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

CompareFctType compareFct(const void *arg1, const void *arg2)
{
  const unsigned int *entry1 = arg1;
  const unsigned int *entry2 = arg2;

  int result = *entry2 - *entry1;

  return result;
}

// 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.
unsigned int* createNumbers(unsigned int len)
{
  srand(time(NULL));

  TreeNode *numbers;

  int isDuplicate = 0;
  int number = rand() % (2 * len) + 1;
  int* array = malloc(len*sizeof(int));

  numbers = addToTree(NULL, &number, sizeof(int), compareFct, &isDuplicate);
  array[0] = number;
  for (int i = 1; i < len; i++)
  {
    number = rand() % (2 * len) + 1;
    addToTree(numbers, &number, sizeof(int), compareFct, &isDuplicate);
    if (isDuplicate == 1)
    {
      isDuplicate = 0;
      i--;
    }else{
      array[i] = number;
    }
  }

  int duplicatePosition1 = rand() % len;
  int duplicatePosition2 = rand() % len;

  while(duplicatePosition2 == duplicatePosition1){
    duplicatePosition2 = rand() % len;
  }

  array[duplicatePosition2] = array[duplicatePosition1];

  return array;
}

// 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)
{
  qsort(numbers, len, sizeof(int), compareFct);
  
  for(int i = 0; i < len-1; i++){
    if(numbers[i] == numbers[i+1]){
      return numbers[i];
    }
  }

  return 0;
}