"""Zendesk logic module."""

import json
from time import time
from uuid import uuid4

import jwt
from owsresponse import response
from pythonfeatures import pythonfeatures
from pythonfeatures.constants import split as split_constants

from users import config, constants
from users.models import identities


class ConfigError(Exception):
    """Configuration error."""


def _get_branded_config(key: str, brand: str):
    secrets = getattr(config, key, None)

    if not secrets:
        raise ConfigError(f'{key} must be set')

    try:
        decoded_secrets = json.loads(secrets)
    except json.decoder.JSONDecodeError as e:
        raise ConfigError(f'{key} must be json') from e

    if brand not in decoded_secrets:
        raise ConfigError(f'{key} is not defined for brand {brand}')

    return decoded_secrets[brand]


def generate_zendesk_token_v1(identity_id, brand_experience):
    """Generate zendesk token for Classic Web Widget.

    Params:
        identity_id (str): The identity id.
    Returns:
        response.Response: containing zendesk jwt token.
    """
    identity_res = identities.get_identity(identity_id)

    if not identity_res:
        return identity_res

    identity_data = identity_res.message

    brand = brand_experience or identity_data.get('default_brand')

    if not brand:
        return response.create_fatal_response('Can not get brand for identity')

    try:
        secret = _get_branded_config('ZENDESK_SECRET_KEY', brand)
    except ConfigError as e:
        return response.create_fatal_response(str(e))

    payload = {
        'name': identity_data['name'],
        'email': identity_data['email'],
        'iat': int(time()),
        'jti': str(uuid4()),
    }

    encoded = jwt.encode(payload, secret, algorithm='HS256')
    return response.Response({'value': encoded})


def generate_zendesk_token_v2(identity_id, brand_experience):
    """Generate zendesk token for Messaging Widget.

    Params:
        identity_id (str): The identity id.
    Returns:
        response.Response: containing zendesk jwt token.
    """
    identity_res = identities.get_identity(identity_id)

    if not identity_res:
        return identity_res

    identity_data = identity_res.message

    brand = brand_experience or identity_data.get('default_brand')

    if not brand:
        return response.create_fatal_response('Can not get brand for identity')

    try:
        secret = _get_branded_config('ZENDESK_MESSAGING_SECRET_KEY', brand)
        kid = _get_branded_config('ZENDESK_KID', brand)
    except ConfigError as e:
        return response.create_fatal_response(str(e))

    payload = {
        'external_id': identity_data['id'],
        'email': identity_data['email'],
        'email_verified': True,
        'name': identity_data['name'],
        'scope': 'user',
    }

    exclude_id = (
        pythonfeatures.get_single_feature_by_attributes(
            constants.FEATURE_ZENDESK_WIDGET_NO_EXTERNAL_ID, {'identity_id': identity_id}
        ).message
        == split_constants.FEATURE_ENABLED
    )

    if exclude_id:
        payload.pop('external_id')

    headers = {
        'alg': 'HS256',
        'typ': 'JWT',
        'kid': kid,
    }

    encoded = jwt.encode(payload, secret, headers=headers)
    return response.Response({'value': encoded})


JWT_GENERATOR_MAP = {
    constants.ZENDESK_CLASSIC_WEB_WIDGET_TOKEN_VERSION: generate_zendesk_token_v1,
    constants.ZENDESK_MESSAGING_WIDGET_TOKEN_VERSION: generate_zendesk_token_v2,
}


def generate_zendesk_token(identity_id, brand_experience, token_version):
    """Generate zendesk token.

    Params:
        identity_id (str): The identity id.
        brand_experience (str): The current brand.
        token_version (str): Version of the JWT generator to use. (Classic Web Widget or Web Widget)
    Returns:
        response.Response: containing zendesk jwt token.
    """
    if token_version not in JWT_GENERATOR_MAP:
        return response.create_error_response(
            code=constants.ERROR_CODE_VALIDATION_ERROR,
            message=f'"{token_version}" is not supported.',
        )

    return JWT_GENERATOR_MAP[token_version](identity_id, brand_experience)