Improve the message and small code cleanup

ee_auth.py

@@ -14,6 +14,11 @@
 # https://github.com/googleapis/google-api-python-client/issues/299
 logging.getLogger('googleapiclient.discovery_cache').setLevel(logging.ERROR)
 
+SCOPES = [
+    "https://www.googleapis.com/auth/earthengine",
+    "https://www.googleapis.com/auth/devstorage.full_control",
+    "https://www.googleapis.com/auth/accounts.reauth"
+]
 
 class MyHandler(BaseHTTPRequestHandler):
     """
@@ -27,69 +32,63 @@ def do_GET(self):
         self.end_headers()
         self.wfile.write(bytes("QGIS Google Earth Engine plugin authentication finished successfully.", 'utf-8'))
 
-
 def authenticate(ee=None):
     """
     Authenticates Google Earth Engine
     """
     if ee is None:
         import ee
 
-    msg = 'This plugin uses Google Earth Engine API and it requires'\
-          'users to be authorized, you must have a Google account for that.\n\n'\
-          'Click OK and follow the instructions on the web page.'
+    # show a dialog to allow users to start or cancel the authentication process
+    msg = 'This plugin uses Google Earth Engine API and it looks like it is not yet\n'\
+          'authenticated on this machine. You need to have a Google account\n'\
+          'registered in Google Earth Engine to continue\n\n'\
+          'Click OK to open a web browser and start the authentication process\n'\
+          'or click Cancel to stop the authentication process.'
     reply = QMessageBox.question(None, 'Google Earth Engine plugin',
                                  msg, QMessageBox.Ok, QMessageBox.Cancel)
 
-    if reply == QMessageBox.Ok:
-        # start the authentication process with Google Earth Engine
-
-        SCOPES = [
-            "https://www.googleapis.com/auth/earthengine",
-            "https://www.googleapis.com/auth/devstorage.full_control",
-            "https://www.googleapis.com/auth/accounts.reauth"
-        ]
+    if reply == QMessageBox.Cancel:
+        return False
 
-        # get user login & consent
-        request_args = {
-            'response_type': 'code',
-            'client_id': ee.oauth.CLIENT_ID,
-            'redirect_uri': "http://localhost:8085/",
-            'scope': ' '.join(SCOPES),
-            'access_type': 'offline'
-        }
-        auth_url = 'https://accounts.google.com/o/oauth2/auth/oauthchooseaccount?' + urllib.parse.urlencode(
-            request_args)
-        webbrowser.open_new(auth_url)
-        print('Starting Google Earth Engine Authorization ...')
+    # start the authentication, getting user login & consent
+    request_args = {
+        'response_type': 'code',
+        'client_id': ee.oauth.CLIENT_ID,
+        'redirect_uri': "http://localhost:8085/",
+        'scope': ' '.join(SCOPES),
+        'access_type': 'offline'
+    }
+    auth_url = 'https://accounts.google.com/o/oauth2/auth/oauthchooseaccount?' \
+        + urllib.parse.urlencode(request_args)
+    webbrowser.open_new(auth_url)
+    print('Starting Google Earth Engine Authorization ...')
 
-        server = HTTPServer(('localhost', 8085), MyHandler)
-        server.handle_request()
+    server = HTTPServer(('localhost', 8085), MyHandler)
+    server.handle_request()
 
-        if not MyHandler.auth_code:
-            print('QGIS EE Plugin authentication failed, can not get authentication code')
-            return False
+    if not MyHandler.auth_code:
+        print('QGIS EE Plugin authentication failed, can not get authentication code')
+        return False
 
-        # get refresh token
-        request_args = {
-            'code': MyHandler.auth_code,
-            'client_id': ee.oauth.CLIENT_ID,
-            'client_secret': ee.oauth.CLIENT_SECRET,
-            'redirect_uri': "http://localhost:8085/",
-            'grant_type': 'authorization_code',
-        }
+    # get refresh token
+    request_args = {
+        'code': MyHandler.auth_code,
+        'client_id': ee.oauth.CLIENT_ID,
+        'client_secret': ee.oauth.CLIENT_SECRET,
+        'redirect_uri': "http://localhost:8085/",
+        'grant_type': 'authorization_code',
+    }
 
-        data = urllib.parse.urlencode(request_args).encode()
-        response = urllib.request.urlopen(ee.oauth.TOKEN_URI, data).read().decode()
-        refresh_token = json.loads(response)['refresh_token']
+    data = urllib.parse.urlencode(request_args).encode()
+    response = urllib.request.urlopen(ee.oauth.TOKEN_URI, data).read().decode()
+    refresh_token = json.loads(response)['refresh_token']
 
-        # write refresh token
-        client_info = {}
-        client_info['refresh_token'] = refresh_token
-        client_info['scopes'] = SCOPES
-        ee.oauth.write_private_json(ee.oauth.get_credentials_path(), client_info)
-        print('QGIS EE Plugin authenticated successfully')
-        return True
-    else:
-        return False
+    # write refresh token
+    client_info = {}
+    client_info['refresh_token'] = refresh_token
+    client_info['scopes'] = SCOPES
+    ee.oauth.write_private_json(ee.oauth.get_credentials_path(), client_info)
+    print('QGIS EE Plugin authenticated successfully')
 
+    return True