Gravatar.java

/*
 * Licensed to the Apache Software Foundation (ASF) under one or more
 * contributor license agreements.  See the NOTICE file distributed with
 * this work for additional information regarding copyright ownership.
 * The ASF licenses this file to You 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 org.wicketstuff.minis.gravatar;

import java.io.UnsupportedEncodingException;
import java.net.URLEncoder;
import java.nio.charset.Charset;
import java.security.MessageDigest;

import org.apache.wicket.markup.ComponentTag;
import org.apache.wicket.markup.html.WebComponent;
import org.apache.wicket.model.IModel;
import org.apache.wicket.model.Model;

/**
 * Creates an image that is rendered by the <a
 * href="http://gravatar.com">Gravatar</a> online service. Gravatars are user
 * icons that are registered by a central server and that can be used across the
 * internet with blogs, forums and other profile based websites.
 * <p>
 * The <tt>Gravatar</tt> requires the email address for which the gravatar image
 * needs to be rendered (each gravatar account can have multiple email addresses
 * registered).
 * <p>
 * Available options:
 * <ul>
 * <li>you can set the {@linkplain #setSize(int) size of the rendered image}</li>
 * <li>you can pick a {@linkplain #setRating(String) rating} for the intended
 * audience</li>
 * <li>you can set the {@linkplain #setDefaultImage(String) default image} that
 * is rendered when no gravatar was found with the provided email address</li>
 * <li>you can choose to use a {@linkplain setSecure secure https protocol or
 * plain http}</li>
 * <li>the gravatar supports both the {@link #setAlt(IModel) alt} and
 * {@link #setTitle(IModel) title} attributes</li>
 * </ul>
 * <p>
 * Set the static fields if you want to modify the defaults for your whole
 * application.
 * 
 * @author dashorst
 */
public class Gravatar extends WebComponent {
    private static final long serialVersionUID = 1L;

    /** The non-secure URL for the gravatar service. */
    public static String URL_HTTP = "http://www.gravatar.com/avatar/";

    /** The secure URL for the gravatar service. */
    public static String URL_HTTPS = "https://secure.gravatar.com/avatar";

    /** Default value for the defaultImage property. */
    public static String DEFAULT_IMAGE = "wavatar";

    /** Default rating. */
    public static String DEFAULT_RATING = "G";

    /** Default setting for picking the protocol to retrieve gravatars with. */
    public static boolean DEFAULT_SECURE = false;

    /** Default size of the rendered gravatar images. */
    public static int DEFAULT_SIZE = 80;

    private String defaultCharset = Charset.defaultCharset().name();
    private String defaultImage = DEFAULT_IMAGE;
    private String rating = DEFAULT_RATING;
    private boolean secure = DEFAULT_SECURE;
    private int size = DEFAULT_SIZE;

    private IModel<String> title = new Model<String>("");
    private IModel<String> alt = new Model<String>("");

    /**
     * Constructs the gravatar image. The <tt>email</tt> is used to construct
     * the 'secret' gravatar URL.
     */
    public Gravatar(String id, String email) {
        this(id, new Model<String>(email));
    }

    /**
     * Constructs the gravatar image. The <tt>email</tt> is used to construct
     * the 'secret' gravatar URL.
     */
    public Gravatar(String id, IModel<String> email) {
        super(id, email);
    }

    /**
     * Sets the value for the <tt>title</tt> attribute of the image. Defaults to
     * empty string.
     */
    public Gravatar setTitle(IModel<String> title) {
        this.title = title;
        return this;
    }

    /**
     * Sets the value for the <tt>alt</tt> attribute of the image. Defaults to
     * empty string.
     */
    public Gravatar setAlt(IModel<String> alt) {
        this.alt = alt;
        return this;
    }

    /**
     * Sets the rating for the gravatar: G, PG, R and X are supported by the
     * gravatar service. Defaults to G.
     */
    public Gravatar setRating(String rating) {
        this.rating = rating;
        return this;
    }

    /**
     * Sets the default image that is generated when no gravatar was available
     * for the account. Defaults to <tt>identicon</tt>. The gravatar service
     * supports <tt>identicon</tt>, <tt>monsterid</tt> and <tt>wavatar</tt>. You
     * can also link to a different image by providing the fully qualified URL,
     * for example: <tt>http://example.com/images/example.jpg</tt>
     */
    public Gravatar setDefaultImage(String defaultImage) {
        try {
            this.defaultImage = URLEncoder.encode(defaultImage, defaultCharset);
        } catch (UnsupportedEncodingException e) {
        }
        return this;
    }

    /**
     * Sets the charset that is used to encode the default image with, defaults
     * to the platform's default charset.
     * 
     * @throws UnsupportedEncodingException
     */
    public void setDefaultCharset(String defaultCharset)
            throws UnsupportedEncodingException {
        URLEncoder.encode(URL_HTTP, defaultCharset);
        this.defaultCharset = defaultCharset;
    }

    /**
     * Sets the render size of the gravatar, sizes between 1 and 512 are
     * supported. Defaults to 80 pixels. The size will also be set on the
     * <tt>width</tt> and <tt>height</tt> attributes of this tag.
     */
    public Gravatar setSize(int size) {
        this.size = size;
        return this;
    }

    /**
     * Sets whether to use the secure gravatar URL links or normal http links.
     */
    public Gravatar setSecure(boolean secure) {
        this.secure = secure;
        return this;
    }

    @Override
    protected void onComponentTag(ComponentTag tag) {
        tag.setName("img");
        tag.put("src", getGravatarUrl());
        if (title != null) {
            tag.put("title", getDefaultModelObjectAsString(title.getObject()));
        }
        if (alt != null) {
            tag.put("alt", getDefaultModelObjectAsString(alt.getObject()));
        }
        tag.put("width", size);
        tag.put("height", size);
        super.onComponentTag(tag);
    }

    private String getGravatarUrl() {
        return (secure ? URL_HTTPS : URL_HTTP)
            + md5Hex(getDefaultModelObjectAsString()) + "?r=" + rating
            + "&amp;s=" + size + "&amp;d=" + defaultImage;
    }

    private String md5Hex(String message) {
        try {
            MessageDigest md = MessageDigest.getInstance("MD5");
            return hex(md.digest(message.getBytes("CP1252")));
        } catch (Exception e) {
        }
        return null;
    }

    private String hex(byte[] array) {
        StringBuffer sb = new StringBuffer();
        for (int i = 0; i < array.length; ++i) {
            sb.append(Integer.toHexString((array[i] & 0xFF) | 0x100).substring(
                1, 3));
        }
        return sb.toString();
    }
}