package jrummikub.control;

import java.util.Arrays;
import java.util.Comparator;
import java.util.List;
import java.util.TreeMap;

import jrummikub.model.Stone;
import jrummikub.model.StoneColor;
import jrummikub.util.Pair;

/**
 * A collection of several AI utility methods
 * 
 */
public class AIUtil {

	private AIUtil() {
	}

	/**
	 * Finds sets with a certain total of points
	 * 
	 * @param pointsMissing
	 *          the desired number of points
	 * @param stoneCounts
	 *          the number of each stone
	 * @param jokerCount
	 *          the total number of jokers in the game
	 * @return whether such sets exist
	 */
	@SuppressWarnings("unchecked")
	public static boolean findSetsWithTotalPoints(int pointsMissing,
			TreeMap<Pair<Integer, StoneColor>, Integer> stoneCounts, int jokerCount) {

		if (pointsMissing <= 0) {
			return true;
		}

		stoneCounts = (TreeMap<Pair<Integer, StoneColor>, Integer>) stoneCounts
				.clone();

		for (int value = 13; value >= 1; value--) {
			for (StoneColor color : StoneColor.values()) {
				Pair<Integer, StoneColor> stone = new Pair<Integer, StoneColor>(value,
						color);

				if (stoneCounts.containsKey(stone)) {
					decrementStoneCount(stoneCounts, stone);

					if (findRunsWithTotalPoints(pointsMissing - value, stoneCounts,
							jokerCount, stone, 1))
						return true;
					if (findGroupsWithTotalPoints(pointsMissing - value, stoneCounts,
							jokerCount, stone, 1))
						return true;
				}

				if (jokerCount > 0) {
					if (findRunsWithTotalPoints(pointsMissing - value, stoneCounts,
							jokerCount - 1, stone, 1))
						return true;
					if (findGroupsWithTotalPoints(pointsMissing - value, stoneCounts,
							jokerCount - 1, stone, 1))
						return true;
				}
			}
		}

		return false;
	}

	static boolean findGroupsWithTotalPoints(int pointsMissing,
			TreeMap<Pair<Integer, StoneColor>, Integer> stoneCounts, int jokerCount,
			Pair<Integer, StoneColor> stone, int groupSize) {

		StoneColor nextColor = getNextColor(stone.getSecond());
		Pair<Integer, StoneColor> nextStone = new Pair<Integer, StoneColor>(
				stone.getFirst(), nextColor);

		if (nextColor != null) {
			if (stoneCounts.containsKey(nextStone)) {
				decrementStoneCount(stoneCounts, nextStone);
				if (findGroupsWithTotalPoints(pointsMissing - stone.getFirst(),
						stoneCounts, jokerCount, nextStone, groupSize + 1))
					return true;
				incrementStoneCount(stoneCounts, nextStone);
			}
			if (jokerCount > 0) {
				if (findGroupsWithTotalPoints(pointsMissing - stone.getFirst(),
						stoneCounts, jokerCount - 1, nextStone, groupSize + 1))
					return true;
			}
			if (findGroupsWithTotalPoints(pointsMissing, stoneCounts, jokerCount,
					nextStone, groupSize))
				return true;
		}

		if (groupSize >= 3) {
			if (findSetsWithTotalPoints(pointsMissing, stoneCounts, jokerCount))
				return true;
		}
		return false;
	}

	static boolean findRunsWithTotalPoints(int pointsMissing,
			TreeMap<Pair<Integer, StoneColor>, Integer> stoneCounts, int jokerCount,
			Pair<Integer, StoneColor> stone, int runLength) {

		Pair<Integer, StoneColor> nextStone = null;
		if (stone.getFirst() > 1) {
			int nextValue = stone.getFirst() - 1;
			nextStone = new Pair<Integer, StoneColor>(nextValue, stone.getSecond());

			if (stoneCounts.containsKey(nextStone)) {
				decrementStoneCount(stoneCounts, nextStone);
				if (findRunsWithTotalPoints(pointsMissing - nextValue, stoneCounts,
						jokerCount, nextStone, runLength + 1))
					return true;
				incrementStoneCount(stoneCounts, nextStone);

			}
			if (jokerCount > 0) {
				if (findRunsWithTotalPoints(pointsMissing - nextValue, stoneCounts,
						jokerCount - 1, nextStone, runLength + 1))
					return true;
			}
		}

		if (runLength >= 3) {
			if (findSetsWithTotalPoints(pointsMissing, stoneCounts, jokerCount))
				return true;
		}
		return false;
	}

	static void incrementStoneCount(
			TreeMap<Pair<Integer, StoneColor>, Integer> stones,
			Pair<Integer, StoneColor> stone) {
		if (stones.containsKey(stone)) {
			stones.put(stone, stones.get(stone) + 1);
		} else {
			stones.put(stone, 1);
		}
	}

	static void decrementStoneCount(
			TreeMap<Pair<Integer, StoneColor>, Integer> stones,
			Pair<Integer, StoneColor> stone) {
		int count = stones.get(stone);
		count--;

		if (count == 0) {
			stones.remove(stone);
		} else {
			stones.put(stone, count);
		}
	}

	static StoneColor getNextColor(StoneColor color) {
		int index = Arrays.binarySearch(StoneColor.values(), color) + 1;
		if (index >= StoneColor.values().length) {
			return null;
		}
		return StoneColor.values()[index];
	}

	private final static Comparator<Pair<Integer, StoneColor>> comparator = new Comparator<Pair<Integer, StoneColor>>() {

		@Override
		public int compare(Pair<Integer, StoneColor> o1,
				Pair<Integer, StoneColor> o2) {
			int firstComparison = o1.getFirst().compareTo(o2.getFirst());
			if (firstComparison != 0) {
				return -firstComparison;
			} else {
				return o1.getSecond().compareTo(o2.getSecond());
			}
		}
	};

	/**
	 * Counts the numbers of stones
	 * 
	 * @param stones
	 *          the stones to count
	 * @return the numbers for all stones
	 */
	public static Pair<TreeMap<Pair<Integer, StoneColor>, Integer>, Integer> countStones(
			List<Stone> stones) {
		int jokerCount = 0;
		TreeMap<Pair<Integer, StoneColor>, Integer> stoneCounts = new TreeMap<Pair<Integer, StoneColor>, Integer>(
				comparator);

		for (Stone stone : stones) {
			if (stone.isJoker()) {
				jokerCount++;
			} else {
				Pair<Integer, StoneColor> key = new Pair<Integer, StoneColor>(
						stone.getValue(), stone.getColor());

				incrementStoneCount(stoneCounts, key);
			}
		}
		return new Pair<TreeMap<Pair<Integer, StoneColor>, Integer>, Integer>(
				stoneCounts, jokerCount);
	}
}