from http import HTTPStatus
from typing import Annotated
from uuid import uuid4

from aws_lambda_powertools.event_handler import (
    Response,
)
from aws_lambda_powertools.event_handler.api_gateway import Router
from aws_lambda_powertools.event_handler.exceptions import (
    NotFoundError,
    UnauthorizedError,
)
from aws_lambda_powertools.event_handler.openapi.params import Body
from aws_lambda_powertools.shared.cookies import Cookie
from layercake.dateutils import now, ttl
from layercake.dynamodb import DynamoDBPersistenceLayer, KeyPair, SortKey
from passlib.hash import pbkdf2_sha256

from boto3clients import dynamodb_client, idp_client
from config import SESSION_EXPIRES_IN, USER_TABLE

router = Router()
dyn = DynamoDBPersistenceLayer(USER_TABLE, dynamodb_client)


class InvalidCredentialsError(UnauthorizedError): ...


class UserNotFoundError(NotFoundError): ...


@router.post('/authentication')
def authentication(
    username: Annotated[str, Body()],
    password: Annotated[str, Body()],
):
    user_id, password_hash = _get_user(username)

    if not password_hash:
        _get_idp_user(user_id, username, password)
    else:
        if not pbkdf2_sha256.verify(password, password_hash):
            dyn.update_item(
                key=KeyPair(user_id, 'FAILED_ATTEMPTS'),
                update_expr='SET #count = if_not_exists(#count, :zero) + :one, \
                                 updated_at = :now',
                expr_attr_names={
                    '#count': 'failed_attempts',
                },
                expr_attr_values={
                    ':zero': 0,
                    ':one': 1,
                    ':now': now(),
                },
            )

            raise InvalidCredentialsError('Invalid credentials')

    return Response(
        status_code=HTTPStatus.OK,
        cookies=[
            Cookie(
                name='SID',
                value=new_session(user_id),
                http_only=True,
                secure=True,
                same_site=None,
                max_age=SESSION_EXPIRES_IN,
            )
        ],
    )


def _get_user(username: str) -> tuple[str, str | None]:
    sk = SortKey(username, path_spec='user_id')
    user = dyn.collection.get_items(
        KeyPair(pk='email', sk=sk, rename_key=sk.path_spec)
        + KeyPair(pk='cpf', sk=sk, rename_key=sk.path_spec),
    )

    if not user:
        raise UserNotFoundError('User not found')

    password = dyn.collection.get_item(
        KeyPair(
            pk=user['user_id'],
            sk=SortKey(
                sk='PASSWORD',
                path_spec='hash',
                rename_key='password',
            ),
        ),
        raise_on_error=False,
        default=None,
        # Uncomment the following line when removing support for Cognito
        # exc_cls=UserNotFoundError,
    )

    return user['user_id'], password


def _get_idp_user(
    user_id: str,
    username: str,
    password: str,
) -> bool:
    import base64
    import hashlib
    import hmac

    # That should be removed when completing the migration
    # to our own OAuth2 implementation.
    client_id = '3ijacqc7r2jc9l4oli2b41f7te'
    client_secret = 'amktf9l40g1mlqdo9fjlcfvpn2cp3mvh4pt97hu55sfelccos58'

    dig = hmac.new(
        client_secret.encode('utf-8'),
        msg=(username + client_id).encode('utf-8'),
        digestmod=hashlib.sha256,
    ).digest()

    try:
        idp_client.initiate_auth(
            AuthFlow='USER_PASSWORD_AUTH',
            AuthParameters={
                'USERNAME': username,
                'PASSWORD': password,
                'SECRET_HASH': base64.b64encode(dig).decode(),
            },
            ClientId=client_id,
        )

        dyn.put_item(
            item={
                'id': user_id,
                'sk': 'PASSWORD',
                'hash': pbkdf2_sha256.hash(password),
                'created_at': now(),
            }
        )
    except Exception:
        raise InvalidCredentialsError('Invalid credentials')

    return True


def new_session(user_id: str) -> str:
    session_id = str(uuid4())
    now_ = now()
    exp = ttl(start_dt=now_, seconds=SESSION_EXPIRES_IN)

    with dyn.transact_writer() as transact:
        transact.delete(
            key=KeyPair(user_id, 'FAILED_ATTEMPTS'),
        )
        transact.update(
            key=KeyPair(user_id, '0'),
            # Post-migration (users): uncomment the following line
            # update_expr='SET last_login = :now',
            update_expr='SET lastLogin = :now',
            expr_attr_values={
                ':now': now_,
            },
        )
        transact.put(
            item={
                'id': 'SESSION',
                'sk': session_id,
                'user_id': user_id,
                'ttl': exp,
                'created_at': now_,
            }
        )
        transact.put(
            item={
                'id': user_id,
                'sk': f'SESSION#{session_id}',
                'ttl': exp,
                'created_at': now_,
            }
        )

    return f'{session_id}:{user_id}'