"""
Authentication dependencies for FastAPI.
"""

from typing import Optional
from fastapi import Depends, HTTPException, status
from fastapi.security import (
    OAuth2PasswordBearer,
    HTTPBearer,
    HTTPAuthorizationCredentials,
)
from sqlalchemy.ext.asyncio import AsyncSession
from sqlalchemy import select

from app.core.database import get_db
from app.core.security import decode_token
from app.models.database_models import User

# OAuth2 scheme for token authentication
oauth2_scheme = OAuth2PasswordBearer(tokenUrl="/api/v1/auth/login", auto_error=False)
http_bearer = HTTPBearer(auto_error=False)


async def get_current_user(
    token: Optional[str] = Depends(oauth2_scheme),
    credentials: Optional[HTTPAuthorizationCredentials] = Depends(http_bearer),
    db: AsyncSession = Depends(get_db),
) -> User:
    """
    Get current authenticated user from JWT token.
    Supports both OAuth2 password bearer and HTTP Bearer authentication.
    """
    # Get token from either source
    auth_token = token or (credentials.credentials if credentials else None)

    if not auth_token:
        raise HTTPException(
            status_code=status.HTTP_401_UNAUTHORIZED,
            detail="Not authenticated",
            headers={"WWW-Authenticate": "Bearer"},
        )

    # Decode token
    payload = decode_token(auth_token)
    if not payload:
        raise HTTPException(
            status_code=status.HTTP_401_UNAUTHORIZED,
            detail="Invalid authentication credentials",
            headers={"WWW-Authenticate": "Bearer"},
        )

    # Verify token type
    token_type = payload.get("type")
    if token_type != "access":
        raise HTTPException(
            status_code=status.HTTP_401_UNAUTHORIZED,
            detail="Invalid token type",
            headers={"WWW-Authenticate": "Bearer"},
        )

    # Get user ID from token (sub claim is a string per JWT spec)
    sub: Optional[str] = payload.get("sub")
    if sub is None:
        raise HTTPException(
            status_code=status.HTTP_401_UNAUTHORIZED,
            detail="Invalid token payload",
            headers={"WWW-Authenticate": "Bearer"},
        )

    try:
        user_id = int(sub)
    except (ValueError, TypeError):
        raise HTTPException(
            status_code=status.HTTP_401_UNAUTHORIZED,
            detail="Invalid token payload",
            headers={"WWW-Authenticate": "Bearer"},
        )

    # Fetch user from database
    result = await db.execute(select(User).where(User.id == user_id))
    user = result.scalar_one_or_none()

    if user is None:
        raise HTTPException(
            status_code=status.HTTP_401_UNAUTHORIZED,
            detail="User not found",
            headers={"WWW-Authenticate": "Bearer"},
        )

    if not user.is_active:
        raise HTTPException(
            status_code=status.HTTP_403_FORBIDDEN, detail="User account is inactive"
        )

    return user


async def get_current_active_user(
    current_user: User = Depends(get_current_user),
) -> User:
    """Get current active user"""
    if not current_user.is_active:
        raise HTTPException(
            status_code=status.HTTP_403_FORBIDDEN, detail="Inactive user"
        )
    return current_user


async def get_current_superuser(
    current_user: User = Depends(get_current_user),
) -> User:
    """Get current superuser"""
    if not current_user.is_superuser:
        raise HTTPException(
            status_code=status.HTTP_403_FORBIDDEN, detail="Not enough permissions"
        )
    return current_user


def check_subscription_tier(required_tier: str):
    """
    Dependency factory to check if user has required subscription tier.
    Returns a dependency function.
    """
    tier_hierarchy = {"free": 0, "basic": 1, "pro": 2, "enterprise": 3}

    async def check_tier(current_user: User = Depends(get_current_active_user)) -> User:
        user_tier_level = tier_hierarchy.get(current_user.subscription_tier.value, 0)
        required_tier_level = tier_hierarchy.get(required_tier, 0)

        if user_tier_level < required_tier_level:
            raise HTTPException(
                status_code=status.HTTP_402_PAYMENT_REQUIRED,
                detail=f"This feature requires {required_tier} subscription or higher",
            )

        return current_user

    return check_tier