"""
Authentication API routes.
Handles user signup and signin endpoints.
"""

from fastapi import APIRouter, HTTPException, status, Depends
from sqlmodel import Session, select
from app.schemas.auth import (
    SignupRequest,
    SignupResponse,
    SigninRequest,
    SigninResponse,
    UserResponse
)
from app.models.user import User
from app.core.security import hash_password
from app.services.auth_service import authenticate_user
from app.services.jwt_service import create_access_token
from app.api.deps import get_current_user_id
from app.core.database import get_db
from datetime import datetime

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


@router.post("/signup", response_model=SignupResponse, status_code=status.HTTP_201_CREATED)
async def signup(request: SignupRequest, db: Session = Depends(get_db)):
    """
    Create a new user account.

    - **username**: Unique username (3-50 chars, alphanumeric + underscore)
    - **password**: Password (minimum 8 characters)

    Returns created user information.
    """
    # Check if username already exists
    statement = select(User).where(User.username == request.username)
    existing_user = db.exec(statement).first()

    if existing_user:
        raise HTTPException(
            status_code=status.HTTP_400_BAD_REQUEST,
            detail="Username already exists"
        )

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

    # Hash password before storing
    hashed_password = hash_password(request.password)

    # Create user
    new_user = User(
        username=request.username,
        hashed_password=hashed_password,
        created_at=datetime.utcnow(),
        updated_at=datetime.utcnow()
    )

    db.add(new_user)
    db.commit()
    db.refresh(new_user)

    return SignupResponse(
        message="Account created successfully",
        user=UserResponse.model_validate(new_user)
    )


@router.post("/signin", response_model=SigninResponse)
async def signin(request: SigninRequest, db: Session = Depends(get_db)):
    """
    Sign in with username and password.

    - **username**: Username
    - **password**: Password

    Returns JWT token and user information.
    """
    # Authenticate user
    user = authenticate_user(db, request.username, request.password)

    if not user:
        raise HTTPException(
            status_code=status.HTTP_401_UNAUTHORIZED,
            detail="Invalid username or password"
        )

    # Generate JWT token
    token = create_access_token(user.id, user.username)

    return SigninResponse(
        token=token,
        token_type="bearer",
        user=UserResponse.model_validate(user)
    )


@router.get("/me", response_model=UserResponse)
async def get_current_user(
    user_id: str = Depends(get_current_user_id),
    db: Session = Depends(get_db)
):
    """
    Get current authenticated user information.

    Requires valid JWT token in Authorization header.
    """
    user = db.get(User, user_id)

    if not user:
        raise HTTPException(
            status_code=status.HTTP_404_NOT_FOUND,
            detail="User not found"
        )

    return UserResponse.model_validate(user)