Complete all serverbound packets

libmc-common/src/commonMain/kotlin/cn/rtast/libmc/common/buffer.kt

@@ -73,6 +73,22 @@ public fun BytesBuffer.writePrefixedByteArray(data: ByteArray) {
     this.writeBytes(data)
 }
 
+public fun BytesBuffer.readOptionalPrefixedByteArray(): ByteArray? {
+    val isPresent = this.readBoolean()
+    return if (isPresent) {
+        val length = this.readVarInt()
+        this.readBytes(length)
+    } else null
+}
+
+public fun BytesBuffer.writeOptionalPrefixedByteArray(data: ByteArray?) {
+    if (data != null) {
+        this.writeBoolean(true)
+        this.writeVarInt(data.size)
+        this.writeBytes(data)
+    } else this.writeBoolean(false)
+}
+
 public fun BytesBuffer.readPrefixedVarIntArray(): List<Int> {
     val length = readVarInt()
     val list = ArrayList<Int>(length)

libmc-common/src/commonMain/kotlin/cn/rtast/libmc/common/mc_primitives.kt

@@ -74,4 +74,25 @@ public object McStringCodec : PacketCodec<String> {
         val bytes = buffer.readBytes(length)
         return bytes.decodeToString()
     }
+}
+
+public sealed interface IdOrX<out T> {
+    public data class Inline<T>(val value: T) : IdOrX<T>
+    public data class Reference(val registryId: Int) : IdOrX<Nothing>
+}
+
+public inline fun <T> BytesBuffer.writeIdOrX(value: IdOrX<T>, writeX: BytesBuffer.(T) -> Unit) {
+    when (value) {
+        is IdOrX.Inline -> {
+            this.writeVarInt(0)
+            this.writeX(value.value)
+        }
+
+        is IdOrX.Reference -> this.writeVarInt(value.registryId + 1)
+    }
+}
+
+public inline fun <T> BytesBuffer.readIdOrX(readX: BytesBuffer.() -> T): IdOrX<T> {
+    val id = this.readVarInt()
+    return if (id == 0) IdOrX.Inline(this.readX()) else IdOrX.Reference(id - 1)
 }