package com.onaro.util.jfc.grouping;

/**
 * Count the rows in a group and all its descendants for which a given condition
 * is true.
 */
public class ConditionalCountSummarizer implements Summarizer {

    /**
     * The column to put the count of rows in.
     */
    private int column;

    /**
     * The condition that tells if a row should be counted or not.
     */
    private Condition condition;

    /**
     * Initialize a counter for the given column.
     * @param column the column to put the number of rows in
     * @param condition the condition that tells if a row should be counted or not
     */
    public ConditionalCountSummarizer(int column, Condition condition) {
        this.column = column;
        this.condition = condition;
    }

    /**
     * Count the number of rows in the node and all its descendants.
     * @param node the node
     */
    public void updateSummary(Node node) {
        int count = 0;
        for (int i = 0; i < node.getChildCount(); ++i) {
            Node child = node.getChild(i);
            if (child.getChildCount() == 0) {
                if (condition.count(child.getValueAt(column))) ++count;
            } else {
	        Integer childCount = (Integer)child.getValueAt(column);
	        count += childCount.intValue();

            }
        }

	node.setValueAt(column, Integer.valueOf(count));
    }

    /**
     * Defines how a row is evaluated.
     */
    public interface Condition {
        /**
         * Tells if a row with this value should be counted or not.
         * @param value the value to test
         * @return true if a row with such value should be counted
         */
        public boolean count(Object value);
    }

    /**
     * A condition that compares to a given value.
     */
    public static class EqualsCondition implements Condition {

        /**
         * If a row has this value than this condition will tell to count it.
         */
        private Object targetValue;

        /**
         * Initialize the condition for the given value.
         * @param targetValue if a row has this value than this condition will tell to count it
         */
        public EqualsCondition(Object targetValue) {
            this.targetValue = targetValue;
        }

        public boolean count(Object value) {
            if (targetValue == null) {
                return value == null;
            }

            else {
                return targetValue.equals(value);
            }
        }
    }
}