#define _GNU_SOURCE

#include <stdio.h>
#include <stdlib.h>
#include <fcntl.h>
#include <sys/mman.h>
#include <unistd.h>
#include <errno.h>
#include <string.h>
#include <pthread.h>
#include <signal.h>
#include <time.h>

#include "fonts.h"
#include "input_gadgets.h"
#include "multiplexer.h"

void drop_privileges();
void handle_signals(int signo);

t_scroll_data scroll_data;
time_t next_update = 0;

int main(int argc, char **argv)
{
  int ret_val;
  #define TEXT_BUFFER_LENGTH    SCROLL_BUF_LEN / 5
  char *text_buffer;
  char *text_buffer_end;

  // Set up gpi pointer for direct register access
  ret_val = multiplexer_setup_root();
  if (ret_val)
    return ret_val;

  // Drop root privileges
  drop_privileges();

  // set up / register signal handler
  struct sigaction new_action, old_action;
  new_action.sa_handler = handle_signals;
  sigemptyset (&new_action.sa_mask);
  new_action.sa_flags = 0;
  const int fetch_signals[4] = {
    SIGINT, SIGHUP, SIGTERM, SIGUSR1
  };
  for (int i = 0; i < sizeof(fetch_signals)/sizeof(fetch_signals[0]); i++) {
    sigaction (fetch_signals[i], NULL, &old_action);
    if (old_action.sa_handler != SIG_IGN)
      sigaction (fetch_signals[i], &new_action, NULL);
  }

  init_symbols_boundaries();

 /************************************************************************\
  * You are about to change the GPIO settings of your computer.          *
  * Mess this up and it will stop working!                               *
  * It might be a good idea to 'sync' before running this program        *
  * so at least you still have your code changes written to the SD-card! *
 \************************************************************************/

  // configure the gpio pins and start the multiplexer thread
  multiplexer_setup_scroll(&scroll_data);

  text_buffer = malloc(TEXT_BUFFER_LENGTH);
  if (text_buffer == NULL) {
    fprintf(stderr, "malloc failed to allocate %d bytes\n", TEXT_BUFFER_LENGTH);
    turn_off_display();
    return EXIT_FAILURE;
  }

  scroll_data . shine_until = time(NULL) + 10;

  int i=0;

  while (scroll_data . keep_running) {
    if (got_input()) {
      next_update = 0; // update now!
      scroll_data . shine_until = time(NULL) + 60;
    }
    if ((time(NULL) >= next_update) && (scroll_data . update == 0)) {
      next_update = time(NULL) + 600; // 10 minutes ahead

      memset(text_buffer, 0, TEXT_BUFFER_LENGTH);

      text_buffer_end = text_buffer;

      double temperature, humidity;

      text_buffer_end = gadgets_retrieve_weather_warnings(text_buffer_end,text_buffer + TEXT_BUFFER_LENGTH - text_buffer_end);
      if (text_buffer_end == NULL) {
        fprintf(stderr, "gadgets_retrieve_weather_warnings failed\n");
        free(text_buffer);
        turn_off_display();
        return EXIT_FAILURE;
      }
      if (text_buffer + TEXT_BUFFER_LENGTH - text_buffer_end > 0)
        text_buffer_end += snprintf(text_buffer_end, text_buffer + TEXT_BUFFER_LENGTH - text_buffer_end, "; ");
      text_buffer_end = gadgets_retrieve_current_temperature(text_buffer_end, text_buffer + TEXT_BUFFER_LENGTH - text_buffer_end, &temperature, &humidity);
      if (text_buffer_end == NULL) {
        fprintf(stderr, "gadgets_retrieve_current_temperature failed\n");
        free(text_buffer);
        turn_off_display();
        return EXIT_FAILURE;
      }
      if (text_buffer + TEXT_BUFFER_LENGTH - text_buffer_end > 0)
        text_buffer_end += snprintf(text_buffer_end, text_buffer + TEXT_BUFFER_LENGTH - text_buffer_end, "; ");
      text_buffer_end = gadgets_retrieve_weather_forecast(text_buffer_end,text_buffer + TEXT_BUFFER_LENGTH - text_buffer_end);
      if (text_buffer_end == NULL) {
        fprintf(stderr, "gadgets_retrieve_weather_forecast failed\n");
        free(text_buffer);
        turn_off_display();
        return EXIT_FAILURE;
      }
      struct tm time_struct;
      memset(&time_struct, 0, sizeof(time_struct));
      localtime_r(&next_update, &time_struct);
      for (int i = 0; i < (time_struct . tm_wday + 6) % 7 + 1; i++) {
        if (text_buffer + TEXT_BUFFER_LENGTH - text_buffer_end <= 0)
          break;
        text_buffer_end += snprintf(
          text_buffer_end,
          text_buffer + TEXT_BUFFER_LENGTH - text_buffer_end,
          "%c%c%c%c",
          0xEE,
          i==0 ? 0x01 : 0x03 + 2 * (i & 0x01),
          0xEE,
          i==0 ? 0x02 : 0x04 + 2 * (i & 0x01)
        );
      }

      scroll_data . input_len =
        render(
          text_buffer,
          text_buffer_end - text_buffer,
          scroll_data . input,
          sizeof(scroll_data . input),
          1
        );
      scroll_data . update = 1;
    }

    usleep(100000);
  }

  free(text_buffer);
  pthread_join(scroll_data . thread_id, NULL);
  turn_off_display();

  return EXIT_SUCCESS;

} // main

//
// Drop (root) privileges
//
void drop_privileges()
{
  /*  Drop superuser privileges in correct order */

  int is_already_unprivileged = 0;

  if (setgid(65534) == -1) { // nobody
    perror("can't drop group privileges");
    if (! (is_already_unprivileged = (errno == 1)))
      exit(-1);
  }
  if (setuid(65534) == -1) { // nobody
    perror("can't drop user privileges");
    if (is_already_unprivileged != (errno == 1))
      exit(-1);
  }
} // drop_root

void handle_signals(int signo)
{
  switch (signo) {
    case SIGINT:
    case SIGHUP:
    case SIGTERM:
      fprintf(stderr, "stopping\n");
      scroll_data . keep_running = 0;
    break;
    case SIGUSR1:
      next_update = 0;
      scroll_data . shine_until = time(NULL) + 60;
    break;
  }
}