 2;
  // The client ID provided by the OAuth2 provider.
  string client_id = 3;
  // The client secret provided by the OAuth2 provider.
  string client_secret = 4;
  // The authorization URL of the OAuth2 provider.
  string auth_url = 5;
  // The token URL of the OAuth2 provider.
  string token_url = 6;
  // The redirect URI registered with the OAuth2 provider.
  string redirect_uri = 7;
  // A list of scopes requested for authorization.
  repeated string scopes = 8;
  // A map of extra parameters to include in OAuth2 requests.
  map<string, string> extra_params = 9;
  // Indicates whether this OAuth2 configuration is enabled.
  bool enabled = 10;
  // The timestamp when the OAuth2 configuration was created.
  int64 created_at = 11;
  // The timestamp when the OAuth2 configuration was last updated.
  int64 updated_at = 12;
  // Optional: The ID of a proxy to use for OAuth2 related requests.
  optional uint64 use_proxy = 13;
  // The grant type used for this OAuth2 configuration.
  OAuth2GrantType grant_type = 14;
}

// GetOAuth2Request is used to retrieve a specific OAuth2 configuration by its ID.
message GetOAuth2Request {
  // The ID of the OAuth2 configuration to retrieve.
  uint64 id = 1;
}

// DeleteOAuth2Request is used to delete a specific OAuth2 configuration by its ID.
message DeleteOAuth2Request {
  // The ID of the OAuth2 configuration to delete.
  uint64 id = 1;
}

// OAuth2CreateRequest defines the parameters for creating a new OAuth2 configuration.
message OAuth2CreateRequest {
  // Optional: A description for the new OAuth2 configuration.
  optional string description = 2;
  // The client ID for the new OAuth2 configuration.
  string client_id = 3;
  // The client secret for the new OAuth2 configuration.
  string client_secret = 4;
  // The authorization URL for the new OAuth2 configuration.
  string auth_url = 5;
  // The token URL for the new OAuth2 configuration.
  string token_url = 6;
  // The redirect URI for the new OAuth2 configuration.
  string redirect_uri = 7;
  // A list of scopes for the new OAuth2 configuration.
  repeated string scopes = 8;
  // A map of extra parameters for the new OAuth2 configuration.
  map<string, string> extra_params = 9;
  // Indicates whether the new OAuth2 configuration should be enabled.
  bool enabled = 10;
  // Optional: The ID of a proxy to use for OAuth2 related requests.
  optional uint64 use_proxy = 11;
  // The grant type to use for authentication.
  OAuth2GrantType grant_type = 15;
}

// UpdateOAuth2Request defines the parameters for updating an existing OAuth2 configuration.
message UpdateOAuth2Request {
  // The ID of the OAuth2 configuration to update.
  uint64 id = 1;
  // Optional: Update the description.
  optional string description = 2;
  // Optional: Update the client ID.
  optional string client_id = 3;
  // Optional: Update the client secret.
  optional string client_secret = 4;
  // Optional: Update the authorization URL.
  optional string auth_url = 5;
  // Optional: Update the token URL.
  optional string token_url = 6;
  // Optional: Update the redirect URI.
  optional string redirect_uri = 7;
  // A list of scopes to set (replaces existing scopes).
  repeated string scopes = 8;
  // A map of extra parameters to set (replaces existing params).
  map<string, string> extra_params = 9;
  // Optional: Update the enabled status.
  optional bool enabled = 10;
  // Optional: The ID of a proxy to use for OAuth2 related requests.
  optional uint64 use_proxy = 11;
  // Optional: Update the grant type.
  optional OAuth2GrantType grant_type = 16;
}

// ListOAuth2Request defines parameters for paginating lists of OAuth2 configurations.
message ListOAuth2Request {
  // Optional: The requested page number (1-based).
  optional uint64 page = 1;
  // Optional: The number of items to return per page.
  optional uint64 page_size = 2;
  // Optional: If true, results will be returned in descending order.
  optional bool desc = 3;
}

// PagedOAuth2 represents a paginated list of OAuth2 messages.
message PagedOAuth2 {
  // Optional: The current page number being returned.
  optional uint64 current_page = 1;
  // Optional: The number of items per page.
  optional uint64 page_size = 2;
  // The total number of items available across all pages.
  uint64 total_items = 3;
  // The list of OAuth2 items for the current page.
  repeated OAuth2 items = 4;
  // Optional: The total number of pages available.
  optional uint64 total_pages = 5;
}

// AuthorizeUrlRequest is used to generate an OAuth2 authorization URL.
message AuthorizeUrlRequest {
  // The ID of the account for which to generate the URL.
  uint64 account_id = 1;
  // The ID of the OAuth2 configuration to use.
  uint64 oauth2_id = 2;
}

// AuthorizeUrlResponse contains the generated OAuth2 authorization URL.
message AuthorizeUrlResponse {
  // The generated authorization URL.
  string url = 1;
}

// ClientCredentialsRequest is used to exchange client credentials for an access token.
message ClientCredentialsRequest {
  // The ID of the account to associate the token with.
  uint64 account_id = 1;
  // The ID of the OAuth2 configuration to use (must have grant_type = CLIENT_CREDENTIALS).
  uint64 oauth2_id = 2;
}

// OAuth2AccessToken represents stored OAuth2 access and refresh tokens.
message OAuth2AccessToken {
  // The ID of the account associated with these tokens.
  uint64 account_id = 1;
  // The ID of the OAuth2 configuration used to obtain these tokens.
  uint64 oauth2_id = 2;
  // Optional: The OAuth2 access token.
  optional string access_token = 3;
  // Optional: The OAuth2 refresh token.
  optional string refresh_token = 4;
  // The timestamp when the tokens were created.
  int64 created_at = 5;
  // The timestamp when the tokens were last updated.
  int64 updated_at = 6;
}

// GetOAuth2TokensRequest is used to retrieve OAuth2 tokens for a given account.
message GetOAuth2TokensRequest {
  // The ID of the account for which to retrieve tokens.
  uint64 account_id = 1;
}

// Represents a request to configure or update an external OAuth2 token
// for a given account in RustMailer.
message ExternalOAuth2Request {
  // The ID of the RustMailer account associated with this token.
  uint64 account_id = 1;

  // The ID of the OAuth2 configuration associated with this access token.
  // Must reference an existing OAuth2 configuration in RustMailer.
  // Required if a refresh_token is provided.
  optional uint64 oauth2_id = 2;

  // The OAuth2 access token used to authenticate requests to the provider.
  // If provided without refresh_token, RustMailer will store it directly,
  // but cannot refresh it automatically.
  optional string access_token = 3;

  // The OAuth2 refresh token used to obtain new access tokens.
  // If provided, `oauth2_id` must also be set, and RustMailer will
  // use the refresh token together with the stored client_secret to
  // refresh the access token when needed.
  optional string refresh_token = 4;
}

// OAuth2Service provides APIs for managing OAuth2 configurations and tokens.
service OAuth2Service {
  // Retrieves a specific OAuth2 configuration.
  rpc GetOAuth2Config(GetOAuth2Request) returns (OAuth2);
  // Removes an OAuth2 configuration.
  rpc RemoveOAuth2Config(DeleteOAuth2Request) returns (Empty);
  // Creates a new OAuth2 configuration.
  rpc CreateOAuth2Config(OAuth2CreateRequest) returns (Empty);
  // Updates an existing OAuth2 configuration.
  rpc UpdateOAuth2Config(UpdateOAuth2Request) returns (Empty);
  // Lists OAuth2 configurations with pagination.
  rpc ListOAuth2Config(ListOAuth2Request) returns (PagedOAuth2);
  // Generates an OAuth2 authorization URL for an account.
  rpc CreateAuthorizeUrl(AuthorizeUrlRequest) returns (AuthorizeUrlResponse);
  // Retrieves OAuth2 access and refresh tokens for an account.
  rpc GetOAuth2Tokens(GetOAuth2TokensRequest) returns (OAuth2AccessToken);
  // Exchanges client credentials for an access token and stores it.
  // Only applicable for OAuth2 configurations with grant_type = CLIENT_CREDENTIALS.
  rpc ExchangeClientCredentials(ClientCredentialsRequest) returns (Empty);
  // Upserts an external OAuth2 token for a specified account.
  //
  // If only an access_token is provided, RustMailer stores it directly.
  // The caller must periodically refresh it by calling this method again.
  //
  // If both oauth2_id and refresh_token are provided, RustMailer assumes
  // the OAuth2 flow is completed externally but will handle refreshing
  // access tokens internally using the stored client_secret.
  rpc UpsertExternalOAuth2Token(ExternalOAuth2Request) returns (Empty);
}

// MessageFormat specifies the format of an email template's content.
enum MessageFormat {
  // HTML content format.
  HTML_FORMAT = 0;
  // Markdown content format.
  MARKDOWN = 1;
}

// EmailTemplate represents a reusable email template.
message EmailTemplate {
  // The unique identifier for the email template.
  uint64 id = 1;
  // Optional: A description for the template.
  optional string description = 2;
  // The account information associated with this template.
  AccountInfo account = 3;
  // The subject line of the email template.
  string subject = 4;
  // Optional: A preview text for the template.
  optional string preview = 5;
  // Optional: The format of the template's content (HTML_FORMAT or MARKDOWN).
  optional MessageFormat format = 6;
  // Optional: The plain text content of the template.
  optional string text = 7;
  // Optional: The HTML content of the template.
  optional string html = 8;
  // The timestamp when the template was created.
  int64 created_at = 9;
  // The timestamp when the template was last updated.
  int64 updated_at = 10;
  // The timestamp of the last time this template was accessed or used.
  int64 last_access_at = 11;
}

// EmailTemplateCreateRequest defines the parameters for creating a new email template.
message EmailTemplateCreateRequest {
  // Optional: A description for the new template.
  optional string description = 1;
  // Optional: The ID of the account to associate with this template.
  optional uint64 account_id = 2;
  // The subject line of the new template.
  string subject = 3;
  // Optional: A preview text for the new template.
  optional string preview = 4;
  // Optional: The plain text content for the new template.
  optional string text = 5;
  // Optional: The HTML content for the new template.
  optional string html = 6;
  // Optional: The format of the template's content.
  optional MessageFormat format = 7;
}

// UpdateTemplateRequest defines the parameters for updating an existing email template.
message UpdateTemplateRequest {
  // The ID of the template to update.
  uint64 id = 1;
  // Optional: Update the description of the template.
  optional string description = 2;
  // Optional: Update the subject line of the template.
  optional string subject = 3;
  // Optional: Update the preview text of the template.
  optional string preview = 4;
  // Optional: Update the plain text content of the template.
  optional string text = 5;
  // Optional: Update the HTML content of the template.
  optional string html = 6;
  // Optional: Update the format of the template's content.
  optional MessageFormat format = 7;
}

// PagedEmailTemplate represents a paginated list of EmailTemplate messages.
message PagedEmailTemplate {
  // Optional: The current page number being returned.
  optional uint64 current_page = 1;
  // Optional: The number of items per page.
  optional uint64 page_size = 2;
  // The total number of items available across all pages.
  uint64 total_items = 3;
  // The list of EmailTemplate items for the current page.
  repeated EmailTemplate items = 4;
  // Optional: The total number of pages available.
  optional uint64 total_pages = 5;
}

// Message representing a request to send a test email based on a template.
message TemplateSentTestRequest {
  // Template ID to identify which template to use.
  uint64 template_id = 1;
  // Account ID associated with the template and sending request.
  uint64 account_id = 2;
  // Email address of the recipient who will receive the test email.
  // Must be a valid email address format (e.g., user@example.com).
  string recipient = 3;
  // Optional parameters to be used for template variable substitution.
  // When provided, should be a valid JSON object that matches the template's expected variables.
  // Example: {"name": "John Doe", "order_id": 12345}
  optional google.protobuf.Value template_params = 4;
}

// GetTemplateRequest is used to retrieve a specific email template by its ID.
message GetTemplateRequest {
  // The ID of the template to retrieve.
  uint64 id = 1;
}

// DeleteTemplateRequest is used to delete a specific email template by its ID.
message DeleteTemplateRequest {
  // The ID of the template to delete.
  uint64 id = 1;
}

// ListTemplatesRequest defines parameters for paginating lists of email templates.
message ListTemplatesRequest {
  // Optional: The requested page number (1-based).
  optional uint64 page = 1;
  // Optional: The number of items to return per page.
  optional uint64 page_size = 2;
  // Optional: If true, results will be returned in descending order.
  optional bool desc = 3;
}

// ListAccountTemplatesRequest defines parameters for paginating lists of email templates associated with a specific account.
message ListAccountTemplatesRequest {
  // The ID of the account whose templates are to be listed.
  uint64 account_id = 1;
  // Optional: The requested page number (1-based).
  optional uint64 page = 2;
  // Optional: The number of items to return per page.
  optional uint64 page_size = 3;
  // Optional: If true, results will be returned in descending order.
  optional bool desc = 4;
}

// DeleteAccountTemplatesRequest is used to delete all email templates associated with a specific account.
message DeleteAccountTemplatesRequest {
  // The ID of the account whose templates are to be deleted.
  uint64 account_id = 1;
}

// TemplatesService provides APIs for managing email templates.
service TemplatesService {
  // Retrieves a specific email template by its ID.
  rpc GetTemplate(GetTemplateRequest) returns (EmailTemplate);
  // Removes an email template.
  rpc RemoveTemplate(DeleteTemplateRequest) returns (Empty);
  // Creates a new email template.
  rpc CreateTemplate(EmailTemplateCreateRequest) returns (Empty);
  // Updates an existing email template.
  rpc UpdateTemplate(UpdateTemplateRequest) returns (Empty);
  // Lists all email templates with pagination.
  rpc ListTemplates(ListTemplatesRequest) returns (PagedEmailTemplate);
  // Lists email templates associated with a specific account with pagination.
  rpc ListAccountTemplates(ListAccountTemplatesRequest) returns (PagedEmailTemplate);
  // Removes all email templates associated with a specific account.
  rpc RemoveAccountTemplates(DeleteAccountTemplatesRequest) returns (Empty);
  // Sends a test email using a specified template.
  rpc SendTestEmail(TemplateSentTestRequest) returns (Empty);
}

// ServerStatus provides information about the current state and uptime of the server.
message ServerStatus {
  // The server's uptime in milliseconds.
  int64 uptime_ms = 1;
  // A human-readable string representing the uptime (e.g., "1 hour ago").
  string timeago = 2;
  // The timezone of the server.
  string timezone = 3;
  // The version of the server software.
  string version = 4;
}

// Release represents information about a software release.
message Release {
  // The tag name of the release (e.g., "v1.0.0").
  string tag_name = 1;
  // The date and time when the release was published.
  string published_at = 2;
  // The description or body of the release notes.
  string body = 3;
  // The URL to the release page.
  string html_url = 4;
}

// ReleaseNotification provides information about new software releases and update availability.
message ReleaseNotification {
  // Optional: The latest available software release.
  optional Release latest = 1;
  // Indicates if a newer version of the software is available.
  bool is_newer = 2;
  // Optional: An error message if fetching release information failed.
  optional string error_message = 3;
}

// LicenseCheckResult provides information about the software license status.
message LicenseCheckResult {
  // Indicates if the license has expired.
  bool expired = 1;
  // The number of days remaining until license expiration.
  uint32 days = 2;
}

// Notifications aggregates various system notifications, such as release and license status.
message Notifications {
  // Release notification details.
  ReleaseNotification release = 1;
  // License check result details.
  LicenseCheckResult license = 2;
}

// StatusService provides APIs for retrieving server status and notifications.
service StatusService {
  // Retrieves the current server status.
  rpc GetStatus (Empty) returns (ServerStatus);
  // Retrieves system notifications, including release updates and license status.
  rpc GetNotifications (Empty) returns (Notifications);
}

// EmailAddress represents an email address with an optional display name.
message EmailAddress {
  // Optional: The display name (e.g., "John Doe").
  optional string name = 1;
  // The actual email address (e.g., "john.doe@example.com").
  string address = 2;
}

// Recipient defines the recipients of an email and their associated parameters.
message Recipient {
  // A list of primary recipients (To).
  repeated EmailAddress to = 1;
  // A list of carbon copy (CC) recipients.
  repeated EmailAddress cc = 2;
  // A list of blind carbon copy (BCC) recipients.
  repeated EmailAddress bcc = 3;
  // A list of reply-to addresses.
  repeated EmailAddress reply_to = 4;
  // Optional: Parameters for template variable substitution, if applicable.
  optional google.protobuf.Value template_params = 5;
  // Optional: The scheduled time to send the email (Unix timestamp).
  optional int64 send_at = 6;
}

// AttachmentRef references an attachment already stored on the server.
message AttachmentRef {
  // The mailbox name where the source message is located.
  string mailbox_name = 1;
  // The UID of the source message containing the attachment.
  uint32 uid = 2;
  // The data identifying the specific attachment within the source message.
  ImapAttachment attachment_data = 3;
}

// AttachmentPayload describes the content source for a mail attachment.
message AttachmentPayload {
  // The payload can be either base64 encoded content or a reference to an existing attachment.
  oneof payload_type {
    // The base64 encoded content of the attachment.
    string base64_content = 1;
    // A reference to an existing attachment on the mail server.
    AttachmentRef attachment_ref = 2;
  }
}

// MailAttachment represents an attachment to be sent with an email.
message MailAttachment {
  // Optional: The filename of the attachment.
  optional string file_name = 1;
  // The payload containing the attachment content or reference.
  AttachmentPayload payload = 2;
  // The MIME type of the attachment (e.g., "image/png").
  string mime_type = 3;
  // Indicates if the attachment should be displayed inline.
  bool inline = 4;
  // Optional: The Content-ID for inline attachments.
  optional string content_id = 5;
}

// SendEmailRequest defines the parameters for sending a new email.
message SendEmailRequest {
  // Optional: The sender's email address. If omitted, the account's primary email will be used.
  optional EmailAddress from = 1;
  // A list of recipients for the email, including To, CC, and BCC.
  repeated Recipient recipients = 2;
  // Optional: The subject line of the email.
  optional string subject = 3;
  // Optional: The plain text body of the email.
  optional string text = 4;
  // Optional: The HTML body of the email.
  optional string html = 5;
  // Optional: A preview text for the email.
  optional string preview = 6;
  // Optional: Raw EML content of the email. If provided, `subject`, `text`, `html`, `attachments` might be ignored.
  optional string eml = 7;
  // Optional: The ID of an email template to use.
  optional uint64 template_id = 8;
  // A list of attachments to include in the email.
  repeated MailAttachment attachments = 9;
  // A map of custom headers to include in the email.
  map<string, HeaderValue> headers = 10;
  // Controls the sending process, including retry policies and DSN.
  SendControl send_control = 11;
}

// ReplyEmailRequest defines the parameters for replying to an existing email.
message ReplyEmailRequest {
  // The name of the mailbox containing the original message.
  string mailbox_name = 1;  
  // The unique ID of the message, either IMAP UID or Gmail API MID.
  // - For IMAP accounts, this is the UID converted to a string. It must be a valid numeric string
  //   that can be parsed back to a `u32`.
  // - For Gmail API accounts, this is the message ID (`mid`) returned by the API.
  string id = 2;
  // Optional: The plain text content of the reply.
  optional string text = 3;
  // Optional: The HTML content of the reply.
  optional string html = 4;
  // Optional: A preview text for the reply.
  optional string preview = 5;
  // A map of custom headers for the reply.
  map<string, HeaderValue> headers = 6;
  // If true, replies to all recipients (To, CC) of the original email.
  optional bool reply_all = 7;
  // A list of attachments to include in the reply.
  repeated MailAttachment attachments = 8;
  // A list of additional CC recipients for the reply.
  repeated EmailAddress cc = 9;
  // A list of additional BCC recipients for the reply.
  repeated EmailAddress bcc = 10;
  // Optional: The timezone for date headers in the reply.
  optional string timezone = 11;
  // If true, includes the original message content in the reply.
  optional bool include_original = 12;
  // If true, includes all attachments from the original message in the reply.
  optional bool include_all_attachments = 13;
  // Controls the sending process, including retry policies and DSN.
  SendControl send_control = 14;
}

// ForwardEmailRequest defines the parameters for forwarding an existing email.
message ForwardEmailRequest {
  // The name of the mailbox containing the original message.
  string mailbox_name = 1;
  // The unique ID of the message, either IMAP UID or Gmail API MID.
  // - For IMAP accounts, this is the UID converted to a string. It must be a valid numeric string
  //   that can be parsed back to a `u32`.
  // - For Gmail API accounts, this is the message ID (`mid`) returned by the API.
  string id = 2;
  // A list of primary recipients (To) for the forwarded email.
  repeated EmailAddress to = 3;
  // A list of carbon copy (CC) recipients for the forwarded email.
  repeated EmailAddress cc = 4;
  // A list of blind carbon copy (BCC) recipients for the forwarded email.
  repeated EmailAddress bcc = 5;
  // Optional: The plain text content to add to the forwarded email.
  optional string text = 6;
  // Optional: The HTML content to add to the forwarded email.
  optional string html = 7;
  // Optional: A preview text for the forwarded email.
  optional string preview = 8;
  // A map of custom headers for the forwarded email.
  map<string, HeaderValue> headers = 9;
  // Optional: The timezone for date headers in the forwarded email.
  optional string timezone = 10;
  // A list of attachments to include in the forwarded email.
  repeated MailAttachment attachments = 11;
  // If true, includes the original message content in the forwarded email.
  optional bool include_original = 12;
  // If true, includes all attachments from the original message in the forwarded email.
  optional bool include_all_attachments = 13;
  // Controls the sending process, including retry policies and DSN.
  SendControl send_control = 14;
}

// ReplyDraft represents the result of saving a draft email.
message ReplyDraft {
  // The message identifier:
  // - For IMAP accounts, this is the UID of the message;
  // - For Gmail / Graph API, this is the message ID.
  string id = 1;
  // The provider-specific draft identifier.
  // This is only populated for Gmail API accounts (the Gmail draft ID).
  // For IMAP and Graph API, use `id` directly.
  optional string draft_id = 2;
  // The name of the drafts folder or label where the draft was saved.
  string draft_folder = 3;
}

// EmailTask represents a single email sending task managed by the system.
message EmailTask {
  // The unique identifier for the email task.
  uint64 id = 1;
  // The timestamp when the task was created.
  int64 created_at = 2;
  // The current status of the task (e.g., SCHEDULED, SUCCESS, FAILED).
  TaskStatus status = 3;
  // Optional: The reason the task was stopped.
  optional string stopped_reason = 4;
  // Optional: An error message if the task failed.
  optional string error = 5;
  // Optional: The duration of the last execution attempt in milliseconds.
  optional uint64 last_duration_ms = 6;
  // Optional: The number of times the task has been retried.
  optional uint32 retry_count = 7;
  // The timestamp when the task is scheduled to be processed.
  int64 scheduled_at = 8;
  // The ID of the account used to send the email.
  uint64 account_id = 9;
  // The email address of the account used to send the email.
  string account_email = 10;
  // Optional: The subject line of the email.
  optional string subject = 11;
  // The Message-ID of the sent email.
  string message_id = 12;
  // The 'From' address of the email.
  string from = 13;
  // A list of 'To' recipients.
  repeated string to = 14;
  // A list of 'CC' recipients.
  repeated string cc = 15;
  // A list of 'BCC' recipients.
  repeated string bcc = 16;
  // The number of attachments included in the email.
  uint32 attachment_count = 17;
  // A cache key associated with the email content.
  string cache_key = 18;
  // Optional: The mail envelope details (sender and recipients for the SMTP transaction).
  optional MailEnvelope envelope = 19;
  // Indicates if the sent email should be saved to the 'Sent' folder.
  bool save_to_sent = 20;
  // Optional: The name of the folder where the sent email should be saved.
  optional string sent_folder = 21;
  // Optional: The specific timestamp when the email was scheduled to be sent.
  optional int64 send_at = 22;
  // Optional: The ID of the MTA used for sending.
  optional uint64 mta = 23;
  // Optional: Delivery Status Notification (DSN) configuration for this email.
  optional DSNConfig dsn = 24;
  // Optional: Indicates if this email is a reply.
  optional bool reply = 25;
  // Optional: The mailbox name from which the original message was replied/forwarded.
  optional string mailbox = 26;
  // Optional: The UID of the original message if this is a reply/forward.
  optional uint32 uid = 27;
}

// TaskStatus enumerates the possible states of an email sending task.
enum TaskStatus {
  // The task is scheduled for future processing.
  SCHEDULED = 0;
  // The task is currently being processed.
  RUNNING = 1;
  // The task completed successfully.
  SUCCESS = 2;
  // The task failed.
  FAILED = 3;
  // The task was removed.
  REMOVED = 4;
  // The task was stopped manually or due to an external condition.
  STOPPED = 5;
}

// HeaderValue allows defining a header value as raw string, plain text, or a list of URLs.
message HeaderValue {
  // A header value can be raw string, plain text, or a list of URLs.
  oneof value {
    // Raw string value for the header.
    Raw raw = 1;
    // Plain text value for the header.
    Text text = 2;
    // A list of URLs for the header.
    Url url = 3;
  }
}

// Raw represents a raw string value.
message Raw {
  // The raw string content.
  string raw = 1;
}

// Text represents a plain text string value.
message Text {
  // The plain text content.
  string text = 1;
}

// Url represents a list of URLs.
message Url {
  // A list of URLs.
  repeated string url = 1;
}

// SendControl defines various options for controlling the email sending process.
message SendControl {
  // Optional: The mail envelope details for the SMTP transaction.
  optional MailEnvelope envelope = 1;
  // If true, saves the sent email to the 'Sent' folder of the sending account.
  optional bool save_to_sent = 2;
  // Optional: The name of the folder where the sent email should be saved (e.g., "Sent Items").
  optional string sent_folder = 3;
  // If true, simulates the email sending process without actually sending.
  optional bool dry_run = 4;
  // Optional: The specific timestamp to schedule the email for sending (Unix timestamp).
  optional int64 send_at = 5;
  // Optional: The retry policy to apply if sending fails.
  optional Retry retry_policy = 6;
  // Optional: The ID of a specific MTA to use for sending this email.
  optional uint64 mta = 7;
  // Optional: Delivery Status Notification (DSN) configuration for this email.
  optional DSNConfig dsn = 8;
  // Optional: A campaign ID to associate with this email for tracking purposes.
  optional string campaign_id = 9;
  // If true, enables tracking (e.g., open tracking, link click tracking) for this email.
  optional bool enable_tracking = 10;
}

// MailEnvelope defines the sender and recipients for the SMTP transaction.
message MailEnvelope {
  // The email address of the sender for the SMTP envelope.
  string from = 1;
  // A list of recipient email addresses for the SMTP envelope.
  repeated string recipients = 2;
}

// Retry defines the retry strategy and parameters for failed email sending attempts.
message Retry {
  // The retry strategy to use (LINEAR or EXPONENTIAL).
  Strategy strategy = 1;
  // The base delay in seconds between retries.
  uint32 seconds = 2;
  // The maximum number of retry attempts.
  uint32 max_retries = 3;
}

// Strategy enumerates retry strategies.
enum Strategy {
  // Linear backoff strategy.
  LINEAR = 0;
  // Exponential backoff strategy.
  EXPONENTIAL = 1;
}

// DSNConfig defines Delivery Status Notification (DSN) options.
message DSNConfig {
  // Specifies what content to return in DSN reports (FULL or HDRS).
  ReturnContent ret = 1;
  // Optional: Envelope ID for enhanced DSN tracking.
  optional string envid = 2;
  // A list of notification options (e.g., SUCCESS, FAILURE).
  repeated NotifyOption notify = 3;
  // Optional: Original recipient address for DSN.
  optional string orcpt = 4;
}

// NotifyOption enumerates options for DSN notifications.
enum NotifyOption {
  // Notify on successful delivery.
  SUCCESS_N = 0;
  // Notify on delivery failure.
  FAILURE = 1;
  // Notify on delayed delivery.
  DELAY = 2;
  // Never send DSN notifications.
  NEVER = 3;
}

// ReturnContent specifies the content to be returned in a DSN.
enum ReturnContent {
  // Return the full message in the DSN.
  FULL = 0;
  // Return only the message headers in the DSN.
  HDRS = 1;
}

// PagedEmailTask represents a paginated list of EmailTask messages.
message PagedEmailTask {
  // Optional: The current page number being returned.
  optional uint64 current_page = 1;
  // Optional: The number of items per page.
  optional uint64 page_size = 2;
  // The total number of items available across all pages.
  uint64 total_items = 3;
  // The list of EmailTask items for the current page.
  repeated EmailTask items = 4;
  // Optional: The total number of pages available.
  optional uint64 total_pages = 5;
}

// SendNewMailRequest is used to send a completely new email.
message SendNewMailRequest {
  // The ID of the account from which to send the email.
  uint64 account_id = 1;
  // The details of the email to send.
  SendEmailRequest request = 2;
}

// ReplyMailRequest is used to reply to an existing email.
message ReplyMailRequest {
  // The ID of the account from which to send the reply.
  uint64 account_id = 1;
  // The details of the reply email.
  ReplyEmailRequest request = 2;
}

// ForwardMailRequest is used to forward an existing email.
message ForwardMailRequest {
  // The ID of the account from which to send the forwarded email.
  uint64 account_id = 1;
  // The details of the forwarded email.
  ForwardEmailRequest request = 2;
}

// SaveDraftRequest is used to create a new draft email without sending it.
message SaveDraftRequest {
  // The ID of the account for which the draft is created.
  uint64 account_id = 1;
  // The details of the draft email to save.
  SendEmailRequest request = 2;
}

// SendDraftRequest is used to send an existing draft email.
message SendDraftRequest {
  // The ID of the account that owns the draft.
  uint64 account_id = 1;
  // The draft identifier returned by SaveDraft (ReplyDraft.draft_id for Gmail, ReplyDraft.id for others).
  string id = 2;
}

// ListTasksRequest defines parameters for listing email tasks with pagination and filtering by status.
message ListTasksRequest {
  // Optional: The requested page number (1-based).
  optional uint64 page = 1;
  // Optional: The number of items to return per page.
  optional uint64 page_size = 2;
  // Optional: If true, results will be returned in descending order.
  optional bool desc = 3;
  // Optional: Filter tasks by their status.
  optional TaskStatus status = 4;
}

// GetTaskRequest is used to retrieve a specific email task by its ID.
message GetTaskRequest {
  // The ID of the email task to retrieve.
  uint64 id = 1;
}

// RemoveTaskRequest is used to remove a specific email task by its ID.
message RemoveTaskRequest {
  // The ID of the email task to remove.
  uint64 id = 1;
}

// SendMailService provides APIs for sending new emails, replying, forwarding, and managing email tasks.
service SendMailService {
  // Sends a new email.
  rpc SendNewMail (SendNewMailRequest) returns (Empty);
  // Replies to an existing email.
  rpc ReplyMail (ReplyMailRequest) returns (Empty);
  // Forwards an existing email.
  rpc ForwardMail (ForwardMailRequest) returns (Empty);
  // Lists email sending tasks with pagination and optional status filtering.
  rpc ListEmailTasks (ListTasksRequest) returns (PagedEmailTask);
  // Retrieves a specific email task by its ID.
  rpc GetEmailTask (GetTaskRequest) returns (EmailTask);
  // Removes an email task.
  rpc RemoveEmailTask (RemoveTaskRequest) returns (Empty);
  // Creates a new draft email without sending it.
  rpc SaveDraft (SaveDraftRequest) returns (ReplyDraft);
  // Sends an existing draft email.
  rpc SendDraft (SendDraftRequest) returns (Empty);
}

// EventType enumerates the types of events that can trigger webhooks.
enum EventType {
  // An email was added to a folder.
  EMAIL_ADDED_TO_FOLDER = 0;
  // An email's flags changed.
  EMAIL_FLAGS_CHANGED = 1;
  // An email was sent successfully.
  EMAIL_SENT_SUCCESS = 2;
  // An error occurred during email sending.
  EMAIL_SENDING_ERROR = 3;
  // The UID validity of a mailbox changed, indicating a potential rebuild.
  UID_VALIDITY_CHANGE = 4;
  // A mailbox was deleted.
  MAILBOX_DELETION = 5;
  // A mailbox was created.
  MAILBOX_CREATION = 6;
  // An account's first synchronization process completed.
  ACCOUNT_FIRST_SYNC_COMPLETED = 7;
  // An email bounce notification was received.
  EMAIL_BOUNCE = 8;
  // An email feedback report (e.g., spam report) was received.
  EMAIL_FEEDBACK_REPORT = 9;
  // An email was opened (requires tracking enabled).
  EmailOpened = 10;
  // A link within an email was clicked (requires tracking enabled).
  EmailLinkClicked = 11;
}

// HookType specifies the type of event hook.
enum HookType {
  // HTTP webhook.
  Http = 0;
  // NATS message queue hook.
  Nats = 1;
}

// HttpMethod enumerates HTTP methods for webhook requests.
enum HttpMethod {
  // HTTP POST method.
  POST = 0;
  // HTTP PUT method.
  PUT = 1;
}

// HttpConfig defines the configuration for an HTTP webhook.
message HttpConfig {
  // Target URL where the webhook payload is sent.
  string target_url = 1;
  // HTTP method used to send the webhook payload.
  HttpMethod http_method = 2;
  // Custom headers for the webhook request.
  map<string, string> custom_headers = 3;
}

// NatsAuthType specifies authentication types for NATS connections.
enum NatsAuthType {
  // No authentication.
  None = 0;
  // Password-based authentication.
  Password = 1;
  // Token-based authentication.
  Token = 2;
}

// NatsConfig defines the configuration for a NATS event hook.
message NatsConfig {
  // The NATS server host.
  string host = 1;
  // The NATS server port.
  uint32 port = 2;
  // The authentication type for the NATS connection.
  NatsAuthType auth_type = 3;
  // Optional: Token used when auth_type is TOKEN.
  optional string token = 4;
  // Optional: Username used when auth_type is PASSWORD.
  optional string username = 5;
  // Optional: Password used when auth_type is PASSWORD.
  optional string password = 6;
  // The NATS stream name to publish to.
  string stream_name = 7;
  // The NATS namespace for the message.
  string namespace = 8;
}

// EventHooks represents a configuration for an event-driven webhook or NATS message.
message EventHooks {
  // The unique identifier for the event hook.
  uint64 id = 1;
  // Optional: Unique ID of the account associated with the webhook.
  optional uint64 account_id = 2;
  // Optional: Email of the account associated with the webhook.
  optional string email = 3;
  // Optional: Description of the webhook.
  optional string description = 4;
  // When the webhook was created.
  int64 created_at = 5;
  // When the webhook was last updated.
  int64 updated_at = 6;
  // Indicates whether the hook is global and applies to all accounts (1: true, 0: false).
  uint32 global = 7;
  // Whether the webhook is currently active.
  bool enabled = 8;
  // The type of the hook (HTTP or NATS).
  HookType hook_type = 9;
  // Optional: HTTP configuration if hook_type is Http.
  optional HttpConfig http = 10;
  // Optional: NATS configuration if hook_type is Nats.
  optional NatsConfig nats = 11;
  // Optional: VRL (Vector Remap Language) script for customizing the payload.
  optional string vrl_script = 12;
  // Total number of times the hook has been triggered.
  uint64 call_count = 13;
  // Number of successful executions.
  uint64 success_count = 14;
  // Number of failed executions.
  uint64 failure_count = 15;
  // Optional: Details of the last error encountered during execution.
  optional string last_error = 16;
  // List of event types to monitor that will trigger this hook.
  repeated EventType watched_events = 17;
}

// GetEventHookRequest is used to retrieve a specific event hook by its ID.
message GetEventHookRequest {
  // The ID of the event hook to retrieve.
  uint64 id = 1;
}

// RemoveEventHookRequest is used to remove a specific event hook by its ID.
message RemoveEventHookRequest {
  // The ID of the event hook to remove.
  uint64 id = 1;
}

// CreateEventHookRequest defines the parameters for creating a new event hook.
message CreateEventHookRequest {
  // Optional: The account associated with the webhook. If omitted, the hook is global.
  optional uint64 account_id = 1;
  // Optional: Description of the webhook.
  optional string description = 2;
  // Status indicating whether the webhook is active.
  bool enabled = 3;
  // The type of the hook (HTTP or NATS).
  HookType hook_type = 4;
  // Optional: HTTP configuration for the new hook.
  optional HttpConfig http = 5;
  // Optional: NATS configuration for the new hook.
  optional NatsConfig nats = 6;
  // Optional: VRL script for the payload that will be sent.
  optional string vrl_script = 7;
  // List of event types the webhook is watching.
  repeated EventType watched_events = 8;
  // Optional: The ID of a proxy to use.
  optional uint64 use_proxy = 9;
}

// UpdateEventhookRequest defines the parameters for updating an existing event hook.
message UpdateEventhookRequest {
  // The ID of the event hook to update.
  uint64 id = 1;
  // Optional: Update the description.
  optional string description = 2;
  // Optional: Update the enabled status.
  optional bool enabled = 3;
  // Optional: Update the HTTP configuration.
  optional HttpConfig http = 4;
  // Optional: Update the NATS configuration.
  optional NatsConfig nats = 5;
  // Optional: Update the VRL script.
  optional string vrl_script = 6;
  // Update the list of watched events (replaces existing events).
  repeated EventType watched_events = 7;
  // Optional: The ID of a proxy to use.
  optional uint64 use_proxy = 8;
}

// ListEventHookRequest defines parameters for paginating lists of event hooks.
message ListEventHookRequest {
  // Optional: The requested page number (1-based).
  optional uint64 page = 1;
  // Optional: The number of items to return per page.
  optional uint64 page_size = 2;
  // Optional: If true, results will be returned in descending order.
  optional bool desc = 3;
}

// PagedEventHooks represents a paginated list of EventHooks messages.
message PagedEventHooks {
  // Optional: The current page number being returned.
  optional uint64 current_page = 1;
  // Optional: The number of items per page.
  optional uint64 page_size = 2;
  // The total number of items available across all pages.
  uint64 total_items = 3;
  // The list of EventHooks items for the current page.
  repeated EventHooks items = 4;
  // Optional: The total number of pages available.
  optional uint64 total_pages = 5;
}

// VrlScriptTestRequest is used to test a VRL script with a given event payload.
message VrlScriptTestRequest {
  // The VRL program to execute.
  string program = 1;
  // Optional: The event payload (JSON string) to use as input for the VRL script.
  optional string event = 2;
}

// ResolveResult contains the result of a VRL script execution or an error.
message ResolveResult {
  // Optional: The result of the VRL script execution (as a Protobuf Value).
  optional google.protobuf.Value result = 1;
  // Optional: An error message if the VRL script execution failed.
  optional string error = 2;
}

// EventHookTask represents a single execution of an event hook.
message EventHookTask {
  // The unique identifier for the event hook task.
  uint64 id = 1;
  // The timestamp when the task was created.
  int64 created_at = 2;
  // The current status of the task (e.g., SCHEDULED, SUCCESS, FAILED).
  TaskStatus status = 3;
  // Optional: The reason the task was stopped.
  optional string stopped_reason = 4;
  // Optional: An error message if the task failed.
  optional string error = 5;
  // Optional: The duration of the last execution attempt in milliseconds.
  optional uint32 last_duration_ms = 6;
  // Optional: The number of times the task has been retried.
  optional uint32 retry_count = 7;
  // The timestamp when the task is scheduled to be processed.
  int64 scheduled_at = 8;
  // The ID of the account associated with the event.
  uint64 account_id = 9;
  // The event payload that triggered the hook.
  google.protobuf.Value event = 10;
  // The type of event that triggered this task.
  EventType event_type = 11;
}

// PagedEventHookTask represents a paginated list of EventHookTask messages.
message PagedEventHookTask {
  // Optional: The current page number being returned.
  optional uint64 current_page = 1;
  // Optional: The number of items per page.
  optional uint64 page_size = 2;
  // The total number of items available across all pages.
  uint64 total_items = 3;
  // The list of EventHookTask items for the current page.
  repeated EventHookTask items = 4;
  // Optional: The total number of pages available.
  optional uint64 total_pages = 5;
}

// EventHooksService provides APIs for managing event-driven webhooks.
service EventHooksService {
  // Retrieves a specific event hook by its ID.
  rpc GetEventHook (GetEventHookRequest) returns (EventHooks);
  // Removes an event hook.
  rpc RemoveEventHook (RemoveEventHookRequest) returns (Empty);
  // Creates a new event hook.
  rpc CreateEventHook (CreateEventHookRequest) returns (EventHooks);
  // Updates an existing event hook.
  rpc UpdateEventHook (UpdateEventhookRequest) returns (Empty);
  // Lists event hooks with pagination.
  rpc ListEventHook (ListEventHookRequest) returns (PagedEventHooks);
  // Returns examples of event payloads for testing VRL scripts.
  rpc EventExamples (Empty) returns (google.protobuf.Value);
  // Tests a VRL script against a given event payload and returns the result.
  rpc VrlScriptResolve(VrlScriptTestRequest) returns (ResolveResult);
  // Lists event hook tasks with pagination and optional filtering.
  rpc ListEventHookTasks (ListTasksRequest) returns (PagedEventHookTask);
  // Retrieves a specific event hook task by its ID.
  rpc GetEventHookTask (GetTaskRequest) returns (EventHookTask);
  // Removes an event hook task.
  rpc RemoveEventHookTask (RemoveTaskRequest) returns (Empty);
}