/*******************************************************************************
 * Copyright (c) 2000, 2011 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.python.pydev.utils;

import org.eclipse.core.runtime.Assert;
import org.eclipse.jface.dialogs.IDialogConstants;
import org.eclipse.jface.layout.PixelConverter;
import org.eclipse.jface.resource.JFaceResources;
import org.eclipse.swt.SWT;
import org.eclipse.swt.accessibility.ACC;
import org.eclipse.swt.accessibility.AccessibleAdapter;
import org.eclipse.swt.accessibility.AccessibleEvent;
import org.eclipse.swt.dnd.DragSource;
import org.eclipse.swt.dnd.DropTarget;
import org.eclipse.swt.layout.GridData;
import org.eclipse.swt.layout.GridLayout;
import org.eclipse.swt.widgets.Button;
import org.eclipse.swt.widgets.Caret;
import org.eclipse.swt.widgets.Combo;
import org.eclipse.swt.widgets.Control;
import org.eclipse.swt.widgets.Menu;
import org.eclipse.swt.widgets.ScrollBar;
import org.eclipse.swt.widgets.Shell;
import org.eclipse.swt.widgets.Table;
import org.eclipse.swt.widgets.Text;
import org.eclipse.swt.widgets.Widget;

/**
 * Utility class to simplify access to some SWT resources.
 */
public class SWTUtil {

    /**
     * The default visible item count for {@link Combo}s.
     * Workaround for https://bugs.eclipse.org/bugs/show_bug.cgi?id=245569 .
     *
     * @see Combo#setVisibleItemCount(int)
     *
     * @since 3.5
     */
    public static final int COMBO_VISIBLE_ITEM_COUNT = 30;

    /**
     * Returns the shell for the given widget. If the widget doesn't represent
     * a SWT object that manage a shell, <code>null</code> is returned.
     * @param widget the widget
     *
     * @return the shell for the given widget
     */
    public static Shell getShell(Widget widget) {
        if (widget instanceof Control) {
            return ((Control) widget).getShell();
        }
        if (widget instanceof Caret) {
            return ((Caret) widget).getParent().getShell();
        }
        if (widget instanceof DragSource) {
            return ((DragSource) widget).getControl().getShell();
        }
        if (widget instanceof DropTarget) {
            return ((DropTarget) widget).getControl().getShell();
        }
        if (widget instanceof Menu) {
            return ((Menu) widget).getParent().getShell();
        }
        if (widget instanceof ScrollBar) {
            return ((ScrollBar) widget).getParent().getShell();
        }

        return null;
    }

    /**
     * Returns a width hint for a button control.
     * @param button the button
     * @return the width hint
     */
    public static int getButtonWidthHint(Button button) {
        button.setFont(JFaceResources.getDialogFont());
        PixelConverter converter = new PixelConverter(button);
        int widthHint = converter.convertHorizontalDLUsToPixels(IDialogConstants.BUTTON_WIDTH);
        return Math.max(widthHint, button.computeSize(SWT.DEFAULT, SWT.DEFAULT, true).x);
    }

    /**
     * Sets width and height hint for the button control.
     * <b>Note:</b> This is a NOP if the button's layout data is not
     * an instance of <code>GridData</code>.
     *
     * @param button    the button for which to set the dimension hint
     */
    public static void setButtonDimensionHint(Button button) {
        Assert.isNotNull(button);
        Object gd = button.getLayoutData();
        if (gd instanceof GridData) {
            ((GridData) gd).widthHint = getButtonWidthHint(button);
            ((GridData) gd).horizontalAlignment = GridData.FILL;
        }
    }

    public static int getTableHeightHint(Table table, int rows) {
        if (table.getFont().equals(JFaceResources.getDefaultFont())) {
            table.setFont(JFaceResources.getDialogFont());
        }
        int result = table.getItemHeight() * rows + table.getHeaderHeight();
        if (table.getLinesVisible()) {
            result += table.getGridLineWidth() * (rows - 1);
        }
        return result;
    }

    /**
     * Adds an accessibility listener returning the given fixed name.
     *
     * @param control the control to add the accessibility support to
     * @param text the name
     */
    public static void setAccessibilityText(Control control, final String text) {
        control.getAccessible().addAccessibleListener(new AccessibleAdapter() {
            @Override
            public void getName(AccessibleEvent e) {
                if (e.childID == ACC.CHILDID_SELF) {
                    e.result = text;
                }
            }
        });
    }

    /**
     * Sets the default visible item count for {@link Combo}s.
     * Workaround for https://bugs.eclipse.org/bugs/show_bug.cgi?id=7845 .
     *
     * @param combo the combo
     *
     * @see Combo#setVisibleItemCount(int)
     * @see #COMBO_VISIBLE_ITEM_COUNT
     *
     * @since 3.5
     */
    public static void setDefaultVisibleItemCount(Combo combo) {
        combo.setVisibleItemCount(COMBO_VISIBLE_ITEM_COUNT);
    }

    public static GridLayout newLayoutNoMargins(int columns) {
        GridLayout layout = new GridLayout(columns, false);
        layout.marginWidth = 0;
        layout.marginHeight = 0;
        return layout;
    }

    /**
     * Fixes https://bugs.eclipse.org/71765 by setting the background
     * color to {@code SWT.COLOR_WIDGET_BACKGROUND}.
     * <p>
     * Should be applied to all SWT.READ_ONLY Texts in dialogs (or at least those which don't have an SWT.BORDER).
     * Search regex: {@code new Text\([^,]+,[^\)]+SWT\.READ_ONLY}
     * 
     * @param textField the text field
     */
    public static void fixReadonlyTextBackground(Text textField) {
        textField.setBackground(textField.getDisplay().getSystemColor(SWT.COLOR_WIDGET_BACKGROUND));
    }

}