Implement local HTTP Api usage

lib/api/webuntis/queries/authenticate/authenticate.dart

@@ -0,0 +1,55 @@
+import 'dart:async';
+import 'dart:convert';
+import 'dart:developer';
+
+import 'package:marianum_mobile/api/webuntis/webuntisApi.dart';
+import 'package:shared_preferences/shared_preferences.dart';
+
+import 'authenticateParams.dart';
+import 'authenticateResponse.dart';
+
+class Authenticate extends WebuntisApi {
+  AuthenticateParams param;
+
+  Authenticate(this.param) : super("authenticate", param, authenticatedResponse: false);
+
+  @override
+  Future<AuthenticateResponse> run() async {
+    awaitingResponse = true;
+    String rawAnswer = await query(this);
+    AuthenticateResponse response = finalize(AuthenticateResponse.fromJson(jsonDecode(rawAnswer)['result']));
+    _lastResponse = response;
+    awaitedResponse.complete();
+    return response;
+  }
+
+  static bool awaitingResponse = false;
+  static Completer awaitedResponse = Completer();
+  static AuthenticateResponse? _lastResponse;
+
+  static Future<void> createSession() async {
+    SharedPreferences preferences = await SharedPreferences.getInstance();
+
+    _lastResponse = await Authenticate(
+        AuthenticateParams(
+          user: preferences.getString("username")!,
+          password: preferences.getString("password")!,
+        )
+    ).run();
+  }
+
+  static Future<AuthenticateResponse> getSession() async {
+    if(awaitingResponse) {
+      log("Other query in progress... waiting");
+      await awaitedResponse.future;
+    }
+
+    if(_lastResponse == null) {
+      log("Not authenticated... requesting");
+      awaitingResponse = true;
+      await createSession();
+    }
+    return _lastResponse!;
+
+  }
+}