package com.onaro.util.jfc.grouping;

import java.util.HashSet;
import java.util.Set;

import org.apache.commons.lang3.StringUtils;

/**
 * Count the rows in a group and all its descendants making sure that they are unique.
 */
public class CountUniqueSummarizer implements Summarizer {

    /**
     * The column to put the count of rows in.
     */
    private final int column;
    
    /**
     * Column value used to determine uniqueness
     */
    private final int identifierColumn;

    /**
     * Initialize a counter for the given column.
     * @param column the column to put the number of rows in
     * @param identifierColumn the unique identifier column for the given row
     */
    public CountUniqueSummarizer(int column, int identifierColumn) {
        this.column = column;
        this.identifierColumn = identifierColumn;
    }

    /**
     * Count the number of rows in the node and all its descendants.
     * @param node the node
     */
    public void updateSummary(Node node) {
        Object value = null;
        Set<Object> valueSet = new HashSet<Object>();
        for (int i = 0; i < node.getChildCount(); ++i) {
            Node child = node.getChild(i);
            value = child.getValueAt(column);
            
            if ((value instanceof CountValue)) {
                valueSet.addAll(((CountValue)value).valuesSet);
            } else {
                Object identifier = child.getValueAt(identifierColumn);
                valueSet.add(identifier);
            }
        }

        if (!valueSet.isEmpty()) {
            if (valueSet.size() == 1) {
                node.setValueAt(column, new CountValue(valueSet, value));
            } else  {
                node.setValueAt(column, new CountValue(valueSet));
            }
        }
    }

    /**
     * Allows to distinguish values generated by the summarizer from the values that it
     * is counting.
     */
    private static class CountValue implements Comparable<CountValue> {
        private final Set<Object> valuesSet;
        private final String display;
        
        public CountValue(Set<Object> valuesSet) {
            this.valuesSet = valuesSet;
            this.display = new StringBuilder().append('(').append(valuesSet.size()).append(')').toString();
        }
        
        public CountValue(Set<Object> valuesSet, Object singleValue) {
            this.valuesSet = valuesSet;
            this.display = (singleValue == null) ? StringUtils.EMPTY : singleValue.toString();
        }

        public boolean equals(Object o) {
            if (this == o) return true;
            if (!(o instanceof CountValue)) return false;

            final CountValue countValue = (CountValue) o;

            if (display != null ? !display.equals(countValue.display) : countValue.display != null) return false;

            return true;
        }

        public int hashCode() {
            return (display != null ? display.hashCode() : 0);
        }

        public String toString() {
            return display;
        }

        public int compareTo(CountValue o) {
            if (o == null) return 1;
            return display.compareTo(o.toString());
        }
    }
}