#include <stdio.h>
#include <stdlib.h>
#include <stdbool.h>
#include <assert.h>
#include "miniunit.h"

// Let's plant a bug.
//
/*  OUTPUT FROM RUNNING CODE:

    b.c.temp: b.c:39: destroy_tree: Assertion `*a_root == ((void *)0)' failed.
    /bin/bash: line 1: 21929 Aborted                 (core dumped) ~/b.c.temp

    // Caveat:  This code might not compile for students.
 */

typedef struct _BSTNode {
    int value;
    struct _BSTNode* left;
    struct _BSTNode* right;
} BSTNode;

void insert(int value, BSTNode** a_root) {
    if(*a_root == NULL) {  // If the tree is empty...  // Create a tree of size 1
        BSTNode* new_node = malloc(sizeof(*new_node));
        *new_node = (BSTNode) { .value = value, .left = NULL, .right = NULL };
        *a_root = new_node;
        assert((*a_root) -> value == value);
        assert((*a_root) -> left == NULL && (*a_root) -> right == NULL);
    }
    else if(value < (*a_root) -> value) {
        insert(value, &((*a_root) -> left));
    }
    else {
        assert(value >= (*a_root) -> value);
        insert(value, &((*a_root) -> right));
    }
}

void destroy_tree(BSTNode** a_root) {
    if(*a_root != NULL) {
        destroy_tree(&(*a_root) -> left);
        destroy_tree(&(*a_root) -> right);
        free(*a_root);
        *a_root == NULL;  // <<<< BUG:  '==' instead of '='  <<<<<<<<<<<<<
    }
    assert(*a_root == NULL);
}

int main(int argc, char* argv[]) {
    // size == 0  (empty tree)
    BSTNode* root = NULL;

    insert(4, &root);
    insert(2, &root);

    destroy_tree(&root);
    
    return EXIT_SUCCESS;
}
/* vim: set tabstop=4 shiftwidth=4 fileencoding=utf-8 noexpandtab: */