from datetime import datetime, timedelta
from typing import Optional
from jose import JWTError, jwt
from fastapi import Depends, HTTPException, status
from fastapi.security import OAuth2PasswordBearer, APIKeyHeader
from sqlalchemy.orm import Session
import os

from app.core.config import settings
from app.db.base import get_db
from app.db.models import User
from app.models.token import TokenData

# OAuth2 scheme for token authentication
oauth2_scheme = OAuth2PasswordBearer(tokenUrl=f"{settings.API_V1_STR}/auth/login")

# API Key security scheme
API_KEY_NAME = "X-API-Key"
api_key_header = APIKeyHeader(name=API_KEY_NAME, auto_error=False)

# Use API key from settings
async def get_api_key_user(
    api_key: str = Depends(api_key_header),
) -> bool:
    """
    Validate the API key from the request header.
    
    Args:
        api_key: The API key from the request header
        
    Returns:
        bool: True if the API key is valid
        
    Raises:
        HTTPException: If the API key is invalid
    """
    if not api_key:
        raise HTTPException(
            status_code=status.HTTP_401_UNAUTHORIZED,
            detail="API key required",
            headers={"WWW-Authenticate": "ApiKey"},
        )
    
    if api_key != settings.API_KEY:
        raise HTTPException(
            status_code=status.HTTP_401_UNAUTHORIZED,
            detail="Invalid API key",
            headers={"WWW-Authenticate": "ApiKey"},
        )
    
    return True

def create_access_token(data: dict, expires_delta: Optional[timedelta] = None) -> str:
    """
    Create a new JWT access token.
    
    Args:
        data: The data to encode in the token
        expires_delta: Optional expiration time delta
        
    Returns:
        str: The encoded JWT token
    """
    to_encode = data.copy()
    
    # Set expiration time
    if expires_delta:
        expire = datetime.utcnow() + expires_delta
    else:
        # Use configured expiration time from settings
        expire = datetime.utcnow() + timedelta(minutes=settings.ACCESS_TOKEN_EXPIRE_MINUTES)
    
    to_encode.update({"exp": expire})
    
    # Create the JWT token
    encoded_jwt = jwt.encode(
        to_encode, 
        settings.SECRET_KEY, 
        algorithm=settings.ALGORITHM
    )
    
    return encoded_jwt


async def get_current_user(
    token: str = Depends(oauth2_scheme),
    db: Session = Depends(get_db)
) -> User:
    """
    Get the current authenticated user from the token.
    
    Args:
        token: The JWT token
        db: Database session
        
    Returns:
        User: The authenticated user
        
    Raises:
        HTTPException: If authentication fails
    """
    credentials_exception = HTTPException(
        status_code=status.HTTP_401_UNAUTHORIZED,
        detail="Could not validate credentials",
        headers={"WWW-Authenticate": "Bearer"},
    )
    
    try:
        # Decode the JWT token
        payload = jwt.decode(
            token, 
            settings.SECRET_KEY, 
            algorithms=[settings.ALGORITHM]
        )
        
        # Extract user_id from token
        user_id: str = payload.get("sub")
        if user_id is None:
            raise credentials_exception
            
        token_data = TokenData(user_id=user_id)
    except JWTError as e:
        # Log the specific JWT error for debugging
        print(f"JWT validation error: {str(e)}")
        # If it's a signature verification failure, return a specific error
        if "signature" in str(e).lower() or "invalid" in str(e).lower():
            raise HTTPException(
                status_code=status.HTTP_401_UNAUTHORIZED,
                detail="Invalid token signature",
                headers={"WWW-Authenticate": "Bearer"},
            )
        raise credentials_exception
    
    # Get the user from the database
    user = db.query(User).filter(User.id == token_data.user_id).first()
    if user is None:
        print(f"User not found in database: {token_data.user_id}")
        raise credentials_exception
    
    # Check if token is expired
    try:
        exp = payload.get("exp")
        if exp is None:
            print(f"Token has no expiration: {user.id}")
            raise credentials_exception
            
        expiry_time = datetime.fromtimestamp(exp)
        current_time = datetime.utcnow()
        
        # Add detailed logging for token expiration
        time_until_expiry = expiry_time - current_time
        print(f"Token expiration check: current={current_time}, expiry={expiry_time}, seconds_remaining={time_until_expiry.total_seconds()}")
        
        if expiry_time < current_time:
            print(f"Token expired for user: {user.id}, expired at {expiry_time}")
            raise HTTPException(
                status_code=status.HTTP_401_UNAUTHORIZED,
                detail="Token expired",
                headers={"WWW-Authenticate": "Bearer"},
            )
    except Exception as e:
        print(f"Error checking token expiration: {str(e)}")
        raise credentials_exception
    
    # Check if user is active
    if not user.is_active:
        raise HTTPException(
            status_code=status.HTTP_403_FORBIDDEN,
            detail="Inactive user"
        )
    
    return user


async def get_current_active_user(
    current_user: User = Depends(get_current_user)
) -> User:
    """
    Get the current active user.
    
    Args:
        current_user: The current authenticated user
        
    Returns:
        User: The current active user
        
    Raises:
        HTTPException: If the user is inactive
    """
    if not current_user.is_active:
        raise HTTPException(
            status_code=status.HTTP_403_FORBIDDEN,
            detail="Inactive user"
        )
    return current_user