diff --git a/pom.xml b/pom.xml
new file mode 100644
index 0000000..4687afc
--- /dev/null
+++ b/pom.xml
@@ -0,0 +1,48 @@
+<?xml version="1.0" encoding="UTF-8"?>
+
+<project xmlns="http://maven.apache.org/POM/4.0.0" xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance"
+  xsi:schemaLocation="http://maven.apache.org/POM/4.0.0 http://maven.apache.org/xsd/maven-4.0.0.xsd">
+  <modelVersion>4.0.0</modelVersion>
+
+  <groupId>tyze.bukkit.bartender</groupId>
+  <artifactId>Bartender</artifactId>
+  <version>1.0</version>
+
+  <name>Bartender</name>
+  <!-- FIXME change it to the project's website -->
+  <url>http://www.example.com</url>
+
+  <properties>
+    <project.build.sourceEncoding>UTF-8</project.build.sourceEncoding>
+    <maven.compiler.source>1.7</maven.compiler.source>
+    <maven.compiler.target>1.7</maven.compiler.target>
+  </properties>
+
+  <repositories>
+      <repository>
+          <id>spigot-repo</id>
+          <url>https://hub.spigotmc.org/nexus/content/repositories/snapshots/</url>
+      </repository>
+  </repositories>
+
+  <dependencies>
+      <dependency>
+            <groupId>org.spigotmc</groupId>
+            <artifactId>spigot-api</artifactId>
+            <version>1.12.2-R0.1-SNAPSHOT</version>
+            <scope>provided</scope>
+      </dependency>
+  </dependencies>
+
+  <build>
+    <sourceDirectory>${project.basedir}/src/main/java</sourceDirectory>
+    <resources>
+      <resource>
+        <directory>${project.basedir}/src/main/resources</directory>
+        <includes>
+          <include>plugin.yml</include>
+        </includes>
+      </resource>
+    </resources>
+  </build>
+</project>
diff --git a/src/main/java/tyze/bukkit/bartender/App.java b/src/main/java/tyze/bukkit/bartender/App.java
new file mode 100644
index 0000000..5c29c72
--- /dev/null
+++ b/src/main/java/tyze/bukkit/bartender/App.java
@@ -0,0 +1,97 @@
+package tyze.bukkit.bartender;
+
+import java.util.ArrayList;
+
+import org.bukkit.Bukkit;
+import org.bukkit.Material;
+import org.bukkit.block.Block;
+import org.bukkit.entity.Player;
+import org.bukkit.event.EventHandler;
+import org.bukkit.event.Listener;
+import org.bukkit.event.player.PlayerInteractEvent;
+import org.bukkit.inventory.EquipmentSlot;
+import org.bukkit.inventory.ItemStack;
+import org.bukkit.plugin.java.JavaPlugin;
+
+import net.md_5.bungee.api.ChatMessageType;
+import net.md_5.bungee.api.chat.TextComponent;
+
+public class App extends JavaPlugin implements Listener {
+    private static ArrayList<Integer> expTotalTable = new ArrayList<Integer>();
+    private static ArrayList<Integer> expRequireTable = new ArrayList<Integer>();
+    private static int cost = 15;
+
+    @EventHandler
+    public void onRightClick(PlayerInteractEvent event) {
+        // prevent event triggered twice.
+        if (event.getHand().equals(EquipmentSlot.HAND) == false)
+            return;
+
+        Block block = event.getClickedBlock();
+        if (block == null || block.getType().equals(Material.DIAMOND_BLOCK) == false)
+            return;
+
+        Player p = event.getPlayer();
+        ItemStack itemInHand = p.getInventory().getItemInMainHand();
+        if (itemInHand == null || itemInHand.getType().equals(Material.GLASS_BOTTLE) == false)
+            return;
+
+        int level = p.getLevel();
+        float exp = p.getExp();
+
+        int total = getTotalExp(level, exp);
+
+        if (level <= 1 || total < cost) {
+            p.spigot().sendMessage(ChatMessageType.ACTION_BAR, TextComponent.fromLegacyText("§c§l經驗值不夠哦！快去打怪升等吧"));
+            event.setCancelled(true);
+            return;
+        }
+
+        int now = (int) (expRequireTable.get(level) * exp);
+
+        // lv3 -> lv4 needs 13 exp, there is not enough. here should be while-loop
+        while (now < cost) {
+            level -= 1;
+            now += expRequireTable.get(level);
+        }
+        now -= cost;
+        exp = now * 1f / expRequireTable.get(level);
+
+        if (p.getInventory().addItem(new ItemStack(Material.EXP_BOTTLE)).isEmpty()) {
+            int amount = p.getInventory().getItemInMainHand().getAmount();
+            p.getInventory().getItemInMainHand().setAmount(amount - 1);
+            p.setExp(exp * 1f);
+            p.setLevel(level);
+        }
+    }
+
+    private int getTotalExp(Integer level, float exp) {
+        return expTotalTable.get(level) + (int) (expRequireTable.get(level) * exp);
+    }
+
+    @Override
+    public void onEnable() {
+        getLogger().info("Bartender enable.");
+        int sum = 0;
+        int req = 0;
+        for (int level = 0; level <= 25000; level++) {
+            expTotalTable.add(sum);
+            if (level <= 15) {
+                req = level * 2 + 7;
+            } else if (level <= 30) {
+                req = level * 5 - 38;
+            } else {
+                req = 9 * level - 158;
+            }
+            sum += req;
+            expRequireTable.add(req);
+        }
+        getLogger().info("Bartender built exp table.");
+        Bukkit.getPluginManager().registerEvents(this, this);
+    }
+
+    @Override
+    public void onDisable() {
+        getLogger().info("Bartender disable.");
+    }
+}
\ No newline at end of file
diff --git a/src/main/resources/plugin.yml b/src/main/resources/plugin.yml
new file mode 100644
index 0000000..bd618b0
--- /dev/null
+++ b/src/main/resources/plugin.yml
@@ -0,0 +1,3 @@
+main: tyze.bukkit.bartender.App
+name: Bartender
+version: 1.0
\ No newline at end of file