from datetime import timedelta, timezone, datetime
from typing import Annotated
from fastapi import Depends, HTTPException, Response, status
from pydantic import BaseModel
import jwt
from jwt.exceptions import InvalidTokenError
from sqlmodel import Session, select
from db import engine, User
from fastapi.security import OAuth2PasswordBearer, OAuth2PasswordRequestForm
from pydantic_settings import BaseSettings, SettingsConfigDict
from passlib.context import CryptContext


class Config(BaseSettings):
    secret_key: str = ""
    access_token_expire_minutes: int = 30
    model_config = SettingsConfigDict(
        env_file=".env", env_file_encoding="utf-8", extra="ignore"
    )


config = Config()


class Token(BaseModel):
    access_token: str
    token_type: str


class TokenData(BaseModel):
    username: str | None = None


pwd_context = CryptContext(schemes=["argon2"], deprecated="auto")


oauth2_scheme = OAuth2PasswordBearer(tokenUrl="api/token")


def verify_password(plain_password, hashed_password):
    return pwd_context.verify(plain_password, hashed_password)


def get_password_hash(password):
    return pwd_context.hash(password)


def get_user(username: str | None):
    if username:
        with Session(engine) as session:
            return session.exec(
                select(User).where(User.username == username)
            ).one_or_none()


def authenticate_user(username: str, password: str):
    user = get_user(username)
    if not user:
        return False
    if not verify_password(password, user.hashed_password):
        return False
    return user


def create_access_token(data: dict, expires_delta: timedelta | None = None):
    to_encode = data.copy()
    if expires_delta:
        expire = datetime.now(timezone.utc) + expires_delta
    else:
        expire = datetime.now(timezone.utc) + timedelta(minutes=15)
    to_encode.update({"exp": expire})
    encoded_jwt = jwt.encode(to_encode, config.secret_key, algorithm="HS256")
    return encoded_jwt


async def get_current_user(token: Annotated[str, Depends(oauth2_scheme)]):
    credentials_exception = HTTPException(
        status_code=status.HTTP_401_UNAUTHORIZED,
        detail="Could not validate credentials",
        headers={"WWW-Authenticate": "Bearer"},
    )
    try:
        payload = jwt.decode(token, config.secret_key, algorithms=["HS256"])
        username: str = payload.get("sub")
        if username is None:
            raise credentials_exception
        token_data = TokenData(username=username)
    except InvalidTokenError:
        raise credentials_exception
    user = get_user(username=token_data.username)
    if user is None:
        raise credentials_exception
    return user


async def get_current_active_user(
    current_user: Annotated[User, Depends(get_current_user)],
):
    if current_user.disabled:
        raise HTTPException(status_code=400, detail="Inactive user")
    return current_user


async def login_for_access_token(
    form_data: Annotated[OAuth2PasswordRequestForm, Depends()], response: Response
) -> Token:
    user = authenticate_user(form_data.username, form_data.password)
    if not user:
        raise HTTPException(
            status_code=status.HTTP_401_UNAUTHORIZED,
            detail="Incorrect username or password",
            headers={"WWW-Authenticate": "Bearer"},
        )
    access_token_expires = timedelta(minutes=config.access_token_expire_minutes)
    access_token = create_access_token(
        data={"sub": user.username}, expires_delta=access_token_expires
    )
    response.set_cookie(
        "Authorization", value=f"Bearer {access_token}", httponly=True, samesite="none"
    )
    return Token(access_token=access_token, token_type="bearer")


async def read_users_me(
    current_user: Annotated[User, Depends(get_current_active_user)],
):
    return current_user


async def read_own_items(
    current_user: Annotated[User, Depends(get_current_active_user)],
):
    return [{"item_id": "Foo", "owner": current_user.username}]