"""
FastAPI dependency injection container.

Provides shared resources and services to route handlers.
"""

from functools import lru_cache
from typing import Optional
import asyncio

from fastapi import Request, Depends, HTTPException
from jinja2 import Environment

from artdag_common.middleware.auth import UserContext, get_user_from_cookie, get_user_from_header

from .config import settings


# Lazy imports to avoid circular dependencies
_redis_client = None
_cache_manager = None
_database = None


def get_redis_client():
    """Get the Redis client singleton."""
    global _redis_client
    if _redis_client is None:
        import redis
        _redis_client = redis.from_url(settings.redis_url, decode_responses=True)
    return _redis_client


def get_cache_manager():
    """Get the cache manager singleton."""
    global _cache_manager
    if _cache_manager is None:
        from cache_manager import get_cache_manager as _get_cache_manager
        _cache_manager = _get_cache_manager()
    return _cache_manager


def get_database():
    """Get the database singleton."""
    global _database
    if _database is None:
        import database
        _database = database
    return _database


def get_templates(request: Request) -> Environment:
    """Get the Jinja2 environment from app state."""
    return request.app.state.templates


async def get_current_user(request: Request) -> Optional[UserContext]:
    """
    Get the current user from request (cookie or header).

    This is a permissive dependency - returns None if not authenticated.
    Use require_auth for routes that require authentication.
    """
    # Try header first (API clients)
    ctx = get_user_from_header(request)
    if ctx:
        # Add l2_server from settings
        ctx.l2_server = settings.l2_server
        return ctx

    # Fall back to cookie (browser)
    ctx = get_user_from_cookie(request)
    if ctx:
        ctx.l2_server = settings.l2_server
    return ctx


async def require_auth(request: Request) -> UserContext:
    """
    Require authentication for a route.

    Raises:
        HTTPException 401 if not authenticated
        HTTPException 302 redirect to login for HTML requests
    """
    ctx = await get_current_user(request)
    if ctx is None:
        # Check if HTML request for redirect
        accept = request.headers.get("accept", "")
        if "text/html" in accept:
            raise HTTPException(
                status_code=302,
                headers={"Location": "/login"}
            )
        raise HTTPException(status_code=401, detail="Authentication required")
    return ctx


async def get_user_context_from_cookie(request: Request) -> Optional[UserContext]:
    """
    Legacy compatibility: get user from cookie.

    Validates token with L2 server if configured.
    """
    ctx = get_user_from_cookie(request)
    if ctx is None:
        return None

    # If L2 server configured, could validate token here
    # For now, trust the cookie
    return ctx


# Service dependencies (lazy loading)

def get_run_service():
    """Get the run service."""
    from .services.run_service import RunService
    return RunService(
        database=get_database(),
        redis=get_redis_client(),
        cache=get_cache_manager(),
    )


def get_recipe_service():
    """Get the recipe service."""
    from .services.recipe_service import RecipeService
    return RecipeService(
        redis=get_redis_client(),  # Kept for API compatibility, not used
        cache=get_cache_manager(),
    )


def get_cache_service():
    """Get the cache service."""
    from .services.cache_service import CacheService
    return CacheService(
        cache_manager=get_cache_manager(),
        database=get_database(),
    )