package com.google.code.facebookapi;

import java.net.URL;

/**
 * A simple Pair consisting of a Facebook Photos photo ID for an image appearing in a newsfeed/minifeed story and the destination URL for a click on that image.
 * 
 * @see IFacebookRestClient
 * @see IFacebookRestClient#photos_get
 * @see FacebookRestClient#handleFeedImages
 */
@SuppressWarnings("serial")
public class FeedUserPhoto extends Pair<Object,URL> implements IFeedImage {

	/**
	 * Creates a linked Facebook Photos photo to appear in a user's newsfeed/minifeed.
	 * 
	 * @param userId
	 *            the photo ID of a Facebook photo to appear in a user's newsfeed/minifeed
	 * @param link
	 *            the URL to which the image should link
	 * @see IFacebookRestClient#photos_get
	 * @see FacebookRestClient#handleFeedImages
	 */
	public FeedUserPhoto( Long userId, URL link ) {
		super( userId, link );
		if ( null == userId || null == link ) {
			throw new IllegalArgumentException( "Both userId and linkUrl should be provided" );
		}
		if ( 0 >= userId ) {
			throw new IllegalArgumentException( "photoId should be a Facebook user ID" );
		}
	}

	/**
	 * @return the Facebook user ID of the feed image
	 */
	public Object getUserId() {
		return getFirst();
	}

	/**
	 * @return the String representation of the feed image "URL"
	 */
	public String getImageUrlString() {
		return getFirst().toString();
	}

	/**
	 * @return the link URL to which the feed image should link
	 */
	public URL getLinkUrl() {
		return getSecond();
	}
}