/**
 * Copyright 2011 Bill Brown
 *
 * Licensed under the Apache License, Version 2.0 (the "License");
 * you may not use this file except in compliance with the License.
 * You may obtain a copy of the License at
 *
 * http://www.apache.org/licenses/LICENSE-2.0
 *
 * Unless required by applicable law or agreed to in writing, software
 * distributed under the License is distributed on an "AS IS" BASIS,
 * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
 * See the License for the specific language governing permissions and
 * limitations under the License.
 */
package com.colorfulsoftware.rss;

import java.io.Serializable;

/**
 * <p>
 * The &lt;image> element.
 * </p>
 * <p>
 * From the <a href="http://cyber.law.harvard.edu/rss/rss.html">RSS 2.0
 * specification</a>...
 * </p>
 * <p>
 * Specifies a GIF, JPEG or PNG image that can be displayed with the channel.
 * More info <a href=
 * "http://cyber.law.harvard.edu/rss/rss.html#ltimagegtSubelementOfLtchannelgt"
 * >here</a>.
 * </p>
 * 
 * <p>
 * &lt;image> is an optional sub-element of &lt;channel>, which contains three
 * required and three optional sub-elements.
 * </p>
 * 
 * <p>
 * &lt;url> is the URL of a GIF, JPEG or PNG image that represents the channel.
 * </p>
 * 
 * <p>
 * &lt;title> describes the image, it's used in the ALT attribute of the HTML
 * &lt;img> tag when the channel is rendered in HTML.
 * </p>
 * 
 * <p>
 * &lt;link> is the URL of the site, when the channel is rendered, the image is
 * a link to the site. (Note, in practice the image &lt;title> and &lt;link>
 * should have the same value as the channel's &lt;title> and &lt;link>.
 * </p>
 * 
 * <p>
 * Optional elements include &lt;width> and &lt;height>, numbers, indicating the
 * width and height of the image in pixels. &lt;description> contains text that
 * is included in the TITLE attribute of the link formed around the image in the
 * HTML rendering.
 * </p>
 * 
 * <p>
 * Maximum value for width is 144, default value is 88.
 * </p>
 * 
 * <p>
 * Maximum value for height is 400, default value is 31.
 * </p>
 * 
 * @author Bill Brown
 * 
 */
public class Image implements Serializable {

        private static final long serialVersionUID = -812074455770644390L;

        /* required sub elements */
        private final URL url;

        private final Title title;

        private final Link link;

        /* optional sub elements */
        private final Width width;

        private final Height height;

        private final Description description;

        Image(URL url, Title title, Link link, Width width, Height height,
                        Description description) throws RSSpectException {
                // make sure id is present
                if (url == null) {
                        throw new RSSpectException(
                                        "image elements MUST contain a url element.");
                }
                this.url = new URL(url);

                // make sure title is present
                if (title == null) {
                        throw new RSSpectException(
                                        "image elements MUST contain a title element.");
                }
                this.title = new Title(title.getTitle());

                // make sure updated is present
                if (link == null) {
                        throw new RSSpectException(
                                        "image elements MUST contain a link element.");
                }
                this.link = new Link(link);

                this.width = (width == null) ? null : new Width(width);
                this.height = (height == null) ? null : new Height(height);
                this.description = (description == null) ? null : new Description(
                                description.getDescription());
        }

        Image(Image image) {
                this.url = image.getUrl();
                this.title = image.getTitle();
                this.link = image.getLink();
                this.width = image.getWidth();
                this.height = image.getHeight();
                this.description = image.getDescription();
        }

        /**
         * @return the url element.
         */
        public URL getUrl() {
                return new URL(url);
        }

        /**
         * @return the title element.
         */
        public Title getTitle() {
                return new Title(title);
        }

        /**
         * @return the link element.
         */
        public Link getLink() {
                return new Link(link);

        }

        /**
         * @return the width element.
         */
        public Width getWidth() {
                return (width == null) ? null : new Width(width);
        }

        /**
         * @return the height element.
         */
        public Height getHeight() {
                return (height == null) ? null : new Height(height);
        }

        /**
         * @return the description element.
         */
        public Description getDescription() {
                return (description == null) ? null : new Description(description
                                .getDescription());
        }

        /**
         * Shows the contents of the &lt;image> element.
         */
        @Override
        public String toString() {
                StringBuilder sb = new StringBuilder("<image>" + url + title + link);

                if (width != null) {
                        sb.append(width);
                }

                if (height != null) {
                        sb.append(height);
                }

                if (description != null) {
                        sb.append(description);
                }

                sb.append("</image>");
                return sb.toString();
        }
        
        @Override
        public boolean equals(Object obj) {
                if (obj == this) {
                        return true;
                }
                if (!(obj instanceof Image)) {
                        return false;
                }
                return this.toString().equals(obj.toString());
        }
        
        @Override public int hashCode() {
                return toString().hashCode();
        }
}