Load vault economy in a dedicated package

plugin/src/main/java/de/epiceric/shopchest/ShopChest.java

@@ -22,7 +22,6 @@ import org.bukkit.Bukkit;
 import org.bukkit.Chunk;
 import org.bukkit.World;
 import org.bukkit.entity.Player;
-import org.bukkit.plugin.RegisteredServiceProvider;
 import org.bukkit.plugin.java.JavaPlugin;
 import org.bukkit.scheduler.BukkitRunnable;
 
@@ -43,7 +42,7 @@ public class ShopChest extends JavaPlugin {
     private Platform platform;
     private HologramFormat hologramFormat;
     private ShopCommand shopCommand;
-    private Economy econ = null;
+    private Economy economy;
     private Database database;
     private boolean isUpdateNeeded = false;
     private String latestVersion = "";
@@ -62,19 +61,6 @@ public class ShopChest extends JavaPlugin {
         return instance;
     }
 
-    /**
-     * Sets up the economy of Vault
-     * @return Whether an economy plugin has been registered
-     */
-    private boolean setupEconomy() {
-        RegisteredServiceProvider<Economy> rsp = getServer().getServicesManager().getRegistration(Economy.class);
-        if (rsp == null) {
-            return false;
-        }
-        econ = rsp.getProvider();
-        return econ != null;
-    }
-
     @Override
     public void onLoad() {
         instance = this;
@@ -103,14 +89,11 @@ public class ShopChest extends JavaPlugin {
         debugLogger.debug("Enabling ShopChest version " + getDescription().getVersion());
 
         // Load Vault
-        // TODO Load Vault in dedicated class
-        if (!getServer().getPluginManager().isPluginEnabled("Vault")) {
-            cancelLoading("Could not find plugin \"Vault\"");
-            return;
-        }
-
-        if (!setupEconomy()) {
-            cancelLoading("Could not find any Vault economy dependency!");
+        final EconomyLoader economyLoader = new EconomyLoader();
+        try {
+            economy = economyLoader.loadEconomy();
+        } catch (RuntimeException e) {
+            cancelLoading(e.getMessage());
             return;
         }
 
@@ -385,7 +368,7 @@ public class ShopChest extends JavaPlugin {
      * @return Registered Economy of Vault
      */
     public Economy getEconomy() {
-        return econ;
+        return economy;
     }
 
     /**

plugin/src/main/java/de/epiceric/shopchest/utils/EconomyLoader.java

@@ -0,0 +1,58 @@
+package de.epiceric.shopchest.utils;
+
+import net.milkbowl.vault.economy.Economy;
+import org.bukkit.Bukkit;
+import org.bukkit.plugin.Plugin;
+import org.bukkit.plugin.PluginManager;
+import org.bukkit.plugin.RegisteredServiceProvider;
+
+public class EconomyLoader {
+
+    /**
+     * Load the Vault {@link Economy}
+     *
+     * @return The loaded {@link Economy} implementation
+     */
+    public Economy loadEconomy() {
+        checkVaultPlugin();
+        return getEconomy();
+    }
+
+    /**
+     * Check Vault plugin.
+     *
+     * @throws RuntimeException if vault is not present, not enable or is not the correct 'Vault' plugin
+     */
+    private void checkVaultPlugin() {
+        final PluginManager plManager = Bukkit.getPluginManager();
+        final Plugin vaultPlugin = plManager.getPlugin("Vault");
+        if (vaultPlugin == null) {
+            // Supposed to be impossible as Vault is in the 'depend' section in plugin.yml
+            throw new RuntimeException("'Vault' plugin is not present");
+        }
+        if (!plManager.isPluginEnabled(vaultPlugin)) {
+            throw new RuntimeException("'Vault' plugin is not enable");
+        }
+        try {
+            Class.forName("net.milkbowl.vault.economy.Economy");
+        } catch (ClassNotFoundException e) {
+            throw new RuntimeException("Can retrieve the 'Vault' economy interface." +
+                    " You may use an unsupported version of the 'Vault' plugin or the wrong 'Vault' plugin");
+        }
+    }
+
+    /**
+     * Retrieve the registered {@link Economy} implementation
+     *
+     * @return The Vault {@link Economy} implementation
+     * @throws RuntimeException if vault does not provide an {@link Economy} implementation
+     */
+    private Economy getEconomy() {
+        final RegisteredServiceProvider<Economy> rsp = Bukkit.getServicesManager().getRegistration(Economy.class);
+        if (rsp == null) {
+            throw new RuntimeException("Could not retrieve any economy implementation. Maybe you did not install any economy plugin.");
+        }
+        return rsp.getProvider();
+    }
+
+}