implement the activity system

src/main/java/emu/grasscutter/server/packet/send/PacketActivityScheduleInfoNotify.java

+package emu.grasscutter.server.packet.send;
+
+import emu.grasscutter.game.activity.ActivityConfigItem;
+import emu.grasscutter.net.packet.BasePacket;
+import emu.grasscutter.net.packet.PacketOpcodes;
+import emu.grasscutter.net.proto.ActivityScheduleInfoNotifyOuterClass;
+import emu.grasscutter.net.proto.ActivityScheduleInfoOuterClass;
+import emu.grasscutter.utils.DateHelper;
+
+import java.util.Collection;
+
+public class PacketActivityScheduleInfoNotify extends BasePacket {
+
+	public PacketActivityScheduleInfoNotify(Collection<ActivityConfigItem> activityConfigItemList) {
+		super(PacketOpcodes.ActivityScheduleInfoNotify);
+
+		var proto = ActivityScheduleInfoNotifyOuterClass.ActivityScheduleInfoNotify.newBuilder();
+
+        activityConfigItemList.forEach(item -> {
+            proto.addActivityScheduleList(ActivityScheduleInfoOuterClass.ActivityScheduleInfo.newBuilder()
+                .setActivityId(item.getActivityId())
+                .setScheduleId(item.getScheduleId())
+                .setIsOpen(true)
+                .setBeginTime(DateHelper.getUnixTime(item.getBeginTime()))
+                .setEndTime(DateHelper.getUnixTime(item.getEndTime()))
+                .build());
+        });
+
+		this.setData(proto);
+	}
+}

src/main/java/emu/grasscutter/server/packet/send/PacketActivityUpdateWatcherNotify.java

+package emu.grasscutter.server.packet.send;
+
+import emu.grasscutter.game.activity.PlayerActivityData;
+import emu.grasscutter.net.packet.BasePacket;
+import emu.grasscutter.net.packet.PacketOpcodes;
+import emu.grasscutter.net.proto.ActivityUpdateWatcherNotifyOuterClass;
+
+public class PacketActivityUpdateWatcherNotify extends BasePacket {
+
+	public PacketActivityUpdateWatcherNotify(int activityId, PlayerActivityData.WatcherInfo watcherInfo) {
+		super(PacketOpcodes.ActivityUpdateWatcherNotify);
+
+        var proto = ActivityUpdateWatcherNotifyOuterClass.ActivityUpdateWatcherNotify.newBuilder();
+
+        proto.setActivityId(activityId)
+            .setWatcherInfo(watcherInfo.toProto());
+
+        this.setData(proto);
+	}
+}

src/main/java/emu/grasscutter/server/packet/send/PacketGetActivityInfoRsp.java

 package emu.grasscutter.server.packet.send;
 
+import emu.grasscutter.game.activity.ActivityManager;
 import emu.grasscutter.net.packet.BasePacket;
 import emu.grasscutter.net.packet.PacketOpcodes;
 import emu.grasscutter.net.proto.GetActivityInfoRspOuterClass.GetActivityInfoRsp;
 
+import java.util.Set;
+
 public class PacketGetActivityInfoRsp extends BasePacket {
-	public PacketGetActivityInfoRsp() {
+	public PacketGetActivityInfoRsp(Set<Integer> activityIdList, ActivityManager activityManager) {
 		super(PacketOpcodes.GetActivityInfoRsp);
 
-		GetActivityInfoRsp proto = GetActivityInfoRsp.newBuilder().build();
+		var proto = GetActivityInfoRsp.newBuilder();
+
+        activityIdList.stream()
+            .map(activityManager::getInfoProto)
+            .forEach(proto::addActivityInfoList);
 
 		this.setData(proto);
 	}

src/main/java/emu/grasscutter/server/packet/send/PacketMusicGameSettleRsp.java

+package emu.grasscutter.server.packet.send;
+
+import emu.grasscutter.net.packet.BasePacket;
+import emu.grasscutter.net.packet.PacketOpcodes;
+import emu.grasscutter.net.proto.MusicGameSettleRspOuterClass;
+
+public class PacketMusicGameSettleRsp extends BasePacket {
+
+	public PacketMusicGameSettleRsp(int musicBasicId) {
+		super(PacketOpcodes.MusicGameSettleRsp);
+
+		var proto = MusicGameSettleRspOuterClass.MusicGameSettleRsp.newBuilder();
+
+		proto.setMusicBasicId(musicBasicId)
+				.setIsNewRecord(true);
+
+		this.setData(proto);
+	}
+}

src/main/java/emu/grasscutter/server/packet/send/PacketMusicGameStartRsp.java

+package emu.grasscutter.server.packet.send;
+
+import emu.grasscutter.net.packet.BasePacket;
+import emu.grasscutter.net.packet.PacketOpcodes;
+import emu.grasscutter.net.proto.MusicGameStartRspOuterClass;
+
+public class PacketMusicGameStartRsp extends BasePacket {
+
+	public PacketMusicGameStartRsp(int musicBasicId) {
+		super(PacketOpcodes.MusicGameStartRsp);
+
+		var proto = MusicGameStartRspOuterClass.MusicGameStartRsp.newBuilder();
+
+		proto.setMusicBasicId(musicBasicId);
+
+		this.setData(proto);
+	}
+}

src/main/resources/defaults/data/ActivityConfig.json

+[
+    {
+        "activityId" : 5072,
+        "activityType" : 2202,
+        "meetCondList" : [
+            5072001,
+            5072002,
+            5072003,
+            5072004,
+            5072005,
+            5072006,
+            5072007
+        ],
+        "beginTime" : "2022-05-01T00:00:00+08:00",
+        "endTime" : "2023-05-01T00:00:00+08:00"
+    }
+]
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