import asyncio
import os
from contextlib import asynccontextmanager
from pathlib import Path
from fastapi import FastAPI, Request
from fastapi.responses import FileResponse
from fastapi.staticfiles import StaticFiles

from lightsync.devices.registry import DeviceRegistry
from lightsync.store.show_store import ShowStore
from lightsync.audio.engine import MPVEngine

# Module-level containers populated in lifespan
registry: DeviceRegistry | None = None
show_store: ShowStore | None = None
engine: MPVEngine | None = None


@asynccontextmanager
async def lifespan(app: FastAPI):
    global registry, show_store, engine
    # Startup
    registry = DeviceRegistry(Path("devices.json"))
    await registry.load()
    show_store = ShowStore(Path("shows"))
    show_store.ensure_dir()
    ao = os.environ.get("MPV_AO", "null")
    engine = MPVEngine(ao=ao)
    engine.start()
    app.state.engine = engine
    from lightsync.api.ws import broadcast_loop
    task = asyncio.create_task(broadcast_loop(lambda: engine))
    yield
    # Shutdown
    task.cancel()
    try:
        await task
    except asyncio.CancelledError:
        pass
    engine.stop()
    await registry.save()


def create_app() -> FastAPI:
    app = FastAPI(title="LightSync", lifespan=lifespan, redirect_slashes=False)

    # API routes (registered before static mount — see Pattern 7)
    from lightsync.api import shows, devices, ws, audio
    app.include_router(shows.router, prefix="/api/shows")
    app.include_router(devices.router, prefix="/api/devices")
    app.include_router(ws.router)
    app.include_router(audio.router, prefix="/api/audio")

    # Static file serving — no-cache headers to prevent stale JS/CSS
    frontend_dir = Path(__file__).parent / "frontend"

    @app.get("/{filename:path}")
    async def static_files(request: Request, filename: str):
        path = frontend_dir / (filename or "index.html")
        if not path.exists() or not path.is_file():
            path = frontend_dir / "index.html"
        response = FileResponse(path)
        response.headers["Cache-Control"] = "no-cache, no-store, must-revalidate"
        return response

    return app


app = create_app()