//! Manager socket listener. Privileged tool surface: agent-style send/recv
//! plus lifecycle verbs (Phase 4). Phase 5 will gate Spawn/Kill behind the
//! commit-approval flow; for now they hit the same code path the host admin
//! socket uses.

use std::sync::Arc;

use anyhow::{Context, Result};
use hive_sh4re::{MANAGER_AGENT, ManagerRequest, ManagerResponse, Message};
use tokio::io::{AsyncBufReadExt, AsyncWriteExt, BufReader};
use tokio::net::{UnixListener, UnixStream};

use crate::coordinator::Coordinator;
use crate::lifecycle;

pub fn start(coord: Arc<Coordinator>) -> Result<()> {
    let dir = Coordinator::manager_dir();
    std::fs::create_dir_all(&dir)
        .with_context(|| format!("create manager dir {}", dir.display()))?;
    let socket = Coordinator::manager_socket_path();
    if socket.exists() {
        std::fs::remove_file(&socket).context("remove stale manager socket")?;
    }
    let listener = UnixListener::bind(&socket)
        .with_context(|| format!("bind manager socket {}", socket.display()))?;
    tracing::info!(socket = %socket.display(), "manager socket listening");

    tokio::spawn(async move {
        loop {
            match listener.accept().await {
                Ok((stream, _)) => {
                    let coord = coord.clone();
                    tokio::spawn(async move {
                        if let Err(e) = serve(stream, coord).await {
                            tracing::warn!(error = ?e, "manager connection failed");
                        }
                    });
                }
                Err(e) => {
                    tracing::warn!(error = ?e, "manager listener accept failed");
                    return;
                }
            }
        }
    });
    Ok(())
}

async fn serve(stream: UnixStream, coord: Arc<Coordinator>) -> Result<()> {
    let (read, mut write) = stream.into_split();
    let mut reader = BufReader::new(read);
    let mut line = String::new();
    loop {
        line.clear();
        let n = reader.read_line(&mut line).await?;
        if n == 0 {
            return Ok(());
        }
        let resp = match serde_json::from_str::<ManagerRequest>(line.trim()) {
            Ok(req) => dispatch(&req, &coord).await,
            Err(e) => ManagerResponse::Err {
                message: format!("parse error: {e}"),
            },
        };
        let mut payload = serde_json::to_string(&resp)?;
        payload.push('\n');
        write.write_all(payload.as_bytes()).await?;
        write.flush().await?;
    }
}

const MANAGER_RECV_LONG_POLL: std::time::Duration = std::time::Duration::from_secs(30);

#[allow(clippy::too_many_lines)]
async fn dispatch(req: &ManagerRequest, coord: &Coordinator) -> ManagerResponse {
    match req {
        ManagerRequest::Send { to, body } => match coord.broker.send(&Message {
            from: MANAGER_AGENT.to_owned(),
            to: to.clone(),
            body: body.clone(),
        }) {
            Ok(()) => ManagerResponse::Ok,
            Err(e) => ManagerResponse::Err {
                message: format!("{e:#}"),
            },
        },
        ManagerRequest::OperatorMsg { body } => match coord.broker.send(&Message {
            from: hive_sh4re::OPERATOR_RECIPIENT.to_owned(),
            to: MANAGER_AGENT.to_owned(),
            body: body.clone(),
        }) {
            Ok(()) => ManagerResponse::Ok,
            Err(e) => ManagerResponse::Err {
                message: format!("{e:#}"),
            },
        },
        ManagerRequest::Status => match coord.broker.count_pending(MANAGER_AGENT) {
            Ok(unread) => ManagerResponse::Status { unread },
            Err(e) => ManagerResponse::Err {
                message: format!("{e:#}"),
            },
        },
        ManagerRequest::Recv => match coord
            .broker
            .recv_blocking(MANAGER_AGENT, MANAGER_RECV_LONG_POLL)
            .await
        {
            Ok(Some(msg)) => ManagerResponse::Message {
                from: msg.from,
                body: msg.body,
            },
            Ok(None) => ManagerResponse::Empty,
            Err(e) => ManagerResponse::Err {
                message: format!("{e:#}"),
            },
        },
        ManagerRequest::RequestSpawn { name } => {
            tracing::info!(%name, "manager: request_spawn");
            match coord
                .approvals
                .submit_kind(name, hive_sh4re::ApprovalKind::Spawn, "")
            {
                Ok(id) => {
                    tracing::info!(%id, %name, "spawn approval queued");
                    ManagerResponse::Ok
                }
                Err(e) => ManagerResponse::Err {
                    message: format!("{e:#}"),
                },
            }
        }
        ManagerRequest::Kill { name } => {
            tracing::info!(%name, "manager: kill");
            if name == crate::lifecycle::MANAGER_NAME {
                return ManagerResponse::Err {
                    message: "refusing to kill the manager".into(),
                };
            }
            let result: Result<()> = async {
                lifecycle::kill(name).await?;
                coord.unregister_agent(name);
                Ok(())
            }
            .await;
            match result {
                Ok(()) => {
                    coord.notify_manager(&hive_sh4re::HelperEvent::Killed {
                        agent: name.clone(),
                    });
                    ManagerResponse::Ok
                }
                Err(e) => ManagerResponse::Err {
                    message: format!("{e:#}"),
                },
            }
        }
        ManagerRequest::Start { name } => {
            tracing::info!(%name, "manager: start");
            if name == crate::lifecycle::MANAGER_NAME {
                return ManagerResponse::Err {
                    message: "refusing to start the manager from itself".into(),
                };
            }
            match lifecycle::start(name).await {
                Ok(()) => ManagerResponse::Ok,
                Err(e) => ManagerResponse::Err {
                    message: format!("{e:#}"),
                },
            }
        }
        ManagerRequest::Restart { name } => {
            tracing::info!(%name, "manager: restart");
            if name == crate::lifecycle::MANAGER_NAME {
                return ManagerResponse::Err {
                    message: "refusing to restart the manager from itself".into(),
                };
            }
            match lifecycle::restart(name).await {
                Ok(()) => ManagerResponse::Ok,
                Err(e) => ManagerResponse::Err {
                    message: format!("{e:#}"),
                },
            }
        }
        ManagerRequest::AskOperator { question, options } => {
            tracing::info!(%question, ?options, "manager: ask_operator");
            match coord.questions.submit(MANAGER_AGENT, question, options) {
                Ok(id) => {
                    tracing::info!(%id, "operator question queued");
                    ManagerResponse::QuestionQueued { id }
                }
                Err(e) => ManagerResponse::Err {
                    message: format!("{e:#}"),
                },
            }
        }
        ManagerRequest::RequestApplyCommit { agent, commit_ref } => {
            tracing::info!(%agent, %commit_ref, "manager: request_apply_commit");
            match coord.approvals.submit(agent, commit_ref) {
                Ok(id) => {
                    tracing::info!(%id, %agent, %commit_ref, "approval queued");
                    ManagerResponse::Ok
                }
                Err(e) => ManagerResponse::Err {
                    message: format!("{e:#}"),
                },
            }
        }
    }
}