package eg.edu.alexu.csd.filestructure.avl;

public class AVLTree<T extends Comparable<T>> implements IAVLTree<T> {
	private Node<T> root;

	public AVLTree() {
		root = new Node<T>(null, null);
	}

	@Override
	public INode<T> getTree() {
		return root;
	}

	@Override
	public void insert(T key) {
		Node<T> cursor = null; // y
		Node<T> current = root; // x
		Node<T> newNode = new Node<T>(key, null); // z
		while (current != null && current.getValue() != null) {
			cursor = current;
			try {
				if (newNode.getValue().compareTo(current.getValue()) < 0) {
					current = (Node<T>) current.getLeftChild();
				} else if (newNode.getValue().compareTo(current.getValue()) > 0) {
					current = (Node<T>) current.getRightChild();
				}
			} catch (NullPointerException ex) {
				break;
			}
		}

		newNode.setParent(cursor);
		if (cursor == null) {
			root = newNode;
		} else if (newNode.getValue().compareTo(cursor.getValue()) < 0) {
			cursor.setLeftChild(newNode);
			newNode.setParent(cursor);
			reBalance((Node<T>) cursor.getLeftChild());
		} else if (newNode.getValue().compareTo(cursor.getValue()) > 0) {
			cursor.setRightChild(newNode);
			newNode.setParent(cursor);
			reBalance((Node<T>) cursor.getRightChild());
		}

	}

	@Override
	public boolean delete(T key) {
		if (!search(key))
			return false;

		Node<T> toBeDeleted = searchReturnsNode(key);
		if (!toBeDeleted.hasLeftChild()) {
			this.transplant(toBeDeleted, (Node<T>) toBeDeleted.getRightChild());
		} else if (!toBeDeleted.hasRightChild()) {
			this.transplant(toBeDeleted, (Node<T>) toBeDeleted.getLeftChild());
		} else {
			Node<T> node = minimum((Node<T>) toBeDeleted.getRightChild());
			this.transplant(toBeDeleted, node);
		}

		return true;
	}

	@Override
	public boolean search(T key) {
		return this.search(key, root);
	}

	public Node<T> getNodes() {
		return this.root;
	}

	public void inOrder(Node<T> root) {

		if (root != null) {
			inOrder((Node<T>) root.getLeftChild());
			System.out.println(root.getValue());
			inOrder((Node<T>) root.getRightChild());
		}
	}

	@Override
	public int height() {
		if (root.getValue() == null)
			return -1;
		return Math.max(root.getLeftHeight(), root.getLeftHeight());
	}

	private void reBalance(Node<T> t) {
		Node<T> parent = null; // up
		Node<T> check = t;
		Node<T> child = t;
		while (check.hasParent()) {
			child = check;
			check = (Node<T>) check.getParent();
			int balanceFactor = check.getBalanceFactor();
			if (balanceFactor == 2) {
				if (check.getParent() != null)
					parent = (Node<T>) check.getParent();
				if (child.getBalanceFactor() == 1) {
					leftLeft(check, child, parent);
					break;
				} else if (child.getBalanceFactor() == -1) {
					leftRight(check, child, parent);
					break;
				}
			} else if (balanceFactor == -2) {

				if (check.getParent() != null)
					parent = (Node<T>) check.getParent();
				if (child.getBalanceFactor() == 1) {
					rightLeft(check, child, parent);
					break;
				} else if (child.getBalanceFactor() == -1) {
					rightRight(check, child, parent);
					break;

				}
			}
		}
	}

	private void rightRight(Node<T> check, Node<T> child, Node<T> parent) {
		boolean right = false, noParent = false;
		check.setRightChild(null);
		child.setParent(null);
		if (parent == null)
			noParent = true;
		else if (parent.getValue().compareTo(check.getValue()) < 0)
			right = true;

		if (!noParent) {
			if (right)
				parent.setRightChild(child);
			else
				parent.setLeftChild(child);
			child.setParent(parent);
		}
		if (child.hasLeftChild()) {
			((Node<T>) child.getLeftChild()).setParent(check);
			check.setRightChild((Node<T>) child.getLeftChild());
		}
		child.setLeftChild(check);
		check.setParent(child);
		if (check == root)
			root = child;
	}

	private void rightLeft(Node<T> check, Node<T> child, Node<T> parent) {
		Node<T> n = (Node<T>) child.getLeftChild();
		boolean right = false, noParent = false;
		check.setRightChild(null);
		child.setLeftChild(null);
		if (parent == null)
			noParent = true;
		else if (parent.getValue().compareTo(check.getValue()) < 0)
			right = true;

		if (!noParent) {
			if (right)
				parent.setRightChild(n);
			else
				parent.setLeftChild(n);
			n.setParent(parent);
		}

		if (n.hasRightChild()) {
			((Node<T>) n.getRightChild()).setParent(child);
			child.setLeftChild((Node<T>) n.getRightChild());
		}
		n.setRightChild(child);
		child.setParent(n);
		if (n.hasLeftChild()) {
			((Node<T>) n.getLeftChild()).setParent(check);
			check.setRightChild((Node<T>) n.getLeftChild());
		}
		n.setLeftChild(check);
		check.setParent(n);
		if (check == root)
			root = n;

	}

	private void leftRight(Node<T> check, Node<T> child, Node<T> parent) {
		Node<T> n = (Node<T>) child.getRightChild();
		boolean right = false, noParent = false;
		check.setLeftChild(null);
		child.setRightChild(null);
		if (parent == null)
			noParent = true;
		else if (parent.getValue().compareTo(check.getValue()) < 0)
			right = true;

		if (!noParent) {
			if (right)
				parent.setRightChild(n);
			else
				parent.setLeftChild(n);
			n.setParent(parent);
		}

		if (n.hasRightChild()) {
			((Node<T>) n.getRightChild()).setParent(check);
			check.setLeftChild((Node<T>) n.getRightChild());
		}
		n.setRightChild(check);
		check.setParent(n);
		if (n.hasLeftChild()) {
			((Node<T>) n.getLeftChild()).setParent(child);
			child.setRightChild((Node<T>) n.getLeftChild());
		}
		n.setLeftChild(child);
		child.setParent(n);
		if (check == root)
			root = n;

	}

	private void leftLeft(Node<T> check, Node<T> child, Node<T> parent) {
		boolean right = false, noParent = false;
		check.setLeftChild(null);
		child.setParent(null);
		if (parent == null)
			noParent = true;
		else if (parent.getValue().compareTo(check.getValue()) < 0)
			right = true;

		if (!noParent) {
			if (right)
				parent.setRightChild(child);
			else
				parent.setLeftChild(child);
			child.setParent(parent);
		}
		if (child.hasRightChild()) {
			((Node<T>) child.getRightChild()).setParent(check);
			check.setLeftChild((Node<T>) child.getRightChild());

		}
		child.setRightChild(check);
		check.setParent(child);
		if (check == root)
			root = child;
	}

	private Node<T> minimum(Node<T> node) {
		if (!node.hasLeftChild())
			return node;
		return minimum((Node<T>) node.getLeftChild());

	}

	private void transplant(Node<T> toBeRemoved, Node<T> toBePlanted) {
		Node<T> toBeRemovedParent = (Node<T>) toBeRemoved.getParent();
		if (!toBeRemoved.hasParent()) {
			root = toBePlanted;
		} else if (toBeRemoved.equals(toBeRemovedParent.getLeftChild())) {
			toBeRemovedParent.setLeftChild(toBePlanted);
		} else {
			toBeRemovedParent.setRightChild(toBePlanted);
		}
		toBeRemoved.setParent(null);
		if (toBePlanted != null) {
			Node<T> toBePlantedParent = (Node<T>) toBePlanted.getParent();

			if (toBePlantedParent.hasLeftChild() && toBePlantedParent.getLeftChild().equals(toBePlanted))
				toBePlantedParent.setLeftChild(null);
			else if (toBePlantedParent.hasRightChild())
				toBePlantedParent.setRightChild(null);
			toBePlanted.setParent(toBeRemovedParent);
			if (toBeRemoved.hasLeftChild()) {
				Node<T> leftOfToBeRemoved = ((Node<T>) toBeRemoved.getLeftChild());
				toBePlanted.setLeftChild(leftOfToBeRemoved);
				leftOfToBeRemoved.setParent(toBePlanted);
			}
			if (toBeRemoved.hasRightChild()) {
				Node<T> rightOfToBeRemoved = ((Node<T>) toBeRemoved.getRightChild());
				toBePlanted.setRightChild(rightOfToBeRemoved);
				rightOfToBeRemoved.setParent(toBePlanted);
			}
		}

	}

	private Node<T> searchReturnsNode(T key, Node<T> node) {
		if (key.compareTo(node.getValue()) == 0)
			return node;
		if (key.compareTo(node.getValue()) < 0)
			return searchReturnsNode(key, (Node<T>) node.getLeftChild());
		else
			return searchReturnsNode(key, (Node<T>) node.getRightChild());

	}

	private Node<T> searchReturnsNode(T key) {
		return this.searchReturnsNode(key, root);
	}

	private boolean search(T key, Node<T> node) {
		if (node != null) {
			if (key.compareTo(node.getValue()) == 0)
				return true;
			if (key.compareTo(node.getValue()) < 0)
				return search(key, (Node<T>) node.getLeftChild());
			else
				return search(key, (Node<T>) node.getRightChild());
		}
		return false;

	}

}