import type {
  AgentSessionBackgroundTask,
  AgentSessionBackgroundTaskState
} from './agent-session-background-task-wire'
import type { AgentSessionRewindReason, AgentSessionRewindSupport } from './agent-session-rewind'
import type { AgentSessionWireRefusal } from './agent-session-wire-refusals'

export * from './agent-session-wire-refusals'
import type { AgentSessionConversationCommand } from './agent-session-conversation-command'
import type { AgentSessionContextUsage } from './agent-session-context-usage'
// ─── Structured agent-session wire contract ─────────────────────────────────
// The shapes `agentSession.*` accepts and publishes. Phase 2 builds provider
// adapters and clients against exactly these types, so everything here must be
// plain JSON. The whole surface is gated by agent-session.structured.v1, which
// no released baseline advertises; after that capability ships, every new field
// must remain optional to old readers (docs/reference/remote-wire-compatibility.md).

import type {
  AgentJournalCursor,
  AgentJournalRenderItem,
  AgentJournalResetReason,
  AgentJournalResolution,
  AgentJournalSubmission,
  AgentJournalThreadGoal,
  AgentJournalTurnOutcome
} from './agent-session-journal-types'
import {
  agentSessionScopeKey,
  type AgentSessionExecutionLocation,
  type AgentSessionHandoffStage,
  type AgentSessionRecord
} from './agent-session-record'
import type { AgentProviderSessionMetadata } from './agent-session-resume'
import type { StructuredAgentSessionProjectedStatus } from './structured-agent-session-projection'

/** `agentSession.handoffStatus`. Named for the removed terminal handoff; released desktop clients
 *  still read `owner`. Clients parse the reply as unknown, since older hosts sent more fields. */
export type AgentSessionHandoffStatus = {
  owner: 'native' | 'none'
  direction: 'to-native' | null
  phase: 'idle' | 'switching' | 'failed'
  stage: AgentSessionHandoffStage | null
  operationId: string | null
  error?: { message: string; recoverableOwner: 'none' }
}

export type {
  AgentSessionBackgroundTask,
  AgentSessionBackgroundTaskRunState,
  AgentSessionBackgroundTaskState
} from './agent-session-background-task-wire'
export { agentSessionBackgroundTasksEqual } from './agent-session-background-task-wire'

export type AgentSessionTurnActivity = {
  turnId: string
  text: string
}

export const AGENT_SESSION_ID_MAX_LENGTH = 512

/** Backward paging is the client's normal read; 40 matches the page size the
 *  mobile list renders without a visible fill-in. */
export const AGENT_SESSION_HISTORY_DEFAULT_LIMIT = 40
export const AGENT_SESSION_HISTORY_MAX_LIMIT = 200

export const AGENT_SESSION_HISTORY_DIRECTIONS = ['tail', 'before', 'after'] as const
/** `tail` is the newest page, `before` pages backward, `after` catches a live
 *  reader up. Only `after` needs replayable rows; the other two read the
 *  reduced timeline and so survive compaction. */
export type AgentSessionHistoryDirection = (typeof AGENT_SESSION_HISTORY_DIRECTIONS)[number]

export type AgentSessionHistoryRequest = {
  sessionId: string
  direction: AgentSessionHistoryDirection
  /** Required for `before` and `after`; ignored for `tail`. */
  cursor?: AgentJournalCursor
  limit?: number
}

export type AgentSessionHistoryPage = {
  sessionId: string
  epoch: string
  /** Optional for mixed-version readers; write-capable clients use the
   *  checkpoint without forcing a second attach or a redundant snapshot. */
  fence?: number
  direction: AgentSessionHistoryDirection
  items: AgentJournalRenderItem[]
  /** Populated by `after` reads so a disconnected client can apply tombstones. */
  removedItemIds: string[]
  /** Submissions overlapping this page, so an unconfirmed bubble renders with
   *  its dispatch state instead of as a plain message. */
  submissions: AgentJournalSubmission[]
  /** Page edges. `nextCursor` is what the client sends back for the same
   *  direction; it equals the request cursor when the page is empty. */
  window: {
    oldest: AgentJournalCursor | null
    newest: AgentJournalCursor | null
    nextCursor: AgentJournalCursor
  }
  /** Current journal head for switching from a bounded page to live subscribe. */
  liveCursor?: AgentJournalCursor
  hasOlder: boolean
  hasNewer: boolean
  /** Present on hosts that expose provider-owned background task lifecycle. */
  backgroundTasks?: AgentSessionBackgroundTaskState | null
  /** Host wall clock (ms epoch) when the page was read, so a client attaching mid-turn
   *  can anchor a live counter on the real start. Absent from older hosts. */
  hostNow?: number
}

export type AgentSessionHistoryResult =
  | { ok: true; page: AgentSessionHistoryPage; providerSession?: AgentProviderSessionMetadata }
  /** Every reset carries a byte-bounded tail page so recovery cannot exceed
   *  remote outbound admission or require another call before resubscribing. */
  | {
      ok: false
      reset: AgentJournalResetReason
      page: AgentSessionHistoryPage
      fence?: number
      providerSession?: AgentProviderSessionMetadata
    }

/** Cursor-qualified incremental publication. Items and submissions carry their
 *  CURRENT reduced state rather than a delta, so applying a batch twice
 *  converges instead of double-appending. */
export type AgentSessionJournalBatch = {
  cursor: AgentJournalCursor
  items: AgentJournalRenderItem[]
  removedItemIds: string[]
  submissions: AgentJournalSubmission[]
}

/** Host wall clock (ms epoch) stamped once per published frame; see `AgentSessionHistoryPage`. */
type AgentSessionHostClockField = { hostNow?: number }

export type AgentSessionSubscribeEvent =
  | ({
      type: 'snapshot'
      sessionId: string
      page: AgentSessionHistoryPage
      fence: number
      backgroundTasks?: AgentSessionBackgroundTaskState | null
      /** Omitted when unchanged; null clears a previous provider catalog. */
      commands?: AgentSessionSlashCommand[] | null
      /** Latest provider-authored turn activity; optional for mixed-version hosts. */
      activity?: AgentSessionTurnActivity | null
    } & AgentSessionHostClockField)
  | ({
      type: 'batch'
      sessionId: string
      batch: AgentSessionJournalBatch
      /** Optional so mixed-version cursors retain the ownership fence. */
      fence?: number
      backgroundTasks?: AgentSessionBackgroundTaskState | null
      /** Omitted when unchanged; null clears a previous provider catalog. */
      commands?: AgentSessionSlashCommand[] | null
      /** Additive ephemeral state; it never creates or advances journal rows. */
      activity?: AgentSessionTurnActivity | null
    } & AgentSessionHostClockField)
  | ({
      type: 'reset'
      sessionId: string
      reset: AgentJournalResetReason
      page: AgentSessionHistoryPage
      fence: number
      backgroundTasks?: AgentSessionBackgroundTaskState | null
      /** Omitted when unchanged; null clears a previous provider catalog. */
      commands?: AgentSessionSlashCommand[] | null
      activity?: AgentSessionTurnActivity | null
    } & AgentSessionHostClockField)
  | { type: 'end' }

// ─── Status feed ────────────────────────────────────────────────────────────

/** What a session list needs to know about one session. The host projects it
 *  from the journal so no client has to replay a transcript to learn whether a
 *  turn is running. Additive surface: an older host has no such method. */
export type AgentSessionStatusSummary = {
  rewindBlockedReason?: AgentSessionRewindReason
  sessionId: string
  workspaceId: string
  agent: AgentSessionRecord['provider']
  /** Null until the journal holds a persisted user or assistant message. */
  status: StructuredAgentSessionProjectedStatus | null
  /** Present only while this host has the provider child executing the session. */
  hostExecutionOwned?: true
  /** With `hostExecutionOwned`: whether that child has proven its start. `starting` is a
   *  published session whose provider has not yet answered startup; absent on older hosts. */
  hostExecutionPhase?: 'starting' | 'ready'
  latestPrompt: string
  /** Provider model in force for the next turn; absent until the host has read the options. */
  model?: string
  /** The tool the running turn is inside, else the last one it used. Absent unless `status`
   *  is 'working'. */
  toolName?: string
  toolInput?: string
  /** Preview of the newest assistant prose, so a settled row says what the agent said. */
  lastAssistantMessage?: string
  /** The provider's verdict on the newest settled root turn. Present only while `status` is
   *  `idle`: a running or attention-blocked turn has no verdict yet, and a stale one must not
   *  ride along. Absent means UNKNOWN, never success. Optional for mixed-version hosts; the
   *  agent-status row publishes it as `mainAgent.outcome`. */
  turnOutcome?: AgentJournalTurnOutcome
  /** Live provider-owned background tasks, so session lists can render
   *  subagent children without holding a journal reader open. Optional for
   *  mixed-version hosts. */
  backgroundTasks?: AgentSessionBackgroundTask[]
  providerSession?: AgentProviderSessionMetadata
  updatedAt: number
  /** When the session's own agent entered `status`, dated by its own lifecycle edges and never by
   *  row activity: `updatedAt` also moves for a subagent's rows. Absent from older hosts, and when
   *  the journal records no such edge; readers then keep dating the state themselves. */
  statusStartedAt?: number
}

/** A summary outlives its provider child: an evicted idle session is still idle, so the host
 *  keeps the last projection and never retracts one. Tabs, not this feed, decide what is listed. */
export type AgentSessionStatusEvent =
  | { type: 'snapshot'; sessions: AgentSessionStatusSummary[] }
  | { type: 'status'; session: AgentSessionStatusSummary }
  | { type: 'end' }

// ─── Turn completion feed ───────────────────────────────────────────────────

/**
 * One root turn reaching a terminal outcome, derived by the EXECUTION HOST at journal commit.
 *
 * This is the EDGE, with turn identity; `AgentSessionStatusSummary.turnOutcome` is the STATE.
 * The summary carries the verdict only while the session is idle, as a fact about the main agent's
 * last turn that a status reader may act on (attention alerts, the `mainAgent.outcome` row field),
 * and never a turn id: a reader that needs to know WHICH turn finished, or to react exactly once
 * per finish, subscribes here. Re-broadcasting the summary on every status change therefore
 * repeats a state, not a completion.
 *
 * `outcome` is A0's provider verdict and is never inferred — a turn the host only observed ending
 * carries no outcome and produces no event at all, because absent means UNKNOWN, not success.
 */
export type AgentSessionTurnCompletion = {
  /** Host-and-workspace scope; a bare provider turn id is not globally unique. */
  scope: AgentSessionExecutionLocation
  sessionId: string
  /** Root turn identity from the journal turn record; no second identity is minted. */
  turnId: string
  outcome: AgentJournalTurnOutcome
  /** Execution host's clock at journal commit. */
  completedAt: number
}

/**
 * LIVE-ONLY: there is no snapshot arm and no replay arm, by decision. A subscriber is told what
 * completes while it is subscribed and nothing else; completions that land while it is away are
 * dropped rather than queued, so nothing durable can strand. On reconnect the client baselines.
 */
export type AgentSessionTurnCompletionEvent =
  | { type: 'completion'; completion: AgentSessionTurnCompletion }
  | { type: 'end' }

/** Delivery dedupe address. Unread is idempotent and does not need it; mobile fanout does. */
export function agentSessionTurnCompletionKey(completion: AgentSessionTurnCompletion): string {
  return [agentSessionScopeKey(completion.scope), completion.sessionId, completion.turnId].join(
    '\u0000'
  )
}

// ─── Mutation envelope ──────────────────────────────────────────────────────

/**
 * The four fields every mutating call carries. Same operation id and same
 * fingerprint replays the recorded outcome; a different fingerprint under one
 * operation id is a conflict, never a second effect.
 */
export type AgentSessionMutationEnvelope = {
  sessionId: string
  clientOperationId: string
  /** Null only on a create for a session that does not exist yet. */
  expectedRuntimeFence: number | null
  /** Client-declared; the host recomputes it and compares. */
  payloadFingerprint: string
}

export type AgentSessionMutationResult<TValue> =
  | {
      ok: true
      /** True when the recorded outcome was returned instead of a new effect. */
      replayed: boolean
      fence: number
      cursor: AgentJournalCursor
      value: TValue
    }
  | { ok: false; refusal: AgentSessionWireRefusal }

// ─── Per-method payloads ────────────────────────────────────────────────────

export type AgentSessionAttachResult = {
  sessionId: string
  fence: number
  page: AgentSessionHistoryPage
  /** Submissions the crash boundary settled as `unknown` while attaching. */
  unconfirmedClientMessageIds: string[]
  /** The host-owned id of the tab showing this chat, when it has one. Absent from older hosts. */
  tabId?: string
}

export type AgentSessionSendResult = {
  clientMessageId: string
  submission: AgentJournalSubmission
}

export type AgentSessionCancelResult = {
  /** The turn the client named, echoed so a late reply can be matched. */
  turnId: string
  cancelled: boolean
}

export type AgentSessionPromptResult = {
  itemId: string
  revision: number
  resolution: AgentJournalResolution
}

export type AgentSessionOptionResult = {
  key: string
  value: string
  /** Full effective next-turn values when the provider reconciled related options. */
  options?: Record<string, string>
}

export type AgentSessionOptionChoice = {
  value: string
  label: string
  description?: string
}

export type AgentSessionModelOption = {
  id: string
  label: string
  description?: string
  isDefault: boolean
  defaultEffort?: string
  efforts: AgentSessionOptionChoice[]
  /** Provider catalog fact. Absent means the host could not determine support. */
  supportsFastMode?: boolean
}

export type AgentSessionFastModeState = 'off' | 'cooldown' | 'on'

export type AgentSessionFastModeSupport = {
  supported: boolean
  /** Provider-authored or host-normalized reason code; presentation may ignore unknown values. */
  reason?: string
}

/**
 * The host's model catalog for an agent, answered from its own store and
 * never through a session's queue. `unknown` means this host has no listing
 * for the key yet — the client keeps its static seed. Additive read-only
 * surface: an older host simply lacks the method.
 */
export type AgentSessionModelCatalogResult =
  | { origin: 'unknown' }
  | {
      /** What produced the listing; any age is served, `fetchedAt` carries it. */
      origin: 'live-session' | 'probe'
      models: AgentSessionModelOption[]
      fastModeSupport?: AgentSessionFastModeSupport
      fetchedAt: number
    }

/** One entry of the `/` menu the running provider reports for itself. `skill`
 *  marks a name the session loaded as a skill rather than a built-in command;
 *  commands the provider reserves for a terminal UI are already removed. */
export type AgentSessionSlashCommand = {
  name: string
  kind: 'command' | 'skill'
  /** Membership is authoritative, but this provider report did not classify the name. */
  kindUnspecified?: true
  /** Provider-authored row text; absent when the report carried names only. */
  description?: string
  /** Provider-authored argument sketch, e.g. `<issue-url>`. */
  argumentHint?: string
}

/** The provider's own command surface, read per session. Additive read-only
 *  surface: a host that predates it answers `method_not_found`, and the client
 *  keeps rendering its curated catalog. */
export type AgentSessionCommandsResult = {
  commands?: AgentSessionSlashCommand[]
}

/** Longest objective a client may send; matches the provider's own limit. */
export const AGENT_SESSION_THREAD_GOAL_OBJECTIVE_MAX_LENGTH = 4000

/** A client's change to the thread goal. `set` replaces the objective and makes
 *  it active, which the provider pursues without a separate turn. */
export type AgentSessionThreadGoalChange =
  | { kind: 'set'; objective: string }
  | { kind: 'status'; status: 'active' | 'paused' }
  | { kind: 'clear' }

export type AgentSessionThreadGoalResult = {
  change: AgentSessionThreadGoalChange['kind']
}

/** Provider-reported choices and effective next-turn values. Additive read-only
 *  surface so older hosts can reject it without changing structured v1 writes. */
export type AgentSessionOptionsResult = {
  rewind?: AgentSessionRewindSupport
  conversationCommands?: readonly AgentSessionConversationCommand[]
  /** Present only where this session can change its goal, so a host without
   *  `agentSession.threadGoal` never offers the controls. `current` is the
   *  latest goal the whole journal records, for a client whose loaded page
   *  starts after it. */
  threadGoal?: { current: AgentJournalThreadGoal | null }
  /** Present only where this session writes context facts to its turn rows.
   *  `current` is the newest of each part the whole journal records, for a
   *  client whose loaded page starts after the row that carries it. */
  contextUsage?: { current: AgentSessionContextUsage }
  models: AgentSessionModelOption[]
  /** Session/account/transport support. Absent means unknown, never unsupported. */
  fastModeSupport?: AgentSessionFastModeSupport
  current: {
    model: string
    effort?: string
    /** Canonical preference for the next turn. Explicit false is meaningful. */
    fastMode?: boolean
    /** Provider-reported effective routing, distinct from the next-turn preference. */
    fastModeState?: AgentSessionFastModeState
    /**
     * Option ids whose value the provider reported back, not merely accepted.
     * Optional: a host that predates it sends nothing and the client keeps
     * treating the value as unconfirmed, which is what it was before.
     */
    confirmed?: readonly string[]
  }
}