import asyncio
import logging
from contextlib import asynccontextmanager
from pathlib import Path

from fastapi import FastAPI, Request
from fastapi.middleware.cors import CORSMiddleware
from fastapi.middleware.gzip import GZipMiddleware
from fastapi.responses import JSONResponse

from app.config import settings as server_settings
from app.config import setup_logging
from app.database import db
from app.frontend_static import (
    register_first_available_frontend_static_routes,
    register_frontend_missing_fallback,
)
from app.radio import RadioDisconnectedError
from app.radio_sync import (
    stop_message_polling,
    stop_periodic_advert,
    stop_periodic_sync,
)
from app.routers import (
    channels,
    contacts,
    debug,
    fanout,
    health,
    messages,
    packets,
    radio,
    read_state,
    repeaters,
    rooms,
    settings,
    statistics,
    ws,
)
from app.security import add_optional_basic_auth_middleware
from app.services.radio_runtime import radio_runtime as radio_manager
from app.version_info import get_app_build_info

setup_logging()
logger = logging.getLogger(__name__)


async def _startup_radio_connect_and_setup() -> None:
    """Connect/setup the radio in the background so HTTP serving can start immediately."""
    try:
        connected = await radio_manager.reconnect_and_prepare(broadcast_on_success=True)
        if connected:
            logger.info("Connected to radio")
        else:
            logger.warning("Failed to connect to radio on startup")
    except Exception:
        logger.exception("Failed to connect to radio on startup")


@asynccontextmanager
async def lifespan(app: FastAPI):
    """Manage database and radio connection lifecycle."""
    await db.connect()
    logger.info("Database connected")

    # Ensure default channels exist in the database even before the radio
    # connects. Without this, a fresh or disconnected instance would return
    # zero channels from GET /channels until the first successful radio sync.
    from app.radio_sync import ensure_default_channels

    await ensure_default_channels()

    # Always start connection monitor (even if initial connection failed)
    await radio_manager.start_connection_monitor()

    # Start fanout modules (MQTT, etc.) from database configs
    from app.fanout.manager import fanout_manager

    try:
        await fanout_manager.load_from_db()
    except Exception:
        logger.exception("Failed to start fanout modules")

    startup_radio_task = asyncio.create_task(_startup_radio_connect_and_setup())
    app.state.startup_radio_task = startup_radio_task

    yield

    logger.info("Shutting down")
    if startup_radio_task and not startup_radio_task.done():
        startup_radio_task.cancel()
        try:
            await startup_radio_task
        except asyncio.CancelledError:
            pass
    await fanout_manager.stop_all()
    await radio_manager.stop_connection_monitor()
    await stop_message_polling()
    await stop_periodic_advert()
    await stop_periodic_sync()
    if radio_manager.meshcore:
        await radio_manager.meshcore.stop_auto_message_fetching()
    await radio_manager.disconnect()
    await db.disconnect()


app = FastAPI(
    title="RemoteTerm for MeshCore API",
    description="API for interacting with MeshCore mesh radio networks",
    version=get_app_build_info().version,
    lifespan=lifespan,
)

add_optional_basic_auth_middleware(app, server_settings)
app.add_middleware(GZipMiddleware, minimum_size=500)
app.add_middleware(
    CORSMiddleware,
    allow_origins=["*"],
    allow_credentials=True,
    allow_methods=["*"],
    allow_headers=["*"],
)


@app.exception_handler(RadioDisconnectedError)
async def radio_disconnected_handler(request: Request, exc: RadioDisconnectedError):
    """Return 503 when a radio disconnect race occurs during an operation."""
    return JSONResponse(status_code=503, content={"detail": "Radio not connected"})


# API routes - all prefixed with /api for production compatibility
app.include_router(health.router, prefix="/api")
app.include_router(debug.router, prefix="/api")
app.include_router(fanout.router, prefix="/api")
app.include_router(radio.router, prefix="/api")
app.include_router(contacts.router, prefix="/api")
app.include_router(repeaters.router, prefix="/api")
app.include_router(rooms.router, prefix="/api")
app.include_router(channels.router, prefix="/api")
app.include_router(messages.router, prefix="/api")
app.include_router(packets.router, prefix="/api")
app.include_router(read_state.router, prefix="/api")
app.include_router(settings.router, prefix="/api")
app.include_router(statistics.router, prefix="/api")
app.include_router(ws.router, prefix="/api")

# Serve frontend static files in production
FRONTEND_DIST_DIR = Path(__file__).parent.parent / "frontend" / "dist"
FRONTEND_PREBUILT_DIR = Path(__file__).parent.parent / "frontend" / "prebuilt"
if not register_first_available_frontend_static_routes(
    app, [FRONTEND_DIST_DIR, FRONTEND_PREBUILT_DIR]
):
    register_frontend_missing_fallback(app)
