#include <stdlib.h>
#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 == NULL) {
        TreeNode *node = (TreeNode *)malloc(sizeof(TreeNode));
        if (node == NULL) return NULL;
        node->data = malloc(dataSize);
        if (node->data == NULL) { 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) {
        root->left = addToTree(root->left, data, dataSize, compareFct, isDuplicate);
    } else if (cmp > 0) {
        root->right = addToTree(root->right, data, dataSize, compareFct, isDuplicate);
    } else { // cmp == 0 -> duplicate
        if (isDuplicate) {
            *isDuplicate = 1;
            return root;
        } else {
            // accept duplicates when isDuplicate == NULL: insert to the right subtree
            root->right = addToTree(root->right, data, dataSize, compareFct, NULL);
        }
    }
    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 *iterStack = NULL;

    if (root != NULL) {
        // (re)initialize iterator for new tree
        clearStack(iterStack);
        iterStack = NULL;
        TreeNode *cur = root;
        while (cur != NULL) {
            iterStack = push(iterStack, cur);
            cur = cur->left;
        }
    }

    if (iterStack == NULL) return NULL;

    TreeNode *node = (TreeNode *)top(iterStack);
    iterStack = pop(iterStack);
    void *ret = node->data;

    // push right subtree (and all its left descendants)
    TreeNode *cur = node->right;
    while (cur != NULL) {
        iterStack = push(iterStack, cur);
        cur = cur->left;
    }

    return ret;
}

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