New Year cards + Info on PlayerShops/HiredMerchants

New Year is coming soon! Figured out implementation for the New Year cards. Opcodes and packet structures are thanks to Eric.
New Year effect crashes/dc's the player in some cases.
Added informative notes to shop owners when transactioning an item/bundle.

src/net/server/channel/handlers/NewYearCardHandler.java

@@ -0,0 +1,153 @@
+/*
+ * This file is part of the HeavenMS (MapleSolaxiaV2) Maple Story Server
+ *
+ * Copyright (C) 2017 RonanLana
+ *
+ * This program is free software: you can redistribute it and/or modify
+ * it under the terms of the GNU General Public License as published by
+ * the Free Software Foundation, either version 3 of the License, or
+ * (at your option) any later version.
+ *
+ * This program is distributed in the hope that it will be useful,
+ * but WITHOUT ANY WARRANTY; without even the implied warranty of
+ * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+ * GNU General Public License for more details.
+ *
+ * You should have received a copy of the GNU General Public License
+ * along with this program.  If not, see <http://www.gnu.org/licenses/>.
+ */
+
+package net.server.channel.handlers;
+
+import constants.ItemConstants;
+
+import client.MapleCharacter;
+import client.MapleClient;
+import client.inventory.Item;
+import client.newyear.NewYearCardRecord;
+import java.sql.Connection;
+import java.sql.PreparedStatement;
+import java.sql.ResultSet;
+import java.sql.SQLException;
+import net.AbstractMaplePacketHandler;
+import net.server.Server;
+import server.MapleItemInformationProvider;
+import tools.DatabaseConnection;
+import tools.MaplePacketCreator;
+import tools.data.input.SeekableLittleEndianAccessor;
+
+/**
+ *
+ * @author Ronan - header layout courtesy of Eric 
+ */
+public final class NewYearCardHandler extends AbstractMaplePacketHandler {
+
+    @Override
+    public final void handlePacket(SeekableLittleEndianAccessor slea, MapleClient c) {        
+        final MapleCharacter player = c.getPlayer();
+        byte reqMode = slea.readByte();                 //[00] -> NewYearReq (0 = Send) 
+        
+        if(reqMode == 0) {  // card has been sent
+            if(player.haveItem(2160101)) {  // new year's card
+                short slot = slea.readShort();                      //[00 2C] -> nPOS (Item Slot Pos) 
+                int itemid = slea.readInt();                        //[00 20 F5 E5] -> nItemID (item id) 
+
+                int status = getValidNewYearCardStatus(itemid, player, slot);
+                if(status == 0) {
+                    if(player.canHold(4300000, 1)) {
+                        String receiver = slea.readMapleAsciiString();  //[04 00 54 65 73 74] -> sReceiverName (person to send to) 
+
+                        int receiverid = getReceiverId(receiver, c.getWorld());
+                        if(receiverid != -1) {
+                            if(receiverid != c.getPlayer().getId()) {
+                                String message = slea.readMapleAsciiString();   //[06 00 4C 65 74 74 65 72] -> sContent (message)  
+
+                                NewYearCardRecord newyear = new NewYearCardRecord(player.getId(), player.getName(), receiverid, receiver, message);
+                                NewYearCardRecord.saveNewYearCard(newyear);
+                                player.addNewYearRecord(newyear);
+
+                                player.getClient().getAbstractPlayerInteraction().gainItem(2160101, (short)-1);
+                                player.getClient().getAbstractPlayerInteraction().gainItem(4300000, (short) 1);
+
+                                Server.getInstance().setNewYearCard(newyear);
+                                newyear.startNewYearCardTask();
+                                player.announce(MaplePacketCreator.onNewYearCardRes(player, newyear, 4, 0));    // successfully sent
+                            } else {
+                                player.announce(MaplePacketCreator.onNewYearCardRes(player, -1, 5, 0xF));   // cannot send to yourself
+                            }
+                        } else {
+                            player.announce(MaplePacketCreator.onNewYearCardRes(player, -1, 5, 0x13));  // cannot find such character
+                        }
+                    } else {
+                        player.announce(MaplePacketCreator.onNewYearCardRes(player, -1, 5, 0x10));  // inventory full
+                    }
+                } else {
+                    player.announce(MaplePacketCreator.onNewYearCardRes(player, -1, 5, status));  // item and inventory errors
+                }
+            } else {
+                player.announce(MaplePacketCreator.onNewYearCardRes(player, -1, 5, 0x11));  // have no card to send
+            }
+        } else {    //receiver accepted the card
+            int cardid = slea.readInt();
+            
+            NewYearCardRecord newyear = NewYearCardRecord.loadNewYearCard(cardid);
+            
+            if(newyear != null && newyear.getReceiverId() == player.getId() && !newyear.isReceiverCardReceived()) {
+                if(!newyear.isSenderCardDiscarded()) {
+                    if(player.canHold(4301000, 1)) {
+                        newyear.stopNewYearCardTask();
+                        NewYearCardRecord.updateNewYearCard(newyear);
+
+                        player.getClient().getAbstractPlayerInteraction().gainItem(4301000, (short)1);
+                        if(!newyear.getMessage().isEmpty()) player.dropMessage(6, "[NEW YEAR] " + newyear.getSenderName() + ": " + newyear.getMessage());
+
+                        player.addNewYearRecord(newyear);
+                        player.announce(MaplePacketCreator.onNewYearCardRes(player, newyear, 6, 0));    // successfully rcvd
+
+                        player.getMap().broadcastMessage(MaplePacketCreator.onNewYearCardRes(player, newyear, 0xD, 0));
+
+                        MapleCharacter sender = c.getWorldServer().getPlayerStorage().getCharacterById(newyear.getSenderId());
+                        if(sender != null && sender.isLoggedin() && !sender.isAwayFromWorld()) {
+                            sender.getMap().broadcastMessage(MaplePacketCreator.onNewYearCardRes(sender, newyear, 0xD, 0));
+                            sender.dropMessage(6, "[NEW YEAR] Your addressee successfully received the New Year card.");
+                        }
+                    } else {
+                        player.announce(MaplePacketCreator.onNewYearCardRes(player, -1, 5, 0x10));  // inventory full
+                    }
+                } else {
+                    player.dropMessage(6, "[NEW YEAR] The sender of the New Year card already dropped it. Nothing to receive.");
+                }
+            } else {
+                if(newyear == null) {
+                    player.dropMessage(6, "[NEW YEAR] The sender of the New Year card already dropped it. Nothing to receive.");
+                }
+            }
+        }
+    }
+    
+    private static int getReceiverId(String receiver, int world) {
+        try (Connection con = DatabaseConnection.getConnection()) {
+            try (PreparedStatement ps = con.prepareStatement("SELECT id, world FROM characters WHERE name LIKE ?")) {
+                ps.setString(1, receiver);
+                try (ResultSet rs = ps.executeQuery()) {
+                    if (rs.next()) {
+                        if(rs.getInt("world") == world) {
+                            return rs.getInt("id");
+                        }
+                    }
+                }
+            }
+        } catch(SQLException sqle) {
+            sqle.printStackTrace();
+        }
+        
+        return -1;
+    }
+    
+    private static int getValidNewYearCardStatus(int itemid, MapleCharacter player, short slot) {
+        if(!ItemConstants.isNewYearCardUse(itemid)) return 0x14;
+        
+        Item it = player.getInventory(MapleItemInformationProvider.getInstance().getInventoryType(itemid)).getItem(slot);        
+        return (it != null && it.getItemId() == itemid) ? 0 : 0x12;
+    } 
+}