from database import execute, fetch_one
import bcrypt
from jose import jwt, JWTError
from datetime import datetime, timedelta
from fastapi import Header, HTTPException
from dotenv import load_dotenv
import os   

load_dotenv()

SECRET_KEY = os.getenv("SECRET_KEY")
ALGORITHM = "HS256"


def create_token(user_id):
    payload = {
        "user_id": user_id,
        "exp": datetime.utcnow() + timedelta(hours=24)
    }

    token = jwt.encode(
        payload,
        SECRET_KEY,
        algorithm=ALGORITHM
    )

    return token


def create_user(username, password):

    password_hash = bcrypt.hashpw(
        password.encode(),
        bcrypt.gensalt()
    ).decode()

    user_id = execute(
        """
        INSERT INTO users (username, password_hash)
        VALUES (?, ?)
        """,
        (username, password_hash)
    )

    return user_id


def verify_user(username, password):

    user = fetch_one(
        "SELECT * FROM users WHERE username = ?",
        (username,)
    )

    if not user:
        return None

    if bcrypt.checkpw(
        password.encode(),
        user["password_hash"].encode()
    ):
        return user["id"]

    return None


def get_current_user(authorization: str = Header(None)):

    if authorization is None:
        raise HTTPException(
            status_code=401,
            detail="Missing token"
        )

    try:
        scheme, token = authorization.split(" ")

        if scheme.lower() != "bearer":
            raise Exception()

        payload = jwt.decode(
            token,
            SECRET_KEY,
            algorithms=[ALGORITHM]
        )

        user_id = payload["user_id"]

        return user_id

    except JWTError:
        raise HTTPException(
            status_code=401,
            detail="Invalid token"
        )