package jrummikub.model;

import java.util.HashMap;
import java.util.Iterator;
import java.util.Map;

import jrummikub.util.Pair;

/**
 * A StoneTray is a collection of positioned objects (for example {@link Stone}s
 * or {@link StoneSet}s.
 * 
 * @param <E>
 *          Type of positioned objects (must implement Sizeable)
 */
public class StoneTray<E extends Sizeable> implements IStoneTray<E> {
	protected HashMap<E, Position> objects = new HashMap<E, Position>();

	/** Possible move directions in case of overlapping Stones/Sets */

	private static enum Direction {
		LEFT, RIGHT, TOP, BOTTOM;
	}

	/*
	 * (non-Javadoc)
	 * 
	 * @see jrummikub.model.IStoneTray#pickUp(jrummikub.model.Position)
	 */
	@Override
	public E pickUp(Position position) {
		for (Map.Entry<E, Position> i : objects.entrySet()) {
			Position currentPosition = i.getValue();
			E currentObject = i.getKey();
			// Tests if position is left of, above ... the current object
			if (position.getX() < currentPosition.getX()) {
				continue;
			}
			if (position.getY() < currentPosition.getY()) {
				continue;
			}
			if (position.getX() > currentPosition.getX() + currentObject.getWidth()) {
				continue;
			}
			if (position.getY() > currentPosition.getY() + currentObject.getHeight()) {
				continue;
			}
			// Position is inside the current object
			objects.remove(i.getKey());
			return currentObject;
		}
		return null;
	}

	/*
	 * (non-Javadoc)
	 * 
	 * @see jrummikub.model.IStoneTray#drop(E, jrummikub.model.Position)
	 */
	@Override
	public void drop(E object, Position position) {
		if (object != null) {
			drop(object, position, null);
		}
	}

	@SuppressWarnings("unchecked")
	private void drop(E object, Position position, Direction direction) {
		for (Map.Entry<E, Position> i : ((Map<E, Position>) objects.clone())
				.entrySet()) {
			Position currentPosition = i.getValue();
			E currentObject = i.getKey();
			if (!objectsOverlap(object, position, currentObject, currentPosition)) {
				continue;
			}
			// Object would be placed inside the current object
			if (direction == null) {
				direction = getMoveDirection(object, position, i);
			}
			Position newPosition = null;
			// Move object to avoid overlap
			switch (direction) {
			case TOP:
				newPosition = new Position(currentPosition.getX(), position.getY()
						- currentObject.getHeight());
				break;
			case BOTTOM:
				newPosition = new Position(currentPosition.getX(), position.getY()
						+ object.getHeight());
				break;
			case LEFT:
				newPosition = new Position(position.getX() - currentObject.getWidth(),
						currentPosition.getY());
				break;
			case RIGHT:
				newPosition = new Position(position.getX() + object.getWidth(),
						currentPosition.getY());
				break;
			}

			objects.remove(i.getKey());
			drop(currentObject, newPosition, direction);
		}
		objects.put(object, position);
	}

	/** Tests whether two objects overlap **/
	private boolean objectsOverlap(E object1, Position position1, E object2,
			Position position2) {
		// Tests if position is left of, above ... the current object
		if (position1.getX() + object1.getWidth() <= position2.getX()) {
			return false;
		}
		if (position1.getY() + object1.getHeight() <= position2.getY()) {
			return false;
		}
		if (position1.getX() >= position2.getX() + object2.getWidth()) {
			return false;
		}
		if (position1.getY() >= position2.getY() + object2.getHeight()) {
			return false;
		}
		return true;
	}

	private Direction getMoveDirection(E object, Position position,
			Map.Entry<E, Position> blocking) {
		boolean isVertical = getMoveOrientationn(object, position, blocking);
		float objectMidpointX = position.getX() + object.getWidth() / 2;
		float objectMidpointY = position.getY() + object.getHeight() / 2;
		float blockingMidpointX = blocking.getValue().getX()
				+ blocking.getKey().getWidth() / 2;
		float blockingMidpointY = blocking.getValue().getY()
				+ blocking.getKey().getHeight() / 2;
		if (isVertical) {
			if (objectMidpointY < blockingMidpointY) {
				return Direction.BOTTOM;
			} else {
				return Direction.TOP;
			}
		} else {
			if (objectMidpointX < blockingMidpointX) {
				return Direction.RIGHT;
			} else {
				return Direction.LEFT;
			}
		}
	}

	private boolean getMoveOrientationn(E object, Position position,
			Map.Entry<E, Position> blocking) {
		float objectRight = position.getX() + object.getWidth();
		float blockingRight = blocking.getValue().getX()
				+ blocking.getKey().getWidth();
		float overlapRight = Math.min(objectRight, blockingRight);
		float overlapLeft = Math.max(position.getX(), blocking.getValue().getX());
		float overlapX = overlapRight - overlapLeft;
		float objectBottom = position.getY() + object.getHeight();
		float blockingBottom = blocking.getValue().getY()
				+ blocking.getKey().getHeight();
		float overlapBottom = Math.min(objectBottom, blockingBottom);
		float overlapTop = Math.max(position.getY(), blocking.getValue().getY());
		float overlapY = overlapBottom - overlapTop;
		// vertical or horizontal Shift
		// TODO magic factor
		return overlapX > overlapY;
	}

	/*
	 * (non-Javadoc)
	 * 
	 * @see jrummikub.model.IStoneTray#getPosition(E)
	 */
	@Override
	public Position getPosition(E object) {
		return objects.get(object);
	}

	@Override
	public Iterator<Pair<E, Position>> iterator() {
		final Iterator<Map.Entry<E, Position>> entryIterator = objects.entrySet()
				.iterator();
		return new Iterator<Pair<E, Position>>() {
			Iterator<Map.Entry<E, Position>> iterator = entryIterator;

			@Override
			public boolean hasNext() {
				return iterator.hasNext();
			}

			@Override
			public Pair<E, Position> next() {
				Map.Entry<E, Position> entry = iterator.next();
				return new Pair<E, Position>(entry.getKey(), entry.getValue());
			}

			@Override
			public void remove() {
				iterator.remove();
			}

		};
	}

	/*
	 * (non-Javadoc)
	 * 
	 * @see jrummikub.model.IStoneTray#pickUp(E)
	 */
	@Override
	public void pickUp(E object) {
		objects.remove(object);
	}

	/*
	 * (non-Javadoc)
	 * 
	 * @see jrummikub.model.IStoneTray#clone()
	 */
	@SuppressWarnings("unchecked")
	@Override
	public IStoneTray<E> clone() {
		StoneTray<E> copy = new StoneTray<E>();
		copy.objects = (HashMap<E, Position>) objects.clone();
		return copy;
	}

}