Support group disband kind decoding (#1525)

* Support group disband kind decoding

* Update mirai-core-api/src/commonMain/kotlin/event/events/group.kt

* Add useless comment for triggering build

Co-authored-by: Him188 <Him188@mamoe.net>

mirai-core-api/src/commonMain/kotlin/event/events/group.kt

@@ -57,6 +57,18 @@ public sealed class BotLeaveEvent : BotEvent, Packet, AbstractEvent(), GroupMemb
         public override fun toString(): String = "BotLeaveEvent.Kick(group=${group.id},operator=${operator.id})"
     }
 
+    /**
+     * 机器人因群主解散群而退出群. 操作人一定是群主
+     * @since 2.8
+     */
+    @MiraiExperimentalApi("BotLeaveEvent 的子类可能在将来改动. 使用 BotLeaveEvent 以保证兼容性.")
+    public data class Disband @MiraiInternalApi constructor(
+        public override val group: Group
+    ) : BotLeaveEvent(), GroupOperableEvent {
+        public override val operator: NormalMember = group.owner
+        public override fun toString(): String = "BotLeaveEvent.Disband(group=${group.id})"
+    }
+
     public override val bot: Bot get() = group.bot
 }
 

mirai-core/src/commonMain/kotlin/network/notice/group/GroupOrMemberListNoticeProcessor.kt

@@ -361,6 +361,12 @@ internal class GroupOrMemberListNoticeProcessor(
         groupUin: Long,
     ) {
         when (kind) {
+            // 01 为bot为群主时解散群
+            1, 0x81 -> bot.getGroupByUinOrCode(groupUin)?.let { group ->
+                collect(BotLeaveEvent.Disband(group))
+                bot.groups.delegate.remove(group)
+                group.cancel(CancellationException("Being Disband"))
+            }
             2, 0x82 -> bot.getGroupByUinOrCode(groupUin)?.let { group ->
                 if (target == bot.id) {
                     collect(BotLeaveEvent.Active(group))
@@ -531,4 +537,4 @@ internal class GroupOrMemberListNoticeProcessor(
         } else return
     }
     */
-}
+}