#include <stdlib.h>
#include <stdio.h>
#include <math.h>
#include <getopt.h>
#include <time.h>

#define RANDOM_SEED time(NULL)

void printUsage()
{
  fprintf(stderr, "usage: matrixMult -n <INT> -m <INT> -p <INT> [-h]\n"
          "  Generate random matrices of sizes n*m, m*p and multiply them\n"
          "  \n"
          "  n and m need to be nonzero\n"
          );
}

void generateMatrix(int *matrix, unsigned int height, unsigned int width)
{
  for (int n = 0; n < height; n++)
    {
      for (int m = 0; m < width; m++)
        {
          matrix[n * width + m] = rand() % 100;
        }
    }
}

void matrixMultiply(int *m1, int *m2, int *res, unsigned int n, unsigned int m, unsigned int p)
{
  for (int i = 0; i < n; i++)
    {
      for (int j = 0; j < p; j++)
        {
          res[i * p + j] = 0;
          for (int r = 0; r < m; r++)
            res[i * p + j] += m1[i * m + r] * m2[r * p + j];
        }
    }
}

void main(int argc, char* argv[])
{
  int c;
  unsigned int n = 0;
  unsigned int m = 0;
  unsigned int p = 0;

  int *m1;
  int *m2;
  int *r;
  
  while((c = getopt(argc, argv, "n:m:p:")) != -1)
    {
      switch (c)
        {
        case 'n':
          sscanf(optarg, "%u", &n);
          break;
        case 'm':
          sscanf(optarg, "%u", &m);
          break;
        case 'p':
          sscanf(optarg, "%u", &p);
          break;
        case 'h':
          printUsage();
          exit(0);
          break;
        default:
          printUsage();
          exit(2);
        }
    }

  if (n == 0)
    fprintf(stderr, "n is zero\n");
  if (m == 0)
    fprintf(stderr, "m is zero\n");
  if (p == 0)
    fprintf(stderr, "p is zero\n");

  if (n == 0 || m == 0 || p == 0)
    {
      printUsage();
      exit(2);
    }

  m1 = malloc(sizeof(int) * n * m);
  m2 = malloc(sizeof(int) * m * p);
  r = malloc(sizeof(int) * n * p);

  srand(RANDOM_SEED);
  generateMatrix(m1, n, m);
  generateMatrix(m2, m, p);

  matrixMultiply(m1, m2, r, n, m, p);

  for (int h = 0; h < (n > m ? n : m); h++)
    {
      if (h < n)
        {
          printf("(");
          for (int w = 0; w < m; w++)
            {
              printf(" %5d", m1[h * n + w]);
            }
          printf(" )");
        }
      else
        {
          printf("   ");
          for (int w = 0; w < m; w++)
            printf(" %5s", "");
        }

      if (h == 0)
        printf(" * ");
      else
        printf("   ");

      if (h < m)
        {
          printf("(");
          for (int w = 0; w < p; w++)
            {
              printf(" %5d", m2[h * p + w]);
            }
          printf(" )");
        }
      else
        {
          printf("   ");
          for (int w = 0; w < p; w++)
            printf(" %5s", "");
        }

      if (h == 0)
        printf(" = ");
      else
        printf("   ");

      if (h < n)
        {
          printf("(");
          for (int w = 0; w < p; w++)
            {
              printf(" %5d", r[h * p + w]);
            }
          printf(" )");
        }
      else
        {
          printf("   ");
          for (int w = 0; w < p; w++)
            printf(" %5s", "");
        }
      
      printf("\n");
    }

  free(m1); free(m2); free(r);
}