#include <pthread.h>
#include <stdint.h>
#include <stdio.h>
#include <stdlib.h>
#include <string.h>

struct {
  pthread_mutex_t mtx;
  char text[256];
} item[5];

const char *arg0;

void *threadFunc(intptr_t num) {
  char name[1024], cmd[1024];
  sprintf(name, "%s.pipe.%ld", arg0, num);
  sprintf(cmd, "rm -f %s; mkfifo %s", name, name);
  system(cmd);
  FILE *myPipe = fopen(name, "r+");

  while (1) {
    char line[1024], nl;
    fscanf(myPipe, "%1023[^\n]%c", line, &nl);

    int argOne = atoi(line);
    if (argOne >= 5 || argOne < 0)
      continue;

    char *argTwoTxt = strchr(line, ' ');

    if (!argTwoTxt) {
      pthread_mutex_lock(&item[argOne].mtx);
      printf("T%ld reads %d as: %s\n", num, argOne, item[argOne].text);
      pthread_mutex_unlock(&item[argOne].mtx);
      continue;
    }

    argTwoTxt++;
    char *e;
    int argTwo = strtol(argTwoTxt, &e, 10);

    if (!*e && argTwo < 5 && argTwo >= 0 && argOne != argTwo) {
      pthread_mutex_lock(&item[argOne].mtx);
      pthread_mutex_lock(&item[argTwo].mtx);
      printf("T%ld copies %d to %d\n", num, argTwo, argOne);
      memcpy(item[argOne].text, item[argTwo].text, sizeof(item[argOne].text));
      pthread_mutex_unlock(&item[argTwo].mtx);
      pthread_mutex_unlock(&item[argOne].mtx);
    } else {
      pthread_mutex_lock(&item[argOne].mtx);
      printf("T%ld assigns to %d the value: %s\n", num, argOne, argTwoTxt);
      memset(item[argOne].text, 0, sizeof(item[argOne].text));
      strncpy(item[argOne].text, argTwoTxt, sizeof(item[argOne].text) - 1);
      pthread_mutex_unlock(&item[argOne].mtx);
    }
  }
}

int main(int argc, char **argv) {
  arg0 = argv[0];

  printf("To use this program, write to one of the %s.pipe.<thread_id> the "
         "following:\n"
         "  <num>             prints <text> from item <num>\n"
         "  <num> <text>      puts <text> to item <num>\n"
         "  <num1> <num2>     copies to item <num1> the text from item <num2>\n"
         "Valid pipe numbers are 0-4, valid item numbers are 0-4.",
         arg0);

  for (int i = 0; i < 5; ++i)
    pthread_mutex_init(&item[i].mtx, NULL);

  for (intptr_t i = 1; i < 5; ++i) {
    pthread_t tid;
    pthread_create(&tid, NULL, (void *(*)(void *))threadFunc, (void *)i);
    pthread_detach(tid);
  }
  threadFunc(0);
}