"""Authentication endpoints."""
from datetime import timedelta
from fastapi import APIRouter, Depends, HTTPException, status
from fastapi.security import OAuth2PasswordBearer, OAuth2PasswordRequestForm
from sqlalchemy.orm import Session
from typing import List

from app.core.database import get_db
from app.core.security import verify_password, create_access_token, decode_access_token, get_password_hash
from app.core.config import settings
from app.models.user import User
from app.schemas.auth import Token
from app.schemas.user import UserCreate, UserResponse, UserUpdate, UserAdminUpdate

router = APIRouter()
oauth2_scheme = OAuth2PasswordBearer(tokenUrl="/api/v1/auth/login")

def get_current_user(token: str = Depends(oauth2_scheme), db: Session = Depends(get_db)) -> User:
    """Get the current authenticated user."""
    credentials_exception = HTTPException(
        status_code=status.HTTP_401_UNAUTHORIZED,
        detail="Could not validate credentials",
        headers={"WWW-Authenticate": "Bearer"},
    )
    
    payload = decode_access_token(token)
    if payload is None:
        raise credentials_exception
    
    username: str = payload.get("sub")
    if username is None:
        raise credentials_exception
    
    user = db.query(User).filter(User.username == username).first()
    if user is None:
        raise credentials_exception
    
    return user

def get_current_admin_user(current_user: User = Depends(get_current_user)) -> User:
    """Get current user and verify they are an admin."""
    if not current_user.is_admin:
        raise HTTPException(
            status_code=status.HTTP_403_FORBIDDEN,
            detail="Not enough permissions"
        )
    return current_user

@router.post("/register", response_model=UserResponse, status_code=status.HTTP_201_CREATED)
async def register(user_data: UserCreate, db: Session = Depends(get_db)):
    """Register a new user."""
    # Check if username already exists
    if db.query(User).filter(User.username == user_data.username).first():
        raise HTTPException(
            status_code=status.HTTP_400_BAD_REQUEST,
            detail="Username already registered"
        )
    
    # Check if email already exists
    if db.query(User).filter(User.email == user_data.email).first():
        raise HTTPException(
            status_code=status.HTTP_400_BAD_REQUEST,
            detail="Email already registered"
        )
    
    # Create new user
    db_user = User(
        username=user_data.username,
        email=user_data.email,
        full_name=user_data.full_name,
        discord_id=user_data.discord_id,
        profile_picture=user_data.profile_picture,
        hashed_password=get_password_hash(user_data.password),
        is_active=True,
        is_admin=False
    )
    
    db.add(db_user)
    db.commit()
    db.refresh(db_user)
    
    return db_user

@router.post("/login", response_model=Token)
async def login(form_data: OAuth2PasswordRequestForm = Depends(), db: Session = Depends(get_db)):
    """Login and get access token."""
    user = db.query(User).filter(User.username == form_data.username).first()
    
    if not user or not verify_password(form_data.password, user.hashed_password):
        raise HTTPException(
            status_code=status.HTTP_401_UNAUTHORIZED,
            detail="Incorrect username or password",
            headers={"WWW-Authenticate": "Bearer"},
        )
    
    if not user.is_active:
        raise HTTPException(
            status_code=status.HTTP_400_BAD_REQUEST,
            detail="Inactive user"
        )
    
    access_token_expires = timedelta(minutes=settings.ACCESS_TOKEN_EXPIRE_MINUTES)
    access_token = create_access_token(
        data={"sub": user.username},
        expires_delta=access_token_expires
    )
    
    return {"access_token": access_token, "token_type": "bearer"}

@router.get("/me", response_model=UserResponse)
async def get_current_user_info(current_user: User = Depends(get_current_user)):
    """Get current user information."""
    return current_user

@router.put("/me", response_model=UserResponse)
async def update_current_user(
    user_update: UserUpdate,
    current_user: User = Depends(get_current_user),
    db: Session = Depends(get_db)
):
    """Update current user's own profile."""
    update_data = user_update.model_dump(exclude_unset=True)
    
    # Hash password if provided
    if "password" in update_data and update_data["password"]:
        update_data["hashed_password"] = get_password_hash(update_data.pop("password"))
    
    # Check email uniqueness if being updated
    if "email" in update_data:
        existing_user = db.query(User).filter(
            User.email == update_data["email"],
            User.id != current_user.id
        ).first()
        if existing_user:
            raise HTTPException(
                status_code=status.HTTP_400_BAD_REQUEST,
                detail="Email already in use"
            )
    
    # Update user fields
    for field, value in update_data.items():
        setattr(current_user, field, value)
    
    db.commit()
    db.refresh(current_user)
    return current_user

@router.get("/users", response_model=List[UserResponse])
async def list_users(
    db: Session = Depends(get_db),
    admin_user: User = Depends(get_current_admin_user)
):
    """Admin endpoint to list all users."""
    users = db.query(User).all()
    return users

@router.put("/users/{user_id}", response_model=UserResponse)
async def update_user_admin(
    user_id: int,
    user_update: UserAdminUpdate,
    db: Session = Depends(get_db),
    admin_user: User = Depends(get_current_admin_user)
):
    """Admin endpoint to update any user."""
    user = db.query(User).filter(User.id == user_id).first()
    if not user:
        raise HTTPException(
            status_code=status.HTTP_404_NOT_FOUND,
            detail="User not found"
        )
    
    update_data = user_update.model_dump(exclude_unset=True)
    
    # Hash password if provided
    if "password" in update_data and update_data["password"]:
        update_data["hashed_password"] = get_password_hash(update_data.pop("password"))
    
    # Check email uniqueness if being updated
    if "email" in update_data:
        existing_user = db.query(User).filter(
            User.email == update_data["email"],
            User.id != user.id
        ).first()
        if existing_user:
            raise HTTPException(
                status_code=status.HTTP_400_BAD_REQUEST,
                detail="Email already in use"
            )
    
    # Update user fields
    for field, value in update_data.items():
        setattr(user, field, value)
    
    db.commit()
    db.refresh(user)
    return user