//! Wire types for the unix socket protocol between `hive-bash-daemon`
//! and `hive-bash-mcp`. One JSON request line in, one JSON response line
//! out per connection. Connections are short-lived (per tool call).

use serde::{Deserialize, Serialize};

// ---------------------------------------------------------------------------
// Task state (shared between runner and protocol)
// ---------------------------------------------------------------------------

/// Lifecycle state of a bash task.
#[derive(Debug, Clone, Serialize, Deserialize, PartialEq, Eq)]
#[serde(rename_all = "snake_case")]
pub enum TaskStatus {
    Pending,
    Running,
    Done,
    TimedOut,
    /// Daemon was restarted while the task was running; process is gone.
    Interrupted,
}

/// Task metadata + result written to `<id>.json` under the tasks dir.
#[derive(Debug, Clone, Serialize, Deserialize)]
pub struct TaskFile {
    pub id: String,
    pub cmd: String,
    /// Kill timeout in seconds. `None` means no timeout — task runs until
    /// natural exit. Old task files with a numeric value are still readable
    /// (serde coerces `u64` → `Some(u64)` is handled by the caller).
    #[serde(default, skip_serializing_if = "Option::is_none")]
    pub timeout_secs: Option<u64>,
    pub status: TaskStatus,
    pub created_at: i64,
    #[serde(default, skip_serializing_if = "Option::is_none")]
    pub started_at: Option<i64>,
    #[serde(default, skip_serializing_if = "Option::is_none")]
    pub completed_at: Option<i64>,
    #[serde(default, skip_serializing_if = "Option::is_none")]
    pub exit_code: Option<i32>,
    /// Last [`crate::runner::SUMMARY_BYTES`] of stdout.
    #[serde(default, skip_serializing_if = "Option::is_none")]
    pub stdout_tail: Option<String>,
    /// Last [`crate::runner::SUMMARY_BYTES`] of stderr.
    #[serde(default, skip_serializing_if = "Option::is_none")]
    pub stderr_tail: Option<String>,
}

// ---------------------------------------------------------------------------
// Request / response
// ---------------------------------------------------------------------------

/// Requests the MCP bridge sends to the daemon.
#[derive(Debug, Serialize, Deserialize)]
#[serde(tag = "kind", rename_all = "snake_case")]
pub enum DaemonRequest {
    /// Liveness probe — fast round-trip that doesn't touch any subprocess.
    Ping,

    /// Submit a new bash task. Returns the task ID on success.
    /// `wait_seconds`: optional inline poll (capped at 30s); when the
    /// task finishes within the window the response carries the full
    /// status payload. When it doesn't, the response carries just the
    /// task ID so the caller can check back with `BashStatus`.
    BashRun {
        cmd: String,
        #[serde(default)]
        timeout_secs: Option<u64>,
        /// Inline wait cap: 30s. Pass `None` or `0` to get the
        /// task-started-id response immediately.
        #[serde(default)]
        wait_seconds: Option<u64>,
    },

    /// Query the current status of a task. Returns the full `TaskFile`
    /// (formatted as text by the bridge). `wait_seconds`: optional
    /// inline poll (capped at 30s) — daemon returns as soon as the
    /// task reaches a terminal state or the window expires.
    BashStatus {
        id: String,
        #[serde(default)]
        wait_seconds: Option<u64>,
    },

    /// Return all tasks currently in `Pending` or `Running` state.
    /// Used by the harness `get_loose_ends` to surface active
    /// background work.
    ActiveTasks,
}

/// Response shape from the daemon. `Ok` carries a JSON payload; `Error`
/// carries a human-readable message.
#[derive(Debug, Serialize, Deserialize)]
#[serde(tag = "kind", rename_all = "snake_case")]
pub enum DaemonResponse {
    Ok { payload: serde_json::Value },
    Error { message: String },
}

impl DaemonResponse {
    /// Build an Ok response from any serialisable value.
    pub fn ok<T: Serialize>(payload: &T) -> Self {
        let payload = serde_json::to_value(payload)
            .unwrap_or_else(|e| serde_json::json!({ "serialise_error": e.to_string() }));
        Self::Ok { payload }
    }

    /// Build an Error response from any `Display` value.
    pub fn error(msg: impl std::fmt::Display) -> Self {
        Self::Error {
            message: msg.to_string(),
        }
    }
}