implement autocomplete for /enchantinfo

Plugin/src/main/java/com/willfp/ecoenchants/command/AbstractCommand.java

@@ -6,6 +6,7 @@ import org.bukkit.Bukkit;
 import org.bukkit.command.Command;
 import org.bukkit.command.CommandExecutor;
 import org.bukkit.command.CommandSender;
+import org.bukkit.command.PluginCommand;
 import org.bukkit.entity.Player;
 
 import java.util.Arrays;
@@ -43,7 +44,9 @@ public abstract class AbstractCommand implements CommandExecutor, Registerable {
 
     @Override
     public final void register() {
-        Bukkit.getPluginCommand(name).setExecutor(this);
+        PluginCommand pluginCommand = Bukkit.getPluginCommand(name);
+        pluginCommand.setExecutor(this);
+        pluginCommand.setTabCompleter(new EcoEnchantsTabCompleter());
     }
 
     public abstract void onExecute(CommandSender sender, List<String> args);

Plugin/src/main/java/com/willfp/ecoenchants/command/EcoEnchantsTabCompleter.java

@@ -0,0 +1,60 @@
+package com.willfp.ecoenchants.command;
+
+import com.willfp.ecoenchants.enchantments.EcoEnchant;
+import com.willfp.ecoenchants.enchantments.EcoEnchants;
+import org.bukkit.command.Command;
+import org.bukkit.command.CommandSender;
+import org.bukkit.command.TabCompleter;
+import org.bukkit.util.StringUtil;
+import org.jetbrains.annotations.NotNull;
+
+import java.util.ArrayList;
+import java.util.Arrays;
+import java.util.Collections;
+import java.util.List;
+import java.util.stream.Collectors;
+
+
+public class EcoEnchantsTabCompleter implements TabCompleter {
+    private final List<String> enchantsNames;
+
+    public EcoEnchantsTabCompleter() {
+        // Fetching the list of all enchants takes longer than anything inside onTabComplete, so caching is effective
+        enchantsNames = EcoEnchants.getAll().stream().map(EcoEnchant::getName).collect(Collectors.toList());
+    }
+
+    private static String removePrefix(String s, String prefix) {
+        if (s != null && prefix != null && s.startsWith(prefix)) {
+            return s.substring(prefix.length());
+        }
+        return s;
+    }
+
+    @Override
+    public List<String> onTabComplete(@NotNull CommandSender sender, @NotNull Command command, @NotNull String label, @NotNull String[] args) {
+        try {
+            if (command.getLabel().equalsIgnoreCase("enchantinfo") && (sender.isOp() || sender.hasPermission("ecoenchants.enchantinfo"))) {
+                List<String> completions = new ArrayList<>();
+
+                if (args.length == 0) {
+                    // Currently, this case is not ever reached
+                    return enchantsNames;
+                }
+
+                StringUtil.copyPartialMatches(String.join(" ", args), enchantsNames, completions);
+
+                if (args.length > 1) { // Remove all previous words from the candidate of completions
+                    ArrayList<String> finishedArgs = new ArrayList<>(Arrays.asList(args));
+                    finishedArgs.remove(args.length - 1);
+
+                    String prefix = String.join(" ", finishedArgs);
+                    completions = completions.stream().map(enchantName -> removePrefix(enchantName, prefix).trim()).collect(Collectors.toList());
+                }
+
+                Collections.sort(completions);
+                return completions;
+            }
+        } catch (Exception ignored) {}
+        return null;
+    }
+}

Plugin/src/main/java/com/willfp/ecoenchants/command/commands/CommandEnchantinfo.java

@@ -126,7 +126,6 @@ public final class CommandEnchantinfo extends AbstractCommand {
         final String finalTargets = allTargets;
         final String finalConflicts = allConflicts;
         final String finalMaxLevel = maxLevel;
-
         Arrays.asList(ConfigManager.getLang().getMessage("enchantinfo").split("\\r?\\n")).forEach((string -> {
             string = string.replaceAll("%name%", finalName)
                     .replaceAll("%description%", finalDescription)

Plugin/src/main/java/com/willfp/ecoenchants/loader/Loader.java

@@ -5,6 +5,7 @@ import com.willfp.ecoenchants.EcoEnchantsPlugin;
 import com.willfp.ecoenchants.command.commands.CommandEcodebug;
 import com.willfp.ecoenchants.command.commands.CommandEcoreload;
 import com.willfp.ecoenchants.command.commands.CommandEnchantinfo;
+import com.willfp.ecoenchants.command.EcoEnchantsTabCompleter;
 import com.willfp.ecoenchants.config.ConfigManager;
 import com.willfp.ecoenchants.display.EnchantDisplay;
 import com.willfp.ecoenchants.display.packets.PacketOpenWindowMerchant;