Add MemberJoinPacket

mirai-core/src/commonMain/kotlin/net.mamoe.mirai/network/protocol/tim/packet/event/MemberJoin.kt

-@file:Suppress("EXPERIMENTAL_UNSIGNED_LITERALS")
+@file:Suppress("EXPERIMENTAL_UNSIGNED_LITERALS", "EXPERIMENTAL_API_USAGE", "unused", "MemberVisibilityCanBePrivate")
 
 package net.mamoe.mirai.network.protocol.tim.packet.event
 
 import kotlinx.io.core.ByteReadPacket
+import kotlinx.io.core.readUInt
 import net.mamoe.mirai.Bot
+import net.mamoe.mirai.contact.Group
 import net.mamoe.mirai.contact.Member
-import net.mamoe.mirai.event.events.BotEvent
+import net.mamoe.mirai.contact.MemberPermission
+import net.mamoe.mirai.contact.internal.MemberImpl
+import net.mamoe.mirai.event.Event
+import net.mamoe.mirai.getGroup
+import net.mamoe.mirai.getQQ
 import net.mamoe.mirai.network.BotNetworkHandler
 import net.mamoe.mirai.network.protocol.tim.packet.Packet
 import net.mamoe.mirai.utils.MiraiInternalAPI
+import net.mamoe.mirai.utils.io.discardExact
 
 
 //群有新成员加入
@@ -20,18 +27,51 @@ import net.mamoe.mirai.utils.MiraiInternalAPI
  * 新成员加入. 此时这个人还没被添加到群列表
  */
 internal class MemberJoinEventPacket(
-    val member: Member
+    val member: Member,
+    val inviter: Member?
 ) : Packet
 
-class MemberJoinEvent : BotEvent() {
+/**
+ * 成员加入前的事件. 群的成员列表中还没有这个人
+ */
+data class PreMemberJoinEvent(val member: Member, private val _inviter: Member?) : Event() {
+    val group: Group get() = member.group
+    val inviter: Member get() = _inviter ?: error("The new member is not a invitee")
+    val isInvitee: Boolean get() = _inviter != null
+}
 
+/**
+ * 成员加入后的事件. 群的成员列表中已经有这个人
+ */
+data class PostMemberJoinEvent(val member: Member, private val _inviter: Member?) : Event() {
+    val group: Group get() = member.group
+    val inviter: Member get() = _inviter ?: error("The new member is not a invitee")
+    val isInvitee: Boolean get() = _inviter != null
 }
 
 @UseExperimental(MiraiInternalAPI::class)
 internal object MemberJoinPacketHandler : KnownEventParserAndHandler<MemberJoinEventPacket>(0x0021u) {
     override suspend fun ByteReadPacket.parse(bot: Bot, identity: EventPacketIdentity): MemberJoinEventPacket {
+        //由 1040400290 邀请的新成员加入
+        //00 00 00 08 00 0A 00 04 01 00 00
+        // 00 32 DC FC C8
+        // 01 2D 5C 53 A6
+        // 03 3E 03 3F A2
+        // 06 B4 B4 BD A8 D5 DF
+        // 00 30 44 31 43 37 36 30 41 43 33 42 46 37 32 39 38 36 41 42 43 44 33 37 41 37 46 30 35 35 46 37 32 39 46 31 31 36 36 37 42 35 45 33 37 43 37 46 44 37
+        discardExact(11) //00 00 00 08 00 0A 00 04 01 00 00
+
+        discardExact(1) // 00
+        val group = bot.getGroup(readUInt())
+
+        discardExact(1) // 01
+        val member = MemberImpl(bot.getQQ(readUInt()), group, MemberPermission.MEMBER)
 
-        TODO()
+        return if (readByte().toInt() == 0x03) {
+            MemberJoinEventPacket(member, null)
+        } else {
+            MemberJoinEventPacket(member, group.getMember(readUInt()))
+        }
     }
 
     override suspend fun BotNetworkHandler<*>.handlePacket(packet: MemberJoinEventPacket) {