"""
Imago — Application principale FastAPI
"""
import logging
from contextlib import asynccontextmanager
from fastapi import FastAPI, Request
from fastapi.middleware.cors import CORSMiddleware
from fastapi.staticfiles import StaticFiles
from slowapi import _rate_limit_exceeded_handler
from slowapi.errors import RateLimitExceeded

from app.config import settings
from app.database import init_db
from app.logging_config import configure_logging
from app.routers import images_router, ai_router, auth_router, files_router
from app.middleware import limiter
from app.middleware.logging_middleware import LoggingMiddleware
from app.workers.redis_client import get_redis_pool, close_redis_pool

# Configure le logging structuré dès l'import
configure_logging(debug=settings.DEBUG)

logger = logging.getLogger(__name__)

try:
    from arq import create_pool
    from arq.connections import RedisSettings
    _arq_available = True
except ImportError:
    _arq_available = False

try:
    from prometheus_fastapi_instrumentator import Instrumentator
    _prometheus_available = True
except ImportError:
    _prometheus_available = False


def _arq_redis_settings() -> "RedisSettings":
    """Parse REDIS_URL en RedisSettings ARQ."""
    url = settings.REDIS_URL
    if url.startswith("redis://"):
        url = url[8:]
    elif url.startswith("rediss://"):
        url = url[9:]

    password = None
    host = "localhost"
    port = 6379
    database = 0

    if "@" in url:
        auth_part, url = url.rsplit("@", 1)
        if ":" in auth_part:
            password = auth_part.split(":", 1)[1]
        else:
            password = auth_part

    if "/" in url:
        host_port, db_str = url.split("/", 1)
        if db_str:
            database = int(db_str)
    else:
        host_port = url

    if ":" in host_port:
        host, port_str = host_port.rsplit(":", 1)
        if port_str:
            port = int(port_str)
    else:
        host = host_port

    return RedisSettings(
        host=host or "localhost",
        port=port,
        password=password,
        database=database,
    )


# ─────────────────────────────────────────────────────────────
# Lifespan — initialisation au démarrage
# ─────────────────────────────────────────────────────────────

@asynccontextmanager
async def lifespan(app: FastAPI):
    # Création des répertoires de données
    settings.upload_path
    settings.thumbnails_path

    # Initialisation de la base de données (création des tables)
    await init_db()

    active_model = settings.OPENROUTER_MODEL if settings.AI_PROVIDER == "openrouter" else settings.GEMINI_MODEL

    logger.info("startup.db_initialized", extra={"upload_dir": settings.UPLOAD_DIR})
    logger.info("startup.ai_config", extra={
        "provider": settings.AI_PROVIDER,
        "model": active_model,
        "ocr_enabled": settings.OCR_ENABLED,
    })

    # Initialisation Redis + ARQ pool
    try:
        app.state.redis = await get_redis_pool()
        logger.info("startup.redis_connected", extra={"url": settings.REDIS_URL})
    except Exception as e:
        app.state.redis = None
        logger.warning("startup.redis_unavailable", extra={"error": str(e)})

    if _arq_available:
        try:
            app.state.arq_pool = await create_pool(_arq_redis_settings())
            logger.info("startup.arq_pool_created")
        except Exception as e:
            app.state.arq_pool = _FallbackArqPool()
            logger.warning("startup.arq_fallback", extra={"error": str(e)})
    else:
        app.state.arq_pool = _FallbackArqPool()
        logger.warning("startup.arq_not_installed")

    yield

    # Fermeture propre
    if hasattr(app.state, "arq_pool") and hasattr(app.state.arq_pool, "close"):
        await app.state.arq_pool.close()
    await close_redis_pool()
    logger.info("shutdown.complete")


class _FallbackArqPool:
    """Fallback quand Redis/ARQ n'est pas disponible."""

    async def enqueue_job(self, *args, **kwargs):
        logger.warning("arq.fallback_enqueue", extra={"args": str(args)})
        return None

    async def close(self):
        pass


# ─────────────────────────────────────────────────────────────
# Application
# ─────────────────────────────────────────────────────────────

app = FastAPI(
    title=settings.APP_NAME,
    version=settings.APP_VERSION,
    description="""
## Imago

Backend de gestion d'images et fonctionnalités AI pour l'interface Shaarli.

### Fonctionnalités
- 📸 **Upload et stockage d'images** avec génération de thumbnails
- 🔍 **Extraction EXIF** automatique (appareil, GPS, paramètres de prise de vue)
- 📝 **OCR** — extraction de texte depuis les images (Tesseract)
- 🤖 **Vision AI** — description et classification par tags (Gemini)
- 🔗 **Résumé d'URL** — scraping + résumé AI de pages web
- ✅ **Rédaction de tâches** — génération structurée via AI
- 📋 **File de tâches ARQ** — pipeline persistant avec retry automatique
- 📊 **Métriques Prometheus** — /metrics endpoint

### Pipeline de traitement
Chaque image uploadée est automatiquement traitée via ARQ (Redis) :
`EXIF → OCR → Vision AI → stockage BDD`
    """,
    lifespan=lifespan,
    docs_url="/docs",
    redoc_url="/redoc",
)

# ─────────────────────────────────────────────────────────────
# Middleware CORS
# ─────────────────────────────────────────────────────────────

app.add_middleware(
    CORSMiddleware,
    allow_origins=settings.CORS_ORIGINS,
    allow_credentials=True,
    allow_methods=["*"],
    allow_headers=["*"],
)

# ─────────────────────────────────────────────────────────────
# Middleware Logging HTTP
# ─────────────────────────────────────────────────────────────

app.add_middleware(LoggingMiddleware)

# ─────────────────────────────────────────────────────────────
# Rate Limiting (slowapi)
# ─────────────────────────────────────────────────────────────

app.state.limiter = limiter
app.add_exception_handler(RateLimitExceeded, _rate_limit_exceeded_handler)

# ─────────────────────────────────────────────────────────────
# Prometheus Metrics
# ─────────────────────────────────────────────────────────────

if _prometheus_available:
    Instrumentator(
        should_group_status_codes=True,
        should_ignore_untemplated=True,
        excluded_handlers=["/health", "/health/detailed", "/metrics"],
    ).instrument(app).expose(app, endpoint="/metrics", tags=["Observabilité"])

# ─────────────────────────────────────────────────────────────
# Fichiers statiques / URLs signées
# ─────────────────────────────────────────────────────────────

if settings.STORAGE_BACKEND == "local":
    app.include_router(files_router)
    app.mount("/static/uploads", StaticFiles(directory=str(settings.upload_path)), name="uploads")
    app.mount("/static/thumbnails", StaticFiles(directory=str(settings.thumbnails_path)), name="thumbnails")

# ─────────────────────────────────────────────────────────────
# Routers
# ─────────────────────────────────────────────────────────────

app.include_router(images_router)
app.include_router(ai_router)
app.include_router(auth_router)


# ─────────────────────────────────────────────────────────────
# Routes utilitaires
# ─────────────────────────────────────────────────────────────

@app.get("/", tags=["Santé"])
async def root():
    return {
        "app": settings.APP_NAME,
        "version": settings.APP_VERSION,
        "status": "running",
        "docs": "/docs",
    }


@app.get("/health", tags=["Santé"])
async def health():
    ai_configured = (
        (settings.AI_PROVIDER == "gemini" and bool(settings.GEMINI_API_KEY)) or
        (settings.AI_PROVIDER == "openrouter" and bool(settings.OPENROUTER_API_KEY))
    )
    active_model = settings.OPENROUTER_MODEL if settings.AI_PROVIDER == "openrouter" else settings.GEMINI_MODEL

    return {
        "status": "healthy",
        "ai_enabled": settings.AI_ENABLED,
        "ai_provider": settings.AI_PROVIDER,
        "ai_configured": ai_configured,
        "ocr_enabled": settings.OCR_ENABLED,
        "model": active_model,
    }


@app.get("/health/detailed", tags=["Santé"])
async def health_detailed(request: Request):
    """Endpoint de santé détaillé pour monitoring avancé."""
    checks = {}

    # DB check
    try:
        from app.database import AsyncSessionLocal
        from sqlalchemy import text
        async with AsyncSessionLocal() as session:
            await session.execute(text("SELECT 1"))
        checks["database"] = {"status": "ok"}
    except Exception as e:
        checks["database"] = {"status": "error", "error": str(e)}

    # Redis check
    redis = getattr(request.app.state, "redis", None)
    if redis:
        try:
            await redis.ping()
            checks["redis"] = {"status": "ok"}
        except Exception as e:
            checks["redis"] = {"status": "error", "error": str(e)}
    else:
        checks["redis"] = {"status": "not_configured"}

    # ARQ check
    arq_pool = getattr(request.app.state, "arq_pool", None)
    if arq_pool and not isinstance(arq_pool, _FallbackArqPool):
        checks["arq"] = {"status": "ok"}
    else:
        checks["arq"] = {"status": "fallback"}

    # OCR check
    checks["ocr"] = {"status": "enabled" if settings.OCR_ENABLED else "disabled"}

    # Storage check
    checks["storage"] = {
        "backend": settings.STORAGE_BACKEND,
        "status": "ok",
    }

    overall = "healthy" if all(
        c.get("status") in ("ok", "enabled", "disabled", "not_configured", "fallback")
        for c in checks.values()
    ) else "degraded"

    return {
        "status": overall,
        "checks": checks,
        "version": settings.APP_VERSION,
    }