add welcome message

src/main/kotlin/com/wire/broadcastapp/BroadcastService.kt

@@ -9,7 +9,7 @@ class BroadcastService(private val repository: Repository) {
     private lateinit var manager: WireApplicationManager
 
     companion object {
-        private const val COMMAND_PREFIX = "/broadcast"
+        const val COMMAND_PREFIX = "/broadcast"
         private val NOT_AUTHORIZED = """
             ⛔ You’re not authorized to send broadcasts.
             Only approved broadcasters can use the `$COMMAND_PREFIX` command.

src/main/kotlin/com/wire/broadcastapp/EventsHandler.kt

@@ -1,7 +1,10 @@
 package com.wire.broadcastapp
 
+import com.wire.broadcastapp.BroadcastService.Companion.COMMAND_PREFIX
 import com.wire.broadcastapp.dao.Repository
 import com.wire.sdk.WireEventsHandlerSuspending
+import com.wire.sdk.model.ConversationData
+import com.wire.sdk.model.ConversationMember
 import com.wire.sdk.model.WireMessage
 
 class EventsHandler : WireEventsHandlerSuspending() {
@@ -12,4 +15,24 @@ class EventsHandler : WireEventsHandlerSuspending() {
     override suspend fun onTextMessageReceived(wireMessage: WireMessage.Text) {
         broadcast.handleMessage(wireMessage)
     }
+
+    override suspend fun onAppAddedToConversation(
+        conversation: ConversationData,
+        members: List<ConversationMember>
+    ) {
+        val welcomeMessage = WireMessage.Text.create(
+            conversationId = conversation.id,
+            text = WELCOME_TEXT
+        )
+
+        manager.sendMessage(welcomeMessage)
+    }
+
+    private companion object {
+        const val WELCOME_TEXT =
+            "👋 Hi, I'm the Broadcast App. Thanks for adding me to the conversation.\n" +
+                "You can use me to message multiple conversations simultaneously.\n" +
+                "I'm here to help make everyday work a little easier.\n" +
+                "Use the `$COMMAND_PREFIX <your message here>` command to get started."
+    }
 }