/*******************************************************************************
 * Copyright (c) 2012 Original authors 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:
 *     Original authors and others - initial API and implementation
 ******************************************************************************/
package org.eclipse.nebula.widgets.nattable.extension.builder.util;

import java.util.HashMap;
import java.util.HashSet;
import java.util.Map;
import java.util.Set;

import org.eclipse.nebula.widgets.nattable.extension.builder.model.TableColumn;
import org.eclipse.nebula.widgets.nattable.group.ColumnGroupModel;

public class ColumnGroupModelAssembler {

    public static ColumnGroupModel setupColumnGroups(TableColumn[] columnProps) {
        ColumnGroupModel columnGroupModel;
        columnGroupModel = new ColumnGroupModel();
        Map<String, Set<Integer>> columnGroupToColumnIndexesMap = new HashMap<String, Set<Integer>>();

        for (int columnIndex = 0; columnIndex < columnProps.length; columnIndex++) {
            String columnGroupName = columnProps[columnIndex].groupName;

            // Column if part of a group
            if (columnGroupName != null) {
                Set<Integer> columnGroupIndexes = columnGroupToColumnIndexesMap
                        .get(columnGroupName);
                // Create an entry in the map for the group
                if (columnGroupIndexes == null) {
                    columnGroupIndexes = new HashSet<Integer>();
                    columnGroupToColumnIndexesMap.put(columnGroupName,
                            columnGroupIndexes);
                }
                // Add to map
                columnGroupIndexes.add(columnIndex);
            }
        }

        // Transfer the map created to the model
        for (String columnGroupName : columnGroupToColumnIndexesMap.keySet()) {
            Set<Integer> columnIndexes = columnGroupToColumnIndexesMap
                    .get(columnGroupName);
            int[] intColumnIndexes = new int[columnIndexes.size()];
            int i = 0;
            for (Integer columnIndex : columnIndexes) {
                intColumnIndexes[i] = columnIndex;
                i++;
            }
            columnGroupModel.addColumnsIndexesToGroup(columnGroupName,
                    intColumnIndexes);
        }

        return columnGroupModel;
    }
}