package org.eclipse.swt.internal.qt;

import org.eclipse.swt.SWT;

import org.eclipse.swt.SWTException;

import org.eclipse.swt.widgets.Display;

import org.eclipse.swt.widgets.Internal_PackageSupport;

import org.eclipse.swt.widgets.Widget;

/**

 * Base CSS Engine for eSWT. This engine recognizes only Qt

 * <a href="http://qt.nokia.com/doc/4.6/stylesheet.html">stylesheet</a> syntax.

 *

 * CSS id selectors are supported by setting an id to the widget as follows.

 * <pre>

 *	Button myButton = new Button(composite, SWT.PUSH);

 *	myButton.setData(WidgetConstant.CSS_ID,"myButtonId");

 * </pre>

 *

 * <p><b>NOTE:</b> This class is intended for internal use only.</p>

 */

public final class BaseCSSEngine {

	private Display parent;

	/**

	 * Creates an engine instance.

	 *

	 * @exception IllegalArgumentException

	 *                <ul>

	 *                <li>ERROR_NULL_ARGUMENT - if the parent is null</li>

	 *                <li>ERROR_INVALID_ARGUMENT - if the parent is disposed</li>

	 *                </ul>

	 * @exception SWTException

	 *                <ul>

	 *                <li>ERROR_THREAD_INVALID_ACCESS - if not called from the

	 *                thread that created the parent</li>

	 *                </ul>

	 */

	public BaseCSSEngine(Display display){

		if (display == null) SWT.error (SWT.ERROR_NULL_ARGUMENT);

		if (display.isDisposed ()) SWT.error (SWT.ERROR_INVALID_ARGUMENT);

		if (display.getThread() != Thread.currentThread()) SWT.error (SWT.ERROR_THREAD_INVALID_ACCESS);

		this.parent = display;

	}

	/**

	 * Applies the given string containing valid CSS to all the widgets created for the Display.

	 * CSS used in this method can not have any relative urls (for example for imports and images).

	 * Relative urls will not be resolved.

	 *

	 *<p><b>NOTE:</b> This is intended for internal use.</p>

	 *

	 * @param style

	 * @exception IllegalArgumentException

	 * <ul>

 	 *    <li>ERROR_NULL_ARGUMENT - if style is null</li>

 	 *    <li>ERROR_INVALID_ARGUMENT - if style is not a valid style string</li>

 	 * </ul>

     * @exception SWTException <ul>

     *    <li>ERROR_WIDGET_DISPOSED - if the receiver has been disposed</li>

     *    <li>ERROR_THREAD_INVALID_ACCESS - if not called from the thread that created the receiver</li>

     * </ul>

	 */

	public void applyCSS( String style ){

		checkEngine();

		if( style == null ) SWT.error (SWT.ERROR_NULL_ARGUMENT);

		OS.QApplication_setStyleSheet(style);

	}

	/**

	 * Applies the given string containing valid CSS to the widget.

	 * CSS used in this method can not have any relative urls (for example for imports and images).

	 * Relative urls will not be resolved.

	 *

	 * <p><b>NOTE:</b> This is intended for internal use.</p>

	 *

	 * @param style

	 * @exception IllegalArgumentException

	 * <ul>

 	 *    <li>ERROR_NULL_ARGUMENT - if style is null</li>

 	 *    <li>ERROR_INVALID_ARGUMENT - if style is not a valid style string</li>

 	 * </ul>

     * @exception SWTException <ul>

     *    <li>ERROR_WIDGET_DISPOSED - if the receiver or the widget has been disposed</li>

     *    <li>ERROR_THREAD_INVALID_ACCESS - if not called from the thread that created the receiver</li>

     * </ul>

	 */

	public void applyCSS(Widget widget, String style ){

		checkEngine();

		if( style == null ) SWT.error (SWT.ERROR_NULL_ARGUMENT);

		if( widget == null ) SWT.error (SWT.ERROR_NULL_ARGUMENT);

		if( widget.isDisposed() ) SWT.error( SWT.ERROR_WIDGET_DISPOSED);

		OS.QWidget_setStyleSheet(Internal_PackageSupport.handle(widget), style);

	}

	/**

	 * Loads a file containing valid CSS and applies to all the widgets for Display.

	 * This function bypasses java security checks for accessing the file.

	 *

	 * <p><b>NOTE:</b> This is intended for internal use.</p>

	 *

	 * @param style

	 * @exception IllegalArgumentException <ul>

 	 *    <li>ERROR_NULL_ARGUMENT - if the file name is null</li>

 	 * </ul>

     * @exception SWTException <ul>

     *    <li>ERROR_WIDGET_DISPOSED - if the receiver has been disposed</li>

     *    <li>ERROR_THREAD_INVALID_ACCESS - if not called from the thread that created the receiver</li>

     * </ul>

	 */

	public void loadCSS( String filename ){

		checkEngine();

		if (filename == null) SWT.error(SWT.ERROR_NULL_ARGUMENT);

	}

	/**

	 * Loads a file containing valid CSS and applies to the widget.

	 * This function bypasses Java security checks for accessing the file.

	 *

	 * <p><b>NOTE:</b> This is intended for internal use.</p>

	 *

	 * @param style

	 * @exception IllegalArgumentException

	 * <ul>

 	 *    <li>ERROR_NULL_ARGUMENT - if the file name is null</li>

 	 * </ul>

     * @exception SWTException <ul>

     *    <li>ERROR_WIDGET_DISPOSED - if the receiver or the widget has been disposed</li>

     *    <li>ERROR_THREAD_INVALID_ACCESS - if not called from the thread that created the receiver</li>

     * </ul>

	 */

	public void loadCSS( Widget widget, String filename ){

		if (filename == null) SWT.error(SWT.ERROR_NULL_ARGUMENT);

		if( widget == null ) SWT.error (SWT.ERROR_NULL_ARGUMENT);

		if( widget.isDisposed() ) SWT.error( SWT.ERROR_WIDGET_DISPOSED);

	}

	/**

	 * Dispose the engine.

	 * @exception SWTException <ul>

     *    <li>ERROR_THREAD_INVALID_ACCESS - if not called from the thread that created the receiver</li>

     * </ul>

	 *

	 */

	public void dispose(){

		if(parent != null) {

			if (parent.getThread() != Thread.currentThread()) SWT.error (SWT.ERROR_THREAD_INVALID_ACCESS);

			parent = null;

		}

	}

	private void checkEngine(){

		if ( parent == null || parent.isDisposed() ) SWT.error( SWT.ERROR_WIDGET_DISPOSED);

	    if ( parent.getThread() != Thread.currentThread() ) SWT.error (SWT.ERROR_THREAD_INVALID_ACCESS);

	}

}