Paper command

Co-authored-by: Zach Brown <1254957+zachbr@users.noreply.github.com>

paper-server/src/main/java/io/papermc/paper/command/PaperCommand.java

@@ -0,0 +1,143 @@
+package io.papermc.paper.command;
+
+import io.papermc.paper.command.subcommands.*;
+import it.unimi.dsi.fastutil.Pair;
+import java.util.ArrayList;
+import java.util.Arrays;
+import java.util.Collections;
+import java.util.HashMap;
+import java.util.List;
+import java.util.Locale;
+import java.util.Map;
+import java.util.Set;
+import java.util.stream.Collectors;
+import net.minecraft.Util;
+import org.bukkit.Bukkit;
+import org.bukkit.Location;
+import org.bukkit.command.Command;
+import org.bukkit.command.CommandSender;
+import org.bukkit.permissions.Permission;
+import org.bukkit.permissions.PermissionDefault;
+import org.bukkit.plugin.PluginManager;
+import org.checkerframework.checker.nullness.qual.NonNull;
+import org.checkerframework.checker.nullness.qual.Nullable;
+import org.checkerframework.framework.qual.DefaultQualifier;
+
+import static net.kyori.adventure.text.Component.text;
+import static net.kyori.adventure.text.format.NamedTextColor.RED;
+
+@DefaultQualifier(NonNull.class)
+public final class PaperCommand extends Command {
+    static final String BASE_PERM = "bukkit.command.paper.";
+    // subcommand label -> subcommand
+    private static final Map<String, PaperSubcommand> SUBCOMMANDS = Util.make(() -> {
+        final Map<Set<String>, PaperSubcommand> commands = new HashMap<>();
+
+        commands.put(Set.of("heap"), new HeapDumpCommand());
+        commands.put(Set.of("entity"), new EntityCommand());
+        commands.put(Set.of("reload"), new ReloadCommand());
+        commands.put(Set.of("version"), new VersionCommand());
+
+        return commands.entrySet().stream()
+            .flatMap(entry -> entry.getKey().stream().map(s -> Map.entry(s, entry.getValue())))
+            .collect(Collectors.toMap(Map.Entry::getKey, Map.Entry::getValue));
+    });
+    private static final Set<String> COMPLETABLE_SUBCOMMANDS = SUBCOMMANDS.entrySet().stream().filter(entry -> entry.getValue().tabCompletes()).map(Map.Entry::getKey).collect(Collectors.toSet());
+    // alias -> subcommand label
+    private static final Map<String, String> ALIASES = Util.make(() -> {
+        final Map<String, Set<String>> aliases = new HashMap<>();
+
+        aliases.put("version", Set.of("ver"));
+
+        return aliases.entrySet().stream()
+            .flatMap(entry -> entry.getValue().stream().map(s -> Map.entry(s, entry.getKey())))
+            .collect(Collectors.toMap(Map.Entry::getKey, Map.Entry::getValue));
+    });
+
+    public PaperCommand(final String name) {
+        super(name);
+        this.description = "Paper related commands";
+        this.usageMessage = "/paper [" + String.join(" | ", SUBCOMMANDS.keySet()) + "]";
+        final List<String> permissions = new ArrayList<>();
+        permissions.add("bukkit.command.paper");
+        permissions.addAll(SUBCOMMANDS.keySet().stream().map(s -> BASE_PERM + s).toList());
+        this.setPermission(String.join(";", permissions));
+        final PluginManager pluginManager = Bukkit.getServer().getPluginManager();
+        for (final String perm : permissions) {
+            pluginManager.addPermission(new Permission(perm, PermissionDefault.OP));
+        }
+    }
+
+    private static boolean testPermission(final CommandSender sender, final String permission) {
+        if (sender.hasPermission(BASE_PERM + permission) || sender.hasPermission("bukkit.command.paper")) {
+            return true;
+        }
+        sender.sendMessage(text("I'm sorry, but you do not have permission to perform this command. Please contact the server administrators if you believe that this is in error.", RED));
+        return false;
+    }
+
+    @Override
+    public List<String> tabComplete(
+        final CommandSender sender,
+        final String alias,
+        final String[] args,
+        final @Nullable Location location
+    ) throws IllegalArgumentException {
+        if (args.length <= 1) {
+            return CommandUtil.getListMatchingLast(sender, args, COMPLETABLE_SUBCOMMANDS);
+        }
+
+        final @Nullable Pair<String, PaperSubcommand> subCommand = resolveCommand(args[0]);
+        if (subCommand != null) {
+            return subCommand.second().tabComplete(sender, subCommand.first(), Arrays.copyOfRange(args, 1, args.length));
+        }
+
+        return Collections.emptyList();
+    }
+
+    @Override
+    public boolean execute(
+        final CommandSender sender,
+        final String commandLabel,
+        final String[] args
+    ) {
+        if (!testPermission(sender)) {
+            return true;
+        }
+
+        if (args.length == 0) {
+            sender.sendMessage(text("Usage: " + this.usageMessage, RED));
+            return false;
+        }
+        final @Nullable Pair<String, PaperSubcommand> subCommand = resolveCommand(args[0]);
+
+        if (subCommand == null) {
+            sender.sendMessage(text("Usage: " + this.usageMessage, RED));
+            return false;
+        }
+
+        if (!testPermission(sender, subCommand.first())) {
+            return true;
+        }
+        final String[] choppedArgs = Arrays.copyOfRange(args, 1, args.length);
+        return subCommand.second().execute(sender, subCommand.first(), choppedArgs);
+    }
+
+    private static @Nullable Pair<String, PaperSubcommand> resolveCommand(String label) {
+        label = label.toLowerCase(Locale.ROOT);
+        @Nullable PaperSubcommand subCommand = SUBCOMMANDS.get(label);
+        if (subCommand == null) {
+            final @Nullable String command = ALIASES.get(label);
+            if (command != null) {
+                label = command;
+                subCommand = SUBCOMMANDS.get(command);
+            }
+        }
+
+        if (subCommand != null) {
+            return Pair.of(label, subCommand);
+        }
+
+        return null;
+    }
+}