/**
 * \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_treeDelete(TR_Tree * this, const void * search, TR_TreeComp comp)
{
	TR_Tree node = *this;
	TR_Tree del_node;
	int     found;

	void    * data;

	TR_TREE_FIND(node, search, found, comp);

	/*
	 * nothing was found...return NULL to indicate this.
	 */
	if (found != 0) {
		return NULL;
	}

	/*
	 * we found an element, store its data pointer as we are
	 * up to delete it.
	 */
	data = node->data;

	/*
	 * now remove the element.
	 */
	
	/*
	 * if we have two children replace data with the one from 
	 * out inOrderSuccessor and remove the inOrderSuccessor.
	 */
	if (NULL != TR_TREE_LEFT(node) && NULL != TR_TREE_RIGHT(node)) {
		TR_Tree successor;
		
		TR_TREE_INORDER_SUCC(node, successor);

		node->data = successor->data;
		node       = successor;
	}

	{
		TR_Tree child = TR_TREE_CHILD(node);

		/*
		 * if we still have one child replace ourself with it.
		 */
		TR_TREE_REPLACE_NODE(this, node, child);

		/*
		 * and finally delete the node...and prepare ourselfs
		 * for rebalancing.
		 */
		if (rbBlack == node->color) {
			if (NULL != child && rbRed == child->color) {
				child->color = rbBlack;
				TR_delete(node);
				return data;
			} else {
				del_node = node;
				if (NULL != child) {
					node = child;
				} else {
					node->color = rbBlack;
					node->left  = NULL;
					node->right = NULL;
				}
			}
		} else {
			TR_delete(node);
			return data;
		}
	}

	/*
	 * now comes rebalancing...note that if we came to this point
	 * the node is still not deleted.
	 * This is because I am not sure if it is needed during the
	 * rebalancing process...(this does not make much sense, but
	 * to be honest I don't know now.)
	 */
	{
		TR_Tree sibling = TR_TREE_SIBLING(node);
		TR_TREE_BALANCE_DELETE(this, node, sibling);
	}

	TR_delete(del_node);
	return data;
}

// vim: set ts=4 sw=4: