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

//Komplexität 𝑂(ℎ) mit ℎ = Höhe des Baums ??
//fügt einen kopierten Datensatz in einen binären Suchbaum ein und meldet optional Duplikate.
TreeNode *addToTree(TreeNode *root, const void *data, size_t dataSize, CompareFctType compareFct, int *isDuplicate)
{
    if (root == NULL)
    {
        TreeNode *newNode = (TreeNode *)malloc(sizeof(TreeNode));
        if (newNode == NULL)
            return NULL;

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

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

        if (isDuplicate != NULL) *isDuplicate = 0;
        return newNode;
    }

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

    if (comparison == 0)
    {
        if (isDuplicate != NULL) *isDuplicate = 1;
        return root;
    }
    else if (comparison < 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.

//liefert nacheinander die Elemente in aufsteigender Reihenfolge (Inorder) (also wie sortiert) und merkt sich den Zustand zwischen Aufrufen mit einem Stack.
//Übergabe eines root initialisiert oder startet neu; root == NULL setzt die Iteration fort.
void *nextTreeData(TreeNode *root)
{
    /* static iterator state using stack.c */
    static StackNode *stack = NULL;
    static TreeNode *currentRoot = NULL;

    /* helper: push node and all left descendants */
    void push_lefts(TreeNode *n)
    {
        while (n != NULL)
        {
            stack = push(stack, (void *)n);
            n = n->left;
        }
    }

    /* If a new root is provided and differs from current, or explicit restart with same root, reset iterator */
    if (root != NULL && root != currentRoot)
    {
        clearStack(stack);
        stack = NULL;
        currentRoot = root;
        push_lefts(root);
    }
    else if (root != NULL && root == currentRoot)
    {
        /* explicit restart with same root */
        clearStack(stack);
        stack = NULL;
        push_lefts(root);
    }
    /* if root == NULL: continue with existing stack */

    /* nothing left */
    if (stack == NULL)
    {
        currentRoot = NULL;
        return NULL;
    }

    /* pop top */
    TreeNode *node = (TreeNode *)top(stack);
    stack = pop(stack);

    void *result = node->data;

    /* if right child exists, push it and all its lefts */
    if (node->right != NULL)
    {
        push_lefts(node->right);
    }

    return result;
}

// Gibnt alle Knoten und ihre daten frei.
void clearTree(TreeNode *root)
{
    if (root == NULL)
        return;

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

    if (root->data != NULL)
        free(root->data);

    free(root);
}

// Zählt rekursiv die anzahl an knoten ab *root.
unsigned int treeSize(const TreeNode *root)
{
    if (root == NULL)
        return 0u;

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