API improvements

api/src/main/java/me/filoghost/chestcommands/api/ChestCommandsAPI.java

@@ -53,18 +53,24 @@ public class ChestCommandsAPI {
      * Menus loaded by Chest Commands from the menus folder always display placeholders, including those registered
      * through this method.
      * <p>
-     * The identifier is automatically converted to the appropriate placeholder format. For example, given the
+     * The identifier is used to compute which placeholder formats will invoke the replacer callback. For example, given
-     * identifier "test", the callback would be invoked to replace the the following placeholders:
+     * the identifier "test", the callback would be invoked to replace the following placeholders (case insensitive):
      * <ul>
      *     <li>{test}
-     *     <li>{test: 123}
+     *     <li>{test: argument}
-     *     <li>{test: hello world}
+     *     <li>{pluginName/test}
+     *     <li>{pluginName/test: argument}
      * </ul>
+     * The plugin name is used as optional namespace, to distinguish two placeholders with the same identifier but
+     * registered by distinct plugins.
+     * <p>
+     * This replaces any currently registered placeholder with the same plugin and identifier.
      *
      * @param plugin              the plugin registering the placeholder
      * @param identifier          the identifier of the placeholder, which can only contain letters, digits and
      *                            underscores
      * @param placeholderReplacer the callback that returns the displayed value
+     * @throws IllegalArgumentException if the identifier contains invalid characters
      * @see PlaceholderReplacer#getReplacement(Player, String)
      * @since 1
      */
@@ -74,12 +80,11 @@ public class ChestCommandsAPI {
         BackendAPI.getImplementation().registerPlaceholder(plugin, identifier, placeholderReplacer);
     }
 
-
     /**
      * Returns if a menu with a given file name exists and was loaded successfully by Chest Commands from the menus
      * folder.
      *
-     * @param menuFileName the file name of the menu to check
+     * @param menuFileName the file name of the menu to check, including the {@code .yml} file extension
      * @return true if the menu exists, false otherwise
      * @since 1
      */
@@ -94,7 +99,7 @@ public class ChestCommandsAPI {
      * <b>WARNING</b>: this method opens the menu without checking the permissions of the player.
      *
      * @param player       the player that will see the menu
-     * @param menuFileName the file name of the menu to open
+     * @param menuFileName the file name of the menu to open, including the {@code .yml} file extension
      * @return true if the menu was found and opened successfully, false otherwise
      * @since 1
      */

api/src/main/java/me/filoghost/chestcommands/api/Menu.java

@@ -8,30 +8,34 @@ package me.filoghost.chestcommands.api;
 import me.filoghost.chestcommands.api.internal.BackendAPI;
 import org.bukkit.entity.Player;
 import org.bukkit.plugin.Plugin;
+import org.jetbrains.annotations.ApiStatus;
 import org.jetbrains.annotations.NotNull;
 import org.jetbrains.annotations.Nullable;
 
 /**
- * Menus are containers of {@link Icon}s that can be displayed to players as unmodifiable inventories.
+ * Menus are containers of {@link Icon}s that can be displayed to players as unmodifiable inventories, organized as a
+ * grid with a number of rows and columns.
  * <p>
- * It is not recommended to implement this interface, use the provided constructor {@link Menu#create(Plugin, String,
+ * This interface should not be implemented, use the provided constructor {@link Menu#create(Plugin, String, int)}. Any
- * int)}.
+ * custom implementation will not be handled by Chest Commands' event listener, which relies on internal details. New
+ * methods may also be added, making existing custom implementations incompatible.
  *
  * @since 1
  */
+@ApiStatus.NonExtendable
 public interface Menu {
 
     /**
      * Creates a new menu.
      *
-     * @param owner    the plugin creating the menu
+     * @param plugin the plugin creating the menu
-     * @param title    title of the menu that will be displayed in the inventory
+     * @param title  title of the menu that appears in the displayed inventory
-     * @param rowCount number of rows in the menu (the number of columns is always 9, currently)
+     * @param rows   number of rows in the menu (the number of columns is always 9, currently)
      * @return the created menu
      * @since 1
      */
-    static @NotNull Menu create(@NotNull Plugin owner, @NotNull String title, int rowCount) {
+    static @NotNull Menu create(@NotNull Plugin plugin, @NotNull String title, int rows) {
-        return BackendAPI.getImplementation().createMenu(owner, title, rowCount);
+        return BackendAPI.getImplementation().createMenu(plugin, title, rows);
     }
 
     /**
@@ -40,6 +44,8 @@ public interface Menu {
      * @param row    the row position
      * @param column the column position
      * @param icon   the new icon, null to remove the current one
+     * @throws IndexOutOfBoundsException if the row or the column is outside the limits ({@code row < 0 || row >=
+     *                                   getRows() || column < 0 || column >= getColumns()})
      * @since 1
      */
     void setIcon(int row, int column, @Nullable Icon icon);
@@ -50,39 +56,17 @@ public interface Menu {
      * @param row    the row position
      * @param column the column position
      * @return the icon at the give position, null if absent
+     * @throws IndexOutOfBoundsException if the row or the column is outside the limits ({@code row < 0 || row >=
+     *                                   getRows() || column < 0 || column >= getColumns()})
      * @since 1
      */
     @Nullable Icon getIcon(int row, int column);
 
-    /**
-     * Returns the title of the displayed inventory.
-     *
-     * @return the title
-     * @since 1
-     */
-    @NotNull String getTitle();
-
-    /**
-     * Returns the amount of rows of the displayed inventory.
-     *
-     * @return the amount of rows
-     * @since 1
-     */
-    int getRowCount();
-
-    /**
-     * Returns the amount of columns of the displayed inventory.
-     *
-     * @return the amount of columns
-     * @since 1
-     */
-    int getColumnCount();
-
     /**
      * Displays the menu to a player, creating a rendering of this menu and its icons.
      * <p>
      * If icons are added, removed or changed after the menu is displayed to a player, the view is not updated
-     * automatically and you may want to invoke {@link Menu#refreshOpenMenuViews()}.
+     * automatically and you may want to invoke {@link Menu#refreshOpenViews()}.
      *
      * @param player the player to which the menu will be displayed
      * @return the newly created view for the player
@@ -97,10 +81,42 @@ public interface Menu {
      * This method should be called after adding, removing or changing one or more icons to update the open menu views
      * of players.
      * <p>
-     * This method invokes {@link MenuView#refresh()} on each open view created by this menu.
+     * This method invokes {@link MenuView#refresh()} on each currently open view created by this menu.
      *
      * @since 1
      */
-    void refreshOpenMenuViews();
+    void refreshOpenViews();
+
+    /**
+     * Returns the amount of rows of the displayed inventory.
+     *
+     * @return the amount of rows
+     * @since 1
+     */
+    int getRows();
+
+    /**
+     * Returns the amount of columns of the displayed inventory.
+     *
+     * @return the amount of columns
+     * @since 1
+     */
+    int getColumns();
+
+    /**
+     * Returns the title of the displayed inventory.
+     *
+     * @return the title
+     * @since 1
+     */
+    @NotNull String getTitle();
+
+    /**
+     * Returns the plugin that created the menu.
+     *
+     * @return the plugin that created the menu
+     * @since 1
+     */
+    Plugin getPlugin();
 
 }

api/src/main/java/me/filoghost/chestcommands/api/MenuView.java

@@ -29,7 +29,7 @@ public interface MenuView {
      * player and you want to refresh the money placeholder instantly.
      * <p>
      * Note that {@link ClickHandler} exposes the menu view being interacted with, so you don't need to refresh all the
-     * views of a menu through {@link Menu#refreshOpenMenuViews()}.
+     * views of a menu through {@link Menu#refreshOpenViews()}.
      *
      * @since 1
      */

api/src/main/java/me/filoghost/chestcommands/api/PlaceholderReplacer.java

@@ -27,6 +27,8 @@ public interface PlaceholderReplacer {
      * <p>
      * If this method returns null, the placeholder is not replaced. It is preferred to return a descriptive error
      * message rather than returning null.
+     * <p>
+     * <b>Warning</b>: this method should be performance efficient, as it may be invoked quite often.
      *
      * @param player   the player viewing the placeholder
      * @param argument the argument inside the placeholder, if present

api/src/main/java/me/filoghost/chestcommands/api/internal/BackendAPI.java

@@ -42,7 +42,7 @@ public abstract class BackendAPI {
 
     public abstract boolean openPluginMenu(@NotNull Player player, @NotNull String menuFileName);
 
-    public abstract @NotNull Menu createMenu(@NotNull Plugin owner, @NotNull String title, int rows);
+    public abstract @NotNull Menu createMenu(@NotNull Plugin plugin, @NotNull String title, int rows);
     
     public abstract @NotNull ConfigurableIcon createConfigurableIcon(@NotNull Material material);
 

checkstyle/checkstyle.xml

@@ -75,7 +75,6 @@
         <module name="EqualsAvoidNull"/>
         <module name="EqualsHashCode"/>
         <module name="FallThrough"/>
-        <module name="IllegalCatch"/>
         <module name="IllegalThrows"/>
         <module name="IllegalToken"/>
         <module name="IllegalType"/>

plugin/src/main/java/me/filoghost/chestcommands/ChestCommands.java

@@ -184,7 +184,7 @@ public class ChestCommands extends BaseJavaPlugin {
     }
 
 
-    public static Plugin getPluginInstance() {
+    public static Plugin getInstance() {
         return pluginInstance;
     }
 

plugin/src/main/java/me/filoghost/chestcommands/DefaultBackendAPI.java

@@ -53,8 +53,8 @@ public class DefaultBackendAPI extends BackendAPI {
     }
 
     @Override
-    public @NotNull Menu createMenu(@NotNull Plugin owner, @NotNull String title, int rows) {
+    public @NotNull Menu createMenu(@NotNull Plugin plugin, @NotNull String title, int rows) {
-        return new APIMenu(owner, title, rows);
+        return new APIMenu(plugin, title, rows);
     }
 
     @Override
@@ -63,7 +63,9 @@ public class DefaultBackendAPI extends BackendAPI {
     }
 
     @Override
-    public void registerPlaceholder(@NotNull Plugin plugin, @NotNull String identifier, @NotNull PlaceholderReplacer placeholderReplacer) {
+    public void registerPlaceholder(@NotNull Plugin plugin,
+                                    @NotNull String identifier,
+                                    @NotNull PlaceholderReplacer placeholderReplacer) {
         PlaceholderManager.registerPluginPlaceholder(plugin, identifier, placeholderReplacer);
     }
 

plugin/src/main/java/me/filoghost/chestcommands/action/OpenMenuAction.java

@@ -31,7 +31,7 @@ public class OpenMenuAction implements Action {
              * Delay the task, since this action is executed in ClickInventoryEvent
              * and opening another inventory in the same moment is not a good idea.
              */
-            Bukkit.getScheduler().runTask(ChestCommands.getPluginInstance(), () -> {
+            Bukkit.getScheduler().runTask(ChestCommands.getInstance(), () -> {
                 menu.openCheckingPermission(player);
             });
 

plugin/src/main/java/me/filoghost/chestcommands/command/CommandHandler.java

@@ -42,7 +42,7 @@ public class CommandHandler extends MultiCommandManager {
     @Override
     protected void sendNoArgsMessage(CommandSender sender, String rootCommandLabel) {
         sender.sendMessage(ChestCommands.CHAT_PREFIX);
-        sender.sendMessage(ChatColor.GREEN + "Version: " + ChatColor.GRAY + ChestCommands.getPluginInstance().getDescription().getVersion());
+        sender.sendMessage(ChatColor.GREEN + "Version: " + ChatColor.GRAY + ChestCommands.getInstance().getDescription().getVersion());
         sender.sendMessage(ChatColor.GREEN + "Developer: " + ChatColor.GRAY + "filoghost");
         sender.sendMessage(ChatColor.GREEN + "Commands: " + ChatColor.GRAY + "/" + rootCommandLabel + " help");
     }

plugin/src/main/java/me/filoghost/chestcommands/hook/BungeeCordHook.java

@@ -22,8 +22,8 @@ public enum BungeeCordHook implements PluginHook {
 
     @Override
     public void setup() {
-        if (!Bukkit.getMessenger().isOutgoingChannelRegistered(ChestCommands.getPluginInstance(), BUNGEE_CORD_CHANNEL)) {
+        if (!Bukkit.getMessenger().isOutgoingChannelRegistered(ChestCommands.getInstance(), BUNGEE_CORD_CHANNEL)) {
-            Bukkit.getMessenger().registerOutgoingPluginChannel(ChestCommands.getPluginInstance(), BUNGEE_CORD_CHANNEL);
+            Bukkit.getMessenger().registerOutgoingPluginChannel(ChestCommands.getInstance(), BUNGEE_CORD_CHANNEL);
         }
     }
 
@@ -50,7 +50,7 @@ public enum BungeeCordHook implements PluginHook {
             throw new AssertionError();
         }
 
-        player.sendPluginMessage(ChestCommands.getPluginInstance(), BUNGEE_CORD_CHANNEL, byteArrayOutputStream.toByteArray());
+        player.sendPluginMessage(ChestCommands.getInstance(), BUNGEE_CORD_CHANNEL, byteArrayOutputStream.toByteArray());
     }
 
 }

plugin/src/main/java/me/filoghost/chestcommands/inventory/DefaultMenuView.java

@@ -14,9 +14,6 @@ import org.bukkit.inventory.ItemStack;
 import org.jetbrains.annotations.NotNull;
 import org.jetbrains.annotations.Nullable;
 
-/**
- * Represents a particular view of a menu.
- */
 public class DefaultMenuView implements MenuView {
 
     private final BaseMenu menu;
@@ -26,7 +23,7 @@ public class DefaultMenuView implements MenuView {
     public DefaultMenuView(@NotNull BaseMenu menu, @NotNull Player viewer) {
         this.menu = menu;
         this.viewer = viewer;
-        this.bukkitInventory = new InventoryGrid(new MenuInventoryHolder(this), menu.getRowCount(), menu.getTitle());
+        this.bukkitInventory = new InventoryGrid(new MenuInventoryHolder(this), menu.getRows(), menu.getTitle());
         refresh();
     }
 

plugin/src/main/java/me/filoghost/chestcommands/listener/InventoryListener.java

@@ -8,9 +8,13 @@ package me.filoghost.chestcommands.listener;
 import me.filoghost.chestcommands.ChestCommands;
 import me.filoghost.chestcommands.api.ClickResult;
 import me.filoghost.chestcommands.api.Icon;
+import me.filoghost.chestcommands.api.Menu;
 import me.filoghost.chestcommands.config.Settings;
 import me.filoghost.chestcommands.inventory.DefaultMenuView;
+import me.filoghost.chestcommands.logging.Errors;
+import me.filoghost.chestcommands.menu.InternalMenu;
 import me.filoghost.chestcommands.menu.MenuManager;
+import me.filoghost.fcommons.logging.Log;
 import org.bukkit.Bukkit;
 import org.bukkit.entity.Player;
 import org.bukkit.event.EventHandler;
@@ -75,13 +79,28 @@ public class InventoryListener implements Listener {
         }
 
         // Only handle the click AFTER the event has finished
-        Bukkit.getScheduler().runTask(ChestCommands.getPluginInstance(), () -> {
+        Bukkit.getScheduler().runTask(ChestCommands.getInstance(), () -> {
+            try {
                 ClickResult result = icon.onClick(menuView, clicker);
 
                 if (result == ClickResult.CLOSE) {
                     clicker.closeInventory();
                 }
+            } catch (Throwable t) {
+                handleIconClickException(menuView.getMenu(), t);
+            }
         });
     }
 
+    private void handleIconClickException(Menu menu, Throwable throwable) {
+        String menuDescription;
+        if (menu.getPlugin() == ChestCommands.getInstance()) {
+            menuDescription = "the menu \"" + Errors.formatPath(((InternalMenu) menu).getSourceFile()) + "\"";
+        } else {
+            menuDescription = "a menu created by the plugin \"" + menu.getPlugin().getName() + "\"";
+        }
+
+        Log.severe("Encountered exception while handling a click inside " + menuDescription, throwable);
+    }
+
 }

plugin/src/main/java/me/filoghost/chestcommands/logging/Errors.java

@@ -215,7 +215,7 @@ public class Errors {
 
     }
 
-    private static String formatPath(Path path) {
+    public static String formatPath(Path path) {
         return ConfigErrors.formatPath(ChestCommands.getDataFolderPath(), path);
     }
 

plugin/src/main/java/me/filoghost/chestcommands/menu/APIMenu.java

@@ -11,16 +11,17 @@ import org.jetbrains.annotations.NotNull;
 
 public class APIMenu extends BaseMenu {
 
-    private final Plugin owner;
+    private final Plugin plugin;
 
-    public APIMenu(@NotNull Plugin owner, @NotNull String title, int rows) {
+    public APIMenu(@NotNull Plugin plugin, @NotNull String title, int rows) {
         super(title, rows);
-        Preconditions.notNull(owner, "owner");
+        Preconditions.notNull(plugin, "plugin");
-        this.owner = owner;
+        this.plugin = plugin;
     }
 
-    public @NotNull Plugin getOwner() {
+    @Override
-        return owner;
+    public Plugin getPlugin() {
+        return plugin;
     }
 
 }

plugin/src/main/java/me/filoghost/chestcommands/menu/BaseMenu.java

@@ -42,12 +42,31 @@ public abstract class BaseMenu implements Menu {
     }
 
     @Override
-    public int getRowCount() {
+    public @NotNull MenuView open(@NotNull Player player) {
+        Preconditions.notNull(player, "player");
+
+        DefaultMenuView menuView = new DefaultMenuView(this, player);
+        menuView.open();
+        return menuView;
+    }
+
+    @Override
+    public void refreshOpenViews() {
+        for (Player player : Bukkit.getOnlinePlayers()) {
+            DefaultMenuView menuView = MenuManager.getOpenMenuView(player);
+            if (menuView != null && menuView.getMenu() == this) {
+                menuView.refresh();
+            }
+        }
+    }
+
+    @Override
+    public int getRows() {
         return icons.getRows();
     }
 
     @Override
-    public int getColumnCount() {
+    public int getColumns() {
         return icons.getColumns();
     }
 
@@ -60,22 +79,4 @@ public abstract class BaseMenu implements Menu {
         return icons;
     }
 
-    @Override
-    public @NotNull MenuView open(@NotNull Player player) {
-        Preconditions.notNull(player, "player");
-
-        DefaultMenuView menuView = new DefaultMenuView(this, player);
-        menuView.open();
-        return menuView;
-    }
-
-    @Override
-    public void refreshOpenMenuViews() {
-        for (Player player : Bukkit.getOnlinePlayers()) {
-            DefaultMenuView menuView = MenuManager.getOpenMenuView(player);
-            if (menuView != null && menuView.getMenu() == this) {
-                menuView.refresh();
-            }
-        }
-    }
 }

plugin/src/main/java/me/filoghost/chestcommands/menu/InternalMenu.java

@@ -6,6 +6,7 @@
 package me.filoghost.chestcommands.menu;
 
 import com.google.common.collect.ImmutableList;
+import me.filoghost.chestcommands.ChestCommands;
 import me.filoghost.chestcommands.Permissions;
 import me.filoghost.chestcommands.action.Action;
 import me.filoghost.chestcommands.api.MenuView;
@@ -13,6 +14,7 @@ import me.filoghost.chestcommands.config.Lang;
 import me.filoghost.fcommons.collection.CollectionUtils;
 import org.bukkit.command.CommandSender;
 import org.bukkit.entity.Player;
+import org.bukkit.plugin.Plugin;
 import org.jetbrains.annotations.NotNull;
 
 import java.nio.file.Path;
@@ -63,6 +65,11 @@ public class InternalMenu extends BaseMenu {
         return super.open(player);
     }
 
+    @Override
+    public Plugin getPlugin() {
+        return ChestCommands.getInstance();
+    }
+
     public void openCheckingPermission(Player player) {
         if (player.hasPermission(openPermission)) {
             open(player);

plugin/src/main/java/me/filoghost/chestcommands/parsing/menu/MenuParser.java

@@ -63,16 +63,16 @@ public class MenuParser {
         int row = positionY.getPosition() - 1;
         int column = positionX.getPosition() - 1;
 
-        if (row < 0 || row >= menu.getRowCount()) {
+        if (row < 0 || row >= menu.getRows()) {
             errorCollector.add(
                     Errors.Menu.invalidAttribute(iconSettings, AttributeType.POSITION_Y),
-                    "it must be between 1 and " + menu.getRowCount());
+                    "it must be between 1 and " + menu.getRows());
             return;
         }
-        if (column < 0 || column >= menu.getColumnCount()) {
+        if (column < 0 || column >= menu.getColumns()) {
             errorCollector.add(
                     Errors.Menu.invalidAttribute(iconSettings, AttributeType.POSITION_X),
-                    "it must be between 1 and " + menu.getColumnCount());
+                    "it must be between 1 and " + menu.getColumns());
             return;
         }
 

plugin/src/main/java/me/filoghost/chestcommands/placeholder/Placeholder.java

@@ -0,0 +1,29 @@
+/*
+ * Copyright (C) filoghost and contributors
+ *
+ * SPDX-License-Identifier: GPL-3.0-or-later
+ */
+package me.filoghost.chestcommands.placeholder;
+
+import me.filoghost.chestcommands.api.PlaceholderReplacer;
+import org.bukkit.plugin.Plugin;
+
+public class Placeholder {
+
+    private final Plugin plugin;
+    private final PlaceholderReplacer placeholderReplacer;
+
+    public Placeholder(Plugin plugin, PlaceholderReplacer placeholderReplacer) {
+        this.plugin = plugin;
+        this.placeholderReplacer = placeholderReplacer;
+    }
+
+    public Plugin getPlugin() {
+        return plugin;
+    }
+
+    public PlaceholderReplacer getReplacer() {
+        return placeholderReplacer;
+    }
+
+}

plugin/src/main/java/me/filoghost/chestcommands/placeholder/PlaceholderManager.java

@@ -10,6 +10,7 @@ import me.filoghost.chestcommands.hook.PlaceholderAPIHook;
 import me.filoghost.chestcommands.placeholder.scanner.PlaceholderMatch;
 import me.filoghost.chestcommands.placeholder.scanner.PlaceholderScanner;
 import me.filoghost.fcommons.Preconditions;
+import me.filoghost.fcommons.logging.Log;
 import org.bukkit.entity.Player;
 import org.bukkit.plugin.Plugin;
 import org.jetbrains.annotations.Nullable;
@@ -21,14 +22,13 @@ public class PlaceholderManager {
 
     private static final List<StaticPlaceholder> staticPlaceholders = new ArrayList<>();
     private static final PlaceholderRegistry relativePlaceholderRegistry = new PlaceholderRegistry();
+    private static final PlaceholderCache placeholderCache = new PlaceholderCache();
     static {
         for (DefaultPlaceholder placeholder : DefaultPlaceholder.values()) {
             relativePlaceholderRegistry.registerInternalPlaceholder(placeholder.getIdentifier(), placeholder.getReplacer());
         }
     }
 
-    private static final PlaceholderCache placeholderCache = new PlaceholderCache();
-
     public static boolean hasRelativePlaceholders(List<String> list) {
         for (String element : list) {
             if (hasRelativePlaceholders(element)) {
@@ -61,18 +61,24 @@ public class PlaceholderManager {
     }
 
     private static boolean isValidPlaceholder(PlaceholderMatch placeholderMatch) {
-        return relativePlaceholderRegistry.getPlaceholderReplacer(placeholderMatch) != null;
+        return relativePlaceholderRegistry.getPlaceholder(placeholderMatch) != null;
     }
 
     private static @Nullable String getReplacement(PlaceholderMatch placeholderMatch, Player player) {
-        PlaceholderReplacer placeholderReplacer = relativePlaceholderRegistry.getPlaceholderReplacer(placeholderMatch);
+        Placeholder placeholder = relativePlaceholderRegistry.getPlaceholder(placeholderMatch);
 
-        if (placeholderReplacer == null) {
+        if (placeholder == null) {
             return null; // Placeholder not found
         }
 
         return placeholderCache.computeIfAbsent(placeholderMatch, player, () -> {
-            return placeholderReplacer.getReplacement(player, placeholderMatch.getArgument());
+            try {
+                return placeholder.getReplacer().getReplacement(player, placeholderMatch.getArgument());
+            } catch (Throwable t) {
+                Log.severe("Encountered exception while replacing the placeholder \"" + placeholderMatch
+                        + "\" registered by the plugin \"" + placeholder.getPlugin().getName() + "\"", t);
+                return "[ERROR]";
+            }
         });
     }
 

plugin/src/main/java/me/filoghost/chestcommands/placeholder/PlaceholderRegistry.java

@@ -5,47 +5,54 @@
  */
 package me.filoghost.chestcommands.placeholder;
 
+import me.filoghost.chestcommands.ChestCommands;
 import me.filoghost.chestcommands.api.PlaceholderReplacer;
 import me.filoghost.chestcommands.placeholder.scanner.PlaceholderMatch;
+import me.filoghost.fcommons.collection.CaseInsensitiveMap;
 import org.bukkit.plugin.Plugin;
 import org.jetbrains.annotations.Nullable;
 
-import java.util.HashMap;
 import java.util.LinkedHashMap;
 import java.util.Map;
 
 public class PlaceholderRegistry {
 
-    private final Map<String, PlaceholderReplacer> internalPlaceholders = new HashMap<>();
+    // <identifier, placeholder>
-    private final Map<String, Map<String, PlaceholderReplacer>> externalPlaceholders = new HashMap<>();
+    private final Map<String, Placeholder> internalPlaceholders = new CaseInsensitiveMap<>();
+
+    // <identifier, <pluginName, placeholder>>
+    private final Map<String, Map<String, Placeholder>> externalPlaceholders = new CaseInsensitiveMap<>();
 
     public void registerInternalPlaceholder(String identifier, PlaceholderReplacer replacer) {
-        internalPlaceholders.put(identifier, replacer);
+        internalPlaceholders.put(identifier, new Placeholder(ChestCommands.getInstance(), replacer));
     }
 
     public void registerExternalPlaceholder(Plugin plugin, String identifier, PlaceholderReplacer placeholderReplacer) {
         externalPlaceholders
-                .computeIfAbsent(identifier, key -> new LinkedHashMap<>())
+                .computeIfAbsent(identifier, key -> new CaseInsensitiveMap<>(new LinkedHashMap<>()))
-                .put(plugin.getName(), placeholderReplacer);
+                .put(plugin.getName(), new Placeholder(plugin, placeholderReplacer));
     }
 
-    public @Nullable PlaceholderReplacer getPlaceholderReplacer(PlaceholderMatch placeholderMatch) {
+    public @Nullable Placeholder getPlaceholder(PlaceholderMatch placeholderMatch) {
+        String identifier = placeholderMatch.getIdentifier();
+
         if (placeholderMatch.getPluginNamespace() == null) {
-            PlaceholderReplacer internalReplacer = internalPlaceholders.get(placeholderMatch.getIdentifier());
+            Placeholder internalPlaceholder = internalPlaceholders.get(identifier);
-            if (internalReplacer != null) {
+            if (internalPlaceholder != null) {
-                return internalReplacer;
+                return internalPlaceholder;
             }
         }
 
-        Map<String, PlaceholderReplacer> externalReplacers = externalPlaceholders.get(placeholderMatch.getIdentifier());
+        Map<String, Placeholder> externalPlaceholdersByPlugin = externalPlaceholders.get(identifier);
 
         // Find exact replacer if plugin name is specified
         if (placeholderMatch.getPluginNamespace() != null) {
-            return externalReplacers.get(placeholderMatch.getPluginNamespace());
+            return externalPlaceholdersByPlugin.get(placeholderMatch.getPluginNamespace());
         }
 
-        if (externalReplacers != null && !externalReplacers.isEmpty()) {
+        // Otherwise try find the first one registered
-            return externalReplacers.values().iterator().next();
+        if (externalPlaceholdersByPlugin != null && !externalPlaceholdersByPlugin.isEmpty()) {
+            return externalPlaceholdersByPlugin.values().iterator().next();
         }
 
         return null;

plugin/src/main/java/me/filoghost/chestcommands/placeholder/scanner/PlaceholderMatch.java

@@ -35,9 +35,10 @@ public class PlaceholderMatch {
 
     /*
      * Valid formats:
-     * {pluginName/placeholder: argument}
-     * {placeholder: argument}
      * {placeholder}
+     * {placeholder: argument}
+     * {pluginName/identifier}
+     * {pluginName/identifier: argument}
      */
     public static PlaceholderMatch parse(String placeholderContent) {
         String explicitPluginName = null;