from __future__ import annotations

import logging
import os
import sys
from datetime import datetime
from typing import Any, Dict, Optional

from flask import request
from flask_socketio import SocketIO, emit, join_room

from models import Display, db
from sync import get_current_event, get_trigger_event, mark_trigger_display_ended, server_time_ms


logger = logging.getLogger(__name__)


_env_async_mode = os.environ.get("ASYNC_MODE")  # e.g. gevent | eventlet | threading | None(auto)

# IMPORTANT:
# - On Windows + Python 3.14+, eventlet is currently incompatible and may crash if auto-selected.
# - If ASYNC_MODE is not provided, default to 'threading' on Windows/Py3.14+.
if _env_async_mode:
    _async_mode = _env_async_mode
else:
    if os.name == "nt" or sys.version_info >= (3, 14):
        _async_mode = "threading"
    else:
        _async_mode = None  # let Socket.IO auto-select (eventlet/gevent if installed)

socketio = SocketIO(
    async_mode=_async_mode or None,
    cors_allowed_origins="*",
    logger=False,
    engineio_logger=False,
    ping_interval=5,
    ping_timeout=10,
)


_monitor_started = False


def start_event_monitor(app) -> None:
    """Background task that detects when a trigger event expires by time."""
    global _monitor_started
    if _monitor_started:
        return
    _monitor_started = True

    def _run():
        while True:
            try:
                with app.app_context():
                    trig = get_trigger_event()
            except Exception:
                logger.exception("event monitor failed")
            socketio.sleep(0.5)

    socketio.start_background_task(_run)


# In-memory live stats (for admin dashboard). Keyed by display public_id.
_live: Dict[str, Dict[str, Any]] = {}


def _set_live(public_id: str, **kwargs: Any) -> None:
    d = _live.setdefault(public_id, {})
    d.update(kwargs)


def get_live_snapshot() -> Dict[str, Dict[str, Any]]:
    return {k: dict(v) for k, v in _live.items()}


@socketio.on("connect")
def on_connect():
    # Client will send hello with public_id
    emit("connected", {"server_time_ms": server_time_ms()})


@socketio.on("hello")
def on_hello(data: Dict[str, Any]):
    public_id = (data or {}).get("public_id")
    if not public_id:
        emit("error", {"error": "missing public_id"})
        return

    join_room(f"display:{public_id}")

    disp = db.session.query(Display).filter_by(public_id=public_id).one_or_none()
    if disp is None:
        # Auto-create to be resilient on LAN; admin can rename later.
        disp = Display(name=f"Display {public_id}", public_id=public_id)
        db.session.add(disp)

    disp.is_online = True
    disp.last_seen = datetime.utcnow()
    db.session.commit()

    _set_live(public_id, sid=request.sid, user_agent=request.headers.get("User-Agent", ""), last_seen=disp.last_seen.isoformat())
    emit("hello_ack", {"server_time_ms": server_time_ms()})
    socketio.emit("admin_display_update", {"public_id": public_id, "is_online": True, "last_seen": disp.last_seen.isoformat()}, room="admin")


@socketio.on("heartbeat")
def on_heartbeat(data: Dict[str, Any]):
    public_id = (data or {}).get("public_id")
    if not public_id:
        return
    latency_ms = (data or {}).get("latency_ms")
    offset_ms = (data or {}).get("offset_ms")
    ready = bool((data or {}).get("ready"))
    _set_live(public_id, latency_ms=latency_ms, offset_ms=offset_ms, ready=ready, last_seen=datetime.utcnow().isoformat())

    disp = db.session.query(Display).filter_by(public_id=public_id).one_or_none()
    if disp:
        disp.last_seen = datetime.utcnow()
        disp.is_online = True
        db.session.commit()


@socketio.on("time_sync")
def on_time_sync(data: Dict[str, Any]):
    # NTP-style time sync:
    # - client sends t1 (client send time)
    # - server records t2 (server receive time)
    # - server replies with t1, t2, t3 (server send time)
    # Client will record t4 on receive.
    t1 = float((data or {}).get("t1_ms", 0.0))
    t2 = server_time_ms()
    # Keep a distinct send timestamp (avoid t2==t3 due to same clock read).
    t3 = server_time_ms()
    emit("time_sync", {"t1_ms": t1, "t2_ms": t2, "t3_ms": t3})


@socketio.on("request_state")
def on_request_state(data: Dict[str, Any]):
    public_id = (data or {}).get("public_id")
    if not public_id:
        return
    st = get_current_event()
    if not st:
        emit("event_state", {"active": False, "server_time_ms": server_time_ms()})
        return
    video_url = st.assignments.get(public_id)
    if not video_url:
        emit("event_state", {"active": False, "server_time_ms": server_time_ms()})
        return
    emit(
        "event_state",
        {
            "active": True,
            "event_id": st.event_id,
            "event_name": st.name,
            "video_url": video_url,
            "start_time_ms": st.start_time_ms,
            "server_time_ms": server_time_ms(),
        },
    )


@socketio.on("playback_ended")
def on_playback_ended(data: Dict[str, Any]):
    public_id = (data or {}).get("public_id")
    event_id = (data or {}).get("event_id")
    if not public_id or not event_id:
        return
    try:
        ended_all = mark_trigger_display_ended(int(event_id), str(public_id))
    except Exception:
        return
    if ended_all:
        # Trigger event fully ended; displays will fall back to idle image.
        return


@socketio.on("admin_join")
def on_admin_join():
    join_room("admin")
    emit("admin_snapshot", {"server_time_ms": server_time_ms(), "live": get_live_snapshot()})


@socketio.on("disconnect")
def on_disconnect():
    # We don't know which display disconnected unless tracked in _live
    sid = request.sid
    public_id: Optional[str] = None
    for pid, info in list(_live.items()):
        if info.get("sid") == sid:
            public_id = pid
            break
    if not public_id:
        return
    try:
        disp = db.session.query(Display).filter_by(public_id=public_id).one_or_none()
        if disp:
            disp.is_online = False
            disp.last_seen = datetime.utcnow()
            db.session.commit()
    except Exception:
        logger.exception("Failed to mark display offline")
    _set_live(public_id, is_online=False)
    socketio.emit("admin_display_update", {"public_id": public_id, "is_online": False, "last_seen": datetime.utcnow().isoformat()}, room="admin")