# -*- coding: utf-8 -*-
#
# Copyright (C) 2017 Marcos Pereira <marcospereira.mpj@gmail.com>
#
# This program is free software: you can redistribute it and/or modify
# it under the terms of the GNU Lesser General Public License as published by
# the Free Software Foundation, either version 3 of the License, or
# (at your option) any later version.
#
# This program is distributed in the hope that it will be useful,
# but WITHOUT ANY WARRANTY; without even the implied warranty of
# MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
# GNU Lesser General Public License for more details.
#
# You should have received a copy of the GNU Lesser General Public License
# along with this program.  If not, see <http://www.gnu.org/licenses/>.

from .authorization import Authorization
from .exceptions import raise_error_from_response, KeycloakGetError, \
    KeycloakRPTNotFound, KeycloakAuthorizationConfigError, KeycloakInvalidTokenError
from .urls_patterns import (
    URL_TOKEN,
    URL_USERINFO,
    URL_WELL_KNOWN,
    URL_LOGOUT,
    URL_CERTS,
    URL_ENTITLEMENT,
    URL_INTROSPECT
)
from .connection import ConnectionManager
from jose import jwt
import json


class KeycloakOpenID:

    def __init__(self, server_url, client_id, realm_name, client_secret_key=None):
        self._client_id = client_id
        self._client_secret_key = client_secret_key
        self._realm_name = realm_name

        self._connection = ConnectionManager(base_url=server_url,
                                             headers={},
                                             timeout=60)

        self._authorization = Authorization()

    @property
    def client_id(self):
        return self._client_id

    @client_id.setter
    def client_id(self, value):
        self._client_id = value

    @property
    def client_secret_key(self):
        return self._client_secret_key

    @client_secret_key.setter
    def client_secret_key(self, value):
        self._client_secret_key = value

    @property
    def realm_name(self):
        return self._realm_name

    @realm_name.setter
    def realm_name(self, value):
        self._realm_name = value

    @property
    def connection(self):
        return self._connection

    @connection.setter
    def connection(self, value):
        self._connection = value

    @property
    def authorization(self):
        return self._authorization

    @authorization.setter
    def authorization(self, value):
        self._authorization = value

    def _add_secret_key(self, payload):
        """
        Add secret key if exist.

        :param payload:
        :return:
        """
        if self.client_secret_key:
            payload.update({"client_secret": self.client_secret_key})

        return payload

    def _build_name_role(self, role):
        """

        :param role:
        :return:
        """
        return self.client_id + "/" + role

    def _token_info(self, token, method_token_info, **kwargs):
        """

        :param token:
        :param method_token_info:
        :param kwargs:
        :return:
        """
        if method_token_info == 'introspect':
            token_info = self.introspect(token)
        else:
            token_info = self.decode_token(token, **kwargs)

        return token_info

    def well_know(self):
        """ The most important endpoint to understand is the well-known configuration
            endpoint. It lists endpoints and other configuration options relevant to
            the OpenID Connect implementation in Keycloak.

            :return It lists endpoints and other configuration options relevant.
        """

        params_path = {"realm-name": self.realm_name}
        data_raw = self.connection.raw_get(URL_WELL_KNOWN.format(**params_path))

        return raise_error_from_response(data_raw, KeycloakGetError)

    def auth_url(self, redirect_uri):
        """

        http://openid.net/specs/openid-connect-core-1_0.html#AuthorizationEndpoint

        :return:
        """
        return NotImplemented

    def token(self, username, password, grant_type=["password"]):
        """
        The token endpoint is used to obtain tokens. Tokens can either be obtained by
        exchanging an authorization code or by supplying credentials directly depending on
        what flow is used. The token endpoint is also used to obtain new access tokens
        when they expire.

        http://openid.net/specs/openid-connect-core-1_0.html#TokenEndpoint

        :param username:
        :param password:
        :param grant_type:
        :return:
        """
        params_path = {"realm-name": self.realm_name}
        payload = {"username": username, "password": password,
                   "client_id": self.client_id, "grant_type": grant_type}

        payload = self._add_secret_key(payload)
        data_raw = self.connection.raw_post(URL_TOKEN.format(**params_path),
                                            data=payload)
        return raise_error_from_response(data_raw, KeycloakGetError)

    def userinfo(self, token):
        """
        The userinfo endpoint returns standard claims about the authenticated user,
        and is protected by a bearer token.

        http://openid.net/specs/openid-connect-core-1_0.html#UserInfo

        :param token:
        :return:
        """

        self.connection.add_param_headers("Authorization", "Bearer " + token)
        params_path = {"realm-name": self.realm_name}

        data_raw = self.connection.raw_get(URL_USERINFO.format(**params_path))

        return raise_error_from_response(data_raw, KeycloakGetError)

    def logout(self, refresh_token):
        """
        The logout endpoint logs out the authenticated user.
        :param refresh_token:
        :return:
        """
        params_path = {"realm-name": self.realm_name}
        payload = {"client_id": self.client_id, "refresh_token": refresh_token}

        payload = self._add_secret_key(payload)
        data_raw = self.connection.raw_post(URL_LOGOUT.format(**params_path),
                                            data=payload)

        return raise_error_from_response(data_raw, KeycloakGetError, expected_code=204)

    def certs(self):
        """
        The certificate endpoint returns the public keys enabled by the realm, encoded as a
        JSON Web Key (JWK). Depending on the realm settings there can be one or more keys enabled
        for verifying tokens.

        https://tools.ietf.org/html/rfc7517

        :return:
        """
        params_path = {"realm-name": self.realm_name}
        data_raw = self.connection.raw_get(URL_CERTS.format(**params_path))
        return raise_error_from_response(data_raw, KeycloakGetError)

    def entitlement(self, token, resource_server_id):
        """
        Client applications can use a specific endpoint to obtain a special security token
        called a requesting party token (RPT). This token consists of all the entitlements
        (or permissions) for a user as a result of the evaluation of the permissions and authorization
        policies associated with the resources being requested. With an RPT, client applications can
        gain access to protected resources at the resource server.

        :return:
        """
        self.connection.add_param_headers("Authorization", "Bearer " + token)
        params_path = {"realm-name": self.realm_name, "resource-server-id": resource_server_id}
        data_raw = self.connection.raw_get(URL_ENTITLEMENT.format(**params_path))

        return raise_error_from_response(data_raw, KeycloakGetError)

    def introspect(self, token, rpt=None, token_type_hint=None):
        """
        The introspection endpoint is used to retrieve the active state of a token. It is can only be
        invoked by confidential clients.

        https://tools.ietf.org/html/rfc7662

        :param token:
        :param rpt:
        :param token_type_hint:

        :return:
        """
        params_path = {"realm-name": self.realm_name}

        payload = {"client_id": self.client_id, "token": token}

        if token_type_hint == 'requesting_party_token':
            if rpt:
                payload.update({"token": rpt, "token_type_hint": token_type_hint})
                self.connection.add_param_headers("Authorization", "Bearer " + token)
            else:
                raise KeycloakRPTNotFound("Can't found RPT.")

        payload = self._add_secret_key(payload)

        data_raw = self.connection.raw_post(URL_INTROSPECT.format(**params_path),
                                            data=payload)

        return raise_error_from_response(data_raw, KeycloakGetError)

    def decode_token(self, token, key, algorithms=['RS256'], **kwargs):
        """
        A JSON Web Key (JWK) is a JavaScript Object Notation (JSON) data
        structure that represents a cryptographic key.  This specification
        also defines a JWK Set JSON data structure that represents a set of
        JWKs.  Cryptographic algorithms and identifiers for use with this
        specification are described in the separate JSON Web Algorithms (JWA)
        specification and IANA registries established by that specification.

        https://tools.ietf.org/html/rfc7517

        :param token:
        :param key:
        :param algorithms:
        :return:
        """

        return jwt.decode(token, key, algorithms=algorithms,
                          audience=self.client_id, **kwargs)

    def load_authorization_config(self, path):
        """
        Load Keycloak settings (authorization)

        :param path: settings file (json)
        :return:
        """
        authorization_file = open(path, 'r')
        authorization_json = json.loads(authorization_file.read())
        self.authorization.load_config(authorization_json)
        authorization_file.close()

    def get_policies(self, token, method_token_info='introspect', **kwargs):
        """
        Get policies by user token

        :param token: user token
        :return: policies list
        """

        if not self.authorization.policies:
            raise KeycloakAuthorizationConfigError(
                "Keycloak settings not found. Load Authorization Keycloak settings."
            )

        token_info = self._token_info(token, method_token_info, **kwargs)

        if method_token_info == 'introspect' and not token_info['active']:
            raise KeycloakInvalidTokenError(
                "Token expired or invalid."
            )

        user_resources = token_info['resource_access'].get(self.client_id)

        if not user_resources:
            return None

        policies = []

        for policy_name, policy in self.authorization.policies.items():
            for role in user_resources['roles']:
                if self._build_name_role(role) in policy.roles:
                    policies.append(policy)

        return list(set(policies))

    def get_permissions(self, token, method_token_info='introspect', **kwargs):
        """
        Get permission by user token

        :param token: user token
        :param method_token_info: Decode token method
        :param kwargs: parameters for decode
        :return: permissions list
        """

        if not self.authorization.policies:
            raise KeycloakAuthorizationConfigError(
                "Keycloak settings not found. Load Authorization Keycloak settings."
            )

        token_info = self._token_info(token, method_token_info, **kwargs)

        if method_token_info == 'introspect' and not token_info['active']:
            raise KeycloakInvalidTokenError(
                "Token expired or invalid."
            )

        user_resources = token_info['resource_access'].get(self.client_id)

        if not user_resources:
            return None

        permissions = []

        for policy_name, policy in self.authorization.policies.items():
            for role in user_resources['roles']:
                if self._build_name_role(role) in policy.roles:
                    permissions += policy.permissions

        return list(set(permissions))