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.protocol.udp_sender import UDPSender

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


@asynccontextmanager
async def lifespan(app: FastAPI):
    global registry, show_store
    # Startup
    registry = DeviceRegistry(Path("devices.json"))
    await registry.load()
    show_store = ShowStore(Path("shows"))
    show_store.ensure_dir()

    # Beat analysis cache: filepath -> {"tempo": float, "beats": [float, ...]}
    app.state.beats = {}

    # UDP sender for device communication (Phase 3)
    udp_sender = UDPSender()
    await udp_sender.start()
    app.state.udp_sender = udp_sender

    yield

    # Shutdown
    await app.state.udp_sender.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, timeline
    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")
    app.include_router(timeline.router, prefix="/api")

    # Serve uploaded audio files so <audio src=...> can load them
    shows_dir = Path("/app/shows")
    shows_dir.mkdir(parents=True, exist_ok=True)
    app.mount("/shows", StaticFiles(directory=str(shows_dir)), name="shows")

    # 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()