/*
 * Copyright (c) 2002-2008 Gargoyle Software Inc.
 *
 * 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.gargoylesoftware.htmlunit.html;

import java.io.IOException;
import java.net.MalformedURLException;
import java.net.URL;
import java.util.Map;

import org.apache.commons.logging.Log;
import org.apache.commons.logging.LogFactory;

import com.gargoylesoftware.htmlunit.FailingHttpStatusCodeException;
import com.gargoylesoftware.htmlunit.Page;
import com.gargoylesoftware.htmlunit.SgmlPage;
import com.gargoylesoftware.htmlunit.WebClient;
import com.gargoylesoftware.htmlunit.WebRequestSettings;
import com.gargoylesoftware.htmlunit.WebWindow;
import com.gargoylesoftware.htmlunit.javascript.JavaScriptEngine;
import com.gargoylesoftware.htmlunit.javascript.PostponedAction;

/**
 * Base class for frame and iframe.
 *
 * @version $Revision$
 * @author <a href="mailto:mbowler@GargoyleSoftware.com">Mike Bowler</a>
 * @author David K. Taylor
 * @author <a href="mailto:cse@dynabean.de">Christian Sell</a>
 * @author Marc Guillemot
 * @author David D. Kilzer
 * @author Stefan Anzinger
 * @author Ahmed Ashour
 * @author Dmitri Zoubkov
 * @author Daniel Gredler
 */
public abstract class BaseFrame extends StyledElement {

    private final transient Log mainLog_ = LogFactory.getLog(getClass());
    private final WebWindow enclosedWindow_ = new FrameWindow(this);

    /**
     * Creates an instance of BaseFrame.
     *
     * @param namespaceURI the URI that identifies an XML namespace
     * @param qualifiedName the qualified name of the element type to instantiate
     * @param page the HtmlPage that contains this element
     * @param attributes the initial attributes
     */
    protected BaseFrame(final String namespaceURI, final String qualifiedName, final SgmlPage page,
            final Map<String, DomAttr> attributes) {
        super(namespaceURI, qualifiedName, page, attributes);

        try {
            // put about:blank in the window to allow JS to run on this frame before the
            // real content is loaded
            final WebClient webClient = getPage().getEnclosingWindow().getWebClient();
            webClient.getPage(enclosedWindow_, new WebRequestSettings(WebClient.URL_ABOUT_BLANK));
        }
        catch (final FailingHttpStatusCodeException e) {
            // should never occur
        }
        catch (final IOException e) {
            // should never occur
        }
    }

    /**
     * Called after the node for <frame...> or <iframe> has been added to the containing page.
     * The node needs to be added first to allow js in the frame to see the frame in the parent
     * @throws FailingHttpStatusCodeException if the server returns a
     *      failing status code AND the property
     *      {@link WebClient#setThrowExceptionOnFailingStatusCode(boolean)} is set to true.
     */
    void loadInnerPage() throws FailingHttpStatusCodeException {
        String source = getSrcAttribute();
        if (source.length() == 0) {
            // Nothing to load
            source = "about:blank";
        }
        else {
            loadInnerPageIfPossible(source);
        }
    }

    /**
     * @throws FailingHttpStatusCodeException if the server returns a
     *      failing status code AND the property
     *      {@link WebClient#setThrowExceptionOnFailingStatusCode(boolean)} is set to true.
     */
    private void loadInnerPageIfPossible(final String src) throws FailingHttpStatusCodeException {
        if (src.length() != 0) {
            final URL url;
            try {
                url = ((HtmlPage) getPage()).getFullyQualifiedUrl(src);
            }
            catch (final MalformedURLException e) {
                notifyIncorrectness("Invalid src attribute of " + getTagName() + ": url=[" + src + "]. Ignored.");
                return;
            }
            if (isAlreadyLoadedByAncestor(url)) {
                notifyIncorrectness("Recursive src attribute of " + getTagName() + ": url=[" + src + "]. Ignored.");
                return;
            }
            try {
                final WebRequestSettings settings = new WebRequestSettings(url);
                settings.addAdditionalHeader("Referer", getPage().getWebResponse().getUrl().toExternalForm());
                getPage().getEnclosingWindow().getWebClient().getPage(enclosedWindow_, settings);
            }
            catch (final IOException e) {
                if (mainLog_.isErrorEnabled()) {
                    mainLog_.error("IOException when getting content for " + getTagName()
                            + ": url=[" + url.toExternalForm() + "]", e);
                }
            }
        }
    }

    /**
     * Test if the provided URL is the one of one of the parents which would cause an infinite loop.
     * @param url the URL to test
     * @return <code>false</code> if no parent has already this URL
     */
    private boolean isAlreadyLoadedByAncestor(final URL url) {
        WebWindow window = getPage().getEnclosingWindow();
        while (window != null) {
            if (url.sameFile(window.getEnclosedPage().getWebResponse().getUrl())) {
                return true;
            }
            if (window == window.getParentWindow()) { // should getParentWindow() return null on top windows?
                window = null;
            }
            else {
                window = window.getParentWindow();
            }
        }
        return false;
    }

    /**
     * Returns the value of the attribute "longdesc". Refer to the
     * <a href='http://www.w3.org/TR/html401/'>HTML 4.01</a>
     * documentation for details on the use of this attribute.
     *
     * @return the value of the attribute "longdesc" or an empty string if that attribute isn't defined
     */
    public final String getLongDescAttribute() {
        return getAttributeValue("longdesc");
    }

    /**
     * Returns the value of the attribute "name". Refer to the
     * <a href='http://www.w3.org/TR/html401/'>HTML 4.01</a>
     * documentation for details on the use of this attribute.
     *
     * @return the value of the attribute "name" or an empty string if that attribute isn't defined
     */
    public final String getNameAttribute() {
        return getAttributeValue("name");
    }

    /**
     * Sets the value of the "name" attribute.
     *
     * @param name the new window name
     */
    public final void setNameAttribute(final String name) {
        setAttributeValue("name", name);
    }

    /**
     * Returns the value of the attribute "src". Refer to the
     * <a href='http://www.w3.org/TR/html401/'>HTML 4.01</a>
     * documentation for details on the use of this attribute.
     *
     * @return the value of the attribute "src" or an empty string if that attribute isn't defined
     */
    public final String getSrcAttribute() {
        return getAttributeValue("src");
    }

    /**
     * Returns the value of the attribute "frameborder". Refer to the
     * <a href='http://www.w3.org/TR/html401/'>HTML 4.01</a>
     * documentation for details on the use of this attribute.
     *
     * @return the value of the attribute "frameborder" or an empty string if that attribute isn't defined
     */
    public final String getFrameBorderAttribute() {
        return getAttributeValue("frameborder");
    }

    /**
     * Returns the value of the attribute "marginwidth". Refer to the
     * <a href='http://www.w3.org/TR/html401/'>HTML 4.01</a>
     * documentation for details on the use of this attribute.
     *
     * @return the value of the attribute "marginwidth" or an empty string if that attribute isn't defined
     */
    public final String getMarginWidthAttribute() {
        return getAttributeValue("marginwidth");
    }

    /**
     * Returns the value of the attribute "marginheight". Refer to the
     * <a href='http://www.w3.org/TR/html401/'>HTML 4.01</a>
     * documentation for details on the use of this attribute.
     *
     * @return the value of the attribute "marginheight" or an empty string if that attribute isn't defined
     */
    public final String getMarginHeightAttribute() {
        return getAttributeValue("marginheight");
    }

    /**
     * Returns the value of the attribute "noresize". Refer to the
     * <a href='http://www.w3.org/TR/html401/'>HTML 4.01</a>
     * documentation for details on the use of this attribute.
     *
     * @return the value of the attribute "noresize" or an empty string if that attribute isn't defined
     */
    public final String getNoResizeAttribute() {
        return getAttributeValue("noresize");
    }

    /**
     * Returns the value of the attribute "scrolling". Refer to the
     * <a href='http://www.w3.org/TR/html401/'>HTML 4.01</a>
     * documentation for details on the use of this attribute.
     *
     * @return the value of the attribute "scrolling" or an empty string if that attribute isn't defined
     */
    public final String getScrollingAttribute() {
        return getAttributeValue("scrolling");
    }

    /**
     * Returns the value of the attribute "onload". This attribute is not
     * actually supported by the HTML specification however it is supported
     * by the popular browsers.
     *
     * @return the value of the attribute "onload" or an empty string if that attribute isn't defined
     */
    public final String getOnLoadAttribute() {
        return getAttributeValue("onload");
    }

    /**
     * Returns the currently loaded page in the enclosed window.
     * This is a facility method for <code>getEnclosedWindow().getEnclosedPage()</code>.
     * @see WebWindow#getEnclosedPage()
     * @return the currently loaded page in the enclosed window, or <tt>null</tt> if no page has been loaded
     */
    public Page getEnclosedPage() {
        return getEnclosedWindow().getEnclosedPage();
    }

    /**
     * Gets the window enclosed in this frame.
     * @return the window enclosed in this frame
     */
    public WebWindow getEnclosedWindow() {
        return enclosedWindow_;
    }

    /**
     * Sets the value of the "src" attribute. Also loads the frame with the specified URL, if possible.
     * @param attribute the new value of the "src" attribute
     */
    public final void setSrcAttribute(final String attribute) {
        setAttributeValue("src", attribute);
    }

    /**
     * {@inheritDoc}
     */
    @Override
    protected final void setAttributeValue(final String namespaceURI, final String qualifiedName,
        String attributeValue, final boolean cloning) {

        if (qualifiedName.equals("src")) {
            attributeValue = attributeValue.trim();
        }

        super.setAttributeValue(namespaceURI, qualifiedName, attributeValue, cloning);

        if (qualifiedName.equals("src") && !cloning) {
            final JavaScriptEngine jsEngine = getPage().getWebClient().getJavaScriptEngine();
            // when src is set from a script, loading is postponed until script finishes
            // in fact this implementation is probably wrong: javascript url should be first evaluated
            // and only loading, when any, should be postponed
            if (!jsEngine.isScriptRunning() || attributeValue.startsWith("javascript:")) {
                loadInnerPageIfPossible(attributeValue);
            }
            else {
                final String src = attributeValue;
                final PostponedAction action = new PostponedAction() {
                    public void execute() throws Exception {
                        if (getSrcAttribute().equals(src)) {
                            loadInnerPage();
                        }
                    }
                };
                jsEngine.addPostponedAction(action);
            }
        }
    }

}