#include <stdio.h>
#include <fcntl.h>
#include <sys/types.h>
#include <unistd.h>
#include <string.h>
#include <stdlib.h>
#include <sys/ipc.h>
#include <sys/msg.h>
#include <time.h>

#define MSGSIZE 100
#define STRUCTMSGSIZE (MSGSIZE + sizeof(pid_t))
#define ERRCODE -1
#define NO_FLAGS 0
#define MSGJOINQ 1
#define MSGLEAVEQ 2
#define MSG_TYPE_DATA 3
#define MSG_ALL_TYPES 0
#define QUEUE_RIGHTS 0600
#define PROJECT_PREFIX 97
#define COUNT_MESSAGES 10
#define START_CHAR 32
#define END_CHAR 127
#define SLEEP_TIME 1

struct message {
  long mtype;
  pid_t pid;
  char mtext[MSGSIZE];
};


int qregister(int queue) {
  pid_t pid = getpid();
  struct message buf = {MSGJOINQ, pid, ""};
  char greetings[MSGSIZE];
  struct message hi =  {MSG_TYPE_DATA, pid, ""};
  sprintf(hi.mtext, "hi from %d!", pid);

  if(msgsnd(queue, &buf, sizeof(pid_t), NO_FLAGS) == ERRCODE) {
    perror("msgsnd");
    return EXIT_FAILURE;
  }

  if(msgsnd(queue, &hi, strlen(hi.mtext) + 1 + sizeof(pid_t), NO_FLAGS) ==  ERRCODE) {
    perror("msgsnd");
    return EXIT_FAILURE;
  }

  return EXIT_SUCCESS;
}

int qleave(int queue) {
  pid_t pid = getpid();
  struct message buf = {MSGLEAVEQ, pid, ""};
  struct message bye = {MSG_TYPE_DATA, pid, "bye!"};

  if(msgsnd(queue, &bye, strlen(bye.mtext) + 1 + sizeof(pid_t), NO_FLAGS) ==  ERRCODE) {
    perror("msgsnd");
    return EXIT_FAILURE;
  }

  if(msgsnd(queue, &buf, sizeof(pid_t), NO_FLAGS) ==  ERRCODE) {
    perror("msgsnd");
    return EXIT_FAILURE;
  }

  return EXIT_SUCCESS;
}

int msggen(char *buf) {
  int length = rand() % (MSGSIZE - 2) + 1; //length from 1 to MSGSIZE-1
  int i;
  for(i = 0; i < length; ++i) {
    buf[i] = (char)(rand() % (END_CHAR - START_CHAR) + START_CHAR);
  }
  buf[length] = '\0';
  ++length;

  return length;
}

int qsndmsg(int queue) {
  pid_t pid = getpid();
  struct message buf = {MSG_TYPE_DATA, pid, ""};
  int i;

  printf("I'm %d\n", pid);
  int length;
  for(i = 0; i < COUNT_MESSAGES; ++i) {
    length = msggen(buf.mtext);
    if (length == 0){
      break;
    }
    printf("Send message: %s\n", buf.mtext);

    if(msgsnd(queue, &buf, length + sizeof(pid_t), NO_FLAGS) ==  ERRCODE) {
      perror("msgsnd");
      return EXIT_FAILURE;
    }
    sleep(SLEEP_TIME);
  }

  return EXIT_SUCCESS;
}

int main() {
  srand(time(NULL));

  key_t queueKey = ftok("master.c", PROJECT_PREFIX);
  if(queueKey ==  ERRCODE) {
    perror("ftok");
    return EXIT_FAILURE;
  }

  int queue;
  queue = msgget(queueKey, NO_FLAGS);
  if(queue ==  ERRCODE)     {
    perror("msgget");
    return EXIT_FAILURE;
  }

  printf("Connected to queue\n");

  if(qregister(queue) != EXIT_SUCCESS) {
    return EXIT_FAILURE;
  }

  if(qsndmsg(queue) != EXIT_SUCCESS) {
    qleave(queue);
    return EXIT_FAILURE;
  }

  if(qleave(queue) != EXIT_SUCCESS) {
    return EXIT_FAILURE;
  }

  return EXIT_SUCCESS;
}