#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)
{
    if (isDuplicate)
        *isDuplicate = 0;

    // Wenn kein Knoten angelegt
    if (root == NULL)
    {
        // Neuen Knoten erstellen
        TreeNode *newNode = malloc(sizeof(TreeNode));
        if (!newNode)
            return NULL;
        // mit Daten füllen
        newNode->data = malloc(dataSize);
        if (!(newNode->data))
        {
            free(newNode);
            return NULL;
        }

        memcpy(newNode->data, data, dataSize);
        newNode->left = NULL; // Kinder NULL setzen
        newNode->right = NULL;
        return newNode;
    }
    // auf Doppellungen überprüfen, daten/werte vergelichen
    // int cmp = compareFct(data, root->data);

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

    if (cmp == 0) // Duplikat erkannt
    {
        if (isDuplicate) // nicht einfügen
        {
            *isDuplicate = 1;
            return root;
        }
        else // einfügen erlaubt
        {
            root->right = addToTree(root->right, data, dataSize, compareFct, NULL);
            return root;
        }
    }
    // kein Duplikat
    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);
    }
    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; // Stack für Iterator
    static TreeNode *lastRoot = NULL;
    TreeNode *currentNode;

    if (root != NULL) // Initialisierung bei erstem Aufruf
    {
        lastRoot = root;

        if (stack)
        {
            freeStack(stack);
            stack = NULL;
        }

        stack = createStack();

        // alle linken Knoten vom Wurzelknoten pushen
        currentNode = root;
        while (currentNode)
        {
            push(stack, currentNode);
            currentNode = currentNode->left;
        }
    }
    // Stack ist leer, keine Daten mehr
    if (!stack || isEmpty(stack))
        return NULL;

    TreeNode *newNode = pop(stack); // nächster Knoten

    // Wenn rechter Teilbaum vorhanden → alle linken Knoten pushen
    currentNode = newNode->right;
    while (currentNode)
    {
        push(stack, currentNode);
        currentNode = currentNode->left;
    }
    return newNode->data; // Daten zurückgeben
}

// Releases all memory resources (including data copies).
void clearTree(TreeNode *root)
{
    if (root)
    {
        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)
{
    unsigned int size = 0;
    if (root == NULL)
        return 0;
    size = 1 + treeSize(root->left) + treeSize(root->right);
    return size;
}