Reply Content Type (#98)

* add api client with grpc kotlin

* add reply codec type

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

@@ -0,0 +1,48 @@
+package org.xmtp.android.library
+
+import androidx.test.ext.junit.runners.AndroidJUnit4
+import org.junit.Assert.assertEquals
+import org.junit.Test
+import org.junit.runner.RunWith
+import org.xmtp.android.library.codecs.ContentTypeReply
+import org.xmtp.android.library.codecs.ContentTypeText
+import org.xmtp.android.library.codecs.Reply
+import org.xmtp.android.library.codecs.ReplyCodec
+import org.xmtp.android.library.messages.walletAddress
+
+@RunWith(AndroidJUnit4::class)
+class ReplyTest {
+
+    @Test
+    fun testCanUseReplyCodec() {
+        Client.register(codec = ReplyCodec())
+
+        val fixtures = fixtures()
+        val aliceClient = fixtures.aliceClient
+        val aliceConversation =
+            aliceClient.conversations.newConversation(fixtures.bob.walletAddress)
+
+        aliceConversation.send(text = "hey alice 2 bob")
+
+        val messageToReact = aliceConversation.messages()[0]
+
+        val attachment = Reply(
+            reference = messageToReact.id,
+            content = "Hello",
+            contentType = ContentTypeText
+        )
+
+        aliceConversation.send(
+            content = attachment,
+            options = SendOptions(contentType = ContentTypeReply),
+        )
+        val messages = aliceConversation.messages()
+        assertEquals(messages.size, 2)
+        if (messages.size == 2) {
+            val content: Reply? = messages.first().content()
+            assertEquals("Hello", content?.content)
+            assertEquals(messageToReact.id, content?.reference)
+            assertEquals(ContentTypeText, content?.contentType)
+        }
+    }
+}

library/src/main/java/org/xmtp/android/library/codecs/README.md

@@ -8,6 +8,8 @@ When you build an app with XMTP, all messages are encoded with a [content type](
 - `AttachmentCodec`: Enables sending attachments.
 - `RemoteAttachmentCodec`: Enables sending remote attachments.
 - `ReactionCodec`: Enables sending of reactions.
+- `ReplyCodec`: Enables sending of replies.
+
 
 ## Support remote media attachments
 

library/src/main/java/org/xmtp/android/library/codecs/ReplyCodec.kt

@@ -0,0 +1,34 @@
+package org.xmtp.android.library.codecs
+
+import com.google.gson.GsonBuilder
+import com.google.protobuf.kotlin.toByteStringUtf8
+
+val ContentTypeReply = ContentTypeIdBuilder.builderFromAuthorityId(
+    "xmtp.org",
+    "reply",
+    versionMajor = 1,
+    versionMinor = 0
+)
+
+data class Reply(
+    val reference: String,
+    val content: Any,
+    val contentType: ContentTypeId,
+)
+
+data class ReplyCodec(override var contentType: ContentTypeId = ContentTypeReply) :
+    ContentCodec<Reply> {
+
+    override fun encode(content: Reply): EncodedContent {
+        val gson = GsonBuilder().create()
+        return EncodedContent.newBuilder().also {
+            it.type = ContentTypeReply
+            it.content = gson.toJson(content).toByteStringUtf8()
+        }.build()
+    }
+
+    override fun decode(content: EncodedContent): Reply {
+        val gson = GsonBuilder().create()
+        return gson.fromJson(content.content.toStringUtf8(), Reply::class.java)
+    }
+}