#include <stdlib.h>
#include <stdio.h>
#include <string.h>

#include "stack.h"
#include "bintree.h"

static StackNode *push_left(TreeNode *node, StackNode *stack);

/* Vergleichsfunktion */
int compareFct(const void *argument1, const void *argument2)
{
    int x = *((int *)argument1);
    int y = *((int *)argument2);

    if (x < y) return -1;
    if (x > y) return 1;
    return 0;
}

/* Erzeugt einen neuen Baumknoten mit Datenkopie */
static TreeNode *create_node(const void *data, size_t data_size)
{
    TreeNode *node = malloc(sizeof(TreeNode));
    if (!node)
    {
        perror("Speicher wurde NICHT reserviert!");
        return NULL;
    }

    node->data = malloc(data_size);
    if (!node->data)
    {
        perror("Speicher wurde NICHT reserviert!");
        free(node);
        return NULL;
    }

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

    return node;
}

/* Fügt Daten in den Binärbaum ein */
TreeNode *addToTree(TreeNode *root, const void *data, size_t dataSize,
                    CompareFctType compareFct, int *isDuplicate)
{
    if (root == NULL)
    {
        if (isDuplicate)
            *isDuplicate = 0;
        return create_node(data, dataSize);
    }

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

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

    return root;
}

/* Inorder-Iterator über den Baum */
void *nextTreeData(TreeNode *root)
{
    static StackNode *stack = NULL;

    /* Neuer Start → linken Pfad auf Stack legen */
    if (root != NULL)
        stack = push_left(root, stack);

    if (stack == NULL)
        return NULL;

    /* TOP lesen, dann POP */
    TreeNode *node = (TreeNode *)top(stack);
    stack = pop(stack);

    if (node->right != NULL)
        stack = push_left(node->right, stack);

    return node->data;
}

/* Hilfsfunktion: linken Pfad auf Stack legen */
static StackNode *push_left(TreeNode *node, StackNode *stack)
{
    while (node != NULL)
    {
        stack = push(stack, node);
        node = node->left;
    }
    return stack;
}

/* Gibt gesamten Baum frei */
void clearTree(TreeNode *root)
{
    if (root == NULL)
        return;

    clearTree(root->left);
    clearTree(root->right);
    free(root->data);
    free(root);
}

/* Liefert Anzahl der Knoten */
unsigned int treeSize(const TreeNode *root)
{
    if (root == NULL)
        return 0;

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