TW-1768: Define saas environment for mobile [hardcode]

docs/configurations/config_build_mobile_app_for_public_platform.md

@@ -2,27 +2,49 @@
 
 ### Context
 
-- Twake Chat app can use the values of environment declarations to change its functionality or behavior. 
-  Dart compilers can eliminate the code made unreachable due to 
-  control flow using the environment declaration values.
-- Only support for mobile app.
+- Twake Chat need to config env for Twake Chat service on mobile app for public platform, two ways
+  to config env:
 
-### How to config
+#### 1. Enable for `SaaS` platform
 
-1.Flutter
+1.1. Use `--dart-define` option to config env for mobile app.
+
+- Specify `platform` is `saas`.
 - To specify environment declarations to the Flutter tool, use the `--dart-define` option instead:
 
 ```
 flutter run --dart-define=REGISTRATION_URL=https://example.com/ 
 --dart-define=TWAKE_WORKPLACE_HOMESERVER=https://example.com/ 
---dart-define=PLATFORM=platfomrm 
+--dart-define=PLATFORM=saas 
 --dart-define=HOME_SERVER=https://example.com/ 
 
 ```
 
-- `REGISTRATION_URL`: Registration URL for public platform
-- `TWAKE_WORKPLACE_HOMESERVER`: Twake workplace homeserver
-- `PLATFORM`: Platform, `saas` for the case of public platform
-- `HOME_SERVER`: Homeserver
+1.2. Use `config_saas.dart` to config env for mobile app.
+
+```
+class ConfigurationSaas {
+  static const String registrationUrl = 'https://example.com/';
+
+  static const String twakeWorkplaceHomeserver = 'https://example.com/';
+
+  static const String homeserver = 'https://example.com/';
+
+  static const String platform = 'saas';
+}
+```
+
+#### 2. Disable for `SaaS` platform
+
+- Build without `--dart-define`.
+
+- Change the value `platform` in `config_saas.dart` to any value except `saas`.
+
+```
+class ConfigurationSaas {
 
-If you want to disable it, please change the value or remove when use `--dart-define` option
+  // ...
+  
+  static const String platform = 'platform';
+}
+```

lib/config/app_config.dart

@@ -1,6 +1,7 @@
 import 'dart:async';
 import 'dart:io';
 
+import 'package:fluffychat/config/config_saas/config_saas.dart';
 import 'package:fluffychat/di/global/get_it_initializer.dart';
 import 'package:fluffychat/utils/responsive/responsive_utils.dart';
 import 'package:flutter/foundation.dart';
@@ -28,11 +29,16 @@ abstract class AppConfig {
   static double bubbleSizeFactor = 1;
   static double fontSizeFactor = 1;
 
-  static String registrationUrl = 'https://example.com/';
+  static String sampleValue = 'sampleValue';
 
-  static String twakeWorkplaceHomeserver = 'https://example.com/';
+  ///`REGISTRATION_URL`: Registration URL for public platform, sample is `https://example.com`
+  static String registrationUrl = sampleValue;
 
-  static String homeserver = 'https://example.com/';
+  ///`TWAKE_WORKPLACE_HOMESERVER`: Twake workplace homeserver, sample is `https://example.com`
+  static String twakeWorkplaceHomeserver = sampleValue;
+
+  ///`HOME_SERVER`: Homeserver, sample is `https://example.com`
+  static String homeserver = sampleValue;
 
   static String? platform;
 
@@ -112,22 +118,22 @@ abstract class AppConfig {
 
   static const String _platformEnv = String.fromEnvironment(
     'PLATFORM',
-    defaultValue: 'platform',
+    defaultValue: ConfigurationSaas.platform,
   );
 
   static const String _twakeWorkplaceHomeserverEnv = String.fromEnvironment(
     'TWAKE_WORKPLACE_HOMESERVER',
-    defaultValue: 'https://example.com/',
+    defaultValue: ConfigurationSaas.twakeWorkplaceHomeserver,
   );
 
   static const String _registrationUrlEnv = String.fromEnvironment(
     'REGISTRATION_URL',
-    defaultValue: 'https://example.com/',
+    defaultValue: ConfigurationSaas.registrationUrl,
   );
 
   static const String _homeserverEnv = String.fromEnvironment(
     'HOME_SERVER',
-    defaultValue: 'https://example.com/',
+    defaultValue: ConfigurationSaas.homeserver,
   );
 
   static void loadEnvironment() {

lib/config/config_saas/config_saas.dart

@@ -0,0 +1,10 @@
+class ConfigurationSaas {
+  static const String registrationUrl = 'https://sign-up.stg.lin-saas.com/';
+
+  static const String twakeWorkplaceHomeserver =
+      'https://matrix.stg.lin-saas.com/';
+
+  static const String homeserver = 'https://matrix.stg.lin-saas.com/';
+
+  static const String platform = 'saas';
+}

lib/presentation/mixins/connect_page_mixin.dart

@@ -54,7 +54,7 @@ mixin ConnectPageMixin {
   }
 
   bool get homeserverIsConfigured =>
-      AppConfig.homeserver != 'https://example.com/' ||
+      AppConfig.homeserver != AppConfig.sampleValue ||
       AppConfig.homeserver.isNotEmpty;
 
   String _getRedirectUrlScheme(String redirectUrl) {