use crate::{background_process, local_env::LocalEnv};
use camino::Utf8PathBuf;
use hyper::Method;
use pageserver_api::{
    models::{ShardParameters, TenantCreateRequest, TimelineCreateRequest, TimelineInfo},
    shard::TenantShardId,
};
use pageserver_client::mgmt_api::ResponseErrorMessageExt;
use postgres_backend::AuthType;
use postgres_connection::parse_host_port;
use serde::{de::DeserializeOwned, Deserialize, Serialize};
use std::{path::PathBuf, str::FromStr};
use tracing::instrument;
use utils::{
    auth::{Claims, Scope},
    id::{NodeId, TenantId},
};

pub struct AttachmentService {
    env: LocalEnv,
    listen: String,
    path: PathBuf,
    jwt_token: Option<String>,
    public_key_path: Option<Utf8PathBuf>,
    client: reqwest::Client,
}

const COMMAND: &str = "attachment_service";

#[derive(Serialize, Deserialize)]
pub struct AttachHookRequest {
    pub tenant_shard_id: TenantShardId,
    pub node_id: Option<NodeId>,
}

#[derive(Serialize, Deserialize)]
pub struct AttachHookResponse {
    pub gen: Option<u32>,
}

#[derive(Serialize, Deserialize)]
pub struct InspectRequest {
    pub tenant_shard_id: TenantShardId,
}

#[derive(Serialize, Deserialize)]
pub struct InspectResponse {
    pub attachment: Option<(u32, NodeId)>,
}

#[derive(Serialize, Deserialize)]
pub struct TenantCreateResponseShard {
    pub node_id: NodeId,
    pub generation: u32,
}

#[derive(Serialize, Deserialize)]
pub struct TenantCreateResponse {
    pub shards: Vec<TenantCreateResponseShard>,
}

#[derive(Serialize, Deserialize)]
pub struct NodeRegisterRequest {
    pub node_id: NodeId,

    pub listen_pg_addr: String,
    pub listen_pg_port: u16,

    pub listen_http_addr: String,
    pub listen_http_port: u16,
}

#[derive(Serialize, Deserialize)]
pub struct NodeConfigureRequest {
    pub node_id: NodeId,

    pub availability: Option<NodeAvailability>,
    pub scheduling: Option<NodeSchedulingPolicy>,
}

#[derive(Serialize, Deserialize, Debug)]
pub struct TenantLocateResponseShard {
    pub shard_id: TenantShardId,
    pub node_id: NodeId,

    pub listen_pg_addr: String,
    pub listen_pg_port: u16,

    pub listen_http_addr: String,
    pub listen_http_port: u16,
}

#[derive(Serialize, Deserialize)]
pub struct TenantLocateResponse {
    pub shards: Vec<TenantLocateResponseShard>,
    pub shard_params: ShardParameters,
}

/// Explicitly migrating a particular shard is a low level operation
/// TODO: higher level "Reschedule tenant" operation where the request
/// specifies some constraints, e.g. asking it to get off particular node(s)
#[derive(Serialize, Deserialize, Debug)]
pub struct TenantShardMigrateRequest {
    pub tenant_shard_id: TenantShardId,
    pub node_id: NodeId,
}

#[derive(Serialize, Deserialize, Clone, Copy)]
pub enum NodeAvailability {
    // Normal, happy state
    Active,
    // Offline: Tenants shouldn't try to attach here, but they may assume that their
    // secondary locations on this node still exist.  Newly added nodes are in this
    // state until we successfully contact them.
    Offline,
}

impl FromStr for NodeAvailability {
    type Err = anyhow::Error;

    fn from_str(s: &str) -> Result<Self, Self::Err> {
        match s {
            "active" => Ok(Self::Active),
            "offline" => Ok(Self::Offline),
            _ => Err(anyhow::anyhow!("Unknown availability state '{s}'")),
        }
    }
}

/// FIXME: this is a duplicate of the type in the attachment_service crate, because the
/// type needs to be defined with diesel traits in there.
#[derive(Serialize, Deserialize, Clone, Copy)]
pub enum NodeSchedulingPolicy {
    Active,
    Filling,
    Pause,
    Draining,
}

impl FromStr for NodeSchedulingPolicy {
    type Err = anyhow::Error;

    fn from_str(s: &str) -> Result<Self, Self::Err> {
        match s {
            "active" => Ok(Self::Active),
            "filling" => Ok(Self::Filling),
            "pause" => Ok(Self::Pause),
            "draining" => Ok(Self::Draining),
            _ => Err(anyhow::anyhow!("Unknown scheduling state '{s}'")),
        }
    }
}

impl From<NodeSchedulingPolicy> for String {
    fn from(value: NodeSchedulingPolicy) -> String {
        use NodeSchedulingPolicy::*;
        match value {
            Active => "active",
            Filling => "filling",
            Pause => "pause",
            Draining => "draining",
        }
        .to_string()
    }
}

#[derive(Serialize, Deserialize, Debug)]
pub struct TenantShardMigrateResponse {}

impl AttachmentService {
    pub fn from_env(env: &LocalEnv) -> Self {
        let path = env.base_data_dir.join("attachments.json");

        // Makes no sense to construct this if pageservers aren't going to use it: assume
        // pageservers have control plane API set
        let listen_url = env.control_plane_api.clone().unwrap();

        let listen = format!(
            "{}:{}",
            listen_url.host_str().unwrap(),
            listen_url.port().unwrap()
        );

        // Assume all pageservers have symmetric auth configuration: this service
        // expects to use one JWT token to talk to all of them.
        let ps_conf = env
            .pageservers
            .first()
            .expect("Config is validated to contain at least one pageserver");
        let (jwt_token, public_key_path) = match ps_conf.http_auth_type {
            AuthType::Trust => (None, None),
            AuthType::NeonJWT => {
                let jwt_token = env
                    .generate_auth_token(&Claims::new(None, Scope::PageServerApi))
                    .unwrap();

                // If pageserver auth is enabled, this implicitly enables auth for this service,
                // using the same credentials.
                let public_key_path =
                    camino::Utf8PathBuf::try_from(env.base_data_dir.join("auth_public_key.pem"))
                        .unwrap();
                (Some(jwt_token), Some(public_key_path))
            }
        };

        Self {
            env: env.clone(),
            path,
            listen,
            jwt_token,
            public_key_path,
            client: reqwest::ClientBuilder::new()
                .build()
                .expect("Failed to construct http client"),
        }
    }

    fn pid_file(&self) -> Utf8PathBuf {
        Utf8PathBuf::from_path_buf(self.env.base_data_dir.join("attachment_service.pid"))
            .expect("non-Unicode path")
    }

    pub async fn start(&self) -> anyhow::Result<()> {
        let path_str = self.path.to_string_lossy();

        let mut args = vec!["-l", &self.listen, "-p", &path_str]
            .into_iter()
            .map(|s| s.to_string())
            .collect::<Vec<_>>();
        if let Some(jwt_token) = &self.jwt_token {
            args.push(format!("--jwt-token={jwt_token}"));
        }

        if let Some(public_key_path) = &self.public_key_path {
            args.push(format!("--public-key={public_key_path}"));
        }

        let result = background_process::start_process(
            COMMAND,
            &self.env.base_data_dir,
            &self.env.attachment_service_bin(),
            args,
            [(
                "NEON_REPO_DIR".to_string(),
                self.env.base_data_dir.to_string_lossy().to_string(),
            )],
            background_process::InitialPidFile::Create(self.pid_file()),
            || async {
                match self.status().await {
                    Ok(_) => Ok(true),
                    Err(_) => Ok(false),
                }
            },
        )
        .await;

        // TODO: shouldn't we bail if we fail to spawn the process?
        for ps_conf in &self.env.pageservers {
            let (pg_host, pg_port) =
                parse_host_port(&ps_conf.listen_pg_addr).expect("Unable to parse listen_pg_addr");
            let (http_host, http_port) = parse_host_port(&ps_conf.listen_http_addr)
                .expect("Unable to parse listen_http_addr");
            self.node_register(NodeRegisterRequest {
                node_id: ps_conf.id,
                listen_pg_addr: pg_host.to_string(),
                listen_pg_port: pg_port.unwrap_or(5432),
                listen_http_addr: http_host.to_string(),
                listen_http_port: http_port.unwrap_or(80),
            })
            .await?;
        }

        result
    }

    pub fn stop(&self, immediate: bool) -> anyhow::Result<()> {
        background_process::stop_process(immediate, COMMAND, &self.pid_file())
    }
    /// Simple HTTP request wrapper for calling into attachment service
    async fn dispatch<RQ, RS>(
        &self,
        method: hyper::Method,
        path: String,
        body: Option<RQ>,
    ) -> anyhow::Result<RS>
    where
        RQ: Serialize + Sized,
        RS: DeserializeOwned + Sized,
    {
        let url = self
            .env
            .control_plane_api
            .clone()
            .unwrap()
            .join(&path)
            .unwrap();

        let mut builder = self.client.request(method, url);
        if let Some(body) = body {
            builder = builder.json(&body)
        }
        if let Some(jwt_token) = &self.jwt_token {
            builder = builder.header(
                reqwest::header::AUTHORIZATION,
                format!("Bearer {jwt_token}"),
            );
        }

        let response = builder.send().await?;
        let response = response.error_from_body().await?;

        Ok(response
            .json()
            .await
            .map_err(pageserver_client::mgmt_api::Error::ReceiveBody)?)
    }

    /// Call into the attach_hook API, for use before handing out attachments to pageservers
    #[instrument(skip(self))]
    pub async fn attach_hook(
        &self,
        tenant_shard_id: TenantShardId,
        pageserver_id: NodeId,
    ) -> anyhow::Result<Option<u32>> {
        let request = AttachHookRequest {
            tenant_shard_id,
            node_id: Some(pageserver_id),
        };

        let response = self
            .dispatch::<_, AttachHookResponse>(
                Method::POST,
                "attach-hook".to_string(),
                Some(request),
            )
            .await?;

        Ok(response.gen)
    }

    #[instrument(skip(self))]
    pub async fn inspect(
        &self,
        tenant_shard_id: TenantShardId,
    ) -> anyhow::Result<Option<(u32, NodeId)>> {
        let request = InspectRequest { tenant_shard_id };

        let response = self
            .dispatch::<_, InspectResponse>(Method::POST, "inspect".to_string(), Some(request))
            .await?;

        Ok(response.attachment)
    }

    #[instrument(skip(self))]
    pub async fn tenant_create(
        &self,
        req: TenantCreateRequest,
    ) -> anyhow::Result<TenantCreateResponse> {
        self.dispatch(Method::POST, "tenant".to_string(), Some(req))
            .await
    }

    #[instrument(skip(self))]
    pub async fn tenant_locate(&self, tenant_id: TenantId) -> anyhow::Result<TenantLocateResponse> {
        self.dispatch::<(), _>(Method::GET, format!("tenant/{tenant_id}/locate"), None)
            .await
    }

    #[instrument(skip(self))]
    pub async fn tenant_migrate(
        &self,
        tenant_shard_id: TenantShardId,
        node_id: NodeId,
    ) -> anyhow::Result<TenantShardMigrateResponse> {
        self.dispatch(
            Method::PUT,
            format!("tenant/{tenant_shard_id}/migrate"),
            Some(TenantShardMigrateRequest {
                tenant_shard_id,
                node_id,
            }),
        )
        .await
    }

    #[instrument(skip_all, fields(node_id=%req.node_id))]
    pub async fn node_register(&self, req: NodeRegisterRequest) -> anyhow::Result<()> {
        self.dispatch::<_, ()>(Method::POST, "node".to_string(), Some(req))
            .await
    }

    #[instrument(skip_all, fields(node_id=%req.node_id))]
    pub async fn node_configure(&self, req: NodeConfigureRequest) -> anyhow::Result<()> {
        self.dispatch::<_, ()>(
            Method::PUT,
            format!("node/{}/config", req.node_id),
            Some(req),
        )
        .await
    }

    #[instrument(skip(self))]
    pub async fn status(&self) -> anyhow::Result<()> {
        self.dispatch::<(), ()>(Method::GET, "status".to_string(), None)
            .await
    }

    #[instrument(skip_all, fields(%tenant_id, timeline_id=%req.new_timeline_id))]
    pub async fn tenant_timeline_create(
        &self,
        tenant_id: TenantId,
        req: TimelineCreateRequest,
    ) -> anyhow::Result<TimelineInfo> {
        self.dispatch(
            Method::POST,
            format!("tenant/{tenant_id}/timeline"),
            Some(req),
        )
        .await
    }
}