/*
 * glitchyclock.c
 *
 * Copyright © 2019 Thomas White <taw@bitwiz.me.uk>
 *
 * This program is free software: you can redistribute it and/or modify
 * it under the terms of the GNU General Public License as published by
 * the Free Software Foundation, either version 3 of the License, or
 * (at your option) any later version.
 *
 * This program is distributed in the hope that it will be useful,
 * but WITHOUT ANY WARRANTY; without even the implied warranty of
 * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
 * GNU General Public License for more details.
 *
 * You should have received a copy of the GNU General Public License
 * along with this program.  If not, see <http://www.gnu.org/licenses/>.
 *
 */

/* Get LED display fonts from here: https://www.keshikan.net/fonts-e.html */

#include <gtk/gtk.h>
#include <math.h>

struct glitchyclock
{
	GtkWidget *da;
	PangoFontDescription *fontdesc;
	int nglitch;
	double glitch_base;
};


const int glitch_times[] = {
	 4, 15,
	23, 58,
	-1, -1
};


static double get_monotonic_seconds()
{
	struct timespec tp;
	clock_gettime(CLOCK_MONOTONIC, &tp);
	return tp.tv_sec + (double)tp.tv_nsec/1e9;
}


static void do_glitch(struct glitchyclock *gc)
{
	//if ( glitch_times[2*(gc->nglitch+1)] == -1 ) return;
	//gc->nglitch++;
	gc->glitch_base = get_monotonic_seconds();
}


static gboolean draw_sig(GtkWidget *widget, cairo_t *cr, struct glitchyclock *gc)
{
	int w, h;
	int lw, lh;
	double sf;
	PangoLayout *layout;
	const double screen_w_frac = 0.6;
	int glitch_hours, glitch_minutes;
	char timestr[64];
	double seconds_f;
	char col;
	double seconds_if;
	int hours, minutes, seconds;

	w = gtk_widget_get_allocated_width(widget);
	h = gtk_widget_get_allocated_height(widget);

	/* Overall background */
	cairo_set_source_rgb(cr, 0.0, 0.0, 0.0);
	cairo_paint(cr);

	layout = pango_layout_new(gtk_widget_get_pango_context(widget));
	pango_layout_set_alignment(layout, PANGO_ALIGN_CENTER);
	pango_layout_set_font_description(layout, gc->fontdesc);

	seconds_f = get_monotonic_seconds() - gc->glitch_base;
	col = (modf(seconds_f, &seconds_if) < 0.5) ? ':' : ' ';
	seconds = seconds_if;
	if ( seconds > 16 ) seconds = 16;

	hours = (seconds/3600 + 4) % 24;
	minutes = (seconds/60 + 48) % 60;
	seconds += 15;
	snprintf(timestr, 63, "%02i%c%02i%c%02i", hours, col, minutes, col, seconds);

	double duty = 0.5;
	if ( seconds_f > 17.0 ) {
		duty = 0.5 + (seconds_f - 17.0)/10.0;
		if ( duty > 1.0 ) duty = 1.0;
	}
	if ( ((seconds_f > 7.1) && (seconds_f < 7.9))
	  || ((seconds_f > 12.2) && (seconds_f < 13.1))
	  || ((seconds_f > 17.0)) )
	{
		if ( fmod(seconds_f, 0.05) > duty*0.05 ) {
			strcpy(timestr, "00:rK:c1");
		} else {
			strcpy(timestr, "88:v8:68");
		}
	}

	pango_layout_set_text(layout, "88:88:88", -1);

	pango_cairo_update_layout(cr, layout);
	pango_layout_get_size(layout, &lw, &lh);

	sf = (double)PANGO_SCALE*screen_w_frac*w/lw;
	cairo_scale(cr, sf, sf);
	pango_cairo_update_layout(cr, layout);

	pango_layout_get_size(layout, &lw, &lh);
	lw /= PANGO_SCALE;  lh /= PANGO_SCALE;
	w /= sf;  h /= sf;
	cairo_translate(cr, (w-lw)/2.0, h-lh-20.0);
	pango_cairo_update_layout(cr, layout);

	cairo_set_source_rgb(cr, 0.10, 0.0, 0.0);
	pango_cairo_show_layout(cr, layout);

	pango_layout_set_text(layout, timestr, -1);
	cairo_set_source_rgb(cr, 0.95, 0.0, 0.05);
	pango_cairo_show_layout(cr, layout);

	return FALSE;
}


static gboolean redraw_cb(gpointer data)
{
	gint w, h;
	struct glitchyclock *gc = data;
	w = gtk_widget_get_allocated_width(GTK_WIDGET(gc->da));
	h = gtk_widget_get_allocated_height(GTK_WIDGET(gc->da));
	gtk_widget_queue_draw_area(GTK_WIDGET(gc->da), 0, 0, w, h);
	return G_SOURCE_CONTINUE;
}


static gboolean key_press_sig(GtkWidget *da, GdkEventKey *event, struct glitchyclock *gc)
{
	if ( event->keyval == GDK_KEY_KP_Enter ) {
		do_glitch(gc);
		redraw_cb(gc);
		return TRUE;
	}

	return FALSE;
}


static gint realise_sig(GtkWidget *da, struct glitchyclock *gc)
{
	GdkWindow *win = gtk_widget_get_window(da);

	/* Keyboard and input method stuff */
	gdk_window_set_accept_focus(win, TRUE);
	g_signal_connect(G_OBJECT(da), "key-press-event", G_CALLBACK(key_press_sig), gc);

	gc->fontdesc = pango_font_description_from_string("DSEG7 Modern Bold Italic 16");

	return FALSE;
}


int main(int argc, char *argv[])
{
	struct glitchyclock gc;
	GtkWidget *mainwindow;

	gc.nglitch = 0;
	gc.glitch_base = get_monotonic_seconds();
	gtk_init(&argc, &argv);

	mainwindow = gtk_window_new(GTK_WINDOW_TOPLEVEL);
	gtk_window_fullscreen(GTK_WINDOW(mainwindow));
	g_signal_connect_swapped(G_OBJECT(mainwindow), "destroy", gtk_main_quit, NULL);

	gc.da = gtk_drawing_area_new();
	gtk_container_add(GTK_CONTAINER(mainwindow), GTK_WIDGET(gc.da));
	gtk_widget_set_can_focus(GTK_WIDGET(gc.da), TRUE);
	gtk_widget_add_events(gc.da, GDK_KEY_PRESS_MASK | GDK_KEY_RELEASE_MASK);
	g_signal_connect(G_OBJECT(gc.da), "draw", G_CALLBACK(draw_sig), &gc);
	g_signal_connect(G_OBJECT(gc.da), "realize", G_CALLBACK(realise_sig), &gc);

	gtk_widget_grab_focus(GTK_WIDGET(gc.da));
	gtk_widget_show_all(mainwindow);

	g_timeout_add(20, redraw_cb, &gc);

	gtk_main();

	return 0;
}