Add support to find players based on name, UUID or selectors.

src/main/java/com/onarandombox/MultiverseCore/commands/CheckCommand.java

@@ -11,6 +11,7 @@ import com.onarandombox.MultiverseCore.MultiverseCore;
 import com.onarandombox.MultiverseCore.api.MVDestination;
 import com.onarandombox.MultiverseCore.destination.InvalidDestination;
 import com.onarandombox.MultiverseCore.utils.MVPermissions;
+import com.onarandombox.MultiverseCore.utils.PlayerFinder;
 import org.bukkit.ChatColor;
 import org.bukkit.command.CommandSender;
 import org.bukkit.entity.Player;
@@ -37,7 +38,7 @@ public class CheckCommand extends MultiverseCommand {
 
     @Override
     public void runCommand(CommandSender sender, List<String> args) {
-        Player p = this.plugin.getServer().getPlayerExact(args.get(0));
+        Player p = PlayerFinder.get(args.get(0), sender);
         if (p == null) {
             sender.sendMessage("Could not find player " + ChatColor.GREEN + args.get(0));
             sender.sendMessage("Are they online?");

src/main/java/com/onarandombox/MultiverseCore/commands/SpawnCommand.java

@@ -9,6 +9,7 @@ package com.onarandombox.MultiverseCore.commands;
 
 import com.onarandombox.MultiverseCore.MultiverseCore;
 import com.onarandombox.MultiverseCore.api.MultiverseWorld;
+import com.onarandombox.MultiverseCore.utils.PlayerFinder;
 import org.bukkit.ChatColor;
 import org.bukkit.Location;
 import org.bukkit.command.CommandSender;
@@ -50,7 +51,7 @@ public class SpawnCommand extends MultiverseCommand {
                 sender.sendMessage("You don't have permission to teleport another player to spawn. (multiverse.core.spawn.other)");
                 return;
             }
-            Player target = this.plugin.getServer().getPlayerExact(args.get(0));
+            Player target = PlayerFinder.get(args.get(0), sender);
             if (target != null) {
                 target.sendMessage("Teleporting to this world's spawn...");
                 spawnAccurately(target);

src/main/java/com/onarandombox/MultiverseCore/commands/TeleportCommand.java

@@ -18,6 +18,7 @@ import com.onarandombox.MultiverseCore.destination.WorldDestination;
 import com.onarandombox.MultiverseCore.enums.TeleportResult;
 import com.onarandombox.MultiverseCore.event.MVTeleportEvent;
 import com.onarandombox.MultiverseCore.api.SafeTTeleporter;
+import com.onarandombox.MultiverseCore.utils.PlayerFinder;
 import org.bukkit.ChatColor;
 import org.bukkit.Location;
 import org.bukkit.World;
@@ -59,7 +60,7 @@ public class TeleportCommand extends MultiverseCommand {
         String destinationName;
 
         if (args.size() == 2) {
-            teleportee = this.plugin.getServer().getPlayerExact(args.get(0));
+            teleportee = PlayerFinder.get(args.get(0), sender);
             if (teleportee == null) {
                 this.messaging.sendMessage(sender, String.format("Sorry, I couldn't find player: %s%s",
                         ChatColor.GOLD, args.get(0)), false);

src/main/java/com/onarandombox/MultiverseCore/utils/PlayerFinder.java

@@ -0,0 +1,176 @@
+package com.onarandombox.MultiverseCore.utils;
+
+import com.dumptruckman.minecraft.util.Logging;
+import org.bukkit.Bukkit;
+import org.bukkit.command.CommandSender;
+import org.bukkit.entity.Player;
+import org.jetbrains.annotations.NotNull;
+import org.jetbrains.annotations.Nullable;
+
+import java.util.ArrayList;
+import java.util.List;
+import java.util.UUID;
+import java.util.regex.Pattern;
+import java.util.stream.Collectors;
+
+/**
+ * Helper class to get {@link Player} from name, UUID or Selectors.
+ */
+public class PlayerFinder {
+
+    private static final Pattern UUID_REGEX = Pattern.compile("[0-9a-fA-F]{8}-[0-9a-fA-F]{4}-[34][0-9a-fA-F]{3}-[89ab][0-9a-fA-F]{3}-[0-9a-fA-F]{12}");
+    private static final Pattern COMMA_SPLIT = Pattern.compile(",");
+
+    /**
+     * Get a {@link Player} based on an identifier of name UUID or selector.
+     *
+     * @param playerIdentifier  An identifier of name UUID or selector.
+     * @param sender            Target sender for selector.
+     * @return The player if found, else null.
+     */
+    @Nullable
+    public static Player get(@NotNull String playerIdentifier,
+                             @NotNull CommandSender sender) {
+
+        Player targetPlayer = getByName(playerIdentifier);
+        if (targetPlayer != null) {
+            return targetPlayer;
+        }
+        targetPlayer = getByUuid(playerIdentifier);
+        if (targetPlayer != null) {
+            return targetPlayer;
+        }
+        return getBySelector(playerIdentifier, sender);
+    }
+
+    /**
+     * Get multiple {@link Player} based on many identifiers of name UUID or selector.
+     *
+     * @param playerIdentifiers An identifier of multiple names, UUIDs or selectors, separated by comma.
+     * @param sender            Target sender for selector.
+     * @return A list of all the {@link Player} found.
+     */
+    @Nullable
+    public static List<Player> getMulti(@NotNull String playerIdentifiers,
+                                        @NotNull CommandSender sender) {
+
+        String[] playerIdentifierArray = COMMA_SPLIT.split(playerIdentifiers);
+        if (playerIdentifierArray == null || playerIdentifierArray.length == 0) {
+            return null;
+        }
+
+        List<Player> playerResults = new ArrayList<>();
+        for (String playerIdentifier : playerIdentifierArray) {
+            Player targetPlayer = getByName(playerIdentifier);
+            if (targetPlayer != null) {
+                playerResults.add(targetPlayer);
+                continue;
+            }
+            targetPlayer = getByUuid(playerIdentifier);
+            if (targetPlayer != null) {
+                playerResults.add(targetPlayer);
+                continue;
+            }
+            List<Player> targetPlayers = getMultiBySelector(playerIdentifier, sender);
+            if (targetPlayers != null) {
+                playerResults.addAll(targetPlayers);
+            }
+        }
+        return playerResults;
+    }
+
+    /**
+     * Get a {@link Player} based on player name.
+     *
+     * @param playerName    Name of a {@link Player}.
+     * @return The player if found, else null.
+     */
+    @Nullable
+    public static Player getByName(@NotNull String playerName) {
+        return Bukkit.getPlayerExact(playerName);
+    }
+
+    /**
+     * Get a {@link Player} based on player UUID.
+     *
+     * @param playerUuid    UUID of a player.
+     * @return The player if found, else null.
+     */
+    @Nullable
+    public static Player getByUuid(@NotNull String playerUuid) {
+        if (!UUID_REGEX.matcher(playerUuid).matches()) {
+            return null;
+        }
+        UUID uuid;
+        try {
+            uuid = UUID.fromString(playerUuid);
+        } catch (Exception e) {
+            return null;
+        }
+        return getByUuid(uuid);
+    }
+
+    /**
+     * Get a {@link Player} based on playerUUID.
+     *
+     * @param playerUuid    UUID of a player.
+     * @return The player if found, else null.
+     */
+    @Nullable
+    public static Player getByUuid(@NotNull UUID playerUuid) {
+        return Bukkit.getPlayer(playerUuid);
+    }
+
+    /**
+     * Get a {@link Player} based on vanilla selectors.
+     * https://minecraft.gamepedia.com/Commands#Target_selectors
+     *
+     * @param playerSelector    A target selector, usually starts with an '@'.
+     * @param sender            Target sender for selector.
+     * @return The player if only one found, else null.
+     */
+    @Nullable
+    public static Player getBySelector(@NotNull String playerSelector,
+                                       @NotNull CommandSender sender) {
+
+        List<Player> matchedPlayers = getMultiBySelector(playerSelector, sender);
+        if (matchedPlayers == null || matchedPlayers.isEmpty()) {
+            Logging.warning("No player found with selector '%s' for %s.", playerSelector, sender.getName());
+            return null;
+        }
+        if (matchedPlayers.size() > 1) {
+            Logging.warning("Ambiguous selector result '%s' for %s (more than one player matched) - %s",
+                    playerSelector, sender.getName(), matchedPlayers.toString());
+            return null;
+        }
+        return matchedPlayers.get(0);
+    }
+
+    /**
+     * Get multiple {@link Player} based on selector.
+     * https://minecraft.gamepedia.com/Commands#Target_selectors
+     *
+     * @param playerSelector    A target selector, usually starts with an '@'.
+     * @param sender            Target sender for selector.
+     * @return A list of all the {@link Player} found.
+     */
+    @Nullable
+    public static List<Player> getMultiBySelector(@NotNull String playerSelector,
+                                                  @NotNull CommandSender sender) {
+
+        if (playerSelector.charAt(0) != '@') {
+            return null;
+        }
+        try {
+            return Bukkit.selectEntities(sender, playerSelector).stream()
+                    .filter(e -> e instanceof Player)
+                    .map(e -> ((Player) e))
+                    .collect(Collectors.toList());
+        } catch (IllegalArgumentException e) {
+            Logging.warning("An error occurred while parsing selector '%s' for %s. Is it is the correct format?",
+                    playerSelector, sender.getName());
+            e.printStackTrace();
+            return null;
+        }
+    }
+}