draft

android/app/src/main/AndroidManifest.xml

@@ -35,6 +35,7 @@
                 <category android:name="android.intent.category.DEFAULT" />
                 <category android:name="android.intent.category.BROWSABLE" />
                 <data android:scheme="zulip" android:host="login" />
+                <data android:host="notification_open" />
             </intent-filter>
         </activity>
         <!-- Don't delete the meta-data below.

android/app/src/main/kotlin/com/zulip/flutter/Notifications.g.kt

@@ -87,6 +87,36 @@ data class NotificationChannel (
   }
 }
 
+/**
+ * Corresponds to `android.content.Intent`
+ *
+ * See:
+ *   https://developer.android.com/reference/android/content/Intent
+ *   https://developer.android.com/reference/android/content/Intent#Intent(java.lang.String,%20android.net.Uri,%20android.content.Context,%20java.lang.Class%3C?%3E)
+ *
+ * Generated class from Pigeon that represents data sent in messages.
+ */
+data class AndroidIntent (
+  val action: String,
+  val uri: String
+
+) {
+  companion object {
+    @Suppress("LocalVariableName")
+    fun fromList(__pigeon_list: List<Any?>): AndroidIntent {
+      val action = __pigeon_list[0] as String
+      val uri = __pigeon_list[1] as String
+      return AndroidIntent(action, uri)
+    }
+  }
+  fun toList(): List<Any?> {
+    return listOf(
+      action,
+      uri,
+    )
+  }
+}
+
 /**
  * Corresponds to `android.app.PendingIntent`.
  *
@@ -96,11 +126,7 @@ data class NotificationChannel (
  */
 data class PendingIntent (
   val requestCode: Long,
-  /**
-   * A value set on an extra on the Intent, and passed to
-   * the on-notification-opened callback.
-   */
-  val intentPayload: String,
+  val intent: AndroidIntent,
   /**
    * A combination of flags from [PendingIntent.flags], and others associated
    * with `Intent`; see Android docs for `PendingIntent.getActivity`.
@@ -112,15 +138,15 @@ data class PendingIntent (
     @Suppress("LocalVariableName")
     fun fromList(__pigeon_list: List<Any?>): PendingIntent {
       val requestCode = __pigeon_list[0].let { num -> if (num is Int) num.toLong() else num as Long }
-      val intentPayload = __pigeon_list[1] as String
+      val intent = __pigeon_list[1] as AndroidIntent
       val flags = __pigeon_list[2].let { num -> if (num is Int) num.toLong() else num as Long }
-      return PendingIntent(requestCode, intentPayload, flags)
+      return PendingIntent(requestCode, intent, flags)
     }
   }
   fun toList(): List<Any?> {
     return listOf(
       requestCode,
-      intentPayload,
+      intent,
       flags,
     )
   }
@@ -266,25 +292,30 @@ private object NotificationsPigeonCodec : StandardMessageCodec() {
       }
       130.toByte() -> {
         return (readValue(buffer) as? List<Any?>)?.let {
-          PendingIntent.fromList(it)
+          AndroidIntent.fromList(it)
         }
       }
       131.toByte() -> {
         return (readValue(buffer) as? List<Any?>)?.let {
-          InboxStyle.fromList(it)
+          PendingIntent.fromList(it)
         }
       }
       132.toByte() -> {
         return (readValue(buffer) as? List<Any?>)?.let {
-          Person.fromList(it)
+          InboxStyle.fromList(it)
         }
       }
       133.toByte() -> {
         return (readValue(buffer) as? List<Any?>)?.let {
-          MessagingStyleMessage.fromList(it)
+          Person.fromList(it)
         }
       }
       134.toByte() -> {
+        return (readValue(buffer) as? List<Any?>)?.let {
+          MessagingStyleMessage.fromList(it)
+        }
+      }
+      135.toByte() -> {
         return (readValue(buffer) as? List<Any?>)?.let {
           MessagingStyle.fromList(it)
         }
@@ -298,26 +329,30 @@ private object NotificationsPigeonCodec : StandardMessageCodec() {
         stream.write(129)
         writeValue(stream, value.toList())
       }
-      is PendingIntent -> {
+      is AndroidIntent -> {
         stream.write(130)
         writeValue(stream, value.toList())
       }
-      is InboxStyle -> {
+      is PendingIntent -> {
         stream.write(131)
         writeValue(stream, value.toList())
       }
-      is Person -> {
+      is InboxStyle -> {
         stream.write(132)
         writeValue(stream, value.toList())
       }
-      is MessagingStyleMessage -> {
+      is Person -> {
         stream.write(133)
         writeValue(stream, value.toList())
       }
-      is MessagingStyle -> {
+      is MessagingStyleMessage -> {
         stream.write(134)
         writeValue(stream, value.toList())
       }
+      is MessagingStyle -> {
+        stream.write(135)
+        writeValue(stream, value.toList())
+      }
       else -> super.writeValue(stream, value)
     }
   }

android/app/src/main/kotlin/com/zulip/flutter/ZulipPlugin.kt

@@ -3,6 +3,7 @@ package com.zulip.flutter
 import android.annotation.SuppressLint
 import android.content.Context
 import android.content.Intent
+import android.net.Uri
 import android.os.Bundle
 import android.util.Log
 import androidx.annotation.Keep
@@ -82,13 +83,12 @@ private class AndroidNotificationHost(val context: Context)
             contentIntent?.let { setContentIntent(
                 android.app.PendingIntent.getActivity(context,
                     it.requestCode.toInt(),
-                    Intent(context, MainActivity::class.java).apply {
-                        // This action name and extra name are special to
-                        // FlutterLocalNotificationsPlugin, which handles receiving the Intent.
-                        // TODO take care of receiving the notification-opened Intent ourselves
-                        action = "SELECT_NOTIFICATION"
-                        putExtra("payload", it.intentPayload)
-                    },
+                    it.intent.let { intent -> Intent(
+                        intent.action,
+                        Uri.parse(intent.uri),
+                        context,
+                        MainActivity::class.java
+                    ) },
                     it.flags.toInt())
             ) }
             contentText?.let { setContentText(it) }

lib/api/model/notification.dart

@@ -0,0 +1,100 @@
+import '../../model/narrow.dart';
+
+class NotificationOpenPayload {
+  final Uri realm;
+  final int userId;
+  final Narrow narrow;
+
+  NotificationOpenPayload({
+    required this.realm,
+    required this.userId,
+    required this.narrow,
+  }): assert((narrow is TopicNarrow) ^ (narrow is DmNarrow));
+
+  factory NotificationOpenPayload.parse(Uri url) {
+    if (url case Uri(
+      scheme: 'zulip',
+      host: 'notification_open',
+      queryParameters: {
+        'realm': String realmStr,
+        'user_id': String userIdStr,
+        'narrow_type': String narrowType,
+      },
+    )) {
+      final realm = Uri.tryParse(realmStr);
+      if (realm == null) throw const FormatException();
+
+      final userId = int.tryParse(userIdStr, radix: 10);
+      if (userId == null) throw const FormatException();
+
+      final Narrow narrow;
+      switch (narrowType) {
+        case 'topic':
+          final streamIdStr = url.queryParameters['stream_id'];
+          if (streamIdStr == null) throw const FormatException();
+          final streamId = int.tryParse(streamIdStr, radix: 10);
+          if (streamId == null) throw const FormatException();
+
+          final topic = url.queryParameters['topic'];
+          if (topic == null) throw const FormatException();
+
+          narrow = TopicNarrow(streamId, topic);
+        case 'dm':
+          final allRecipientIdsStr = url.queryParameters['all_recipient_ids'];
+          if (allRecipientIdsStr == null) throw const FormatException();
+          final List<int> allRecipientIds = allRecipientIdsStr
+            .split(',')
+            .map((String idStr) {
+              final id = int.tryParse(idStr, radix: 10);
+              if (id == null) throw const FormatException();
+              return id;
+            })
+            .toList();
+
+          narrow = DmNarrow(allRecipientIds: allRecipientIds, selfUserId: userId);
+        default:
+          throw const FormatException();
+      }
+
+      return NotificationOpenPayload(
+        realm: realm,
+        userId: userId,
+        narrow: narrow,
+      );
+    } else {
+      // TODO(dart): simplify after https://github.com/dart-lang/language/issues/2537
+      throw const FormatException();
+    }
+  }
+
+  Uri toUri() {
+    var queryParameters = <String, String>{
+      'realm': realm.toString(),
+      'user_id': userId.toString(),
+    };
+
+    switch (narrow) {
+      case TopicNarrow(:final streamId, :final topic):
+        queryParameters = {
+          ...queryParameters,
+          'narrow_type': 'topic',
+          'stream_id': streamId.toString(),
+          'topic': topic.toString(),
+        };
+      case DmNarrow(:final allRecipientIds):
+        queryParameters = {
+          ...queryParameters,
+          'narrow_type': 'dm',
+          'all_recipient_ids': allRecipientIds.join(','),
+        };
+      default:
+        throw UnimplementedError();
+    }
+
+    return Uri(
+      scheme: 'zulip',
+      host: 'notification_open',
+      queryParameters: queryParameters,
+    );
+  }
+}

lib/host/android_notifications.dart

@@ -60,3 +60,11 @@ abstract class PendingIntentFlag {
   /// Corresponds to `FLAG_ALLOW_UNSAFE_IMPLICIT_INTENT`.
   static const allowUnsafeImplicitIntent = 1 << 24;
 }
+
+/// For use in [AndroidIntent.action].
+///
+/// See: https://developer.android.com/reference/android/content/Intent#constants_1
+abstract class IntentAction {
+  /// Corresponds to `ACTION_VIEW`.
+  static const view = 'android.intent.action.VIEW';
+}