"""Utility interface for the handlers."""


import base64
from time import time

from oto import response
from oto.adaptors.flask import flaskify
from owsrequest import flask_request

from feature_fm.config import ENVIRONMENT
from feature_fm.constants import error, header, ows_services
from feature_fm.utils import token_verification


def process_variables(request, timestamp, token):
    """Process variables for token based handlers.

    Args:
        request (flask.request): the flask request
        timestamp (str): the timestamp as string
        token (str): the sha-1 encrypted token
    Returns:
        tuple of strings: with variables
        signed_token, unencrypted_token, delta_time
    """
    signed_token = bytes(base64.b64decode(token))
    path = request.full_path
    token_query_param = 'token={0}'.format(request.args.get('token'))
    path = path.replace(
        token_query_param, '').replace('&&', '&').replace('?&', '?')

    if path.endswith('&'):
        path = path[:-1]

    unencrypted_token = bytes(path.encode('utf-8'))
    current_time = int(time())
    delta_time = current_time - int(timestamp)

    return signed_token, unencrypted_token, delta_time


def access_validation(request, account_type, account_id):
    """Get access validation for account_type and account_id.

    Args:
        request (flask.request): the flask request
        account_type (str): The account type (vendor or subaccount)
        account_id (int): The account id e.g. 123

    Returns:
        response.Response: describes whether access is valid.
    """
    if ((account_type not in header.GRASS_ACCOUNT_TYPES) or
            not account_id):
        return flaskify(response.create_error_response(
            code=error.ERROR_CODE_BAD_REQUEST,
            message=error.ERROR_MESSAGE_INVALID_ACCOUNT))

    return flask_request.verify_grass_access(
        request,
        **{account_type: account_id})


def validate_token(request, timestamp, token):
    """Validate the token.

    Args:
        request (flask.request): the flask request
        timestamp (str): the timestamp as string
        token (str): the sha-1 encrypted token
    Returns:
        boolean: flag that confirms the token validation
    """
    if not token:
        return False
    if not timestamp:
        return False
    signed_token, unencrypted_token, delta_time = process_variables(
        request, timestamp, token)
    if delta_time <= ows_services.TIMESTAMP_DELTA[ENVIRONMENT]:
        return token_verification.verify_token(unencrypted_token, signed_token)
    else:
        return False