package jrummikub.model;

import java.util.ArrayList;
import java.util.Iterator;
import java.util.List;

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
		Iterable<Pair<E, Position>> {
	protected ArrayList<Pair<E, Position>> objects = new ArrayList<Pair<E, Position>>();

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

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

	/**
	 * Removes object from tray and returns it
	 * 
	 * @param position
	 *            position of the object that will be removed
	 * @return the picked up stone
	 */
	public E pickUp(Position position) {
		for (Pair<E, Position> i : objects) {
			Position currentPosition = i.getSecond();
			E currentObject = i.getFirst();
			// 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);
			return currentObject;
		}
		return null;
	}

	/**
	 * Adds object to the tray
	 * 
	 * @param object
	 *            object to add to Hand
	 * @param position
	 *            {@link Position} to put the object
	 */
	public void drop(E object, Position position) {
		drop(object, position, null);
	}

	@SuppressWarnings("unchecked")
	private void drop(E object, Position position, Direction direction) {
		for (Pair<E, Position> i : (List<Pair<E, Position>>)objects.clone()) {
			Position currentPosition = i.getSecond();
			E currentObject = i.getFirst();
			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;
			// TODO dinge bewegen
			switch (direction) {
			case TOP:
				newPosition = new Position(i.getSecond().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);
			drop(currentObject, newPosition, direction);
		}
		objects.add(new Pair<E, Position>(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,
			Pair<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.getSecond().getX()
				+ blocking.getFirst().getWidth() / 2;
		float blockingMidpointY = blocking.getSecond().getY()
				+ blocking.getFirst().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,
			Pair<E, Position> blocking) {
		float objectRight = position.getX() + object.getWidth();
		float blockingRight = blocking.getSecond().getX()
				+ blocking.getFirst().getWidth();
		float overlapRight = Math.min(objectRight, blockingRight);
		float overlapLeft = Math.max(position.getX(), blocking.getSecond()
				.getX());
		float overlapX = overlapRight - overlapLeft;
		float objectBottom = position.getY() + object.getHeight();
		float blockingBottom = blocking.getSecond().getY()
				+ blocking.getFirst().getHeight();
		float overlapBottom = Math.min(objectBottom, blockingBottom);
		float overlapTop = Math.max(position.getY(), blocking.getSecond()
				.getY());
		float overlapY = overlapBottom - overlapTop;
		// vertical or horizontal Shift
		// TODO magic factor
		return overlapX > overlapY;
	}

	/**
	 * Returns the position of an object that is already on the tray
	 * 
	 * @param object
	 *            object whose position is requested
	 * @return position of the object or null when the object is not on the tray
	 */
	public Position getPosition(E object) {
		for (Pair<E, Position> i : objects) {
			if (object.equals(i.getFirst())) {
				return i.getSecond();
			}
		}
		return null;
	}

	@Override
	public Iterator<Pair<E, Position>> iterator() {
		return objects.iterator();
	}

}