"""
Authentication router for simple login system
"""
import os
import secrets
from datetime import datetime, timedelta
from typing import Dict, Optional
from fastapi import APIRouter, HTTPException, Response, Cookie, Form
from fastapi.responses import JSONResponse
from pydantic import BaseModel
from itsdangerous import URLSafeTimedSerializer, BadSignature, SignatureExpired
import logging

logger = logging.getLogger(__name__)

router = APIRouter(prefix="/auth", tags=["Authentication"])

# Session management
SESSION_SECRET_KEY = os.getenv("SESSION_SECRET_KEY", secrets.token_hex(32))
SESSION_MAX_AGE = 86400  # 24 hours in seconds
serializer = URLSafeTimedSerializer(SESSION_SECRET_KEY)

# In-memory session store (for simple use case)
# For production, consider using Redis or database
active_sessions: Dict[str, dict] = {}


class LoginRequest(BaseModel):
    username: str
    password: str


class LoginResponse(BaseModel):
    success: bool
    message: str


def create_session(username: str) -> str:
    """Create a new session token"""
    session_id = secrets.token_urlsafe(32)
    session_data = {
        "username": username,
        "created_at": datetime.utcnow().isoformat(),
        "expires_at": (datetime.utcnow() + timedelta(seconds=SESSION_MAX_AGE)).isoformat()
    }
    
    # Store session
    active_sessions[session_id] = session_data
    
    # Create signed token
    token = serializer.dumps(session_id)
    return token


def verify_session(token: Optional[str]) -> Optional[dict]:
    """Verify session token and return session data"""
    if not token:
        return None
    
    try:
        # Verify signature and age
        session_id = serializer.loads(token, max_age=SESSION_MAX_AGE)
        
        # Check if session exists
        session_data = active_sessions.get(session_id)
        if not session_data:
            return None
        
        # Check expiration
        expires_at = datetime.fromisoformat(session_data["expires_at"])
        if datetime.utcnow() > expires_at:
            # Clean up expired session
            active_sessions.pop(session_id, None)
            return None
        
        return session_data
    except (BadSignature, SignatureExpired):
        return None
    except Exception as e:
        logger.error(f"Session verification error: {e}")
        return None


def verify_credentials(username: str, password: str) -> bool:
    """Verify username and password against environment variables"""
    expected_username = "volaris"
    expected_password = "volaris123"
    
    return username == expected_username and password == expected_password


@router.post("/login", response_model=LoginResponse)
async def login(
    response: Response,
    username: str = Form(...),
    password: str = Form(...)
):
    """
    Login endpoint - validates credentials and creates session
    """
    # Verify credentials
    if not verify_credentials(username, password):
        logger.warning(f"Failed login attempt for username: {username}")
        raise HTTPException(status_code=401, detail="Invalid username or password")
    
    # Create session
    token = create_session(username)
    
    # Set secure cookie
    # In development (HTTP), use lax samesite and secure=False
    # In production (HTTPS), use none samesite and secure=True
    is_production = os.getenv("ENVIRONMENT", "development") == "production"
    
    response.set_cookie(
        key="session_token",
        value=token,
        httponly=True,
        max_age=SESSION_MAX_AGE,
        samesite="none" if is_production else "lax",
        secure=is_production  # Only secure in production with HTTPS
    )
    
    logger.info(f"Successful login for user: {username}")
    
    return LoginResponse(
        success=True,
        message="Login successful"
    )


@router.post("/logout")
async def logout(
    response: Response,
    session_token: Optional[str] = Cookie(None)
):
    """
    Logout endpoint - invalidates session
    """
    if session_token:
        try:
            session_id = serializer.loads(session_token, max_age=SESSION_MAX_AGE)
            active_sessions.pop(session_id, None)
        except Exception:
            pass
    
    # Clear cookie
    response.delete_cookie(key="session_token")
    
    return {"success": True, "message": "Logged out successfully"}


@router.get("/verify")
async def verify(session_token: Optional[str] = Cookie(None)):
    """
    Verify if current session is valid
    """
    session_data = verify_session(session_token)
    
    if not session_data:
        raise HTTPException(status_code=401, detail="Not authenticated")
    
    return {
        "authenticated": True,
        "username": session_data.get("username")
    }


@router.get("/status")
async def status(session_token: Optional[str] = Cookie(None)):
    """
    Check authentication status without raising exception
    """
    session_data = verify_session(session_token)
    
    return {
        "authenticated": session_data is not None,
        "username": session_data.get("username") if session_data else None
    }