[cli/utils] Add support for logging in via web view

Also adds pywebview as optional dependency to setup.py

legendary/cli.py

@@ -142,10 +142,15 @@ class LegendaryCLI:
 
         exchange_token = ''
         if not args.auth_code and not args.session_id:
+            # only import here since pywebview import is slow
+            from legendary.utils.webview_login import webview_available, do_webview_login
+
+            if not webview_available or args.no_webview:
                 # unfortunately the captcha stuff makes a complete CLI login flow kinda impossible right now...
                 print('Please login via the epic web login!')
                 webbrowser.open(
-                'https://www.epicgames.com/id/login?redirectUrl=https%3A%2F%2Fwww.epicgames.com%2Fid%2Fapi%2Fredirect'
+                    'https://www.epicgames.com/id/login?redirectUrl='
+                    'https%3A%2F%2Fwww.epicgames.com%2Fid%2Fapi%2Fredirect'
                 )
                 print('If web page did not open automatically, please manually open the following URL: '
                       'https://www.epicgames.com/id/login?redirectUrl=https://www.epicgames.com/id/api/redirect')
@@ -157,6 +162,16 @@ class LegendaryCLI:
                 else:
                     sid = sid.strip('"')
                 exchange_token = self.core.auth_sid(sid)
+            else:
+                def callback(web_sid):
+                    exchange_code = self.core.auth_sid(web_sid)
+                    return exchange_code and self.core.auth_code(exchange_code)
+
+                if do_webview_login(callback=callback):
+                    logger.info(f'Successfully logged in as "{self.core.lgd.userdata["displayName"]}" via WebView')
+                else:
+                    logger.error('WebView login attempt failed, please see log for details.')
+                return
         elif args.session_id:
             exchange_token = self.core.auth_sid(args.session_id)
         elif args.auth_code:
@@ -1646,6 +1661,8 @@ def main():
                              help='Use specified session id instead of interactive authentication')
     auth_parser.add_argument('--delete', dest='auth_delete', action='store_true',
                              help='Remove existing authentication (log out)')
+    auth_parser.add_argument('--disable-webview', dest='no_webview', action='store_true',
+                             help='Do not use embedded browser for login')
 
     install_parser.add_argument('--base-path', dest='base_path', action='store', metavar='<path>',
                                 help='Path for game installations (defaults to ~/legendary)')

legendary/utils/webview_login.py

@@ -0,0 +1,102 @@
+import logging
+import json
+
+logger = logging.getLogger('WebViewHelper')
+webview_available = True
+
+try:
+    import webview
+
+    # silence logger
+    webview.logger.setLevel(logging.FATAL)
+    webview.initialize()
+except Exception as e:
+    logger.debug(f'Webview unavailable, disabling webview login (Exception: {e!r}).')
+    webview_available = False
+
+login_url = 'https://www.epicgames.com/id/login'
+sid_url = 'https://www.epicgames.com/id/api/redirect?'
+logout_url = 'https://www.epicgames.com/id/logout?productName=epic-games&redirectUrl=https://www.epicgames.com/site/'
+window_js = '''
+window.ue = {
+    signinprompt: {
+        requestexchangecodesignin: pywebview.api.complete_login,
+        registersignincompletecallback: pywebview.api.trigger_logout
+    },
+    common: {
+        launchexternalurl: function(url) {
+            window.open(url, "blank");
+        },
+        // not required, just needs to be non-null
+        auth: {
+            completeLogin: pywebview.api.nop
+        }
+    }
+}
+'''
+
+
+class MockLauncher:
+    def __init__(self, callback=None):
+        self.callback = callback
+        self.window = None
+        self.exchange_code = None
+        self.sid = None
+        self.inject_js = True
+        self.destroy_on_load = False
+        self.callback_result = None
+
+    def on_loaded(self):
+        url = self.window.get_current_url()
+        logger.debug(f'Loaded url: {url.partition("?")[0]}')
+        # make sure JS necessary window. stuff is available
+        if self.inject_js:
+            self.window.evaluate_js(window_js)
+
+        if 'id/api/redirect' in url:
+            body = self.window.get_elements('body')[0]['textContent']
+            try:
+                j = json.loads(body)
+                self.sid = j['sid']
+                logger.debug(f'Got SID (stage 2)!')
+                if self.callback:
+                    logger.debug(f'Calling login callback...')
+                    self.callback_result = self.callback(self.sid)
+            except Exception as e:
+                logger.error(f'Loading SID response failed with {e!r}')
+            logger.debug('Starting browser logout...')
+            self.window.load_url(logout_url)
+        elif 'logout' in url:
+            # prepare to close browser after logout redirect
+            self.destroy_on_load = True
+        elif self.destroy_on_load:
+            # close browser after logout
+            logger.info('Closing web view...')
+            self.window.destroy()
+
+    def nop(self, *args, **kwargs):
+        return
+
+    def trigger_logout(self, *args, **kwargs):
+        self.inject_js = False
+        # first obtain SID, then log out
+        self.window.load_url(sid_url)
+
+    def complete_login(self, exchange_code):
+        logger.debug('Got exchange code (stage 1)!')
+        # we cannot use this exchange code as our login would be invalidated
+        # after logging out on the website. Hence we do the dance of using
+        # the SID to create *another* exchange code which will create a session
+        # that remains valid after logging out.
+        self.exchange_code = exchange_code
+
+
+def do_webview_login(callback=None):
+    api = MockLauncher(callback=callback)
+    logger.info('Opening web view with Epic Games Login...')
+    window = webview.create_window('Epic Login', url=login_url, width=1024, height=1024, js_api=api)
+    api.window = window
+    window.loaded += api.on_loaded
+    webview.start()
+
+    return api.callback_result