from datetime import datetime, timedelta
from typing import List, Union
from modules.database import col_users

from fastapi import Depends, HTTPException, Security, status
from fastapi.security import (
    OAuth2PasswordBearer,
    SecurityScopes,
)
from jose import JWTError, jwt
from passlib.context import CryptContext
from pydantic import BaseModel, ValidationError


with open("secret_key", "r", encoding="utf-8") as f:
    SECRET_KEY = f.read()
ALGORITHM = "HS256"
ACCESS_TOKEN_EXPIRE_DAYS = 180


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


class TokenData(BaseModel):
    user: Union[str, None] = None
    scopes: List[str] = []


class User(BaseModel):
    user: str
    email: Union[str, None] = None
    disabled: Union[bool, None] = None


class UserInDB(User):
    hash: str


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

oauth2_scheme = OAuth2PasswordBearer(
    tokenUrl="token",
    scopes={
        "me": "Get current user's data.",
        "albums.list": "List albums.",
        "albums.read": "Read albums data.",
        "albums.write": "Modify albums.",
        "photos.list": "List photos.",
        "photos.read": "View photos.",
        "photos.write": "Modify photos."
    },
)


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(user: str):
    found_user = col_users.find_one( {"user": user} )
    return UserInDB(user=found_user["user"], email=found_user["email"], disabled=found_user["disabled"], hash=found_user["hash"])


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


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


async def get_current_user( security_scopes: SecurityScopes, token: str = Depends(oauth2_scheme) ):

    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},
    )

    try:
        payload = jwt.decode(token, SECRET_KEY, algorithms=[ALGORITHM])
        user: str = payload.get("sub")
        if user is None:
            raise credentials_exception
        token_scopes = payload.get("scopes", [])
        token_data = TokenData(scopes=token_scopes, user=user)
    except (JWTError, ValidationError):
        raise credentials_exception
        
    user = get_user(user=token_data.user)

    if user is None:
        raise credentials_exception

    for scope in security_scopes.scopes:
        if 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: User = Security(get_current_user, scopes=["me"]) ):
    if current_user.disabled:
        raise HTTPException(status_code=400, detail="Inactive user")
    return current_user