"""Simple HTTP API for the Matrix Bridge.

Provides endpoints for agents and scheduled tasks to interact
with the bridge without going through the Matrix protocol.

Endpoints:
    GET  /session-id  — Return the current bridge session ID
    POST /send        — Send a text message to the configured Matrix room
"""

from __future__ import annotations

import json
import logging
import threading
from http.server import HTTPServer, BaseHTTPRequestHandler
from typing import TYPE_CHECKING, Optional

if TYPE_CHECKING:
    from bridge import Bridge

log = logging.getLogger("matrix-bridge.api")


class _Handler(BaseHTTPRequestHandler):
    """HTTP handler that delegates to a shared bridge reference."""

    # Set once before the server starts — shared across all requests.
    bridge: Optional["Bridge"] = None

    # ── Helpers ───────────────────────────────────────────────────────

    def _send_json(self, status: int, data: dict) -> None:
        """Send a JSON response with the given status code."""
        body = json.dumps(data).encode("utf-8")
        self.send_response(status)
        self.send_header("Content-Type", "application/json")
        self.send_header("Content-Length", str(len(body)))
        self.end_headers()
        self.wfile.write(body)

    def _read_body(self) -> Optional[dict]:
        """Read and parse the request body as JSON."""
        try:
            length = int(self.headers.get("Content-Length", 0))
        except (ValueError, TypeError):
            return None
        if length <= 0:
            return None
        raw = self.rfile.read(length)
        try:
            return json.loads(raw)
        except json.JSONDecodeError:
            return None

    # ── Routes ────────────────────────────────────────────────────────

    def do_GET(self) -> None:
        if self.path == "/session-id":
            if self.bridge is None:
                self._send_json(503, {"error": "Bridge not initialized"})
                return
            sid = self.bridge.state.session_id
            self._send_json(200, {"session_id": sid})
        else:
            self._send_json(404, {"error": f"Not found: {self.path}"})

    def do_POST(self) -> None:
        if self.path == "/send":
            if self.bridge is None:
                self._send_json(503, {"error": "Bridge not initialized"})
                return

            body = self._read_body()
            if body is None:
                self._send_json(400, {"error": "Invalid or missing JSON body"})
                return

            message = body.get("message")
            if not message or not isinstance(message, str):
                self._send_json(400, {"error": "Missing or invalid 'message' field"})
                return

            success = self.bridge.matrix.send_message(message)
            if success:
                self._send_json(200, {"ok": True})
            else:
                self._send_json(500, {"error": "Failed to send Matrix message"})
        else:
            self._send_json(404, {"error": f"Not found: {self.path}"})

    # ── Silence default logging ───────────────────────────────────────

    def log_message(self, format: str, *args) -> None:
        log.debug(f"HTTP: {format % args}")


def start_api_server(
    bridge: "Bridge", host: str = "127.0.0.1", port: int = 8082
) -> None:
    """Start the API HTTP server in a background daemon thread.

    The server runs until the main process exits.  It provides a
    lightweight JSON API on ``host:port`` for other components to
    query the bridge state or trigger Matrix messages.
    """
    _Handler.bridge = bridge
    server = HTTPServer((host, port), _Handler)
    server.timeout = 1.0  # Allows clean shutdown without dedicated stop

    thread = threading.Thread(
        target=server.serve_forever,
        name=f"api-{host}:{port}",
        daemon=True,
    )
    thread.start()
    log.info(f"API server listening on http://{host}:{port}")