from datetime import timedelta, timezone, datetime
from typing import Annotated
from fastapi import Depends, HTTPException, Request, Response, status
from fastapi.responses import PlainTextResponse
from pydantic import BaseModel, ValidationError
import jwt
from jwt.exceptions import ExpiredSignatureError, InvalidTokenError
from sqlmodel import Session, select
from db import TokenDB, engine, Player
from fastapi.security import (
    OAuth2PasswordBearer,
    OAuth2PasswordRequestForm,
    SecurityScopes,
)
from pydantic_settings import BaseSettings, SettingsConfigDict
from passlib.context import CryptContext
from sqlalchemy.exc import OperationalError


class Config(BaseSettings):
    secret_key: str = ""
    access_token_expire_minutes: int = 15
    model_config = SettingsConfigDict(
        env_file=".env", env_file_encoding="utf-8", extra="ignore"
    )


config = Config()


class Token(BaseModel):
    access_token: str


class TokenData(BaseModel):
    username: str | None = None
    scopes: list[str] = []


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


class CookieOAuth2(OAuth2PasswordBearer):
    def __init__(self, *args, **kwargs):
        super().__init__(*args, **kwargs)

    async def __call__(self, request: Request):
        cookie_token = request.cookies.get("access_token")
        if cookie_token:
            return cookie_token
        else:
            header_token = await super().__call__(request)
            if header_token:
                return header_token
            else:
                raise HTTPException(status_code=401)


oauth2_scheme = CookieOAuth2(
    tokenUrl="api/token",
    scopes={
        "analysis": "Access the results.",
        "admin": "Maintain DB etc.",
    },
)


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:
        try:
            with Session(engine) as session:
                return session.exec(
                    select(Player).where(Player.username == username)
                ).one_or_none()
        except OperationalError:
            return


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=config.access_token_expire_minutes
        )
    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)],
    security_scopes: SecurityScopes,
):
    if security_scopes.scopes:
        authenticate_value = f'Bearer scope="{security_scopes.scope_str}"'
    else:
        authenticate_value = "Bearer"
    credentials_exception = HTTPException(
        status_code=status.HTTP_401_UNAUTHORIZED,
        detail="Could not validate credentials",
        headers={"WWW-Authenticate": authenticate_value},
    )
    # access_token = request.cookies.get("access_token")
    access_token = token
    if not access_token:
        raise credentials_exception
    try:
        payload = jwt.decode(access_token, config.secret_key, algorithms=["HS256"])
        username: str = payload.get("sub")
        if username is None:
            raise credentials_exception
        token_scopes = payload.get("scopes", [])
        token_data = TokenData(username=username, scopes=token_scopes)
    except ExpiredSignatureError:
        raise HTTPException(
            status_code=status.HTTP_401_UNAUTHORIZED,
            detail="Access token expired",
            headers={"WWW-Authenticate": authenticate_value},
        )
    except (InvalidTokenError, ValidationError):
        raise credentials_exception
    user = get_user(username=token_data.username)
    if user is None:
        raise credentials_exception
    allowed_scopes = set(user.scopes.split())
    for scope in security_scopes.scopes:
        if scope not in allowed_scopes or scope not in token_data.scopes:
            raise HTTPException(
                status_code=status.HTTP_401_UNAUTHORIZED,
                detail="Not enough permissions",
                headers={"WWW-Authenticate": authenticate_value},
            )
    return user


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


async def verify_team_scope(user: Annotated[Player, Depends(get_current_active_user)]):
    allowed_scopes = set(user.scopes.split())


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"},
        )
    allowed_scopes = set(user.scopes.split())
    requested_scopes = set(form_data.scopes)
    access_token = create_access_token(
        data={"sub": user.username, "scopes": list(allowed_scopes)}
    )
    response.set_cookie(
        "access_token",
        value=access_token,
        httponly=True,
        samesite="strict",
        max_age=config.access_token_expire_minutes * 60,
    )
    return Token(access_token=access_token)


async def logout(response: Response):
    response.set_cookie("access_token", "", expires=0, httponly=True, samesite="strict")
    return {"message": "Successfully logged out"}


def generate_one_time_token(username):
    user = get_user(username)
    if user:
        expire = timedelta(days=7)
        token = create_access_token(
            data={"sub": username, "name": user.display_name},
            expires_delta=expire,
        )
        return token


class FirstPassword(BaseModel):
    token: str
    password: str


async def set_first_password(req: FirstPassword):
    credentials_exception = HTTPException(
        status_code=status.HTTP_401_UNAUTHORIZED,
        detail="Could not validate token",
    )
    with Session(engine) as session:
        token_in_db = session.exec(
            select(TokenDB)
            .where(TokenDB.token == req.token)
            .where(TokenDB.used == False)
        ).one_or_none()
        if token_in_db:
            credentials_exception = HTTPException(
                status_code=status.HTTP_401_UNAUTHORIZED,
                detail="Could not validate token",
            )
            try:
                payload = jwt.decode(req.token, config.secret_key, algorithms=["HS256"])
                username: str = payload.get("sub")
                if username is None:
                    raise credentials_exception
            except ExpiredSignatureError:
                raise HTTPException(
                    status_code=status.HTTP_401_UNAUTHORIZED,
                    detail="Access token expired",
                )
            except (InvalidTokenError, ValidationError):
                raise credentials_exception

            user = get_user(username)
            if user:
                user.hashed_password = get_password_hash(req.password)
                session.add(user)
                token_in_db.used = True
                session.add(token_in_db)
                session.commit()
                return Response(
                    "Password set successfully", status_code=status.HTTP_200_OK
                )
        elif session.exec(
            select(TokenDB)
            .where(TokenDB.token == req.token)
            .where(TokenDB.used == True)
        ).one_or_none():
            raise HTTPException(
                status_code=status.HTTP_401_UNAUTHORIZED,
                detail="Token already used",
            )
        else:
            raise credentials_exception


class ChangedPassword(BaseModel):
    current_password: str
    new_password: str


async def change_password(
    request: ChangedPassword,
    user: Annotated[Player, Depends(get_current_active_user)],
):
    if (
        request.new_password
        and user.hashed_password
        and verify_password(request.current_password, user.hashed_password)
    ):
        with Session(engine) as session:
            user.hashed_password = get_password_hash(request.new_password)
            session.add(user)
            session.commit()
            return PlainTextResponse(
                "Password changed successfully",
                status_code=status.HTTP_200_OK,
                media_type="text/plain",
            )
    else:
        raise HTTPException(
            status_code=status.HTTP_400_BAD_REQUEST,
            detail="Wrong password",
        )


async def read_player_me(
    current_user: Annotated[Player, Depends(get_current_active_user)],
):
    return current_user.model_dump(exclude={"hashed_password", "disabled"})


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