from fastapi import APIRouter, HTTPException, status, Depends, Response, Request
from sqlmodel import Session, select
from typing import Annotated
from datetime import datetime, timedelta
from uuid import uuid4
import secrets
import hashlib

from ..models.user import User, UserCreate, UserRead
from ..models.refresh_token import RefreshToken
from ..schemas.auth import RegisterRequest, RegisterResponse, LoginRequest, LoginResponse, ForgotPasswordRequest, ResetPasswordRequest
from ..utils.security import hash_password, create_access_token, verify_password
from ..utils.deps import get_current_user
from ..database import get_session_dep
from ..config import settings


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

# Refresh token settings
REFRESH_TOKEN_EXPIRE_DAYS = 30
REFRESH_TOKEN_COOKIE_NAME = "refresh_token"

# NOTE: For cross-site cookie auth to work (backend on a different domain than the frontend):
# - The frontend must call login/register endpoints with `fetch(..., credentials: 'include')`
# - The backend must have CORS allow_credentials=True and the exact frontend origin in allow_origins
# - Cookies must be set with `Secure=True` and `samesite='none'` in production
# See project README or docs for full details


@router.post("/register", response_model=RegisterResponse, status_code=status.HTTP_201_CREATED)
def register(user_data: RegisterRequest, response: Response, session: Session = Depends(get_session_dep)):
    """Register a new user with email and password.

    This returns a short-lived access token in the response and sets a HttpOnly refresh cookie.
    """

    # Check if user already exists
    existing_user = session.exec(select(User).where(User.email == user_data.email)).first()
    if existing_user:
        raise HTTPException(
            status_code=status.HTTP_409_CONFLICT,
            detail="An account with this email already exists"
        )

    # Validate password length
    if len(user_data.password) < 8:
        raise HTTPException(
            status_code=status.HTTP_400_BAD_REQUEST,
            detail="Password must be at least 8 characters"
        )

    # Hash the password
    password_hash = hash_password(user_data.password)

    # Create new user
    user = User(
        email=user_data.email,
        password_hash=password_hash
    )

    session.add(user)
    session.commit()
    session.refresh(user)

    # Issue short-lived access token and refresh token
    access_token = create_access_token(data={"sub": str(user.id)}, expires_delta=timedelta(minutes=15))

    # Create refresh token, store hashed token in DB
    raw_refresh = secrets.token_urlsafe(64)
    token_hash = hashlib.sha256(raw_refresh.encode()).hexdigest()
    expires_at = datetime.utcnow() + timedelta(days=REFRESH_TOKEN_EXPIRE_DAYS)

    refresh_record = RefreshToken(token_hash=token_hash, user_id=user.id, expires_at=expires_at)
    session.add(refresh_record)
    session.commit()

    # Set HttpOnly refresh cookie
    response.set_cookie(
        key=REFRESH_TOKEN_COOKIE_NAME,
        value=raw_refresh,
        httponly=True,
        secure=settings.JWT_COOKIE_SECURE,
        samesite="none",
        max_age=REFRESH_TOKEN_EXPIRE_DAYS * 24 * 60 * 60,
        path="/api/auth"
    )

    return RegisterResponse(
        id=user.id,
        email=user.email,
        message="Account created successfully"
    )


@router.post("/login", response_model=LoginResponse)
def login(login_data: LoginRequest, response: Response, session: Session = Depends(get_session_dep)):
    """Authenticate user with email and password.

    Returns a short-lived access token in the response body and sets a HttpOnly refresh cookie.
    Frontend should store access token in memory and call protected APIs with Authorization header, or let frontend call `/api/auth/refresh` (with `credentials: 'include'`) to obtain a new access token.
    """

    # Find user by email
    user = session.exec(select(User).where(User.email == login_data.email)).first()

    if not user or not verify_password(login_data.password, user.password_hash):
        raise HTTPException(
            status_code=status.HTTP_401_UNAUTHORIZED,
            detail="Invalid email or password",
            headers={"WWW-Authenticate": "Bearer"},
        )

    # Create short-lived access token (e.g., 15 minutes)
    access_token = create_access_token(data={"sub": str(user.id)}, expires_delta=timedelta(minutes=15))

    # Create refresh token, store hashed token in DB
    raw_refresh = secrets.token_urlsafe(64)
    token_hash = hashlib.sha256(raw_refresh.encode()).hexdigest()
    expires_at = datetime.utcnow() + timedelta(days=REFRESH_TOKEN_EXPIRE_DAYS)

    refresh_record = RefreshToken(token_hash=token_hash, user_id=user.id, expires_at=expires_at)
    session.add(refresh_record)
    session.commit()

    # Set HttpOnly refresh cookie (sent to frontend with credentials: 'include')
    response.set_cookie(
        key=REFRESH_TOKEN_COOKIE_NAME,
        value=raw_refresh,
        httponly=True,
        secure=settings.JWT_COOKIE_SECURE,
        samesite="none",
        max_age=REFRESH_TOKEN_EXPIRE_DAYS * 24 * 60 * 60,
        path="/api/auth"
    )

    print(f"Refresh cookie set (httponly={True}, secure={settings.JWT_COOKIE_SECURE}, samesite=none, max_age={REFRESH_TOKEN_EXPIRE_DAYS * 24 * 60 * 60})")

    # Return short-lived access token in response body for immediate use
    return LoginResponse(
        access_token=access_token,
        token_type="bearer",
        user=RegisterResponse(
            id=user.id,
            email=user.email,
            message="Login successful"
        )
    )


@router.post("/refresh")
def refresh_token(request: Request, response: Response, session: Session = Depends(get_session_dep)):
    """Rotate refresh token and return a new short-lived access token.

    This endpoint reads the HttpOnly refresh cookie, validates it, rotates it (revokes old),
    and sets a new refresh cookie (cookie rotation) and returns a fresh access token.
    Frontend must call this with `credentials: 'include'`.
    """
    raw_refresh = request.cookies.get(REFRESH_TOKEN_COOKIE_NAME)
    if not raw_refresh:
        raise HTTPException(status_code=status.HTTP_401_UNAUTHORIZED, detail="No refresh token provided")

    token_hash = hashlib.sha256(raw_refresh.encode()).hexdigest()
    token_record = session.exec(select(RefreshToken).where(RefreshToken.token_hash == token_hash)).first()

    if not token_record or token_record.revoked:
        raise HTTPException(status_code=status.HTTP_401_UNAUTHORIZED, detail="Invalid refresh token")

    if token_record.expires_at < datetime.utcnow():
        raise HTTPException(status_code=status.HTTP_401_UNAUTHORIZED, detail="Refresh token expired")

    # Get user
    user = session.get(User, token_record.user_id)
    if not user:
        raise HTTPException(status_code=status.HTTP_401_UNAUTHORIZED, detail="User not found")

    # Revoke old token and rotate
    token_record.revoked = True
    session.add(token_record)

    # Create new refresh token
    new_raw_refresh = secrets.token_urlsafe(64)
    new_token_hash = hashlib.sha256(new_raw_refresh.encode()).hexdigest()
    new_expires_at = datetime.utcnow() + timedelta(days=REFRESH_TOKEN_EXPIRE_DAYS)

    new_refresh_record = RefreshToken(token_hash=new_token_hash, user_id=user.id, expires_at=new_expires_at)
    session.add(new_refresh_record)
    session.commit()

    # Set new refresh cookie
    response.set_cookie(
        key=REFRESH_TOKEN_COOKIE_NAME,
        value=new_raw_refresh,
        httponly=True,
        secure=settings.JWT_COOKIE_SECURE,
        samesite="none",
        max_age=REFRESH_TOKEN_EXPIRE_DAYS * 24 * 60 * 60,
        path="/api/auth"
    )

    # Create new short-lived access token and return it
    access_token = create_access_token(data={"sub": str(user.id)}, expires_delta=timedelta(minutes=15))

    return {"access_token": access_token, "token_type": "bearer"}


@router.post("/logout")
def logout(request: Request, response: Response, session: Session = Depends(get_session_dep)):
    """Logout user by revoking the refresh token cookie and clearing the cookie."""
    raw_refresh = request.cookies.get(REFRESH_TOKEN_COOKIE_NAME)
    if raw_refresh:
        token_hash = hashlib.sha256(raw_refresh.encode()).hexdigest()
        token_record = session.exec(select(RefreshToken).where(RefreshToken.token_hash == token_hash)).first()
        if token_record:
            token_record.revoked = True
            session.add(token_record)
            session.commit()

    # Clear the refresh cookie
    response.set_cookie(
        key=REFRESH_TOKEN_COOKIE_NAME,
        value="",
        httponly=True,
        secure=settings.JWT_COOKIE_SECURE,
        samesite="none",
        max_age=0,  # Expire immediately
        path="/api/auth"
    )

    return {"message": "Logged out successfully"}


@router.get("/me", response_model=RegisterResponse)
def get_current_user_profile(request: Request, current_user: User = Depends(get_current_user)):
    """Get the current authenticated user's profile."""
    # Debug: Print the cookies received (do not print token values)
    print(f"Received cookies: { {k: '***' for k in request.cookies.keys()} }")
    
    return RegisterResponse(
        id=current_user.id,
        email=current_user.email,
        message="User profile retrieved successfully"
    )


@router.post("/forgot-password")
def forgot_password(forgot_data: ForgotPasswordRequest, session: Session = Depends(get_session_dep)):
    """Initiate password reset process by verifying email exists."""
    # Check if user exists
    user = session.exec(select(User).where(User.email == forgot_data.email)).first()
    
    if not user:
        # For security reasons, we don't reveal if the email exists or not
        return {"message": "If the email exists, a reset link would be sent"}
    
    # In a real implementation, we would send an email here
    # But as per requirements, we're just simulating the process
    return {"message": "If the email exists, a reset link would be sent"}


@router.post("/reset-password")
def reset_password(reset_data: ResetPasswordRequest, session: Session = Depends(get_session_dep)):
    """Reset user password after verification."""
    # Check if user exists
    user = session.exec(select(User).where(User.email == reset_data.email)).first()
    
    if not user:
        raise HTTPException(
            status_code=status.HTTP_404_NOT_FOUND,
            detail="User not found"
        )
    
    # Validate password length
    if len(reset_data.new_password) < 8:
        raise HTTPException(
            status_code=status.HTTP_400_BAD_REQUEST,
            detail="Password must be at least 8 characters"
        )
    
    # Hash the new password
    user.password_hash = hash_password(reset_data.new_password)
    
    # Update the user
    session.add(user)
    session.commit()
    
    return {"message": "Password reset successfully"}