make canMessage method accessible on the Client class

library/src/androidTest/java/org/xmtp/android/library/ClientTest.kt

@@ -36,7 +36,7 @@ class ClientTest {
         val client = Client().buildFrom(v1Copy)
         assertEquals(
             wallet.address,
-            client.address
+            client.address,
         )
     }
 
@@ -49,11 +49,11 @@ class ClientTest {
         assertEquals(client.address, clientFromV1Bundle.address)
         assertEquals(
             client.privateKeyBundleV1?.identityKey,
-            clientFromV1Bundle.privateKeyBundleV1?.identityKey
+            clientFromV1Bundle.privateKeyBundleV1?.identityKey,
         )
         assertEquals(
             client.privateKeyBundleV1?.preKeysList,
-            clientFromV1Bundle.privateKeyBundleV1?.preKeysList
+            clientFromV1Bundle.privateKeyBundleV1?.preKeysList,
         )
     }
 
@@ -66,13 +66,14 @@ class ClientTest {
         assertEquals(client.address, clientFromV1Bundle.address)
         assertEquals(
             client.privateKeyBundleV1?.identityKey,
-            clientFromV1Bundle.privateKeyBundleV1?.identityKey
+            clientFromV1Bundle.privateKeyBundleV1?.identityKey,
         )
         assertEquals(
             client.privateKeyBundleV1?.preKeysList,
-            clientFromV1Bundle.privateKeyBundleV1?.preKeysList
+            clientFromV1Bundle.privateKeyBundleV1?.preKeysList,
         )
     }
+
     @Test
     fun testCanMessage() {
         val fixtures = fixtures()
@@ -82,4 +83,19 @@ class ClientTest {
         assert(canMessage)
         assert(!cannotMessage)
     }
+
+    @Test
+    fun testPublicCanMessage() {
+        val aliceWallet = PrivateKeyBuilder()
+        val notOnNetwork = PrivateKeyBuilder()
+        val opts = ClientOptions(ClientOptions.Api(XMTPEnvironment.LOCAL, false))
+        val aliceClient = Client().create(aliceWallet, opts)
+        aliceClient.ensureUserContactPublished()
+
+        val canMessage = Client.canMessage(aliceWallet.address, opts)
+        val cannotMessage = Client.canMessage(notOnNetwork.address, opts)
+
+        assert(canMessage)
+        assert(!cannotMessage)
+    }
 }

library/src/main/java/org/xmtp/android/library/ApiClient.kt

@@ -189,6 +189,7 @@ data class GRPCApiClient(
 
         return client.subscribe(request, headers)
     }
+
     override suspend fun subscribe2(request: Flow<SubscribeRequest>): Flow<Envelope> {
         val headers = Metadata()
 

library/src/main/java/org/xmtp/android/library/Client.kt

@@ -114,6 +114,18 @@ class Client() {
                 )
             )
         }
+
+        fun canMessage(peerAddress: String, options: ClientOptions? = null): Boolean {
+            val clientOptions = options ?: ClientOptions()
+            val api = GRPCApiClient(
+                environment = clientOptions.api.env,
+                secure = clientOptions.api.isSecure
+            )
+            return runBlocking {
+                val topics = api.queryTopic(Topic.contact(peerAddress)).envelopesList
+                topics.isNotEmpty()
+            }
+        }
     }
 
     constructor(