# app/auth.py
from datetime import datetime, timedelta
from typing import Optional
from jose import JWTError, jwt
import bcrypt
from fastapi import Depends, HTTPException, status
from fastapi.security import HTTPBearer, HTTPAuthorizationCredentials
from sqlalchemy.orm import Session
from app.config import get_settings
from app.database import get_db
from app.models.admin import Admin

settings = get_settings()
security = HTTPBearer()


def verify_password(plain_password: str, hashed_password: str) -> bool:
    return bcrypt.checkpw(plain_password.encode('utf-8'), hashed_password.encode('utf-8'))


def get_password_hash(password: str) -> str:
    return bcrypt.hashpw(password.encode('utf-8'), bcrypt.gensalt()).decode('utf-8')


def create_access_token(data: dict, expires_delta: Optional[timedelta] = None):
    to_encode = data.copy()
    if expires_delta:
        expire = datetime.utcnow() + expires_delta
    else:
        expire = datetime.utcnow() + timedelta(minutes=15)
    to_encode.update({"exp": expire})
    encoded_jwt = jwt.encode(to_encode, settings.SECRET_KEY, algorithm=settings.ALGORITHM)
    return encoded_jwt


def decode_token(token: str) -> Optional[dict]:
    try:
        payload = jwt.decode(token, settings.SECRET_KEY, algorithms=[settings.ALGORITHM])
        return payload
    except JWTError:
        return None


async def get_current_admin(
    credentials: HTTPAuthorizationCredentials = Depends(security),
    db: Session = Depends(get_db)
) -> Admin:
    token = credentials.credentials
    payload = decode_token(token)
    
    if payload is None:
        raise HTTPException(
            status_code=status.HTTP_401_UNAUTHORIZED,
            detail="Invalid authentication credentials",
            headers={"WWW-Authenticate": "Bearer"},
        )
    
    username: str = payload.get("sub")
    if username is None:
        raise HTTPException(
            status_code=status.HTTP_401_UNAUTHORIZED,
            detail="Invalid authentication credentials",
            headers={"WWW-Authenticate": "Bearer"},
        )
    
    admin = db.query(Admin).filter(Admin.username == username).first()
    if admin is None:
        raise HTTPException(
            status_code=status.HTTP_401_UNAUTHORIZED,
            detail="User not found",
            headers={"WWW-Authenticate": "Bearer"},
        )
    
    return admin


async def get_optional_admin(
    credentials: Optional[HTTPAuthorizationCredentials] = Depends(security),
    db: Session = Depends(get_db)
) -> Optional[Admin]:
    if not credentials:
        return None
    try:
        return await get_current_admin(credentials, db)
    except HTTPException:
        return None