#include <stdlib.h>
#include <stdio.h>
#include <time.h>
#include <string.h>
#include "numbers.h"
#include "bintree.h"

//TODO: getDuplicate und createNumbers implementieren
/*  *   * Erzeugen eines Arrays mit der vom Nutzer eingegebenen Anzahl an Zufallszahlen.
  * Sicherstellen, dass beim Befüllen keine Duplikate entstehen.
  * Duplizieren eines zufälligen Eintrags im Array.
  * in `getDuplicate()`: Sortieren des Arrays und Erkennen der doppelten Zahl durch Vergleich benachbarter Elemente. */

// Returns len random numbers between 1 and 2x len in random order which are all different, except for two entries.
// Returns NULL on errors. Use your implementation of the binary search tree to check for possible duplicates while
// creating random numbers.

// Vergleichsfunktion für qsort
static int cmp_uint(const void *a, const void *b)
{
    unsigned int x = *(const unsigned int*)a;
    unsigned int y = *(const unsigned int*)b;

    if (x < y) return -1;
    if (x > y) return 1;
    return 0;
}

unsigned int *createNumbers(unsigned int len)
{
    if (len < 2) {
        return NULL;
    }

    unsigned int *arr = malloc(len * sizeof(unsigned int));
    if (!arr) {
        return NULL;
    }

    BinTree *tree = createTree();
    if (!tree) {
        free(arr);
        return NULL;

    /* Zahlen generieren: keine Duplikate */
    for (unsigned int i = 0; i < len; i++) {

        unsigned int value;
        int inserted = 0;

        while (!inserted) {
            value = (rand() % (2 * len)) + 1;

            if (!search(tree, value)) {
                insert(tree, value);
                inserted = 1;
            }
        }

        arr[i] = value;
    /* Ein zufälliges Element duplizieren */
    unsigned int a = rand() % len;
    unsigned int b;

    do {
        b = rand() % len;
    } while (b == a);

    arr[b] = arr[a];

    freeTree(tree);
    return arr;
    }
  }
}

// Returns only the only number in numbers which is present twice. Returns zero on errors.
unsigned int getDuplicate(const unsigned int numbers[], unsigned int len)
{
  if (!numbers || len < 2) {
        return 0;
    }

    unsigned int *tmp = malloc(len * sizeof(unsigned int));
    if (!tmp) {
        return 0;
    }

    memcpy(tmp, numbers, len * sizeof(unsigned int));

    qsort(tmp, len, sizeof(unsigned int), cmp_uint);

    unsigned int duplicate = 0;

    for (unsigned int i = 1; i < len; i++) {
        if (tmp[i] == tmp[i - 1]) {
            duplicate = tmp[i];
            break;
        }
    }

    free(tmp);
    return duplicate;
}