Implement server announcement (#1420)

* implement server announcement

* Update src/main/java/emu/grasscutter/command/commands/AnnounceCommand.java

Co-authored-by: Luke H-W <Birdulon@users.noreply.github.com>

* Added arg numbers check

Co-authored-by: Luke H-W <Birdulon@users.noreply.github.com>

src/main/java/emu/grasscutter/game/managers/AnnouncementManager.java

@@ -0,0 +1,112 @@
+package emu.grasscutter.game.managers;
+
+import com.google.gson.reflect.TypeToken;
+import emu.grasscutter.Grasscutter;
+import emu.grasscutter.data.DataLoader;
+import emu.grasscutter.game.player.Player;
+import emu.grasscutter.game.world.World;
+import emu.grasscutter.net.proto.AnnounceDataOuterClass;
+import emu.grasscutter.server.game.GameServer;
+import emu.grasscutter.server.packet.send.PacketServerAnnounceNotify;
+import emu.grasscutter.server.packet.send.PacketServerAnnounceRevokeNotify;
+import emu.grasscutter.utils.Utils;
+import lombok.AccessLevel;
+import lombok.Data;
+import lombok.Getter;
+import lombok.experimental.FieldDefaults;
+
+import java.io.InputStreamReader;
+import java.util.*;
+
+@Getter
+public class AnnouncementManager {
+
+    public final GameServer server;
+    public AnnouncementManager(GameServer server){
+        this.server = server;
+        loadConfig();
+    }
+    Map<Integer, AnnounceConfigItem> announceConfigItemMap = new HashMap<>();
+
+    private int loadConfig() {
+        try (var fileReader = new InputStreamReader(DataLoader.load("Announcement.json"))) {
+            List<AnnounceConfigItem> announceConfigItems = Grasscutter.getGsonFactory().fromJson(fileReader,
+                TypeToken.getParameterized(List.class, AnnounceConfigItem.class).getType());
+
+            announceConfigItemMap = new HashMap<>();
+            announceConfigItems.forEach(i -> announceConfigItemMap.put(i.getTemplateId(), i));
+
+
+        } catch (Exception e) {
+            Grasscutter.getLogger().error("Unable to load server announce config.", e);
+        }
+
+        return announceConfigItemMap.size();
+    }
+
+    public List<Player> getOnlinePlayers() {
+        return getServer().getWorlds().stream()
+            .map(World::getPlayers)
+            .flatMap(Collection::stream)
+            .toList();
+    }
+
+    public void broadcast(List<AnnounceConfigItem> tpl) {
+        if(tpl == null || tpl.size() == 0){
+            return;
+        }
+
+        var list = tpl.stream()
+            .map(AnnounceConfigItem::toProto)
+            .map(AnnounceDataOuterClass.AnnounceData.Builder::build)
+            .toList();
+
+        getOnlinePlayers().forEach(i -> i.sendPacket(new PacketServerAnnounceNotify(list)));
+    }
+
+    public int refresh() {
+        return loadConfig();
+    }
+
+    public void revoke(int tplId) {
+        getOnlinePlayers().forEach(i -> i.sendPacket(new PacketServerAnnounceRevokeNotify(tplId)));
+    }
+
+    @Data
+    @FieldDefaults(level = AccessLevel.PRIVATE)
+    public class AnnounceConfigItem{
+        int templateId;
+        AnnounceType type;
+        int frequency;
+        String content;
+        Date beginTime;
+        Date endTime;
+        boolean tick;
+        int interval;
+
+        public AnnounceDataOuterClass.AnnounceData.Builder toProto(){
+            var proto = AnnounceDataOuterClass.AnnounceData.newBuilder();
+
+            proto.setConfigId(templateId)
+                // I found the time here is useless
+                .setBeginTime(Utils.getCurrentSeconds() + 1)
+                .setEndTime(Utils.getCurrentSeconds() + 10);
+
+            if(type == AnnounceType.CENTER){
+                proto.setCenterSystemText(content)
+                    .setCenterSystemFrequency(frequency)
+                ;
+            }else{
+                proto.setCountDownText(content)
+                    .setCountDownFrequency(frequency)
+                ;
+            }
+
+            return proto;
+        }
+    }
+
+    public enum AnnounceType{
+        CENTER, COUNTDOWN
+    }
+}