feat(example): Implement common argument parsing

examples_dart/bin/omemo_client.dart

@@ -1,10 +1,9 @@
-import 'package:args/args.dart';
 import 'package:chalkdart/chalk.dart';
 import 'package:cli_repl/cli_repl.dart';
+import 'package:example_dart/arguments.dart';
 import 'package:example_dart/socket.dart';
 import 'package:logging/logging.dart';
 import 'package:moxxmpp/moxxmpp.dart';
-import 'package:moxxmpp_socket_tcp/moxxmpp_socket_tcp.dart';
 import 'package:omemo_dart/omemo_dart.dart' as omemo;
 
 void main(List<String> args) async {
@@ -17,43 +16,22 @@ void main(List<String> args) async {
     );
   });
 
-  final parser = ArgParser()
-    ..addOption('jid')
-    ..addOption('password')
-    ..addOption('host')
-    ..addOption('port')
-    ..addOption('to')
-    ..addOption('xmpps-srv');
-  final options = parser.parse(args);
-
-  // Parse a potential xmpps-client SRV record here.
-  // Format: --xmpps-srv <priority>,<weight>,<target>,<port>
-  MoxSrvRecord? srvRecord;
-  if (options['xmpps-srv'] != null) {
-    final parts = (options['xmpps-srv']! as String).split(',');
-    srvRecord = MoxSrvRecord(
-      int.parse(parts[0]),
-      int.parse(parts[1]),
-      parts[2],
-      int.parse(parts[3]),
-    );
+  final parser = ArgumentParser()
+    ..parser.addOption('to', help: 'The JID to send messages to');
+  final options = parser.handleArguments(args);
+  if (options == null) {
+    return;
   }
 
   // Connect
-  final jid = JID.fromString(options['jid']! as String);
+  final jid = parser.jid;
   final to = JID.fromString(options['to']! as String).toBare();
-  final portString = options['port'] as String?;
   final connection = XmppConnection(
     TestingReconnectionPolicy(),
     AlwaysConnectedConnectivityManager(),
     ClientToServerNegotiator(),
-    ExampleTCPSocketWrapper(srvRecord),
-  )..connectionSettings = ConnectionSettings(
-      jid: jid,
-      password: options['password']! as String,
-      host: options['host'] as String?,
-      port: portString != null ? int.parse(portString) : null,
-    );
+    ExampleTCPSocketWrapper(parser.srvRecord),
+  )..connectionSettings = parser.connectionSettings;
 
   // Generate OMEMO data
   omemo.OmemoManager? oom;

examples_dart/lib/arguments.dart

@@ -0,0 +1,84 @@
+import 'package:args/args.dart';
+import 'package:chalkdart/chalk.dart';
+import 'package:moxxmpp/moxxmpp.dart';
+import 'package:moxxmpp_socket_tcp/moxxmpp_socket_tcp.dart';
+
+extension StringToInt on String {
+  int toInt() => int.parse(this);
+}
+
+/// A wrapper around [ArgParser] for providing convenience functions and standard parameters
+/// to the examples.
+class ArgumentParser {
+  ArgumentParser() {
+    parser
+      ..addOption('jid', help: 'The JID to connect as')
+      ..addOption('password', help: 'The password to use for authenticating')
+      ..addOption('host',
+          help:
+              'The host address to connect to (By default uses the domain part of the JID)')
+      ..addOption('port', help: 'The port to connect to')
+      ..addOption('xmpps-srv',
+          help:
+              'Inject a SRV record for _xmpps-client._tcp. Format: <priority>,<weight>,<target>,<port>')
+      ..addFlag('help',
+          abbr: 'h',
+          negatable: false,
+          defaultsTo: false,
+          help: 'Show this help text');
+  }
+
+  /// The [ArgParser] that handles parsing the arguments.
+  final ArgParser parser = ArgParser();
+
+  /// The parsed options. Only valid after calling [handleArguments].
+  late ArgResults options;
+
+  ArgResults? handleArguments(List<String> args) {
+    options = parser.parse(args);
+    if (options['help']!) {
+      print(parser.usage);
+      return null;
+    }
+
+    if (options['jid'] == null) {
+      print(chalk.red('No JID specified'));
+      print(parser.usage);
+      return null;
+    }
+
+    if (options['password'] == null) {
+      print(chalk.red('No password specified'));
+      print(parser.usage);
+      return null;
+    }
+
+    return options;
+  }
+
+  /// The JID to connect as.
+  JID get jid => JID.fromString(options['jid']!).toBare();
+
+  /// Construct connection settings from the parsed options.
+  ConnectionSettings get connectionSettings => ConnectionSettings(
+        jid: jid,
+        password: options['password']!,
+        host: options['host'],
+        port: (options['port'] as String?)?.toInt(),
+      );
+
+  /// Construct an xmpps-client SRV record for injection, if specified.
+  MoxSrvRecord? get srvRecord {
+    if (options['xmpps-srv'] == null) {
+      return null;
+    }
+
+    final parts = options['xmpps-srv']!.split(',');
+    return MoxSrvRecord(
+      int.parse(parts[0]),
+      int.parse(parts[1]),
+      parts[2],
+      int.parse(parts[3]),
+    );
+  }
+}