Simplify and expand tab completion

plugin/src/main/java/com/lishid/openinv/util/TabCompleter.java

@@ -0,0 +1,147 @@
+/*
+ * Copyright (C) 2011-2020 lishid. All rights reserved.
+ *
+ * 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, version 3.
+ *
+ * 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 com.lishid.openinv.util;
+
+import java.util.ArrayList;
+import java.util.Collections;
+import java.util.List;
+import java.util.Locale;
+import java.util.function.Function;
+import org.bukkit.Bukkit;
+import org.bukkit.command.CommandSender;
+import org.bukkit.entity.Player;
+import org.bukkit.util.StringUtil;
+
+/**
+ * Utility class for common tab completions.
+ */
+public class TabCompleter {
+
+    /**
+     * Offer tab completions for whole numbers.
+     *
+     * @param argument the argument to complete
+     * @return integer options
+     */
+    public static List<String> completeInteger(String argument) {
+        // Ensure existing argument is actually a number
+        if (!argument.isEmpty()) {
+            try {
+                Integer.parseInt(argument);
+            } catch (NumberFormatException e) {
+                return Collections.emptyList();
+            }
+        }
+
+        List<String> completions = new ArrayList<>(10);
+        for (int i = 0; i < 10; ++i) {
+            completions.add(argument + i);
+        }
+
+        return completions;
+    }
+
+    /**
+     * Offer tab completions for a given Enum.
+     *
+     * @param argument the argument to complete
+     * @param enumClazz the Enum to complete for
+     * @return the matching Enum values
+     */
+    public static List<String> completeEnum(String argument, Class<? extends Enum<?>> enumClazz) {
+        argument = argument.toLowerCase(Locale.ENGLISH);
+        List<String> completions = new ArrayList<>();
+
+        for (Enum<?> enumConstant : enumClazz.getEnumConstants()) {
+            String name = enumConstant.name().toLowerCase();
+            if (name.startsWith(argument)) {
+                completions.add(name);
+            }
+        }
+
+        return completions;
+    }
+
+    /**
+     * Offer tab completions for a given array of Strings.
+     *
+     * @param argument the argument to complete
+     * @param options the Strings which may be completed
+     * @return the matching Strings
+     */
+    public static List<String> completeString(String argument, String[] options) {
+        argument = argument.toLowerCase(Locale.ENGLISH);
+        List<String> completions = new ArrayList<>();
+
+        for (String option : options) {
+            if (option.startsWith(argument)) {
+                completions.add(option);
+            }
+        }
+
+        return completions;
+    }
+
+    /**
+     * Offer tab completions for visible online Players' names.
+     *
+     * @param sender the command's sender
+     * @param argument the argument to complete
+     * @return the matching Players' names
+     */
+    public static List<String> completeOnlinePlayer(CommandSender sender, String argument) {
+        List<String> completions = new ArrayList<>();
+        Player senderPlayer = sender instanceof Player ? (Player) sender : null;
+
+        for (Player player : Bukkit.getOnlinePlayers()) {
+            if (senderPlayer != null && !senderPlayer.canSee(player)) {
+                continue;
+            }
+
+            if (StringUtil.startsWithIgnoreCase(player.getName(), argument)) {
+                completions.add(player.getName());
+            }
+        }
+
+        return completions;
+    }
+
+    /**
+     * Offer tab completions for a given array of Objects.
+     *
+     * @param argument the argument to complete
+     * @param converter the Function for converting the Object into a comparable String
+     * @param options the Objects which may be completed
+     * @return the matching Strings
+     */
+    public static <T> List<String> completeObject(String argument, Function<T, String> converter, T[] options) {
+        argument = argument.toLowerCase(Locale.ENGLISH);
+        List<String> completions = new ArrayList<>();
+
+        for (T option : options) {
+            String optionString = converter.apply(option).toLowerCase();
+            if (optionString.startsWith(argument)) {
+                completions.add(optionString);
+            }
+        }
+
+        return completions;
+    }
+
+    private TabCompleter() {}
+
+}