package org.pdd.util;

import java.util.ArrayList;
import java.util.Map;

import com.fasterxml.jackson.core.JsonProcessingException;
import com.fasterxml.jackson.databind.ObjectMapper;
import com.google.common.collect.MapDifference;
import com.google.common.collect.MapDifference.ValueDifference;

public class Differences {
	String key = "";
	Object left = null;
	Object right = null;

	public Object getLeft() {
		return left;
	}

	public void setLeft(Object left) {
		this.left = left;
	}

	public Object getRight() {
		return right;
	}

	public void setRight(Object right) {
		this.right = right;
	}

	public String getKey() {
		return key;
	}

	public void setKey(String key) {
		this.key = key;
	}

	/**
	 * Compare the left side map against the right side map and return a json
	 * object containing the differences in the values and the values that are
	 * provided on the left side but not provided on the right side.
	 * 
	 * This is intended to be used in comparing an input set of values (the left
	 * side) against a stored set of values (the right side), with the intention
	 * of updating the stored values with the updated and/or new values from the
	 * input.
	 * 
	 * @param left
	 *            the input values
	 * @param right
	 *            the stored values
	 * @return A JSON formatted string of the update values
	 */
	public static String arrayOfDifferences(Map left,
			Map right) {
		ArrayList differences = new ArrayList();

		MapDifference valueDifferences = com.google.common.collect.Maps
				.difference(left, right);
		Map<String, ValueDifference> diff = valueDifferences
				.entriesDiffering();
		for (String key : diff.keySet()) {
			ValueDifference values = diff.get(key);
			Differences difference = new Differences();
			difference.setKey(key);
			difference.setLeft(values.leftValue());
			difference.setRight(values.rightValue());
			differences.add(difference);
		}
		Map onlyOnLeft = valueDifferences.entriesOnlyOnLeft();
		for (String key : onlyOnLeft.keySet()) {
			Differences difference = new Differences();
			difference.setKey(key);
			difference.setLeft(onlyOnLeft.get(key));
			difference.setRight(null);
			differences.add(difference);
		}
		ObjectMapper mapper = new ObjectMapper();
		try {
			return (String) mapper.writeValueAsString(differences);
		} catch (JsonProcessingException e) {
			e.printStackTrace();
			return "[]";
		}
	}
}