import contextlib
import logging
from collections.abc import AsyncIterator

import fastapi
from fansifter_common.api import error_handlers
from fansifter_common.context.asgi.middleware import CorrelationIdMiddleware
from fastapi.middleware import Middleware
from fastapi.middleware.cors import CORSMiddleware
from fastapi.staticfiles import StaticFiles
from owslogger.asgi import RequestLoggingMiddleware

from resonance_engine.adapters.db import db
from resonance_engine.adapters.kafka import kafka_producer
from resonance_engine.api.routers import (
    auth,
    config,
    dashboard,
    dsp,
    fandata,
    infra,
    tasks,
)
from resonance_engine.config import settings
from resonance_engine.dsp.gateway import dsp_gateway

logger = logging.getLogger(__name__)


def get_app() -> fastapi.FastAPI:
    """Get FastAPI application instance."""

    @contextlib.asynccontextmanager
    async def lifespan(_app: fastapi.FastAPI) -> AsyncIterator[None]:
        with db, kafka_producer, dsp_gateway:
            yield None

    app = fastapi.FastAPI(
        title="Resonance Engine",
        description="Resonance Engine API",
        version=settings.service_version,
        debug=settings.debug,
        lifespan=lifespan,
        middleware=[
            Middleware(CorrelationIdMiddleware),
            Middleware(
                RequestLoggingMiddleware,
                exclude_paths=[
                    "/hello/",
                    "/openapi.json",
                    "/docs",
                    "/redoc",
                    "/dashboard/assets*",
                    "/favicon.ico",
                ],
                logger=logger,
            ),
            Middleware(
                CORSMiddleware,
                allow_origins=["*"],
                allow_credentials=True,
                allow_methods=["*"],
                allow_headers=["*"],
            ),
        ],
    )

    # Register exception error handlers
    error_handlers.register_defaults(app)

    assets_dir = settings.dashboard_dir / "assets"
    if assets_dir.exists():
        app.mount(
            "/dashboard/assets",
            StaticFiles(directory=settings.dashboard_dir / "assets"),
            name="assets",
        )

    # Infra routes
    app.include_router(infra.router)

    # API routes (no prefix — API lives at root)
    app.include_router(auth.router)
    app.include_router(config.router)
    app.include_router(dsp.router)
    app.include_router(fandata.router)
    app.include_router(tasks.router)

    # SPA catch-all must be last.
    app.include_router(dashboard.router)

    return app