#include <string.h>
#include "stack.h"
#include "bintree.h"

//TODO: binären Suchbaum implementieren
/*  * `addToTree`: fügt ein neues Element in den Baum ein (rekursiv),
    * `clearTree`: gibt den gesamten Baum frei (rekursiv),
    * `treeSize`: zählt die Knoten im Baum (rekursiv),
    * `nextTreeData`: Traversierung mit Hilfe des zuvor implementierten Stacks. */

// Adds a copy of data's pointer destination to the tree using compareFct for ordering. Accepts duplicates
// if isDuplicate is NULL, otherwise ignores duplicates and sets isDuplicate to 1 (or to 0 if a new entry is added).
TreeNode *addToTree(TreeNode *root, const void *data, size_t dataSize, CompareFctType compareFct, int *isDuplicate)
{
	/* Neuer Knoten */
	if (root == NULL) {
		TreeNode *node = malloc(sizeof(TreeNode));
		if (!node)
			return NULL;

		node->data = malloc(dataSize);
		if (!node->data) {
			free(node);
			return NULL;
		}

		memcpy(node->data, data, dataSize);
		node->left = NULL;
		node->right = NULL;

		if (isDuplicate)
			*isDuplicate = 0;

		return node;
	}

	int cmp = compareFct(data, root->data);

	if (cmp == 0) {
		/* Duplikat */
		if (isDuplicate)
			*isDuplicate = 1;
		return root;
	}
	else if (cmp < 0) {
		root->left = addToTree(root->left, data, dataSize, compareFct, isDuplicate);
	}
	else {
		root->right = addToTree(root->right, data, dataSize, compareFct, isDuplicate);
	}

	return root;
}

// Iterates over the tree given by root. Follows the usage of strtok. If tree is NULL, the next entry of the last tree given is returned in ordering direction.
// Use your implementation of a stack to organize the iterator. Push the root node and all left nodes first. On returning the next element,
// push the top node and push all its left nodes.
void *nextTreeData(TreeNode *root)
{
	static StackNode *stack = NULL;
	static TreeNode *currentRoot = NULL;

	/* Neuer Baum → Iterator zurücksetzen */
	if (root != NULL) {
		clearStack(stack);
		stack = NULL;
		currentRoot = root;

		/* Alle linken Knoten pushen */
		while (currentRoot) {
			stack = push(stack, currentRoot);
			currentRoot = currentRoot->left;
		}
	}

	if (stack == NULL)
		return NULL;

	/* Nächsten Knoten holen */
	TreeNode *node = top(stack);
	stack = pop(stack);

	void *result = node->data;

	/* Rechter Teilbaum → wieder alle linken pushen */
	node = node->right;
	while (node) {
		stack = push(stack, node);
		node = node->left;
	}

	return result;
}

// Releases all memory resources (including data copies).
void clearTree(TreeNode *root)
{
	if (!root)
		return;

	clearTree(root->left);
	clearTree(root->right);

	free(root->data);
	free(root);
}

// Returns the number of entries in the tree given by root.
unsigned int treeSize(const TreeNode *root)
{
	if (!root)
		return 0;

	return 1 + treeSize(root->left) + treeSize(root->right);
}