Move player mail to MailHandler class

This is so we dont have to save the entire player to the db every time we send mail

src/main/java/emu/grasscutter/game/mail/MailHandler.java

@@ -0,0 +1,104 @@
+package emu.grasscutter.game.mail;
+
+import java.time.Instant;
+import java.util.ArrayList;
+import java.util.Collections;
+import java.util.List;
+
+import emu.grasscutter.Grasscutter;
+import emu.grasscutter.database.DatabaseHelper;
+import emu.grasscutter.game.player.Player;
+import emu.grasscutter.server.event.player.PlayerReceiveMailEvent;
+import emu.grasscutter.server.packet.send.PacketDelMailRsp;
+import emu.grasscutter.server.packet.send.PacketMailChangeNotify;
+
+public class MailHandler {
+	private final Player player;
+	private final List<Mail> mail;
+	
+	public MailHandler(Player player) {
+		this.player = player;
+		this.mail = new ArrayList<>();
+	}
+
+	public Player getPlayer() {
+		return player;
+	}
+
+	public List<Mail> getMail() {
+		return mail;
+	}
+	
+	// ---------------------MAIL------------------------
+
+	public void sendMail(Mail message) {
+		// Call mail receive event.
+		PlayerReceiveMailEvent event = new PlayerReceiveMailEvent(this.getPlayer(), message); event.call();
+		if(event.isCanceled()) return; message = event.getMessage();
+		
+		message.setOwnerUid(this.getPlayer().getUid());
+		
+		this.mail.add(message);
+		
+		Grasscutter.getLogger().debug("Mail sent to user [" + this.getPlayer().getUid()  + ":" + this.getPlayer().getNickname() + "]!");
+		
+		if (this.getPlayer().isOnline()) {
+			this.getPlayer().sendPacket(new PacketMailChangeNotify(this.getPlayer(), message));
+		} // TODO: setup a way for the mail notification to show up when someone receives mail when they were offline
+	}
+
+	public boolean deleteMail(int mailId) {
+		Mail message = getMailById(mailId);
+
+		if (message != null) {
+			this.getMail().remove(mailId);
+			message.expireTime = 0;
+			message.save();
+			
+			return true;
+		}
+
+		return false;
+	}
+	
+	public void deleteMail(List<Integer> mailList) {
+		List<Integer> sortedMailList = new ArrayList<>();
+		sortedMailList.addAll(mailList);
+		Collections.sort(sortedMailList, Collections.reverseOrder());
+		
+		List<Integer> deleted = new ArrayList<>();
+		
+		for (int id : sortedMailList) {
+			if (this.deleteMail(id)) {
+				deleted.add(id);
+			}
+		}
+		
+		player.getSession().send(new PacketDelMailRsp(player, deleted));
+		player.getSession().send(new PacketMailChangeNotify(player, null, deleted));
+	}
+
+	public Mail getMailById(int index) { return this.mail.get(index); }
+	
+	public int getMailIndex(Mail message) {
+		return this.mail.indexOf(message);
+	}
+
+	public boolean replaceMailByIndex(int index, Mail message) {
+		if(getMailById(index) != null) {
+			this.mail.set(index, message);
+			message.save();
+			return true;
+		} else {
+			return false;
+		}
+	}
+
+	public void loadFromDatabase() {
+		List<Mail> mailList = DatabaseHelper.getAllMail(this.getPlayer());
+		
+		for (Mail mail : mailList) {
+			this.getMail().add(mail);
+		}
+	}
+}