#include <math.h>

#include <time.h>

#include <gtk/gtk.h>

#include <al.h>

#include <alc.h>

const double pi = 3.141592653589793;

GtkWidget *hours[3], *minutes[3];

GtkWidget *enable_alarm;

// This function plays beep via OpenAL.

// It's may be difficult to understand how it works, so just use it as is.

// This function uses OpenAL, so you need

//   to include <al.h> and <alc.h>

//   and link with OpenAL library (for GCC add param: -lopenal)

void beep() {

  const int frequency = 440;

  const int rate = 10000;

  ALCshort samples[2000];

  const int count = 2000;

  for(int i = 0; i < count; ++i)

    samples[i] = (int)(32760*sin(2*pi*i*frequency/rate));

  ALCdevice *device = alcOpenDevice(NULL);

  ALCcontext *context = alcCreateContext(device, NULL);

  alcMakeContextCurrent(context);

  ALuint buffer, source;

  alGenBuffers(1, &buffer);

  alBufferData(buffer, AL_FORMAT_MONO16, samples, sizeof(samples), rate);

  alGenSources(1, &source);

  alSourcei(source, AL_BUFFER, buffer);

  alSourcePlay(source);

  g_usleep(count*1000000/rate + 10000);

  alcMakeContextCurrent(NULL);

  alcDestroyContext(context);

  alcCloseDevice(device);

}

gboolean timeout(gpointer data) {

  if (gtk_toggle_button_get_active(GTK_TOGGLE_BUTTON(enable_alarm))) {

    time_t timer = time(NULL);

    struct tm *t = localtime(&timer);

    for(int i = 0; i < 3; ++i) {

      int hour = gtk_spin_button_get_value_as_int(GTK_SPIN_BUTTON(hours[i]));

      int minute = gtk_spin_button_get_value_as_int(GTK_SPIN_BUTTON(minutes[i]));

      if (hour == t->tm_hour && minute == t->tm_min)

        beep();

    }

  }  

  return TRUE;

}

void activate(GtkApplication* app, gpointer data) {

  GtkWidget *window = gtk_application_window_new (app);

  gtk_container_set_border_width(GTK_CONTAINER(window), 10);  

  GtkWidget *vbox = gtk_box_new(GTK_ORIENTATION_VERTICAL, 5);

  gtk_container_add(GTK_CONTAINER(window), vbox);

  GtkWidget *label = gtk_label_new("Set following three alarm clocks,\nenable alarm\nand take a sleep.");

  gtk_container_add(GTK_CONTAINER(vbox), label);

  for(int i = 0; i < 3; ++i) {

    GtkWidget *hbox = gtk_box_new(GTK_ORIENTATION_HORIZONTAL, 5);

    gtk_container_add(GTK_CONTAINER(vbox), hbox);

    hours[i] = gtk_spin_button_new(NULL, 1.2, 0);

    gtk_spin_button_set_range(GTK_SPIN_BUTTON(hours[i]), 0.0, 23.0);

    gtk_spin_button_set_increments(GTK_SPIN_BUTTON(hours[i]), 1.0, 10.0);

    gtk_spin_button_set_wrap(GTK_SPIN_BUTTON(hours[i]), TRUE);

    gtk_container_add(GTK_CONTAINER(hbox), hours[i]);

    minutes[i] = gtk_spin_button_new(NULL, 1.2, 0);

    gtk_spin_button_set_range(GTK_SPIN_BUTTON(minutes[i]), 0.0, 59.0);

    gtk_spin_button_set_increments(GTK_SPIN_BUTTON(minutes[i]), 1.0, 10.0);

    gtk_spin_button_set_wrap(GTK_SPIN_BUTTON(minutes[i]), TRUE);

    gtk_container_add(GTK_CONTAINER(hbox), minutes[i]);

  }

  // set initial values

  time_t timer = time(NULL);

  struct tm *t = localtime(&timer);

  int h = t->tm_hour;

  int m = t->tm_min;

  gtk_spin_button_set_value(GTK_SPIN_BUTTON(hours[0]), h);

  gtk_spin_button_set_value(GTK_SPIN_BUTTON(minutes[0]), m);

  m += 1;

  if (m >= 60) { m -= 60; h = (h + 1)%24; }

  gtk_spin_button_set_value(GTK_SPIN_BUTTON(hours[1]), h);

  gtk_spin_button_set_value(GTK_SPIN_BUTTON(minutes[1]), m);

  m += 4;

  if (m >= 60) { m -= 60; h = (h + 1)%24; }

  gtk_spin_button_set_value(GTK_SPIN_BUTTON(hours[2]), h);

  gtk_spin_button_set_value(GTK_SPIN_BUTTON(minutes[2]), m);

  enable_alarm = gtk_check_button_new_with_label("Enable alarm");

  gtk_container_add(GTK_CONTAINER(vbox), enable_alarm);

  gtk_widget_show_all(window);

  g_timeout_add(1000, timeout, NULL);

}

int main(int argc, char **argv) {

  GtkApplication *application = gtk_application_new(NULL, 0);

  g_signal_connect(application, "activate", G_CALLBACK(activate), NULL);

  int status = g_application_run(G_APPLICATION(application), argc, argv);

  g_object_unref(application);

  return status;

}