//! Embedded MCP server. Claude Code (running inside the agent container)
//! launches this as a stdio child via `--mcp-config`; tool calls land here
//! and are translated to `AgentRequest::*` / `ManagerRequest::*` against
//! hyperhive's own per-container unix socket at `/run/hive/mcp.sock`.
//!
//! Two protocols, two surfaces:
//! - **hyperhive socket** at `/run/hive/mcp.sock` — JSON-line, our
//!   broker-routed protocol. Unaffected by this module.
//! - **MCP stdio** owned by this module — what claude actually speaks.
//!
//! Two server flavors:
//! - `AgentServer` — sub-agent tools (`send`, `recv`).
//! - `ManagerServer` — agent tools + lifecycle (`request_spawn`, `kill`,
//!   `request_apply_commit`).
//!
//! Both go through the same `run_tool_envelope` helper so logging + status
//! line stay uniform.

use std::future::Future;
use std::path::PathBuf;

use anyhow::Result;
use rmcp::{
    ServerHandler, ServiceExt, handler::server::wrapper::Parameters, schemars, tool, tool_handler,
    tool_router, transport::stdio,
};

use crate::client;

/// Wire-protocol-agnostic view of a hyperhive socket response. Both
/// `AgentResponse` and `ManagerResponse` convert into this so the tool
/// formatters can be shared between `AgentServer` and `ManagerServer`.
#[derive(Debug)]
pub enum SocketReply {
    Ok,
    Err(String),
    Message { from: String, body: String },
    Empty,
    Status(u64),
}

impl From<hive_sh4re::AgentResponse> for SocketReply {
    fn from(r: hive_sh4re::AgentResponse) -> Self {
        match r {
            hive_sh4re::AgentResponse::Ok => Self::Ok,
            hive_sh4re::AgentResponse::Err { message } => Self::Err(message),
            hive_sh4re::AgentResponse::Message { from, body } => Self::Message { from, body },
            hive_sh4re::AgentResponse::Empty => Self::Empty,
            hive_sh4re::AgentResponse::Status { unread } => Self::Status(unread),
        }
    }
}

impl From<hive_sh4re::ManagerResponse> for SocketReply {
    fn from(r: hive_sh4re::ManagerResponse) -> Self {
        match r {
            hive_sh4re::ManagerResponse::Ok => Self::Ok,
            hive_sh4re::ManagerResponse::Err { message } => Self::Err(message),
            hive_sh4re::ManagerResponse::Message { from, body } => Self::Message { from, body },
            hive_sh4re::ManagerResponse::Empty => Self::Empty,
            hive_sh4re::ManagerResponse::Status { unread } => Self::Status(unread),
        }
    }
}

/// Format helper for "send-like" tools (anything that expects an `Ok`).
/// `tool` and `ok_msg` only appear in the result string; they don't change
/// behavior.
pub fn format_ack(resp: Result<SocketReply, anyhow::Error>, tool: &str, ok_msg: String) -> String {
    match resp {
        Ok(SocketReply::Ok) => ok_msg,
        Ok(SocketReply::Err(m)) => format!("{tool} failed: {m}"),
        Ok(other) => format!("{tool} unexpected response: {other:?}"),
        Err(e) => format!("{tool} transport error: {e:#}"),
    }
}

/// Format helper for `recv` tools: `Message` → from + body block;
/// `Empty` → marker; anything else surfaces as an error.
pub fn format_recv(resp: Result<SocketReply, anyhow::Error>) -> String {
    match resp {
        Ok(SocketReply::Message { from, body }) => format!("from: {from}\n\n{body}"),
        Ok(SocketReply::Empty) => "(empty)".into(),
        Ok(SocketReply::Err(m)) => format!("recv failed: {m}"),
        Ok(other) => format!("recv unexpected response: {other:?}"),
        Err(e) => format!("recv transport error: {e:#}"),
    }
}

/// Common envelope around every MCP tool handler: pre-log → run →
/// post-log. The inbox-status hint used to be appended to every tool
/// result; that lives in the wake prompt + UI header now, so tool
/// results stay clean.
pub async fn run_tool_envelope<F>(tool: &'static str, args: String, body: F) -> String
where
    F: Future<Output = String>,
{
    tracing::info!(tool, %args, "tool: request");
    let result = body.await;
    tracing::info!(tool, result = %result, "tool: result");
    result
}

#[derive(Debug, serde::Deserialize, schemars::JsonSchema)]
pub struct SendArgs {
    /// Logical agent name to deliver the message to (e.g. `"manager"`,
    /// `"alice"`, or the literal `"operator"` for the dashboard's T4LK box).
    pub to: String,
    /// Message body. Plain text; the broker doesn't parse it.
    pub body: String,
}

#[derive(Debug, serde::Deserialize, schemars::JsonSchema)]
pub struct RecvArgs {}

/// Per-agent tool surface. Holds the socket path so each tool call doesn't
/// re-derive it; the socket itself is the per-container `/run/hive/mcp.sock`.
#[derive(Debug, Clone)]
pub struct AgentServer {
    socket: PathBuf,
}

impl AgentServer {
    #[must_use]
    pub fn new(socket: PathBuf) -> Self {
        Self { socket }
    }
}

#[tool_router]
impl AgentServer {
    #[tool(
        description = "Send a message to another hyperhive agent (or to the operator). \
            Use this to talk to peers or to surface output for the human at the dashboard."
    )]
    async fn send(&self, Parameters(args): Parameters<SendArgs>) -> String {
        let log = format!("{args:?}");
        let to = args.to.clone();
        run_tool_envelope("send", log, async move {
            let resp = client::request::<_, hive_sh4re::AgentResponse>(
                &self.socket,
                &hive_sh4re::AgentRequest::Send {
                    to: args.to,
                    body: args.body,
                },
            )
            .await
            .map(SocketReply::from);
            format_ack(resp, "send", format!("sent to {to}"))
        })
        .await
    }

    #[tool(
        description = "Pop one message from this agent's inbox. Returns the sender and body, \
            or an empty marker if nothing is waiting."
    )]
    async fn recv(&self, Parameters(_args): Parameters<RecvArgs>) -> String {
        run_tool_envelope("recv", String::new(), async move {
            let resp = client::request::<_, hive_sh4re::AgentResponse>(
                &self.socket,
                &hive_sh4re::AgentRequest::Recv,
            )
            .await
            .map(SocketReply::from);
            format_recv(resp)
        })
        .await
    }
}

#[tool_handler(
    instructions = "You are a hyperhive agent. Use `send` to talk to peers (by their logical \
        name) or to the operator (recipient `operator`). Use `recv` to drain your inbox one \
        message at a time."
)]
impl ServerHandler for AgentServer {}

/// Run the agent MCP server over stdio. Returns when the client disconnects.
pub async fn serve_agent_stdio(socket: PathBuf) -> Result<()> {
    let server = AgentServer::new(socket);
    let service = server.serve(stdio()).await?;
    service.waiting().await?;
    Ok(())
}

/// Run the manager MCP server over stdio. Same idea, different tool surface.
pub async fn serve_manager_stdio(socket: PathBuf) -> Result<()> {
    let server = ManagerServer::new(socket);
    let service = server.serve(stdio()).await?;
    service.waiting().await?;
    Ok(())
}

// -----------------------------------------------------------------------------
// Manager tool surface
// -----------------------------------------------------------------------------

#[derive(Debug, serde::Deserialize, schemars::JsonSchema)]
pub struct RequestSpawnArgs {
    /// New sub-agent name (≤9 chars). Queues a Spawn approval; the
    /// operator approves on the dashboard before the container is created.
    pub name: String,
}

#[derive(Debug, serde::Deserialize, schemars::JsonSchema)]
pub struct KillArgs {
    /// Sub-agent name (without the `h-` container prefix).
    pub name: String,
}

#[derive(Debug, serde::Deserialize, schemars::JsonSchema)]
pub struct RequestApplyCommitArgs {
    /// Agent whose config repo the commit lives in (use `"hm1nd"` for the
    /// manager's own config).
    pub agent: String,
    /// Git sha (full or short) pointing at the proposed `agent.nix`.
    pub commit_ref: String,
}

#[derive(Debug, Clone)]
pub struct ManagerServer {
    socket: PathBuf,
}

impl ManagerServer {
    #[must_use]
    pub fn new(socket: PathBuf) -> Self {
        Self { socket }
    }

    /// Helper: issue any `ManagerRequest`, convert the reply through
    /// `SocketReply`. Manager tools that just need an `Ok` ack share this.
    async fn dispatch(
        &self,
        req: hive_sh4re::ManagerRequest,
    ) -> Result<SocketReply, anyhow::Error> {
        client::request::<_, hive_sh4re::ManagerResponse>(&self.socket, &req)
            .await
            .map(SocketReply::from)
    }
}

#[tool_router]
impl ManagerServer {
    #[tool(
        description = "Send a message to a sub-agent (by logical name), to another agent, \
        or to the operator (recipient `operator`, surfaces in the dashboard)."
    )]
    async fn send(&self, Parameters(args): Parameters<SendArgs>) -> String {
        let log = format!("{args:?}");
        let to = args.to.clone();
        run_tool_envelope("send", log, async move {
            let resp = self
                .dispatch(hive_sh4re::ManagerRequest::Send {
                    to: args.to,
                    body: args.body,
                })
                .await;
            format_ack(resp, "send", format!("sent to {to}"))
        })
        .await
    }

    #[tool(
        description = "Pop one message from the manager inbox. Returns sender + body, or \
        empty."
    )]
    async fn recv(&self, Parameters(_args): Parameters<RecvArgs>) -> String {
        run_tool_envelope("recv", String::new(), async move {
            let resp = self.dispatch(hive_sh4re::ManagerRequest::Recv).await;
            format_recv(resp)
        })
        .await
    }

    #[tool(
        description = "Queue a Spawn approval for a brand-new sub-agent. The operator \
        approves on the dashboard before the container is actually created."
    )]
    async fn request_spawn(&self, Parameters(args): Parameters<RequestSpawnArgs>) -> String {
        let log = format!("{args:?}");
        let name = args.name.clone();
        run_tool_envelope("request_spawn", log, async move {
            let resp = self
                .dispatch(hive_sh4re::ManagerRequest::RequestSpawn { name: args.name })
                .await;
            format_ack(
                resp,
                "request_spawn",
                format!("spawn approval queued for {name}"),
            )
        })
        .await
    }

    #[tool(
        description = "Stop a sub-agent container (graceful). The state dir is kept; \
        recreating reuses prior config + Claude credentials."
    )]
    async fn kill(&self, Parameters(args): Parameters<KillArgs>) -> String {
        let log = format!("{args:?}");
        let name = args.name.clone();
        run_tool_envelope("kill", log, async move {
            let resp = self
                .dispatch(hive_sh4re::ManagerRequest::Kill { name: args.name })
                .await;
            format_ack(resp, "kill", format!("killed {name}"))
        })
        .await
    }

    #[tool(
        description = "Submit a config change for operator approval. Pass the agent name \
        (e.g. `alice` or `hm1nd` for the manager's own config) and a commit sha in that \
        agent's proposed config repo. On approval hive-c0re rebuilds the container."
    )]
    async fn request_apply_commit(
        &self,
        Parameters(args): Parameters<RequestApplyCommitArgs>,
    ) -> String {
        let log = format!("{args:?}");
        let agent = args.agent.clone();
        let commit_ref = args.commit_ref.clone();
        run_tool_envelope(
            "request_apply_commit",
            log,
            async move {
                let resp = self
                    .dispatch(hive_sh4re::ManagerRequest::RequestApplyCommit {
                        agent: args.agent,
                        commit_ref: args.commit_ref,
                    })
                    .await;
                format_ack(
                    resp,
                    "request_apply_commit",
                    format!("apply approval queued for {agent} @ {commit_ref}"),
                )
            },
        )
        .await
    }
}

#[tool_handler(
    instructions = "You are the hyperhive manager (hm1nd). You coordinate sub-agents and \
        relay between them and the operator. Use `send` to talk to agents/operator, `recv` \
        to drain your inbox. Privileged: `request_spawn` (new agent, gated on operator \
        approval), `kill` (graceful stop), `request_apply_commit` (config change for \
        any agent including yourself). The manager's own config lives at \
        `/agents/hm1nd/config/agent.nix`."
)]
impl ServerHandler for ManagerServer {}

/// Name of the hyperhive MCP server inside claude's view. Claude prefixes
/// tools as `mcp__<this>__<tool>` (e.g. `mcp__hyperhive__send`).
pub const SERVER_NAME: &str = "hyperhive";

/// Built-in claude tools the turn loop enables via `--tools`. Anything not
/// in this list literally doesn't exist in the session (claude won't even
/// try to call it). Web egress (`WebFetch`/`WebSearch`) and nested agents
/// (`Task`) are intentionally omitted for now; `Bash` is allowed pending a
/// finer-grained allow-list system for shell command patterns. Edit later
/// as our trust model evolves.
pub const ALLOWED_BUILTIN_TOOLS: &[&str] =
    &["Bash", "Edit", "Glob", "Grep", "Read", "TodoWrite", "Write"];

/// Which MCP tool surface to advertise via `--allowedTools`. The agent
/// list is the strict subset of the manager list, so we just thread the
/// flavor through.
#[derive(Debug, Clone, Copy)]
pub enum Flavor {
    Agent,
    Manager,
}

/// MCP tools claude is allowed to call without prompting. Mirrors the
/// hyperhive surface so a new tool added in the corresponding `#[tool_router]`
/// impl needs to be listed here too.
#[must_use]
pub fn allowed_mcp_tools(flavor: Flavor) -> Vec<String> {
    let names: &[&str] = match flavor {
        Flavor::Agent => &["send", "recv"],
        Flavor::Manager => &[
            "send",
            "recv",
            "request_spawn",
            "kill",
            "request_apply_commit",
        ],
    };
    names
        .iter()
        .map(|t| format!("mcp__{SERVER_NAME}__{t}"))
        .collect()
}

/// Combined allow-list passed to `--allowedTools` (auto-approve) — covers
/// both the built-ins and the MCP surface.
#[must_use]
pub fn allowed_tools_arg(flavor: Flavor) -> String {
    let mut all: Vec<String> = ALLOWED_BUILTIN_TOOLS
        .iter()
        .map(|s| (*s).to_owned())
        .collect();
    all.extend(allowed_mcp_tools(flavor));
    all.join(",")
}

/// Built-in tools list for `--tools` (which built-ins exist in this
/// session). Same as `ALLOWED_BUILTIN_TOOLS` but joined comma-separated.
#[must_use]
pub fn builtin_tools_arg() -> String {
    ALLOWED_BUILTIN_TOOLS.join(",")
}

/// Render the MCP config blob claude reads from `--mcp-config <path>`.
/// `agent_binary` is the path (or PATH-resolvable name) of the `hive-ag3nt`
/// executable; `socket` is the hyperhive per-agent socket bind-mounted into
/// the container (forwarded to the child as `--socket <path>`).
#[must_use]
pub fn render_claude_config(agent_binary: &str, socket: &std::path::Path) -> String {
    let config = serde_json::json!({
        "mcpServers": {
            SERVER_NAME: {
                "command": agent_binary,
                "args": ["--socket", socket.display().to_string(), "mcp"],
                "env": {}
            }
        }
    });
    serde_json::to_string_pretty(&config).unwrap_or_else(|_| "{}".into())
}