/*******************************************************************************
 * Copyright (c) 2012, 2020 Original authors and others.
 *
 * This program and the accompanying materials are made
 * available under the terms of the Eclipse Public License 2.0
 * which is available at https://www.eclipse.org/legal/epl-2.0/
 *
 * SPDX-License-Identifier: EPL-2.0
 *
 * Contributors:
 *     Original authors and others - initial API and implementation
 *     Dirk Fauth <dirk.fauth@googlemail.com> - Added scaling
 ******************************************************************************/
package org.eclipse.nebula.widgets.nattable.painter.layer;

import org.eclipse.nebula.widgets.nattable.NatTable;
import org.eclipse.nebula.widgets.nattable.config.CellConfigAttributes;
import org.eclipse.nebula.widgets.nattable.config.IConfigRegistry;
import org.eclipse.nebula.widgets.nattable.layer.ILayer;
import org.eclipse.nebula.widgets.nattable.style.DisplayMode;
import org.eclipse.nebula.widgets.nattable.util.GUIHelper;
import org.eclipse.swt.graphics.Color;
import org.eclipse.swt.graphics.GC;
import org.eclipse.swt.graphics.Rectangle;

/**
 * Specialization of NatLayerPainter that fills the background with grid lines
 * to create the same look and feel as native table controls. It is possible to
 * specify the grid line color directly or via ConfigRegistry
 * {@link CellConfigAttributes#GRID_LINE_COLOR}, where the ConfigRegistry entry
 * will win over direct configuration.
 * <p>
 * If there should be several fake rows rendered, you need to set the default
 * row height that should be used for rendering the fake row lines. Otherwise
 * this will be skipped and only the column lines will be rendered to the
 * bottom.
 * </p>
 */
public class NatGridLayerPainter extends NatLayerPainter {

    private final Color gridColor;

    private int defaultRowHeight = 0;

    /**
     * @param natTable
     *            The NatTable instance for which the NatGridLayerPainter should
     *            render the background.
     */
    public NatGridLayerPainter(NatTable natTable) {
        this(natTable, GUIHelper.COLOR_GRAY);
    }

    /**
     * @param natTable
     *            The NatTable instance for which the NatGridLayerPainter should
     *            render the background.
     * @param gridColor
     *            The Color that should be used to render the grid lines. Note
     *            that an entry for {@link CellConfigAttributes#GRID_LINE_COLOR}
     *            will override this value at runtime.
     */
    public NatGridLayerPainter(NatTable natTable, Color gridColor) {
        super(natTable);
        this.gridColor = gridColor;
    }

    /**
     * @param natTable
     *            The NatTable instance for which the NatGridLayerPainter should
     *            render the background.
     * @param defaultRowHeight
     *            The row height that should be used to render fake rows to the
     *            bottom. Setting a value of 0 will avoid rendering fake row
     *            lines.
     */
    public NatGridLayerPainter(NatTable natTable, int defaultRowHeight) {
        this(natTable, GUIHelper.COLOR_GRAY, defaultRowHeight);
    }

    /**
     * @param natTable
     *            The NatTable instance for which the NatGridLayerPainter should
     *            render the background.
     * @param gridColor
     *            The Color that should be used to render the grid lines. Note
     *            that an entry for {@link CellConfigAttributes#GRID_LINE_COLOR}
     *            will override this value at runtime.
     * @param defaultRowHeight
     *            The row height that should be used to render fake rows to the
     *            bottom. Setting a value of 0 will avoid rendering fake row
     *            lines.
     */
    public NatGridLayerPainter(NatTable natTable, Color gridColor, int defaultRowHeight) {
        super(natTable);
        this.gridColor = gridColor;
        setDefaultRowHeight(defaultRowHeight);
    }

    @Override
    protected void paintBackground(ILayer natLayer, GC gc, int xOffset,
            int yOffset, Rectangle rectangle, IConfigRegistry configRegistry) {
        super.paintBackground(natLayer, gc, xOffset, yOffset, rectangle, configRegistry);

        Color gColor = configRegistry.getConfigAttribute(
                CellConfigAttributes.GRID_LINE_COLOR, DisplayMode.NORMAL);
        gc.setForeground(gColor != null ? gColor : this.gridColor);

        drawHorizontalLines(natLayer, gc, rectangle);
        drawVerticalLines(natLayer, gc, rectangle);
    }

    private void drawHorizontalLines(ILayer natLayer, GC gc, Rectangle rectangle) {
        int endX = rectangle.x + rectangle.width;

        int rowPositionByY = natLayer.getRowPositionByY(rectangle.y + rectangle.height);
        int maxRowPosition = rowPositionByY > 0 ? Math.min(
                natLayer.getRowCount(), rowPositionByY) : natLayer.getRowCount();

        int y = 0;
        for (int rowPosition = natLayer.getRowPositionByY(rectangle.y); rowPosition < maxRowPosition; rowPosition++) {
            y = natLayer.getStartYOfRowPosition(rowPosition)
                    + natLayer.getRowHeightByPosition(rowPosition) - 1;
            gc.drawLine(rectangle.x, y, endX, y);
        }

        // render fake row lines to the bottom
        if (this.defaultRowHeight > 0) {
            int endY = rectangle.y + rectangle.height;
            while (y < endY) {
                y += this.defaultRowHeight;
                gc.drawLine(rectangle.x, y, endX, y);
            }
        }
    }

    private void drawVerticalLines(ILayer natLayer, GC gc, Rectangle rectangle) {
        int endY = rectangle.y + rectangle.height;

        int columnPositionByX = natLayer.getColumnPositionByX(rectangle.x + rectangle.width);
        int maxColumnPosition = columnPositionByX > 0 ? Math.min(
                natLayer.getColumnCount(), columnPositionByX) : natLayer.getColumnCount();
        for (int columnPosition = natLayer.getColumnPositionByX(rectangle.x); columnPosition < maxColumnPosition; columnPosition++) {
            int x = natLayer.getStartXOfColumnPosition(columnPosition)
                    + natLayer.getColumnWidthByPosition(columnPosition) - 1;
            gc.drawLine(x, rectangle.y, x, endY);
        }
    }

    /**
     *
     * @return The currently used height that is used to render fake rows. The
     *         pixel value is locally stored scaled.
     */
    public int getDefaultRowHeight() {
        return this.defaultRowHeight;
    }

    /**
     *
     * @param defaultRowHeight
     *            The value that should be used to render fake rows. The value
     *            needs to be given in pixels, as the scaling calculation is
     *            done in here.
     */
    public void setDefaultRowHeight(int defaultRowHeight) {
        this.defaultRowHeight = GUIHelper.convertVerticalPixelToDpi(defaultRowHeight, this.natTable.getConfigRegistry());
    }

}