/*******************************************************************************
 * 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.ui;

import java.util.ArrayList;
import java.util.List;

import org.eclipse.core.runtime.Assert;
import org.eclipse.jface.viewers.ColumnLayoutData;
import org.eclipse.jface.viewers.ColumnPixelData;
import org.eclipse.jface.viewers.ColumnWeightData;
import org.eclipse.swt.SWT;
import org.eclipse.swt.events.ControlAdapter;
import org.eclipse.swt.events.ControlEvent;
import org.eclipse.swt.graphics.Point;
import org.eclipse.swt.graphics.Rectangle;
import org.eclipse.swt.widgets.Composite;
import org.eclipse.swt.widgets.Table;
import org.eclipse.swt.widgets.TableColumn;

/**
 * A special composite to layout columns inside a table. The composite is needed since we have
 * to layout the columns "before" the actual table gets layouted. Hence we can't use a normal
 * layout manager.
 * <p>
 * XXX: Should switch to use {@link org.eclipse.jface.layout.TableColumnLayout}.
 * </p>
 */
public class TableLayoutComposite extends Composite {

    /**
     * The number of extra pixels taken as horizontal trim by the table column.
     * To ensure there are N pixels available for the content of the column,
     * assign N+COLUMN_TRIM for the column width.
     * <p>
     * XXX: Should either switch to use {@link org.eclipse.jface.layout.TableColumnLayout} or get API from JFace or SWT, see https://bugs.eclipse.org/bugs/show_bug.cgi?id=218483
     * </p>
     *
     * @since 3.1
     */
    private static int COLUMN_TRIM;

    static {
        String platform = SWT.getPlatform();
        if ("win32".equals(platform)) {
            COLUMN_TRIM = 4;
        } else if ("carbon".equals(platform)) {
            COLUMN_TRIM = 24;
        } else {
            COLUMN_TRIM = 3;
        }
    }

    private List<ColumnLayoutData> columns = new ArrayList<ColumnLayoutData>();

    /**
     * Creates a new <code>TableLayoutComposite</code>.
     *
     * @param parent the parent composite
     * @param style the SWT style
     */
    public TableLayoutComposite(Composite parent, int style) {
        super(parent, style);
        addControlListener(new ControlAdapter() {
            @Override
            public void controlResized(ControlEvent e) {
                Rectangle area = getClientArea();
                Table table = (Table) getChildren()[0];
                Point preferredSize = computeTableSize(table);
                int width = area.width - 2 * table.getBorderWidth();
                if (preferredSize.y > area.height) {
                    // Subtract the scrollbar width from the total column width
                    // if a vertical scrollbar will be required
                    Point vBarSize = table.getVerticalBar().getSize();
                    width -= vBarSize.x;
                }
                layoutTable(table, width, area, table.getSize().x < area.width);
            }
        });
    }

    /**
     * Adds a new column of data to this table layout.
     *
     * @param data the column layout data
     */
    public void addColumnData(ColumnLayoutData data) {
        columns.add(data);
    }

    //---- Helpers -------------------------------------------------------------------------------------

    private Point computeTableSize(Table table) {
        Point result = table.computeSize(SWT.DEFAULT, SWT.DEFAULT);

        int width = 0;
        int size = columns.size();
        for (int i = 0; i < size; ++i) {
            ColumnLayoutData layoutData = columns.get(i);
            if (layoutData instanceof ColumnPixelData) {
                ColumnPixelData col = (ColumnPixelData) layoutData;
                width += col.width;
                if (col.addTrim) {
                    width += COLUMN_TRIM;
                }
            } else if (layoutData instanceof ColumnWeightData) {
                ColumnWeightData col = (ColumnWeightData) layoutData;
                width += col.minimumWidth;
            } else {
                Assert.isTrue(false, "Unknown column layout data"); //$NON-NLS-1$
            }
        }
        if (width > result.x) {
            result.x = width;
        }
        return result;
    }

    private void layoutTable(Table table, int width, Rectangle area, boolean increase) {
        // XXX: Layout is being called with an invalid value the first time
        // it is being called on Linux. This method resets the
        // Layout to null so we make sure we run it only when
        // the value is OK.
        if (width <= 1) {
            return;
        }

        TableColumn[] tableColumns = table.getColumns();
        int size = Math.min(columns.size(), tableColumns.length);
        int[] widths = new int[size];
        int fixedWidth = 0;
        int numberOfWeightColumns = 0;
        int totalWeight = 0;

        // First calc space occupied by fixed columns
        for (int i = 0; i < size; i++) {
            ColumnLayoutData col = columns.get(i);
            if (col instanceof ColumnPixelData) {
                ColumnPixelData cpd = (ColumnPixelData) col;
                int pixels = cpd.width;
                if (cpd.addTrim) {
                    pixels += COLUMN_TRIM;
                }
                widths[i] = pixels;
                fixedWidth += pixels;
            } else if (col instanceof ColumnWeightData) {
                ColumnWeightData cw = (ColumnWeightData) col;
                numberOfWeightColumns++;
                // first time, use the weight specified by the column data, otherwise use the actual width as the weight
                // int weight = firstTime ? cw.weight : tableColumns[i].getWidth();
                int weight = cw.weight;
                totalWeight += weight;
            } else {
                Assert.isTrue(false, "Unknown column layout data"); //$NON-NLS-1$
            }
        }

        // Do we have columns that have a weight
        if (numberOfWeightColumns > 0) {
            // Now distribute the rest to the columns with weight.
            int rest = width - fixedWidth;
            int totalDistributed = 0;
            for (int i = 0; i < size; ++i) {
                ColumnLayoutData col = columns.get(i);
                if (col instanceof ColumnWeightData) {
                    ColumnWeightData cw = (ColumnWeightData) col;
                    // calculate weight as above
                    // int weight = firstTime ? cw.weight : tableColumns[i].getWidth();
                    int weight = cw.weight;
                    int pixels = totalWeight == 0 ? 0 : weight * rest / totalWeight;
                    if (pixels < cw.minimumWidth) {
                        pixels = cw.minimumWidth;
                    }
                    totalDistributed += pixels;
                    widths[i] = pixels;
                }
            }

            // Distribute any remaining pixels to columns with weight.
            int diff = rest - totalDistributed;
            for (int i = 0; diff > 0; ++i) {
                if (i == size) {
                    i = 0;
                }
                ColumnLayoutData col = columns.get(i);
                if (col instanceof ColumnWeightData) {
                    ++widths[i];
                    --diff;
                }
            }
        }

        if (increase) {
            table.setSize(area.width, area.height);
        }
        for (int i = 0; i < size; i++) {
            tableColumns[i].setWidth(widths[i]);
        }
        if (!increase) {
            table.setSize(area.width, area.height);
        }
    }
}