/*******************************************************************************
 * 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 org.erlide.ui.util.eclipse;

import java.io.IOException;
import java.io.StringReader;
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.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.events.KeyEvent;
import org.eclipse.swt.events.KeyListener;
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.Menu;
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(final 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 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
	 */
	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 final 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
	 */
	private final String fSymbolicFontName;

	/**
	 * 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 resizable
	 *            <code>true</code> if the control should be resizable
	 * @since 3.4
	 */
	public BrowserInformationControl(final Shell parent,
			final String symbolicFontName, final boolean resizable) {
		super(parent, resizable);
		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(final Shell parent,
			final String symbolicFontName, final String statusFieldText) {
		super(parent, statusFieldText);
		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(final Shell parent,
			final String symbolicFontName, final ToolBarManager toolBarManager) {
		super(parent, toolBarManager);
		fSymbolicFontName = symbolicFontName;
		create();
	}

	/*
	 * @see
	 * org.eclipse.jface.text.AbstractInformationControl#createContent(org.eclipse
	 * .swt.widgets.Composite)
	 */
	@Override
	protected void createContent(final Composite parent) {
		fBrowser = new Browser(parent, SWT.NONE);

		Display display = getShell().getDisplay();
		fBrowser.setForeground(display
				.getSystemColor(SWT.COLOR_INFO_FOREGROUND));
		fBrowser.setBackground(display
				.getSystemColor(SWT.COLOR_INFO_BACKGROUND));
		fBrowser.addKeyListener(new KeyListener() {

			public void keyPressed(final KeyEvent e) {
				if (e.character == 0x1B) {
					dispose(); // XXX: Just hide? Would avoid constant
					// recreations.
				}
			}

			public void keyReleased(final KeyEvent e) {
			}
		});

		fBrowser.addProgressListener(new ProgressAdapter() {
			@Override
			public void completed(final ProgressEvent event) {
				fCompleted = true;
			}
		});

		// Replace browser's built-in context menu with none
		fBrowser.setMenu(new Menu(getShell(), SWT.NONE));

		createTextLayout();
	}

	/**
	 * {@inheritDoc}
	 * 
	 * @deprecated use {@link #setInput(Object)}
	 */
	@Deprecated
	@Override
	public void setInformation(final String content) {
		setInput(new BrowserInformationControlInput(null) {
			@Override
			public String getHtml() {
				return content;
			}

			@Override
			public String getInputName() {
				return ""; //$NON-NLS-1$
			}

			@Override
			public Object getInputElement() {
				return content;
			}
		});
	}

	/**
	 * {@inheritDoc} This control can handle {@link String} and
	 * {@link BrowserInformationControlInput}.
	 */
	public void setInput(final 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;"
													 */};
		} 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)
	 */
	@Override
	public void setVisible(final boolean visible) {
		Shell shell = getShell();
		if (shell.isVisible() == visible) {
			return;
		}

		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())) {
			shell.moveAbove(null);
		}

		super.setVisible(true);
	}

	/*
	 * @see org.eclipse.jface.text.AbstractInformationControl#setSize(int, int)
	 */
	@Override
	public void setSize(final int width, final int height) {
		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()
	 */
	@Override
	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()
	 */
	@SuppressWarnings("unchecked")
	@Override
	public Point computeSizeHint() {
		Point sizeConstraints = getSizeConstraints();
		Rectangle trim = computeTrim();
		int height = trim.height;

		// FIXME: 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 += 15;
		height += 15;

		// 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);
	}

	/*
	 * @see org.eclipse.jface.text.IInformationControlExtension3#computeTrim()
	 */
	@Override
	public Rectangle computeTrim() {
		Rectangle trim = super.computeTrim();
		if (isResizable()) {
			boolean RTL = (getShell().getStyle() & SWT.RIGHT_TO_LEFT) != 0;
			if (RTL) {
				trim.x -= fgScrollBarSize.x;
			}
			trim.width += fgScrollBarSize.x;
			trim.height += fgScrollBarSize.y;
		}
		return trim;
	}

	/**
	 * Adds the listener to the collection of listeners who will be notified
	 * when the current location has changed or is about to change.
	 * 
	 * @param listener
	 *            the location listener
	 * @since 3.4
	 */
	public void addLocationListener(final LocationListener listener) {
		fBrowser.addLocationListener(listener);
	}

	/*
	 * @see IInformationControl#setForegroundColor(Color)
	 */
	@Override
	public void setForegroundColor(final Color foreground) {
		super.setForegroundColor(foreground);
		fBrowser.setForeground(foreground);
	}

	/*
	 * @see IInformationControl#setBackgroundColor(Color)
	 */
	@Override
	public void setBackgroundColor(final Color background) {
		super.setBackgroundColor(background);
		fBrowser.setBackground(background);
	}

	/*
	 * @see IInformationControlExtension#hasContents()
	 */
	public boolean hasContents() {
		return fBrowserHasContent;
	}

	/**
	 * Adds a listener for input changes to this input change provider. Has no
	 * effect if an identical listener is already registered.
	 * 
	 * @param inputChangeListener
	 *            the listener to add
	 * @since 3.4
	 */
	public void addInputChangeListener(
			final IInputChangedListener inputChangeListener) {
		Assert.isNotNull(inputChangeListener);
		fInputChangeListeners.add(inputChangeListener);
	}

	/**
	 * Removes the given input change listener from this input change provider.
	 * Has no effect if an identical listener is not registered.
	 * 
	 * @param inputChangeListener
	 *            the listener to remove
	 * @since 3.4
	 */
	public void removeInputChangeListener(
			final IInputChangedListener inputChangeListener) {
		fInputChangeListeners.remove(inputChangeListener);
	}

	/*
	 * @seeorg.eclipse.jface.text.IDelayedInputChangeProvider#
	 * setDelayedInputChangeListener
	 * (org.eclipse.jface.text.IInputChangedListener)
	 * 
	 * @since 3.4
	 */
	public void setDelayedInputChangeListener(
			final IInputChangedListener inputChangeListener) {
		fDelayedInputChangeListener = inputChangeListener;
	}

	/**
	 * Tells whether a delayed input change listener is registered.
	 * 
	 * @return <code>true</code> iff a delayed input change listener is
	 *         currently registered
	 * @since 3.4
	 */
	public boolean hasDelayedInputChangeListener() {
		return fDelayedInputChangeListener != null;
	}

	/**
	 * Notifies listeners of a delayed input change.
	 * 
	 * @param newInput
	 *            the new input, or <code>null</code> to request cancellation
	 * @since 3.4
	 */
	public void notifyDelayedInputChange(final Object newInput) {
		if (fDelayedInputChangeListener != null) {
			fDelayedInputChangeListener.inputChanged(newInput);
		}
	}

	/*
	 * @see java.lang.Object#toString()
	 * 
	 * @since 3.4
	 */
	@Override
	public String toString() {
		String style = (getShell().getStyle() & SWT.RESIZE) == 0 ? "fixed" : "resizeable"; //$NON-NLS-1$ //$NON-NLS-2$
		return super.toString() + " -  style: " + style; //$NON-NLS-1$
	}

	/**
	 * @return the current browser input or <code>null</code>
	 */
	public BrowserInformationControlInput getInput() {
		return fInput;
	}

	/*
	 * @see
	 * org.eclipse.jface.text.IInformationControlExtension5#computeSizeConstraints
	 * (int, int)
	 */
	@Override
	public Point computeSizeConstraints(final int widthInChars,
			final int heightInChars) {
		if (fSymbolicFontName == null) {
			return null;
		}

		GC gc = new GC(fBrowser);
		Font font = JFaceResources.getFont(fSymbolicFontName);
		gc.setFont(font);
		int width = gc.getFontMetrics().getAverageCharWidth();
		int height = gc.getFontMetrics().getHeight();
		gc.dispose();

		return new Point(widthInChars * width, heightInChars * height);
	}

}
