/*******************************************************************************

 * Copyright (c) 2000, 2008 IBM Corporation and others.

 * All rights reserved. This program and the accompanying materials

 * are made available under the terms of the Eclipse Public License v1.0

 * which accompanies this distribution, and is available at

 * http://www.eclipse.org/legal/epl-v10.html

 *

 * Contributors:

 *     IBM Corporation - initial API and implementation

 *******************************************************************************/

package com.nokia.carbide.cpp.sysdoc.internal.hover.view;

import java.io.IOException;

import java.io.StringReader;

import java.net.URL;

import java.util.Iterator;

import org.eclipse.core.runtime.Assert;

import org.eclipse.core.runtime.ListenerList;

import org.eclipse.jface.action.ToolBarManager;

import org.eclipse.jface.internal.text.html.BrowserInformationControlInput;

import org.eclipse.jface.internal.text.html.HTML2TextReader;

import org.eclipse.jface.internal.text.html.HTMLPrinter;

import org.eclipse.jface.resource.JFaceResources;

import org.eclipse.jface.text.AbstractInformationControl;

import org.eclipse.jface.text.IDelayedInputChangeProvider;

import org.eclipse.jface.text.IInformationControlExtension2;

import org.eclipse.jface.text.IInputChangedListener;

import org.eclipse.jface.text.TextPresentation;

import org.eclipse.swt.SWT;

import org.eclipse.swt.SWTError;

import org.eclipse.swt.browser.Browser;

import org.eclipse.swt.browser.LocationListener;

import org.eclipse.swt.browser.ProgressAdapter;

import org.eclipse.swt.browser.ProgressEvent;

import org.eclipse.swt.custom.StyleRange;

import org.eclipse.swt.graphics.Color;

import org.eclipse.swt.graphics.Font;

import org.eclipse.swt.graphics.FontData;

import org.eclipse.swt.graphics.GC;

import org.eclipse.swt.graphics.Point;

import org.eclipse.swt.graphics.Rectangle;

import org.eclipse.swt.graphics.TextLayout;

import org.eclipse.swt.graphics.TextStyle;

import org.eclipse.swt.widgets.Composite;

import org.eclipse.swt.widgets.Display;

import org.eclipse.swt.widgets.Shell;

import org.eclipse.swt.widgets.Slider;

/**

 * Displays HTML information in a {@link org.eclipse.swt.browser.Browser}

 * widget.

 * <p>

 * This {@link IInformationControlExtension2} expects {@link #setInput(Object)}

 * to be called with an argument of type {@link BrowserInformationControlInput}.

 * </p>

 * <p>

 * Moved into this package from

 * <code>org.eclipse.jface.internal.text.revisions</code>.

 * </p>

 * <p>

 * This class may be instantiated; it is not intended to be subclassed.

 * </p>

 * <p>

 * Current problems:

 * <ul>

 * <li>the size computation is too small</li>

 * <li>focusLost event is not sent - see

 * https://bugs.eclipse.org/bugs/show_bug.cgi?id=84532</li>

 * </ul>

 * </p>

 * 

 * @since 3.2

 */

public class BrowserInformationControl extends AbstractInformationControl

		implements IInformationControlExtension2, IDelayedInputChangeProvider {

	/**

	 * Tells whether the SWT Browser widget and hence this information control

	 * is available.

	 * 

	 * @param parent

	 *            the parent component used for checking or <code>null</code> if

	 *            none

	 * @return <code>true</code> if this control is available

	 */

	public static boolean isAvailable(Composite parent) {

		if (!fgAvailabilityChecked) {

			try {

				Browser browser = new Browser(parent, SWT.NONE);

				browser.dispose();

				fgIsAvailable = true;

				Slider sliderV = new Slider(parent, SWT.VERTICAL);

				Slider sliderH = new Slider(parent, SWT.HORIZONTAL);

				int width = sliderV.computeSize(SWT.DEFAULT, SWT.DEFAULT).x;

				int height = sliderH.computeSize(SWT.DEFAULT, SWT.DEFAULT).y;

				fgScrollBarSize = new Point(width, height);

				sliderV.dispose();

				sliderH.dispose();

			} catch (SWTError er) {

				fgIsAvailable = false;

			} finally {

				fgAvailabilityChecked = true;

			}

		}

		return fgIsAvailable;

	}

	/**

	 * Minimal size constraints.

	 * 

	 * @since 3.2

	 */

	private static final int MIN_WIDTH = 80;

	private static final int MIN_HEIGHT = 50;

	/**

	 * Availability checking cache.

	 */

	private static boolean fgIsAvailable = false;

	private static boolean fgAvailabilityChecked = false;

	/**

	 * Cached scroll bar width and height

	 * 

	 * @since 3.4

	 */

	private static Point fgScrollBarSize;

	/** The control's browser widget */

	private Browser fBrowser;

	/** Tells whether the browser has content */

	private volatile boolean fBrowserHasContent;

	/** Text layout used to approximate size of content when rendered in browser */

	private TextLayout fTextLayout;

	/** Bold text style */

	private TextStyle fBoldStyle;

	private BrowserInformationControlInput fInput;

	/**

	 * <code>true</code> iff the browser has completed loading of the last input

	 * set via {@link #setInformation(String)}.

	 * 

	 * @since 3.4

	 */

	private boolean fCompleted = false;

	/**

	 * The listener to be notified when a delayed location changing event

	 * happened.

	 * 

	 * @since 3.4

	 */

	private IInputChangedListener fDelayedInputChangeListener;

	/**

	 * The listeners to be notified when the input changed.

	 * 

	 * @since 3.4

	 */

	private ListenerList/* <IInputChangedListener> */fInputChangeListeners = new ListenerList(

			ListenerList.IDENTITY);

	/**

	 * The symbolic name of the font used for size computations, or

	 * <code>null</code> to use dialog font.

	 * 

	 * @since 3.4

	 */

	// Our own custom fields...

	private final String fSymbolicFontName;

	private IBrowserInformationControlAgent browserInformationControlAgent = null;

	private static int w = -1;

	private static int h = -1;

	/**

	 * Creates a browser information control with the given shell as parent.

	 * 

	 * @param parent

	 *            the parent shell

	 * @param symbolicFontName

	 *            the symbolic name of the font used for size computations

	 * @param able

	 *            <code>true</code> if the control should be able

	 * @since 3.4

	 */

	public BrowserInformationControl(Shell parent, String symbolicFontName,

			boolean able,

			IBrowserInformationControlAgent browserInformationControlAgent) {

		super(parent, able);

		this.browserInformationControlAgent = browserInformationControlAgent;

		fSymbolicFontName = symbolicFontName;

		create();

	}

	/**

	 * Creates a browser information control with the given shell as parent.

	 * 

	 * @param parent

	 *            the parent shell

	 * @param symbolicFontName

	 *            the symbolic name of the font used for size computations

	 * @param statusFieldText

	 *            the text to be used in the optional status field or

	 *            <code>null</code> if the status field should be hidden

	 * @since 3.4

	 */

	public BrowserInformationControl(Shell parent, String symbolicFontName,

			String statusFieldText,

			IBrowserInformationControlAgent browserInformationControlAgent) {

		super(parent, statusFieldText);

		this.browserInformationControlAgent = browserInformationControlAgent;

		fSymbolicFontName = symbolicFontName;

		create();

	}

	/**

	 * Creates a browser information control with the given shell as parent.

	 * 

	 * @param parent

	 *            the parent shell

	 * @param symbolicFontName

	 *            the symbolic name of the font used for size computations

	 * @param toolBarManager

	 *            the manager or <code>null</code> if toolbar is not desired

	 * @since 3.4

	 */

	public BrowserInformationControl(Shell parent, String symbolicFontName,

			ToolBarManager toolBarManager,

			IBrowserInformationControlAgent browserInformationControlAgent) {

		super(parent, toolBarManager);

		this.browserInformationControlAgent = browserInformationControlAgent;

		fSymbolicFontName = symbolicFontName;

		create();

	}

	/*

	 * @see

	 * org.eclipse.jface.text.AbstractInformationControl#createContent(org.eclipse

	 * .swt.widgets.Composite)

	 */

	protected void createContent(Composite parent) {

		browserInformationControlAgent.setShell(getShell());

		browserInformationControlAgent.createContent(parent);

		fBrowser = browserInformationControlAgent.getBrowser();

		fBrowser.addProgressListener(new ProgressAdapter() {

			public void completed(ProgressEvent event) {

				fCompleted = true;

			}

		});

		createTextLayout();

	}

	/**

	 * {@inheritDoc}

	 * 

	 * @deprecated use {@link #setInput(Object)}

	 */

	public void setInformation(final String content) {

		setInput(new BrowserInformationControlInput(null) {

			public String getHtml() {

				return content;

			}

			public String getInputName() {

				return ""; //$NON-NLS-1$

			}

			public Object getInputElement() {

				return content;

			}

		});

	}

	/**

	 * {@inheritDoc} This control can handle {@link String} and

	 * {@link BrowserInformationControlInput}.

	 */

	public void setInput(Object input) {

		Assert.isLegal(input == null || input instanceof String

				|| input instanceof BrowserInformationControlInput);

		if (input instanceof String) {

			setInformation((String) input);

			return;

		}

		fInput = (BrowserInformationControlInput) input;

		String content = null;

		if (fInput != null)

			content = fInput.getHtml();

		fBrowserHasContent = content != null && content.length() > 0;

		if (!fBrowserHasContent)

			content = "<html><body ></html>"; //$NON-NLS-1$

		boolean RTL = (getShell().getStyle() & SWT.RIGHT_TO_LEFT) != 0;

		boolean resizable = isResizable();

		// The default "overflow:auto" would not result in a predictable width

		// for the client area

		// and the re-wrapping would cause visual noise

		String[] styles = null;

		if (RTL && resizable)

			styles = new String[] {

					"direction:rtl;", "overflow:scroll;", "word-wrap:break-word;" }; //$NON-NLS-1$ //$NON-NLS-2$ //$NON-NLS-3$

		else if (RTL && !resizable)

			styles = new String[] {

					"direction:rtl;", "overflow:hidden;", "word-wrap:break-word;" }; //$NON-NLS-1$ //$NON-NLS-2$ //$NON-NLS-3$

		else if (!resizable)

			// XXX: In IE, "word-wrap: break-word;" causes bogus wrapping even

			// in non-broken words :-(see e.g. Javadoc of String).

			// Re-check whether we really still need this now that the Javadoc

			// Hover header already sets this style.

			styles = new String[] { "overflow:hidden;"/*

													 * ,

													 * "word-wrap: break-word;"

													 */}; //$NON-NLS-1$

		else

			styles = new String[] { "overflow:scroll;" }; //$NON-NLS-1$

		StringBuffer buffer = new StringBuffer(content);

		HTMLPrinter.insertStyles(buffer, styles);

		content = buffer.toString();

		/*

		 * XXX: Should add some JavaScript here that shows something like

		 * "(continued...)" or "..." at the end of the visible area when the

		 * page overflowed with "overflow:hidden;".

		 */

		fCompleted = false;

		fBrowser.setText(content);

		Object[] listeners = fInputChangeListeners.getListeners();

		for (int i = 0; i < listeners.length; i++)

			((IInputChangedListener) listeners[i]).inputChanged(fInput);

	}

	/*

	 * @see IInformationControl#setVisible(boolean)

	 */

	public void setVisible(boolean visible) {

		Shell shell = getShell();

		if (shell.isVisible() == visible)

			return;

		browserInformationControlAgent.setVisible();

		if (!visible) {

			super.setVisible(false);

			setInput(null);

			return;

		}

		/*

		 * The Browser widget flickers when made visible while it is not

		 * completely loaded. The fix is to delay the call to setVisible until

		 * either loading is completed (see ProgressListener in constructor), or

		 * a timeout has been reached.

		 */

		final Display display = shell.getDisplay();

		// Make sure the display wakes from sleep after timeout:

		display.timerExec(100, new Runnable() {

			public void run() {

				fCompleted = true;

			}

		});

		while (!fCompleted) {

			// Drive the event loop to process the events required to load the

			// browser widget's contents:

			if (!display.readAndDispatch()) {

				display.sleep();

			}

		}

		shell = getShell();

		if (shell == null || shell.isDisposed())

			return;

		/*

		 * Avoids flickering when replacing hovers, especially on Vista in

		 * ON_CLICK mode. Causes flickering on GTK. Carbon does not care.

		 */

		if ("win32".equals(SWT.getPlatform())) //$NON-NLS-1$

			shell.moveAbove(null);

		super.setVisible(true);

	}

	/*

	 * @see org.eclipse.jface.text.AbstractInformationControl#setSize(int, int)

	 */

	public void setSize(int width, int height) {

		// When mouse over the popup menu, it will get bigger ...

		if (w == -1) {

			w = width + 100;

			h = height + 50;

		}

		width = w;

		height = h;

		fBrowser.setRedraw(false); // avoid flickering

		try {

			super.setSize(width, height);

		} finally {

			fBrowser.setRedraw(true);

		}

	}

	/**

	 * Creates and initializes the text layout used to compute the size hint.

	 * 

	 * @since 3.2

	 */

	private void createTextLayout() {

		fTextLayout = new TextLayout(fBrowser.getDisplay());

		// Initialize fonts

		Font font = fSymbolicFontName == null ? JFaceResources.getDialogFont()

				: JFaceResources.getFont(fSymbolicFontName);

		fTextLayout.setFont(font);

		fTextLayout.setWidth(-1);

		FontData[] fontData = font.getFontData();

		for (int i = 0; i < fontData.length; i++)

			fontData[i].setStyle(SWT.BOLD);

		font = new Font(getShell().getDisplay(), fontData);

		fBoldStyle = new TextStyle(font, null, null);

		// Compute and set tab width

		fTextLayout.setText("    "); //$NON-NLS-1$

		int tabWidth = fTextLayout.getBounds().width;

		fTextLayout.setTabs(new int[] { tabWidth });

		fTextLayout.setText(""); //$NON-NLS-1$

	}

	/*

	 * @see IInformationControl#dispose()

	 */

	public void dispose() {

		if (fTextLayout != null) {

			fTextLayout.dispose();

			fTextLayout = null;

		}

		if (fBoldStyle != null) {

			fBoldStyle.font.dispose();

			fBoldStyle = null;

		}

		fBrowser = null;

		super.dispose();

	}

	/*

	 * @see IInformationControl#computeSizeHint()

	 */

	public Point computeSizeHint() {

		Point sizeConstraints = getSizeConstraints();

		Rectangle trim = computeTrim();

		int height = trim.height;

		// NOTE: The HTML2TextReader does not render <p> like a browser.

		// Instead of inserting an empty line, it just adds a single line break.

		// Furthermore, the indentation of <dl><dd> elements is too small (e.g

		// with a long @see line)

		TextPresentation presentation = new TextPresentation();

		HTML2TextReader reader = new HTML2TextReader(new StringReader(fInput

				.getHtml()), presentation);

		String text;

		try {

			text = reader.getString();

		} catch (IOException e) {

			text = ""; //$NON-NLS-1$

		}

		fTextLayout.setText(text);

		fTextLayout.setWidth(sizeConstraints == null ? SWT.DEFAULT

				: sizeConstraints.x - trim.width);

		Iterator iter = presentation.getAllStyleRangeIterator();

		while (iter.hasNext()) {

			StyleRange sr = (StyleRange) iter.next();

			if (sr.fontStyle == SWT.BOLD)

				fTextLayout.setStyle(fBoldStyle, sr.start, sr.start + sr.length

						- 1);

		}

		Rectangle bounds = fTextLayout.getBounds(); // does not return minimum

		// width, see

		// https://bugs.eclipse.org/bugs/show_bug.cgi?id=217446

		int lineCount = fTextLayout.getLineCount();

		int textWidth = 0;

		for (int i = 0; i < lineCount; i++) {

			Rectangle rect = fTextLayout.getLineBounds(i);

			int lineWidth = rect.x + rect.width;

			if (i == 0)

				lineWidth += fInput.getLeadingImageWidth();

			textWidth = Math.max(textWidth, lineWidth);

		}

		bounds.width = textWidth;

		fTextLayout.setText(""); //$NON-NLS-1$

		int minWidth = bounds.width;

		height = height + bounds.height;

		// Add some air to accommodate for different browser renderings

		minWidth += 45;

		height += 55;

		// Apply max size constraints

		if (sizeConstraints != null) {

			if (sizeConstraints.x != SWT.DEFAULT)

				minWidth = Math.min(sizeConstraints.x, minWidth + trim.width);

			if (sizeConstraints.y != SWT.DEFAULT)

				height = Math.min(sizeConstraints.y, height);

		}

		// Ensure minimal size

		int width = Math.max(MIN_WIDTH, minWidth);

		height = Math.max(MIN_HEIGHT, height);

		return new Point(width, height);