LiteLoader / LiteLoader · Files

package com.mumfrey.liteloader.messaging;

import java.util.HashMap;
import java.util.Map;
import java.util.regex.Pattern;

import com.google.common.collect.ImmutableMap;

/**
 * Class used to encapsulate a MessageBus message
 * 
 * @author Adam Mummery-Smith
 */
public class Message
{
	/**
	 * Regex for matching valid channels
	 */
	private static final Pattern channelPattern = Pattern.compile("^[a-z0-9]([a-z0-9_\\-]*[a-z0-9])?:[a-z0-9]([a-z0-9_\\-]*[a-z0-9])?$", Pattern.CASE_INSENSITIVE);
	
	private final String channel, replyChannel;
	private final Messenger sender;
	private final Map<String, ?> payload;
	
	Message(String channel, Object value, Messenger sender)
	{
		this(channel, value, sender, null);
	}
	
	Message(String channel, Object value, Messenger sender, String replyChannel)
	{
		Message.validateChannel(channel);
		
		this.channel = channel;
		this.payload = ImmutableMap.<String, Object>of("value", value);
		this.sender = sender;
		this.replyChannel = replyChannel;
	}
	
	Message(String channel, Map<String, ?> payload, Messenger sender)
	{
		this(channel, payload, sender, null);
	}
	
	Message(String channel, Map<String, ?> payload, Messenger sender, String replyChannel)
	{
		Message.validateChannel(channel);
		
		this.channel = channel;
		this.payload = payload != null ? ImmutableMap.copyOf(payload) : ImmutableMap.<String, String>of();
		this.sender = sender;
		this.replyChannel = replyChannel;
	}
	
	/**
	 * Get the channel (fully qualified) that this message was sent on
	 */
	public String getChannel()
	{
		return this.channel;
	}
	
	/**
	 * Get the channel category for this message
	 */
	public String getCategory()
	{
		return this.channel.substring(0, this.channel.indexOf(':'));
	}
	
	/**
	 * Get the specified reply channel (if any) for this message - may return null
	 */
	public String getReplyChannel()
	{
		return this.replyChannel;
	}
	
	/**
	 * Get the message sender (if any) for this message - may return null
	 */
	public Messenger getSender()
	{
		return this.sender;
	}
	
	/**
	 * Get the message payload
	 */
	public Map<String, ?> getPayload()
	{
		return this.payload;
	}
	
	/**
	 * Check if this message is on the specified channel
	 * 
	 * @param channel Full name of the channel to check against (case sensitive)
	 */
	public boolean isChannel(String channel)
	{
		return this.channel.equals(channel);
	}
	
	/**
	 * Check if this message has the specified category
	 * 
	 * @param category
	 */
	public boolean isCategory(String category)
	{
		return this.getCategory().equals(category);
	}
	
	/**
	 * Get (and implicit cast) a value from this message's payload
	 * 
	 * @param key
	 */
	@SuppressWarnings("unchecked")
	public <T> T get(String key)
	{
		return (T)this.payload.get(key);
	}
	
	@SuppressWarnings("unchecked")
	public <T> T get(String key, T defaultValue)
	{
		Object value = this.payload.get(key);
		if (value != null)
		{
			return (T)value;
		}
		return defaultValue;
	}
	
	/**
	 * Gets the payload with the key "value", which is used with messages constructed using a string-only payload 
	 */
	public <T> T getValue()
	{
		return this.get("value");
	}
	
	public static void validateChannel(String channel) throws IllegalArgumentException
	{
		if (channel == null)
		{
			throw new IllegalArgumentException("Channel name cannot be null");
		}
		
		if (!Message.isValidChannel(channel))
		{
			throw new IllegalArgumentException("'" + channel + "' is not a valid channel name");
		}
	}
	
	public static boolean isValidChannel(String channel)
	{
		return Message.channelPattern.matcher(channel).matches();
	}
	
	/**
	 * Build a KV map from interleaved keys and values, convenience function
	 * 
	 * @param args
	 */
	public static Map<String, ?> buildMap(Object... args)
	{
		Map<String, Object> payload = new HashMap<String, Object>();
		for (int i = 0; i < args.length - 1; i += 2)
		{
			if (args[i] instanceof String)
			{
				payload.put((String)args[i], args[i + 1]);
			}
		}
		
		return payload;
	}
}