package com.onaro.util.jfc.grouping;

/**
 * Copies a value from a row in the group to the group. If the group contains
 * different values, than don't copy.
 */
public class CopySummarizer implements Summarizer {
    /**
     * Default value to display in case the values are not the same
     * Leave null if no value should be set
     */
    private String defaultValue;

    /**
     * The column from which the value is copied and to which it is copied.
     */
    private int copyToColumn;

    /**
     * alterntive column from which the value is copied
     */
    private int copyFromColumn;

    /**
     * Initialize a copier for the given column.
     * @param column the column to copy from and to put the value in
     * @param defaultValue Default value to display in case the values are not the same
     */
    public CopySummarizer(int column, String defaultValue) {
        this(column, column, defaultValue);
    }

    /**
     * Initialize a copier for the given column.
     * Note that there should be summarizers for the copyFromColumn itself or the value of the nodes in complex grouping will be empty 
     * @param copyToColumn index of the column where the value will be included
     * @param copyFromColumn index of the column where the value will copied from
     * @param defaultValue Default value to display in case the values are not the same
     */
    public CopySummarizer(int copyFromColumn, int copyToColumn, String defaultValue) {
        this.copyFromColumn = copyFromColumn;
        this.copyToColumn = copyToColumn;
        this.defaultValue = defaultValue;
    }

    /**
     * Copy the value for the specified column to of the first row to the given
     * node. However, if the children has different values, don't copy any of them.
     * @param node the node
     */
    public void updateSummary(Node node) {
        int childCount = node.getChildCount();
        if (childCount > 0) {
            Object commonValue = getCommonValue(node, childCount);
            if (commonValue != null) {
                node.setValueAt(copyToColumn, commonValue);
            }
        }
    }

    /**
     * If all the children has the same value return it, or the default value if not.
     * Note - if the default value is not set, null will be returned
     */
    private Object getCommonValue(Node node, int childCount) {
        Object valueOfFirstChild = node.getChild(0).getValueAt(copyFromColumn);

        for (int child = 1 ; child < childCount; ++child) {
            Object childValue = node.getChild(child).getValueAt(copyFromColumn);
            if (valueOfFirstChild != childValue) {
                if (valueOfFirstChild == null || childValue == null) return defaultValue;
                if (!valueOfFirstChild.equals(childValue)) return defaultValue;
            }
        }

        return valueOfFirstChild;
    }
}