#include <fcntl.h>
#include <poll.h>
#include <stdbool.h>
#include <stdio.h>
#include <stdlib.h>
#include <sys/select.h>
#include <sys/stat.h>
#include <unistd.h>

#include <opencv2/opencv.hpp>

#define FIFO_NAME "cvMat"

int main() {
  unsigned int timeout_seconds = 2;

  while (true) {
    int fd = open(FIFO_NAME, O_RDONLY | O_NONBLOCK);
    if (fd < 0) {
      perror("open");
      return EXIT_FAILURE;
    }

    struct pollfd waiter = {.fd = fd, .events = POLLIN};

    while (true) {
      bool stop = false;

      int poll_result = poll(&waiter, 1, timeout_seconds * 1000);
      switch (poll_result) {
      case 0:
        puts("No data from fifo");
        break;

      case 1:
        if (waiter.revents & POLLIN) {
          std::vector<uchar> buff;
          char tempBuff[256];
          ssize_t bytesRead;

          while ((bytesRead = read(fd, tempBuff, sizeof(tempBuff))) > 0) buff.insert(buff.end(), tempBuff, tempBuff + bytesRead);
          printf("Received: %d\n", buff.size());

          cv::Mat img(cv::Size(810, 1080), CV_8UC3, buff.data());
          cv::imwrite("received.jpg", img);
        } else if (waiter.revents & POLLERR) {
          puts("Got a POLLERR");
          return EXIT_FAILURE;
        } else if (waiter.revents & POLLHUP) {
          stop = true; // Writer closed its end
          break;
        }
        break;

      default:
        perror("poll error");
        return EXIT_FAILURE;
      }

      if (stop) break;
    }

    if (close(fd) < 0) {
      perror("close");
      return EXIT_FAILURE;
    }
  }

  return EXIT_SUCCESS;
}