"""
MeshBay Hub — FastAPI application factory.

Usage:
    from meshbay_hub.app import create_app
    from meshbay_hub.config import load_config

    cfg = load_config()
    app = create_app(cfg)
"""

import asyncio
from contextlib import asynccontextmanager
from pathlib import Path

from fastapi import FastAPI
from slowapi import _rate_limit_exceeded_handler
from slowapi.errors import RateLimitExceeded

from meshbay_hub import __version__
from meshbay_hub.auth import generate_hub_keypair, load_hub_keypair
from meshbay_hub.config import HubConfig
from meshbay_hub.db.engine import close_db, init_db
from meshbay_hub.api.hub        import router as hub_router
from meshbay_hub.api.users      import router as users_router, set_config as users_set_config
from meshbay_hub.api.deps       import set_admin_usernames
from meshbay_hub.api.nodes      import router as nodes_router
from meshbay_hub.api.groups     import router as groups_router, swarm_router
from meshbay_hub.api.revocation  import router as revocation_router
from meshbay_hub.api.moderation  import router as moderation_router
from meshbay_hub.api.federation  import router as federation_router
from meshbay_hub.csam            import csam_router
from meshbay_hub.api.health      import router as health_router
from meshbay_hub.api.relay       import router as relay_router
from meshbay_hub.api.signaling   import router as signaling_router
from meshbay_hub.api.admin       import router as admin_router
from meshbay_hub.api.notifications import router as notifications_router
from meshbay_hub.api.webapp     import router as webapp_router, STATIC_DIR
from meshbay_hub.api.middleware import limiter


async def _sync_admin_roles(admin_usernames: list[str]) -> None:
    """Ensure config-listed admin usernames have role='admin' in the DB."""
    from sqlalchemy import select, update
    from meshbay_hub.db.engine import get_session_factory
    from meshbay_hub.db.models import User

    factory = get_session_factory()
    async with factory() as session:
        result = await session.execute(
            select(User).where(User.username.in_(admin_usernames))
        )
        for user in result.scalars().all():
            if user.role != "admin":
                user.role = "admin"
        await session.commit()


def create_app(cfg: HubConfig | None = None) -> FastAPI:
    from meshbay_hub.config import load_config
    if cfg is None:
        cfg = load_config()

    @asynccontextmanager
    async def lifespan(app: FastAPI):
        # Startup
        await init_db(cfg.db.url)

        kp = cfg.identity.private_key_path
        if not kp.exists():
            generate_hub_keypair(kp)
        load_hub_keypair(kp, cfg.identity.id)
        users_set_config(cfg)
        set_admin_usernames(cfg.identity.admin_usernames)

        if cfg.identity.admin_usernames:
            await _sync_admin_roles(cfg.identity.admin_usernames)

        from meshbay_hub.csam import get_csam_checker
        get_csam_checker().load()

        from meshbay_hub.tasks.cleanup import cleanup_loop
        from meshbay_hub.db.engine import get_session_factory
        cleanup_task = asyncio.create_task(cleanup_loop(get_session_factory()))

        yield

        cleanup_task.cancel()
        try:
            await cleanup_task
        except asyncio.CancelledError:
            pass

        # Shutdown
        await close_db()

    app = FastAPI(
        title="MeshBay Hub",
        version=__version__,
        description="MeshBay identity authority and group registry",
        lifespan=lifespan,
    )

    # Rate limiting
    app.state.limiter = limiter
    app.add_exception_handler(RateLimitExceeded, _rate_limit_exceeded_handler)

    # Routers (webapp last — catches / before API routes)
    app.include_router(hub_router)
    app.include_router(users_router)
    app.include_router(nodes_router)
    app.include_router(groups_router)
    app.include_router(swarm_router)
    app.include_router(revocation_router)
    app.include_router(moderation_router)
    app.include_router(federation_router)
    app.include_router(csam_router)
    app.include_router(health_router)
    app.include_router(relay_router)
    app.include_router(signaling_router)
    app.include_router(admin_router)
    app.include_router(notifications_router)
    app.include_router(webapp_router)

    from starlette.staticfiles import StaticFiles
    app.mount("/", StaticFiles(directory=STATIC_DIR), name="static")

    return app