Make serialization of Snowflake consistent (#316)

Snowflakes are decoded as Longs but encoded as Strings. Mixing these types is allowed in JSON (and is done by Discord quite frequently) but does lead to other encoding types failing.

This commit changes snowflakes to be encoded and decoded as long values exclusively, and should fix the issue.

common/src/main/kotlin/entity/Snowflake.kt

@@ -71,12 +71,12 @@ class Snowflake(val value: Long) : Comparable<Snowflake> {
         override fun deserialize(decoder: Decoder): Snowflake = Snowflake(decoder.decodeLong())
 
         override fun serialize(encoder: Encoder, value: Snowflake) {
-            encoder.encodeString(value.value.toString())
+            encoder.encodeLong(value.value)
         }
     }
 }
 
 private class SnowflakeMark(val epochMilliseconds: Long) : TimeMark() {
 
     override fun elapsedNow(): Duration = Instant.fromEpochMilliseconds(epochMilliseconds) - Clock.System.now()
-}
+}

gateway/src/test/kotlin/json/CommandTest.kt

@@ -70,7 +70,7 @@ class CommandTest {
         val json = json.encodeToString(JsonObject.serializer(), buildJsonObject {
             put("op", OpCode.RequestGuildMembers.code)
             put("d", buildJsonObject {
-                put("guild_id", guildId)
+                put("guild_id", guildId.toLong())
                 put("query", query)
                 put("limit", limit)
             })
@@ -95,8 +95,8 @@ class CommandTest {
         val json = json.encodeToString(JsonObject.serializer(), buildJsonObject {
             put("op", OpCode.VoiceStateUpdate.code)
             put("d", buildJsonObject {
-                put("guild_id", guildId)
-                put("channel_id", channelId)
+                put("guild_id", guildId.toLong())
+                put("channel_id", channelId.toLong())
                 put("self_mute", selfMute)
                 put("self_deaf", selfDeaf)
             })

gateway/src/test/kotlin/json/SnowflakeTest.kt

@@ -0,0 +1,50 @@
+package json
+
+import dev.kord.common.entity.Snowflake
+import kotlinx.serialization.Serializable
+import kotlinx.serialization.decodeFromString
+import kotlinx.serialization.encodeToString
+import kotlinx.serialization.json.Json
+import kotlinx.serialization.json.buildJsonObject
+import kotlinx.serialization.json.decodeFromJsonElement
+import kotlinx.serialization.json.put
+import kotlin.test.Test
+import kotlin.test.assertEquals
+
+class SnowflakeTest {
+
+    @Serializable
+    private data class SnowflakeContainer(val snowflake: Snowflake)
+
+    @Test
+    fun `Deserialization of Snowflake as String completes successfully`() {
+        val value = "1337"
+        val json = buildJsonObject {
+            put("snowflake", value)
+        }
+
+        val container = Json.decodeFromJsonElement<SnowflakeContainer>(json)
+        assertEquals(value, container.snowflake.asString)
+    }
+
+    @Test
+    fun `Deserialization of Snowflake as Long completes successfully`() {
+        val value = 1337L
+        val json = buildJsonObject {
+            put("snowflake", value)
+        }
+
+        val container = Json.decodeFromJsonElement<SnowflakeContainer>(json)
+        assertEquals(value, container.snowflake.value)
+    }
+
+    @Test
+    fun `Reserialization of Snowflake completes successfully`() {
+        val json = buildJsonObject { put("snowflake", 1337L) }
+
+        val container = Json.decodeFromJsonElement<SnowflakeContainer>(json)
+        val reDecodedContainer = Json.decodeFromString<SnowflakeContainer>(Json.encodeToString(container))
+        assertEquals(container, reDecodedContainer)
+    }
+
+}