package com.avoka.lib.click.control;

import java.util.Properties;

import net.tanesha.recaptcha.ReCaptcha;
import net.tanesha.recaptcha.ReCaptchaFactory;
import net.tanesha.recaptcha.ReCaptchaImpl;
import net.tanesha.recaptcha.ReCaptchaResponse;

import org.apache.click.control.AbstractControl;
import org.apache.click.control.Field;
import org.apache.click.util.HtmlStringBuffer;
import org.apache.commons.lang.StringUtils;

/**
 * Provides an implementation of a ReCaptcha fields for a Click form.
 * <p/>
 * ReCaptcha is used by a wide variety of sites such as  Facebook, TicketMaster, 
 * Twitter and StumbleUpon that want to restrict the submission to humans. CAPTCHA 
 * stands for Completely Automated Public Turing test to tell Computers and Humans Apart
 * <p/>
 * It is useful for the following types of forms: 
 * <blockquote><ul>
 * <li>Account registrations.</li>
 * <li>Automated quotations.</li>
 * <li>Sales enquiry.</li>
 * <li>Anonymous support request.</li>
 * </ul></blockquote> 
 * ReCaptcha provides a free service, it uses the responses to the challenges, to digitize books.
 * To use ReCaptcha an individual or company must first register to get a Private and Public key. This   
 * For more information on ReCaptcha visit http://wiki.recaptcha.net
 * <p/>
 * The design allows for only one ReCaptchaField per form. This is because the rendered html will have 
 * 2 constant forms fields see RECAPTCHA_CHALLENGE_FIELD and RECAPTCHA_RESPONSE_FIELD below; 
 * <p/>
 * This class uses the ReCaptcha java lib recaptcha4j-0.0.7.jar downloaded from http://wiki.recaptcha.net
 * <p/> 
 * TODO: Change field error message, that is displayed if a validation error occurs, to come from a 
 * resource bundle. Add more themes names as constants http://wiki.recaptcha.net/index.php/Overview 
 * <p/>
 * @author Larry Bunton
 */

public class ReCaptchaField extends Field {

    private static final String RECAPTCHA_RESPONSE_FIELD = "recaptcha_response_field";

    private static final String RECAPTCHA_CHALLENGE_FIELD = "recaptcha_challenge_field";

    private static final long serialVersionUID = 1L;

    public static final String THEME_CLEAN = "clean";

    private String publicKey;
    private String privateKey;
    Properties options = new Properties();

    /**
     * @param name  the field name
     * @param publicKey  the public key sent by ReCaptcha when you register.
     * @param privateKey  the private key sent by ReCaptcha on registring
     * @param theme  name of ReCaptcha theme as per http://wiki.recaptcha.net/index.php/Overview
     */
    public ReCaptchaField(String name, String publicKey, String privateKey,
            String theme) {
        super(name);
        this.publicKey = publicKey;
        this.privateKey = privateKey;
        if (StringUtils.isNotEmpty(theme)) {
            options.setProperty(ReCaptchaImpl.PROPERTY_THEME, theme);
        }
    }

    /**
     * Render the HTML representation of the ReCaptchaField.
     *
     * @see #toString()
     *
     * @param buffer the specified buffer to render the control's output to
     */
    public void render(HtmlStringBuffer buffer) {
        ReCaptcha recaptcha = ReCaptchaFactory.newReCaptcha(publicKey,
                privateKey, false);
        String output = recaptcha.createRecaptchaHtml(null, options);
        buffer.append(output);
    }
    
    @Override
    public boolean onProcess() {
        bindRequestValue();

        if (getValidate()) {
            validate();
        }

        dispatchActionEvent();

        return true;
    }

    /**
     * Validate the TextField request submission.
     * <p/>
     * A field error message is displayed if a validation error occurs.
     */
    @Override
    public void validate() {
        setError(null);

        String remoteAddr = getContext().getRequest().getRemoteAddr();
        ReCaptchaImpl reCaptcha = new ReCaptchaImpl();
        reCaptcha.setPrivateKey(privateKey);

        String challenge = getContext().getRequestParameter(RECAPTCHA_CHALLENGE_FIELD);
        String userResponse = getContext().getRequestParameter(RECAPTCHA_RESPONSE_FIELD);
        ReCaptchaResponse reCaptchaResponse = reCaptcha.checkAnswer(remoteAddr, challenge, userResponse);

        if (!reCaptchaResponse.isValid()) {
            setError("Incorrect ReCAPTCHA Response, please try again.");
        }
    }

    /**
     * Return the captcha fields html tag: <tt>input</tt>.
     * 
     * @see AbstractControl#getTag()
     * 
     * @return this controls html tag
     */
    public String getTag() {
        return "captcha";
    }
}