#include "header.h"

int generateMessage(char *buf) {
  int length = rand() % (MSGSIZE - 2) + 1; //length from 1 to SIZE_MSG-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 increaseReaders(int             sem,
                    struct sembuf*  incrReaders,
                    struct sembuf*  waitForRead,
                    int*            readcount)
{
  if(semop(sem, incrReaders, 1) == ERRCODE) {
    perror("semop");
    return EXIT_FAILURE;
  }
  if(readcount == 0){
    if(semop(sem, waitForRead, 1) == ERRCODE) {
    perror("semop");
    return EXIT_FAILURE;
    }
  }
  ++*readcount;
return EXIT_SUCCESS;
}

int decreaseReaders(int             sem,
                    struct sembuf*  decrReaders,
                    struct sembuf*  makeWritePossible,
                    int*            readcount)
{
  if(semop(sem, decrReaders, 1) == ERRCODE) {
    perror("semop");
    return EXIT_FAILURE;
  }
  --*readcount;
  if(readcount == 0){
    if(semop(sem, makeWritePossible, 1) == ERRCODE) {
    perror("semop");
    return EXIT_FAILURE;
    }
  }
  return EXIT_SUCCESS;
}


int performRead(char* messageBegin){
  if(*messageBegin == END_PRODUCE) {
    printf("End work\n");
    return EXIT_FAILURE;
  }
  printf("recv: %s\n", messageBegin);

  return EXIT_SUCCESS;
}

int initWrite(int             sem,
              struct sembuf*  blockForWrite,
              struct sembuf*  waitForWrite)
{
  if(semop(sem, blockForWrite, 1) == ERRCODE) {
    perror("semop");
    return EXIT_FAILURE;
  }
  if(semop(sem, waitForWrite, 1) == ERRCODE) {
    perror("semop");
    return EXIT_FAILURE;
  }
  return EXIT_SUCCESS;
}

void performWrite(char* messageBegin){
  generateMessage(messageBegin);
}

int endWrite(int            sem,
             struct sembuf* freeForRead,
             struct sembuf* freeForWrite)
{
  if(semop(sem, freeForRead, 1) == ERRCODE) {
    perror("semop");
    return EXIT_FAILURE;
  }
  if(semop(sem, freeForWrite, 1) == ERRCODE) {
    perror("semop");
    return EXIT_FAILURE;
  }
}