CommandMatcher.java

package org.shininet.bukkit.itemrenamer;

import java.util.Deque;
import java.util.Map;
import java.util.Set;

import com.google.common.collect.Maps;

class CommandMatcher<TType extends Enum<TType>> {
	/**
	 * Represents a possible command.
	 * 
	 * @author Kristian
	 */
	public class CommandNode {
		// NULL for no command
		private final TType command;
		private final String permission;
		
		private final String name;
		private String path = "";
		
		private final Map<String, CommandNode> children = Maps.newHashMap();
		
		private CommandNode(String permission, String name, TType command) {
			this.name = name;
			this.command = command;
			this.permission = permission;
		}

		public String getName() {
			return name;
		}

		public TType getCommand() {
			return command;
		}

		public CommandNode getChild(String name) {
			return children.get(name);
		}
		
		public CommandNode addChild(CommandNode node) {
			if (node == null)
				throw new IllegalArgumentException("Node cannot be NULL.");
			
			node.path = (path.length() > 0 ? (path + " ") : "") + node.getName();
			children.put(node.getName(), node);
			return node;
		}
		
		public CommandNode addOrCreate(String permission, String name, TType command) {
			if (children.containsKey(name)) 
				return children.get(name);
			return addChild(new CommandNode(permission, name, command));
		}
		
		public String getPath() {
			return path;
		}
		
		public boolean isCommand() {
			return command != null;
		}
		
		public String getPermission() {
			return permission;
		}

		public Set<String> getChildren() {
			return children.keySet();
		}
	}
	
	/**
	 * Represents anything.
	 */
	private final CommandNode root = new CommandNode("", "", null);
	
	public CommandNode matchClosest(Deque<String> arguments) {
		CommandNode current = root;
		
		while (!arguments.isEmpty()) {
			CommandNode next = current.getChild(arguments.peekFirst());
			
			// No match
			if (next == null)
				return current;
			arguments.poll();

			// We found the command
			if (next.isCommand())
				return next;
			
			// Next argument
			current = next;
		}
		return current;
	}
	
	public void registerCommand(TType command, String permission, String... arguments) {
		CommandNode current = root;
		
		// Create the tree structure
		for (int i = 0; i < arguments.length; i++) {
			boolean isLast = i == arguments.length - 1;
			current = current.addOrCreate(permission, arguments[i], isLast ? command : null);
		}
	}
}