/**
 * \file
 *
 * \author	Georg Hopp
 *
 * \copyright
 * Copyright © 2012  Georg Hopp
 *
 * This program is free software: you can redistribute it and/or modify
 * it under the terms of the GNU General Public License as published by
 * the Free Software Foundation, either version 3 of the License, or
 * (at your option) any later version.
 *
 * This program is distributed in the hope that it will be useful,
 * but WITHOUT ANY WARRANTY; without even the implied warranty of
 * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
 * GNU General Public License for more details.
 *
 * You should have received a copy of the GNU General Public License
 * along with this program.  If not, see <http://www.gnu.org/licenses/>.
 */

#include "trbase.h"
#include "tr/tree.h"

void *
TR_treeInsert(TR_Tree * this, const void * search, TR_TreeComp comp)
{
	TR_Tree node     = *this;
	TR_Tree new_node = NULL;

	/*
	 * insert the node or return the one in tree if comparison
	 * succeeds.
	 */
	if (NULL == node) {
		/*
		 * if the root is NULL we simple add the element and set
		 * node to it.
		 */
		*this = node = new_node = TR_new(TR_Tree, search);
	} else {
		/*
		 * first search for it and if its found return the data
		 * and we are done...
		 */
		while (NULL != node) {
			int comparison = comp(node->data, search);

			if (0 < comparison) {
				if (NULL != TR_TREE_LEFT(node)) {
					node = TR_TREE_LEFT(node);
					continue;
				} else {
					node->left = TR_new(TR_Tree, search);
					node->left->parent = node;
					node = new_node = node->left;
					break;
				}
			}

			if (0 > comparison) {
				if (NULL != TR_TREE_RIGHT(node)) {
					node = TR_TREE_RIGHT(node);
					continue;
				} else {
					node->right = TR_new(TR_Tree, search);
					node->right->parent = node;
					node = new_node = node->right;
					break;
				}
			}

			if (0 == comparison) {
				// as this is insert and not find this will overwrite an existing value,
				// but return the previos one so that it can be freed if neccessary.
				void * data = node->data;
				node->data = (void *)search;
				return data;
			}
		}
	}

	/*
	 * we expect node not to be NULL and pointing to our
	 * new node at this point...now rabalance the tree
	 */
	while (1) {
		// case 1
		if (NULL == TR_TREE_PARENT(node)) {
			node->color = rbBlack;
			break;
		}

		// case 2
		if (rbBlack == node->parent->color) {
			break;
		}

		// case 3
		TR_Tree uncle = TR_TREE_UNCLE(node);

		if (NULL != uncle && rbRed == uncle->color) {
			node->parent->color         = rbBlack;
			uncle->color                = rbBlack;
			node->parent->parent->color = rbRed;

			node = node->parent->parent;
			continue;
		}

		// case 4
		if (node == node->parent->right
				&& node->parent == node->parent->parent->left) {

			TR_TREE_ROTATE(left, this, node->parent);
			node = TR_TREE_LEFT(node);

		} else if (node == node->parent->left
				&& node->parent == node->parent->parent->right) {

			TR_TREE_ROTATE(right, this, node->parent);
			node = TR_TREE_RIGHT(node);

		}

		// case 5
		node->parent->color         = rbBlack;
		node->parent->parent->color = rbRed;

		if (node == node->parent->left) {
			TR_TREE_ROTATE(right, this, node->parent->parent);
		} else {
			TR_TREE_ROTATE(left, this, node->parent->parent);
		}

		break;
	}

	return new_node->data;
}

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