//! Wire types for the daemon ↔ stdio-MCP-bridge unix socket protocol.
//!
//! Same shape as `damocles-daemon`'s `DaemonRequest`/`DaemonResponse`
//! (which this is forked from in spirit). Each request is a single
//! JSON line; each response is a single JSON line back. The stdio MCP
//! bridge holds a fresh connection per tool call — claude's tool
//! lifecycle is shorter than a persistent matrix-sdk Client wants to
//! live, so the daemon stays alive and the MCP reconnects per call.

use serde::{Deserialize, Serialize};

/// Request envelope from the stdio MCP bridge to the daemon: which
/// matrix `account` to act as, plus the operation itself. The daemon
/// holds an account→Client registry (one client per declared matrix
/// account) and routes `op` to the resolved client.
///
/// `account` is nested rather than flattened onto [`DaemonOp`] so we
/// dodge the serde "internally-tagged enum + `#[serde(flatten)]`"
/// edge cases; the bridge and daemon ship together so the wire shape
/// is private. Wire:
/// `{"account":"ccc","op":{"method":"send_message","room":…,"body":…}}`.
#[derive(Debug, Serialize, Deserialize)]
pub struct DaemonRequest {
    /// Logical account name to act as (matches a `name` in
    /// `hyperhive.matrixAccounts`). `None` selects the primary account
    /// (the first declared one / the single legacy account), so
    /// single-account callers omit it entirely.
    #[serde(default, skip_serializing_if = "Option::is_none")]
    pub account: Option<String>,
    /// The matrix operation to perform on the resolved account.
    pub op: DaemonOp,
}

/// The matrix operation a [`DaemonRequest`] carries. The MCP bridge
/// owns the on-wire shape claude sees; this enum is the internal
/// shape the daemon dispatches over.
#[derive(Debug, Serialize, Deserialize)]
#[serde(tag = "method")]
pub enum DaemonOp {
    /// Post a plain-text or markdown message to a room. `room` accepts
    /// either a matrix room id (`!abc:server`) or a canonical alias
    /// (`#name:server`); the daemon resolves aliases server-side.
    #[serde(rename = "send_message")]
    SendMessage { room: String, body: String },

    /// Open (or reuse) a DM with `user_id` and post `body`. Creates
    /// the DM room if one doesn't already exist between this agent
    /// and the user.
    #[serde(rename = "send_dm")]
    SendDm { user_id: String, body: String },

    /// Upload a local file and post it as an attachment to `room`
    /// (id or alias). `caption`, when set, is sent as a follow-up
    /// text message in the same room.
    #[serde(rename = "send_file")]
    SendFile {
        room: String,
        path: String,
        caption: Option<String>,
    },

    /// Resolve (find-or-create) the DM room with `user_id` and return
    /// its room id, without sending anything. Lets a caller obtain the
    /// DM room id and then use the room-based tools (`send_file`,
    /// `send_message`, …) against it — so there is no per-tool `_dm`
    /// variant.
    #[serde(rename = "open_dm")]
    OpenDm { user_id: String },

    /// React to a specific event with an emoji `key`. Matrix-spec
    /// `m.reaction` annotation.
    #[serde(rename = "send_reaction")]
    SendReaction {
        room: String,
        event_id: String,
        key: String,
    },

    /// Reply to `event_id` in `room` with `body` as a threaded reply.
    /// Sets the `m.in_reply_to` relation so matrix clients render the
    /// thread.
    #[serde(rename = "send_reply")]
    SendReply {
        room: String,
        event_id: String,
        body: String,
    },

    /// Mark `event_id` (in `room`) as read for this agent. Sends a
    /// read receipt; bumps the room's "unread" indicator down on
    /// matrix clients (and for other agents).
    #[serde(rename = "mark_read")]
    MarkRead { room: String, event_id: String },

    /// Redact `event_id` in `room` — ask the homeserver to strip the
    /// event's content (matrix-spec `m.room.redaction`), optionally with
    /// a human-readable `reason`. The agent must have a high enough power
    /// level (its own events, or moderator rights for others'); the
    /// server rejects otherwise.
    #[serde(rename = "send_redact")]
    SendRedact {
        room: String,
        event_id: String,
        reason: Option<String>,
    },

    /// List rooms the agent has joined. Returns each room's id +
    /// canonical alias (when present) + name + member count.
    #[serde(rename = "list_rooms")]
    ListRooms,

    /// List the members of a room. Each entry carries the matrix
    /// user id + the resolved display name (when set).
    #[serde(rename = "list_room_members")]
    ListRoomMembers { room: String },

    /// Read the last `limit` events from a room's timeline. Caller
    /// gets each event's id, sender, `server_ts`, type, and body (best-
    /// effort plain-text extraction from `m.text` / `m.notice` etc.).
    #[serde(rename = "read_room")]
    ReadRoom { room: String, limit: Option<usize> },

    /// Download the media attachment carried by `event_id` in `room`
    /// and write it to a local file (`dest_path`, or a temp file named
    /// after the attachment when omitted), returning the path. The
    /// read-side counterpart of `send_file`.
    #[serde(rename = "download_file")]
    DownloadFile {
        room: String,
        event_id: String,
        dest_path: Option<String>,
    },

    /// List rooms this agent has been invited to but not yet joined.
    /// Returns each room's id, canonical alias (when present), and
    /// display name.
    #[serde(rename = "list_invites")]
    ListInvites,

    /// Join a room by id (`!abc:server`) or alias (`#name:server`).
    /// Accepts a pending invite if one exists; also joins public rooms
    /// the agent hasn't been explicitly invited to. After joining the
    /// room will appear in `list_rooms`.
    #[serde(rename = "join_room")]
    JoinRoom { room: String },

    /// Resolve a pending invite to `room` (id or alias) by either
    /// accepting it (join) or rejecting it (decline + leave). For rooms
    /// you were *invited* to; `join_room` is the path for joining a
    /// public room you weren't invited to.
    #[serde(rename = "resolve_invite")]
    ResolveInvite { room: String, action: InviteAction },

    /// Invite `user_id` (`@user:server`) to `room` (id or alias). The
    /// calling agent must already be a member with a high enough power
    /// level to invite. Idempotent-ish: inviting an already-joined or
    /// already-invited user surfaces the matrix error from the server.
    #[serde(rename = "invite_user")]
    InviteUser { room: String, user_id: String },

    /// Return the count of rooms with unread notifications. Used by
    /// the harness `get_loose_ends` to surface unread matrix activity
    /// without exposing message content.
    #[serde(rename = "unread_count")]
    UnreadCount,

    /// Return per-room unread summaries. For rooms with exactly one
    /// unread notification, attempts to include the sender + truncated
    /// body; rooms with multiple unreads carry only the count. Used by
    /// `get_loose_ends` and the wake-signal formatter.
    #[serde(rename = "unread_summary")]
    UnreadSummary,

    /// List the matrix accounts the daemon currently has a live,
    /// restored session for. Account-agnostic (does not resolve a single
    /// client — handled before client resolution in `socket::dispatch`):
    /// returns each restored account's name, homeserver, user id, primary
    /// flag, and a `live` flag. Backs the dashboard's per-account status
    /// (BE-4) — turns BE-1's token-present list into true online/offline
    /// + backfills the homeserver BE-1 leaves null.
    #[serde(rename = "list_accounts")]
    ListAccounts,

    /// Liveness probe — fast "are you up?" round-trip that doesn't
    /// touch matrix-sdk. Not used by the in-tree stdio MCP bridge
    /// (which surfaces a daemon-down condition as a normal tool-call
    /// connect error); reserved for external clients that want an
    /// explicit health check without doing real work.
    #[serde(rename = "ping")]
    Ping,
}

/// Whether to accept or reject a pending invite in
/// [`DaemonRequest::ResolveInvite`]. Serialises as `"accept"` /
/// `"reject"` on the wire.
#[derive(Debug, Clone, Copy, Serialize, Deserialize)]
#[serde(rename_all = "snake_case")]
pub enum InviteAction {
    /// Accept the invite — join the room (same effect as `join_room`).
    Accept,
    /// Reject the invite — decline it and leave the room.
    Reject,
}

/// One entry in the [`DaemonRequest::UnreadSummary`] response payload.
#[derive(Debug, Serialize, Deserialize)]
pub struct RoomUnread {
    /// Canonical alias (`#name:server`) or room id (`!id:server`).
    pub label: String,
    /// Server-side push-notification count for this room. Always ≥ 1.
    pub count: u32,
    /// Truncated body of the last message in the room. Present only when
    /// `count == 1` and the fetch succeeded; absent otherwise.
    #[serde(skip_serializing_if = "Option::is_none")]
    pub last_body: Option<String>,
    /// Sender of the last message (`@user:server`). Present when
    /// `last_body` is present.
    #[serde(skip_serializing_if = "Option::is_none")]
    pub last_sender: Option<String>,
}

/// Response shape: `ok` carries the payload (any JSON; the MCP bridge
/// passes it back to claude as the tool result), `error` carries a
/// human-readable error string.
#[derive(Debug, Serialize, Deserialize)]
#[serde(tag = "kind", rename_all = "snake_case")]
pub enum DaemonResponse {
    Ok { payload: serde_json::Value },
    Error { message: String },
}

impl DaemonResponse {
    /// Convenience: build an Ok response from any serializable value.
    /// Serialisation failure (impossible for the small handler structs
    /// we use, but the API is generic) surfaces as a structured
    /// `{"serialise_error": "..."}` payload so callers see WHY the
    /// data is missing instead of a silent `null`.
    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 }
    }

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

#[cfg(test)]
mod tests {
    use super::*;

    #[test]
    fn envelope_round_trips_with_account() {
        let req = DaemonRequest {
            account: Some("ccc".to_owned()),
            op: DaemonOp::SendMessage {
                room: "!r:s".to_owned(),
                body: "hi".to_owned(),
            },
        };
        let line = serde_json::to_string(&req).unwrap();
        // account + nested tagged op present on the wire.
        assert!(line.contains("\"account\":\"ccc\""), "wire: {line}");
        assert!(line.contains("\"method\":\"send_message\""), "wire: {line}");
        let back: DaemonRequest = serde_json::from_str(&line).unwrap();
        assert_eq!(back.account.as_deref(), Some("ccc"));
        matches!(back.op, DaemonOp::SendMessage { .. });
    }

    #[test]
    fn envelope_defaults_account_to_none_and_omits_it() {
        // Single-account callers send no `account`; it must default to
        // None and not appear on the wire (skip_serializing_if).
        let req = DaemonRequest {
            account: None,
            op: DaemonOp::ListRooms,
        };
        let line = serde_json::to_string(&req).unwrap();
        assert!(
            !line.contains("account"),
            "wire should omit account: {line}"
        );
        let back: DaemonRequest = serde_json::from_str(&line).unwrap();
        assert!(back.account.is_none());
        matches!(back.op, DaemonOp::ListRooms);
    }

    #[test]
    fn send_redact_round_trips_with_reason() {
        let req = DaemonRequest {
            account: None,
            op: DaemonOp::SendRedact {
                room: "!r:s".to_owned(),
                event_id: "$e".to_owned(),
                reason: Some("spam".to_owned()),
            },
        };
        let line = serde_json::to_string(&req).unwrap();
        assert!(line.contains("\"method\":\"send_redact\""), "wire: {line}");
        let back: DaemonRequest = serde_json::from_str(&line).unwrap();
        match back.op {
            DaemonOp::SendRedact {
                room,
                event_id,
                reason,
            } => {
                assert_eq!(room, "!r:s");
                assert_eq!(event_id, "$e");
                assert_eq!(reason.as_deref(), Some("spam"));
            }
            other => panic!("wrong variant: {other:?}"),
        }
    }

    #[test]
    fn send_redact_round_trips_without_reason() {
        let req = DaemonRequest {
            account: None,
            op: DaemonOp::SendRedact {
                room: "!r:s".to_owned(),
                event_id: "$e".to_owned(),
                reason: None,
            },
        };
        let line = serde_json::to_string(&req).unwrap();
        let back: DaemonRequest = serde_json::from_str(&line).unwrap();
        match back.op {
            DaemonOp::SendRedact { reason, .. } => assert_eq!(reason, None),
            other => panic!("wrong variant: {other:?}"),
        }
    }

    #[test]
    fn unit_variant_op_parses_inside_envelope() {
        // A bare op with no fields still parses when wrapped.
        let parsed: DaemonRequest =
            serde_json::from_str(r#"{"op":{"method":"unread_count"}}"#).unwrap();
        assert!(parsed.account.is_none());
        matches!(parsed.op, DaemonOp::UnreadCount);
    }

    #[test]
    fn list_accounts_parses_as_account_agnostic_unit_variant() {
        // Registry-wide op: no fields, and callers omit `account`.
        let parsed: DaemonRequest =
            serde_json::from_str(r#"{"op":{"method":"list_accounts"}}"#).unwrap();
        assert!(parsed.account.is_none());
        matches!(parsed.op, DaemonOp::ListAccounts);
        // And it serialises back to the same tagged shape.
        let line = serde_json::to_string(&DaemonRequest {
            account: None,
            op: DaemonOp::ListAccounts,
        })
        .unwrap();
        assert!(
            line.contains("\"method\":\"list_accounts\""),
            "wire: {line}"
        );
    }
}