#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 (!root) {
        // allocate new node
        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 = node->right = NULL;

        if (isDuplicate) *isDuplicate = 0;
        return node;
    }

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

    if (cmp == 0) {
        // duplicate
        if (isDuplicate) *isDuplicate = 1;
        return root; // do not insert duplicate
    }

    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;

    // New tree → reset stack and push left path
    if (root != NULL) {
        clearStack(stack);
        stack = NULL;

        TreeNode *curr = root;
        while (curr) {
            stack = push(stack, curr);
            curr = curr->left;
        }
    }

    // No tree / finished
    if (!stack) return NULL;

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

    // After returning node, push its right subtree (all left nodes)
    TreeNode *curr = node->right;
    while (curr) {
        stack = push(stack, curr);
        curr = curr->left;
    }

    return node->data;
}

// 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);
}