from datetime import datetime, timedelta

from fastapi import APIRouter, Depends, HTTPException, status
from fastapi.security import OAuth2PasswordBearer, OAuth2PasswordRequestForm
from jose import JWTError, jwt
from pydantic import BaseModel
from sqlalchemy.orm import Session

from ..config import Config, JWTConfig
from ..db import Connection, schemas

router = APIRouter(prefix="/user")
SCHEME = OAuth2PasswordBearer(
    tokenUrl=f".{router.prefix}/auth",
)


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


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


def create_access_token(
    data: dict,
    jwt_config: JWTConfig,
    expires_delta: timedelta | None = None,
):
    to_encode = data.copy()

    if expires_delta is None:
        expires_delta = timedelta(minutes=jwt_config.expiry_minutes)

    to_encode.update({"exp": datetime.utcnow() + expires_delta})
    return jwt.encode(
        to_encode,
        jwt_config.secret,
        algorithm=jwt_config.hash_algorithm,
    )


@router.post("/auth", response_model=Token)
async def login(
    form_data: OAuth2PasswordRequestForm = Depends(),
    config: Config = Depends(Config.get),
    db: Session = Depends(Connection.get),
):
    user = schemas.User.verify(
        db=db,
        name=form_data.username,
        password=form_data.password,
        crypt_context=config.crypt_context,
    )

    if user is None:
        raise HTTPException(
            status_code=status.HTTP_401_UNAUTHORIZED,
            detail="Could not validate credentials",
            headers={"WWW-Authenticate": "Bearer"},
        )

    access_token = create_access_token(
        data={"sub": user.name},
        jwt_config=config.jwt,
    )

    return {"access_token": access_token, "token_type": "bearer"}


async def dep_get_current_user(
    token: str = Depends(SCHEME),
    db: Session = Depends(Connection.get),
    config: Config = Depends(Config.get),
):
    credentials_exception = HTTPException(
        status_code=status.HTTP_401_UNAUTHORIZED,
        detail="Could not validate credentials",
        headers={"WWW-Authenticate": "Bearer"},
    )
    try:
        payload = jwt.decode(token, config.jwt.secret, algorithms=[
                             config.jwt.hash_algorithm])
        username: str = payload.get("sub")
        if username is None:
            raise credentials_exception
        token_data = TokenData(username=username)
    except JWTError:
        raise credentials_exception

    user = schemas.User.get(db, token_data.username)

    if user is None:
        raise credentials_exception
    return user


@router.get("/current", response_model=schemas.User)
async def get_current_user(
    current_user: schemas.User = Depends(dep_get_current_user),
):
    return current_user