[#5] Add support for DIDComm Out Of Band Messages

core/src/main/kotlin/org/nessus/didcomm/model/MessageParser.kt

@@ -0,0 +1,30 @@
+package org.nessus.didcomm.model
+
+import com.google.gson.Gson
+import org.didcommx.didcomm.message.Message
+
+/**
+ * Parses a JSON string to a DIDComm Message
+ */
+class MessageParser {
+
+    companion object {
+        private val gson = Gson()
+
+        fun fromJson(json: String) : Message {
+            val jsonMap: MutableMap<String, Any> = mutableMapOf()
+            gson.fromJson(json, Map::class.java).forEach { en ->
+                val enval = en.value!!
+                when(val key: String = en.key.toString()) {
+                    "created_time" -> jsonMap[key] = (enval as Double).toLong()
+                    "expires_time" -> jsonMap[key] = (enval as Double).toLong()
+                    "custom_headers" -> if ((enval as Map<String, Any>).isNotEmpty()) {
+                        jsonMap[key] = enval
+                    }
+                    else -> jsonMap[key] = enval
+                }
+            }
+            return Message.parse(jsonMap)
+        }
+    }
+}

core/src/main/kotlin/org/nessus/didcomm/model/MessageWriter.kt

@@ -0,0 +1,31 @@
+package org.nessus.didcomm.model
+
+import com.google.gson.FieldNamingPolicy
+import com.google.gson.Gson
+import com.google.gson.GsonBuilder
+import org.didcommx.didcomm.message.Message
+
+/**
+ * Serializes a DIDComm Message to JSON
+ */
+class MessageWriter {
+
+    companion object {
+        private val gson: Gson = GsonBuilder()
+            .setFieldNamingPolicy(FieldNamingPolicy.LOWER_CASE_WITH_UNDERSCORES)
+            .create()
+        private val prettyGson: Gson = GsonBuilder()
+            .setFieldNamingPolicy(FieldNamingPolicy.LOWER_CASE_WITH_UNDERSCORES)
+            .setPrettyPrinting()
+            .create()
+
+        fun toJson(msg: Message, pretty: Boolean = false) : String {
+            return toJson(msg as Any, pretty)
+        }
+
+        fun toJson(obj: Any, pretty: Boolean = false) : String {
+            val gson = if (pretty) prettyGson else gson
+            return gson.toJson(obj)
+        }
+    }
+}

core/src/main/kotlin/org/nessus/didcomm/model/OutOfBandInvitationV2.kt

@@ -0,0 +1,87 @@
+package org.nessus.didcomm.model
+
+import com.google.gson.Gson
+
+/**
+ * [Out of Band Invitation]https://identity.foundation/didcomm-messaging/spec/#out-of-band-messages
+ *
+ * {
+ *   "type": "https://didcomm.org/out-of-band/2.0/invitation",
+ *   "id": "<id used for context as pthid>",
+ *   "from":"<sender's did>",
+ *   "body": {
+ *     "goal_code": "issue-vc",
+ *     "goal": "To issue a Faber College Graduate credential",
+ *     "accept": [
+ *       "didcomm/v2",
+ *       "didcomm/aip2;env=rfc587"
+ *     ],
+ *   },
+ *   "attachments": [
+ *     {
+ *         "id": "request-0",
+ *         "mime_type": "application/json",
+ *         "data": {
+ *             "json": "<json of protocol message>"
+ *         }
+ *     }
+ *   ]
+ * }
+ */
+data class OutOfBandInvitationV2(
+
+    /**
+     * Message ID. The id attribute value MUST be unique to the sender, across all messages they send.
+     * This value MUST be used as the parent thread ID (pthid) for the response message that follows.
+     * REQUIRED
+     */
+    val id: String,
+
+    /**
+     * The DID representing the sender to be used by recipients for future interactions.
+     * REQUIRED
+     */
+    val from: String,
+
+    /**
+     * A self-attested code the receiver may want to display to the user or use in automatically deciding what to do with the out-of-band message.
+     * OPTIONAL
+     */
+    val goalCode: String?,
+
+    /**
+     * A self-attested string that the receiver may want to display to the user about the context-specific goal of the out-of-band message.
+     * OPTIONAL
+     */
+    val goal: String?,
+
+    /**
+     * An array of media types in the order of preference for sending a message to the endpoint.
+     * These identify a profile of DIDComm Messaging that the endpoint supports.
+     * OPTIONAL
+     */
+    val accept: List<String>?,
+
+    /**
+     * An array of attachments that will contain the invitation messages in order of preference that the receiver can use in responding to the message.
+     * Each message in the array is a rough equivalent of the others, and all are in pursuit of the stated goal and goal_code.
+     * Only one of the messages should be chosen and acted upon.
+     * OPTIONAL
+     */
+    val attachments: List<Any>?,
+) {
+
+    companion object {
+
+        /**
+         * The header conveying the DIDComm MTURI.
+         * REQUIRED
+         */
+        const val type: String = "https://didcomm.org/out-of-band/2.0/invitation"
+
+        fun fromBody(body: Map<String, Any?>): OutOfBandInvitationV2 {
+            val gson = Gson()
+            return gson.fromJson(gson.toJson(body), OutOfBandInvitationV2::class.java)
+        }
+    }
+}

core/src/test/kotlin/org/nessus/didcomm/test/model/Fixtures.kt

@@ -0,0 +1,30 @@
+package org.nessus.didcomm.test.model
+
+import org.didcommx.didcomm.message.Attachment
+import org.didcommx.didcomm.message.Message
+import org.nessus.didcomm.model.OutOfBandInvitationV2
+
+class OutOfBand {
+
+    companion object {
+
+        const val ALICE_DID = "did:example:alice"
+        const val FABER_DID = "did:example:faber"
+
+        private const val ID = "1234567890"
+        private const val TYPE = OutOfBandInvitationV2.type
+
+        val OUT_OF_BAND_INVITATION = Message.builder(ID, mapOf(
+            "goal_code" to "issue-vc",
+            "goal" to "To issue a Faber College Graduate credential",
+            "accept" to listOf("didcomm/v2", "didcomm/aip2;env=rfc587")),
+            TYPE)
+            .from(FABER_DID)
+            .createdTime(1516269022)
+            .expiresTime(1516385931)
+            .attachments(listOf(
+                Attachment.builder(
+                    "request-0", Attachment.Data.parse(mapOf("base64" to "qwerty"))).build()))
+            .build()
+   }
+}

core/src/test/kotlin/org/nessus/didcomm/test/model/OutOfBandInvitationTest.kt

@@ -0,0 +1,34 @@
+package org.nessus.didcomm.test.model
+
+import mu.KotlinLogging
+import org.didcommx.didcomm.message.Message
+import org.junit.jupiter.api.Test
+import org.nessus.didcomm.model.MessageParser
+import org.nessus.didcomm.model.MessageWriter
+import org.nessus.didcomm.model.OutOfBandInvitationV2
+import kotlin.test.Ignore
+import kotlin.test.assertEquals
+
+@Ignore
+class OutOfBandInvitationTest {
+
+    private val log = KotlinLogging.logger {}
+
+    @Test
+    fun testOutOfBandInvitation() {
+
+        val exp: Message = OutOfBand.OUT_OF_BAND_INVITATION
+        val expBody = OutOfBandInvitationV2.fromBody(exp.body)
+        val expJson: String = MessageWriter.toJson(exp)
+        log.info("exp: {}", expJson)
+
+        val was = MessageParser.fromJson(expJson)
+        log.info("was: {}", MessageWriter.toJson(was))
+        assertEquals(exp, was)
+
+        val wasBody = OutOfBandInvitationV2.fromBody(was.body)
+        log.info("body: {}", MessageWriter.toJson(wasBody))
+        assertEquals(expBody, wasBody)
+    }
+
+}