#include <stdio.h>

float farenheitToCelsius(float farenheit) {
  return (farenheit - 32.0) / 1.8;
}

float celsiusToFarenheit(float celsius) {
  return (celsius * 1.8) + 32.0;
}

int sizeofStr(char in[]) {
  int i = 0;
  for (i = 0; in[i] != '\0'; ++i)
    ;
  return i;
}

void printStrArray(char in[]) {
  int i;
  printf("{ ");
  for (i = 0; i < sizeofStr(in); ++i) {
    printf("%c", in[i]);
    if (i == sizeofStr(in) - 1) {
      printf(" }\n");
    } else {
      printf(", ");
    }
  }
}

void printIntArray(int in[], int inLength) {
  int i;
  printf("{ ");
  for (i = 0; i < inLength; ++i) {
    printf("%d", in[i]);
    if (i == inLength - 1) {
      printf(" }\n");
    } else {
      printf(", ");
    }
  }
}

int checkIntArraySorted(int in[], int inLength) {
  int i = 0;
  while(i < inLength - 1) {
    if (in[i] > in[i + 1])
      return 0;
    ++i;
  }
  
  return 1;
}

void swapInt(int *x, int *y) {
  int temp = *x;
  *x = *y;
  *y = temp;
}

/* Count the number of digits an integer has */
unsigned long long intDigitCount(unsigned long long in) {
  unsigned long long largestDigit;
  int digitCount = 0;
  for (largestDigit = 1; in / largestDigit != 0; largestDigit *= 10)
    ++digitCount;
  return digitCount;
}

/* Expand an integer into an integer whose first unit is 1 followed by a leading trail of 0's*/
unsigned long long intDigitExpand(unsigned long long in) {
  int expandedDigit;
  for (expandedDigit = 1; in != 1; --in)
    expandedDigit *= 10;
  return expandedDigit; 
}

/* Convert an integer array into a combined integer */
int intArrayToInt(int in[], int inLength) {
  int i;
  int out = 0;
  int currentDigit = inLength;
  for (i = 1; i <= inLength; ++i) {
    out += in[i - 1] * intDigitExpand(currentDigit);
    --currentDigit;
  }
  return out;
}

/* Split an integer into an integer array */
void intToIntArray(int in, int out[]) {
  int i;
  int j = 0;
  int currentDigit;
  for(i = intDigitCount(in); i >= 1; --i) {
    out[j] = in / intDigitExpand(i);
    in -= intDigitExpand(i) * out[j];
    ++j;
  }
}

/* Pseudo Random Number Generator using the Middle-square method */
int randIntMiddleSquare(unsigned long long *seed, int iteration) {
  int i;
  int oldSeedLength = intDigitCount(*seed);
  for (i = 0; i < iteration; ++i) {
    unsigned long long seedSquared = *seed * *seed;
    unsigned long long seedSquaredLength = intDigitCount(seedSquared);
    printf("Seed squared: %d\n", seedSquared);
    printf("Seed squared length: %d\n", seedSquaredLength);
    int seedSquaredArray[seedSquaredLength]; 
    int middleStart = (seedSquaredLength - oldSeedLength) / 2;
    printf("Middle start: %d\n", middleStart);
    int newSeedArray[oldSeedLength];
    int j;
    intToIntArray(seedSquared, seedSquaredArray);
    for (int j = 0; j < oldSeedLength; ++j) {
      newSeedArray[j] = seedSquaredArray[middleStart];
      ++middleStart;
    }
    printIntArray(newSeedArray, sizeof(newSeedArray) / sizeof(int));
    unsigned long long newSeed = intArrayToInt(newSeedArray, sizeof(newSeedArray) / sizeof(int));
    int newSeedLength = intDigitCount(newSeed);
    /* If the result has fewer than 2n digits, leading zeroes are added to compensate */
    if (newSeedLength < oldSeedLength)
      newSeed *= intDigitExpand(oldSeedLength - newSeedLength) * 10; 
    *seed = newSeed;
  }

  return *seed;
}

int randIntMiddleSquareRange(int start, int end, unsigned long long *seed) {

  int endLength = intDigitCount(end);
  if (endLength > intDigitCount(*seed))
    return -1;
  
  unsigned long long randomNumber = randIntMiddleSquare(seed, 1);
  printf("The random number: %d\n", randomNumber);
  int randomNumberLength = intDigitCount(randomNumber);
  int randomNumberArray[randomNumberLength];
  int truncatedNumber;
  int truncatedNumberArray[endLength];
  int middleStart = (randomNumberLength - endLength) / 2;
  intToIntArray(randomNumber, randomNumberArray);
  for (int j = 0; j < endLength; ++j) {
    truncatedNumberArray[j] = randomNumberArray[middleStart];
    ++middleStart;
  }
  truncatedNumber = intArrayToInt(truncatedNumberArray, sizeof(truncatedNumberArray) / sizeof(int));
  
  if (truncatedNumber <= end && truncatedNumber >= start)
    return truncatedNumber;
  else
    randIntMiddleSquareRange(start, end, seed);
}

int main() {
  int unsortedArray[] = { 1, 5, 2, 1, 4, 8, 3, 2, 6, 7 };
  int sortedArray[] = { 1, 2, 4, 8, 9, 9, 9 };

  printf("Unsorted Array : ");
  printIntArray(unsortedArray, sizeof(unsortedArray) / sizeof(int));
  printf("Unsorted Array Sorted?: %d\n", checkIntArraySorted(unsortedArray, sizeof(unsortedArray) / sizeof(int)));
  printf("Sorted Array : ");
  printIntArray(sortedArray, sizeof(sortedArray) / sizeof(int));
  printf("Sorted Array Sorted?: %d\n", checkIntArraySorted(sortedArray, sizeof(sortedArray) / sizeof(int)));

  int number = 3372; 
  int intArray[4];

  intToIntArray(number, intArray);
  printIntArray(intArray, sizeof(intArray) / sizeof(int));

  printf("Back to int %d\n", intArrayToInt(intArray, sizeof(intArray) / sizeof(int)));

  unsigned long long seed = 3791;
  printf("Squared: %d\n", seed * seed);
  int iteration = 1;
  printf("Starting random number %d\n", seed);
  printf("Random number is %d after iteration %d\n", randIntMiddleSquare(&seed, iteration), iteration);

  printf("Random: %d\n", randIntMiddleSquareRange(1, 10, &seed));

}