Add new SW360OAuth2 class

- Class to retrieve and/or create an oauth2 token from
  sw360 regular user/password.
  Requires oauth2 service.

Signed-off-by: Helio Chissini de Castro <helio.chissini-de-castro@bmw.de>

Author: Helio Chissini de Castro

.gitignore

@@ -31,3 +31,6 @@ sw360.egg-info/
 
 # only for special tests
 tests/sw360/
+
+# To avoid save pyenv .python-version
+.python-version

sw360/__init__.py

@@ -11,3 +11,4 @@
 
 from .sw360_api import SW360  # noqa: F401
 from .sw360error import SW360Error  # noqa: F401
+from .sw360oauth2 import SW360OAuth2  # noqa: F401

sw360/sw360oauth2.py

@@ -0,0 +1,140 @@
+# -------------------------------------------------------------------------------
+# (c) 2022 BMW CarIT GmbH
+# All Rights Reserved.
+# Authors: helio.chissini-de-castro@bmw.de
+#
+# Licensed under the MIT license.
+# SPDX-License-Identifier: MIT
+# -------------------------------------------------------------------------------
+
+from typing import Any, Dict, Optional, Union
+from urllib.parse import urljoin
+
+import requests
+import urllib3
+from requests.auth import HTTPBasicAuth
+from requests.structures import CaseInsensitiveDict
+
+from .sw360error import SW360Error
+
+
+class SW360OAuth2:
+    """SW360 OAuth2 Credentials
+    Restore or create Sw360 oauth2 tokens from user/password if auth server is alive
+    :param url: URL of the SW360 instance
+    :param user: SW360 username
+    :param password: SW360 password
+    :type url: string
+    :type user: string
+    :type password: string
+    """
+
+    _client_id: str
+    _client_secret: str
+    _user: str
+    _password: str
+    _token: str
+    _refresh_token: str
+
+    def __init__(self, url: str, user: str, password: str):
+        self._url, self._user, self._password = url, user, password
+        urllib3.disable_warnings(urllib3.exceptions.InsecureRequestWarning)
+
+        self.__get_credentials()
+
+    def __get_credentials(self) -> None:
+        """Return last valid credentials id and secret
+
+        Raises:
+            SW360Error: If is unable to authorize
+        """
+        data: Dict[str, Any]
+        url = urljoin(self._url, "/authorization/client-management")
+        auth = HTTPBasicAuth(self._user, self._password)
+
+        try:
+            response = requests.get(url, verify=False, auth=auth)
+        except Exception as ex:
+            raise SW360Error(None, url, message="Unable to connect to oauth2 service: " + repr(ex))
+
+        data = response.json()[0]
+        self._client_id = data["client_id"]
+        self._client_secret = data["client_secret"]
+
+    def create_client(self, description: str, writeable: False) -> None:
+        """Create an OAuth2 client
+
+        Args:
+            description (str): Some description of the client
+            writeable (bool): Create the id read/writeable
+
+        Raises:
+            SW360Error: When unable to create a client
+        """
+        scope = ["READ"]
+        if writeable:
+            scope.append("WRITE")
+        payload: Union[str, Any] = {
+            "description": description,
+            "authorities": ["BASIC"],
+            "scope": scope,
+            "access_token_validity": 3600,
+            "refresh_token_validity": 3600,
+        }
+        auth = HTTPBasicAuth(self._user, self._password)
+        headers = {"content-type": "application/json"}
+        url = urljoin(self._url, "/authorization/client-management")
+
+        try:
+            requests.post(url, json=payload, verify=False, auth=auth, headers=headers)
+        except Exception as ex:
+            raise SW360Error(None, url, message="Cant create oauth client: " + repr(ex))
+
+    def generate_token(self) -> str:
+        """Generate a new bearer token
+        """
+        self.__oauth_token(True)
+
+    def __token(self, create: bool = False) -> None:
+        """Create or return Liferay Token
+        :param create: If should create or restore active tokens
+        :type create: bool
+        """
+        data: Dict[str, Any]
+        url = urljoin(self._url, "/authorization/oauth/token")
+        payload: Dict[str, Any] = {
+            "grant_type": "password",
+            "username": self._user,
+            "password": self._password,
+        }
+        auth = HTTPBasicAuth(self._client_id, self._client_secret)
+
+        headers: CaseInsensitiveDict[Any] = CaseInsensitiveDict()
+        headers["Content-Type"] = "application/x-www-form-urlencoded"
+
+        if create:
+            response = requests.post(url, auth=auth, headers=headers, json=payload, verify=False)
+        else:
+            params = f"grant_type=password&username={self._user}&password={self._password}"
+            response = requests.get(url, auth=auth, headers=headers, params=params, verify=False)
+
+        data = response.json()
+        self._token = data["access_token"]
+        self._refresh_token = data["refresh_token"]
+
+    @property
+    def token(self) -> Optional[str]:
+        """Return the valid oauth token"""
+        self.__token()
+        return self._token
+
+    @property
+    def refresh_token(self) -> str:
+        """Return the valid oauth refresh token"""
+        self.__token()
+        return self._refresh_token
+
+    @property
+    def url(self) -> str:
+        """Return current session object url"""
+        return self._url