/*
 * glitchyclock.c
 *
 * Copyright © 2019-2020 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>
#include <string.h>

struct glitchyclock
{
	GtkWidget *da;
	PangoFontDescription *fontdesc;
	int cue;
	double real_time_last_cue;
	double real_time_last_reset;
	double brightness;
	int base_hours;
	int base_minutes;
	int base_seconds;
	int flag;

	double clock_x;
	double clock_y;
	double clock_w;
	double clock_h;
};


enum glitch_type
{
	BLACKOUT,       /* Fade to black, parameter is fade time in seconds */
	FADE_IN,        /* Fade from black to running clock, parameter is fade time in seconds */
	FADE_IN_FROZEN, /* Fade from black to running clock, parameter is fade time in seconds */
	BLACKOUT_FROZEN,
	GLITCH_BACK,    /* Glitch and then jump back, parameter is number of minutes */
	GLITCH_STOP,    /* Glitch and then stop, parameter is number of minutes */
	GLITCH,         /* Glitch for the number of seconds */
	EOL             /* End of list */
};


struct glitch_cue
{
	int type;
	int parameter;
	int hours;
	int minutes;
	int seconds;
};


struct glitch_cue cues[] = {
	{ BLACKOUT, 0, 0,0,0},
	{ FADE_IN, 1, 23, 10, 50 },  /* Act I sc 1 */
	{ BLACKOUT, 1, 0,0,0},
	{ FADE_IN, 1,   9, 52, 50 }, /* Act I sc 2 */
	{ BLACKOUT, 3, 0,0,0 },
	{ FADE_IN, 1,  22, 27, 50 },
	{ BLACKOUT, 1, 0,0,0},
	{ FADE_IN, 1,   1, 13, 50 },
	{ BLACKOUT, 0, 0,0,0},
	{ FADE_IN, 1,  22, 45, 50 },
	{ GLITCH_BACK, 103, 0,0,0},
	{ GLITCH_BACK, 33, 0,0,0},
	{ BLACKOUT, 1,  0,  0, 12 },
	{ FADE_IN, 1,   2,  1, 50 },
	{ BLACKOUT, 1,  0,0,0 },
	{ FADE_IN, 1,   3, 21, 50 },  /* Act I sc VII */
	{ GLITCH, 1, 0,0,0},
	{ GLITCH, 3, 0,0,0},
	{ GLITCH_STOP, 2, 0, 0, 12},
	//{ BLACKOUT_FROZEN, 3,  0, 0, 12 },
	//{ FADE_IN_FROZEN, 3, 0, 0, 12 },
	//{ BLACKOUT_FROZEN, 3 , 0, 0, 12},
	//{ FADE_IN_FROZEN, 3, 0, 0, 12 },
	{ BLACKOUT_FROZEN, 0 , 0, 0, 12},
	{ EOL, 0, 0, 0, 0 }
};

const double screen_w_frac = 0.2;    /* Fraction of screen width */
const double screen_y_offset = 0.5;  /* Fraction of screen height */
const double clock_aspect = 0.305;   /* Clock height divided by width */

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


static void run_cue(struct glitchyclock *gc)
{
	if ( cues[gc->cue].type == EOL ) return;
	gc->cue++;
	gc->real_time_last_cue = get_monotonic_seconds();
	gc->flag = 0;
	if ( cues[gc->cue].type == FADE_IN ) {
		gc->real_time_last_reset = get_monotonic_seconds();
		gc->base_hours = cues[gc->cue].hours;
		gc->base_minutes = cues[gc->cue].minutes;
		gc->base_seconds = cues[gc->cue].seconds;
	}
}


static void back_cue(struct glitchyclock *gc)
{
	if ( gc->cue == 0 ) return;
	gc->cue--;
	gc->real_time_last_cue = get_monotonic_seconds() - 10;
	gc->flag = 1;
	if ( cues[gc->cue].type == FADE_IN ) {
		gc->real_time_last_reset = get_monotonic_seconds() - 10;
		gc->base_hours = cues[gc->cue].hours;
		gc->base_minutes = cues[gc->cue].minutes;
		gc->base_seconds = cues[gc->cue].seconds;
	}
}




static gboolean draw_sig(GtkWidget *widget, cairo_t *cr, struct glitchyclock *gc)
{
	double lw, lh;
	int ilw, ilh;
	PangoLayout *layout;
	char timestr[64];
	double seconds_elapsed, seconds_rounded;
	double real_seconds_elapsed, real_seconds_rounded;
	char col;
	int clock_hours, clock_minutes, clock_seconds;
	int glitch = 0;
	double duty;
	const char *frozenstr = "uK:IW";

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

	cairo_translate(cr, gc->clock_x, gc->clock_y);

	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_elapsed = get_monotonic_seconds() - gc->real_time_last_cue;
	modf(seconds_elapsed, &seconds_rounded);

	real_seconds_elapsed = get_monotonic_seconds() - gc->real_time_last_reset;
	col = (modf(real_seconds_elapsed, &real_seconds_rounded) < 0.5) ? ':' : ' ';
	clock_hours = gc->base_hours;
	clock_minutes = gc->base_minutes;
	clock_seconds = gc->base_seconds + real_seconds_rounded;

	clock_minutes += clock_seconds / 60;
	clock_seconds = clock_seconds % 60;
	clock_hours += clock_minutes / 60;
	clock_minutes = clock_minutes % 60;
	clock_hours = clock_hours % 24;

	snprintf(timestr, 63, "%02i%c%02i", clock_hours, ':', clock_minutes);

	if ( cues[gc->cue].type == FADE_IN ) {
		gc->brightness = seconds_elapsed / cues[gc->cue].parameter;
		if ( gc->brightness > 1.0 ) gc->brightness = 1.0;
	}

	if ( cues[gc->cue].type == FADE_IN_FROZEN ) {
		gc->brightness = seconds_elapsed / cues[gc->cue].parameter;
		if ( gc->brightness > 1.0 ) gc->brightness = 1.0;
		strcpy(timestr, frozenstr);
	}

	if ( cues[gc->cue].type == BLACKOUT ) {
		gc->brightness = 1.0 - (seconds_elapsed / cues[gc->cue].parameter);
		if ( gc->brightness < 0.0 ) gc->brightness = 0.0;
	}

	if ( cues[gc->cue].type == BLACKOUT_FROZEN ) {
		gc->brightness = 1.0 - (seconds_elapsed / cues[gc->cue].parameter);
		if ( gc->brightness < 0.0 ) gc->brightness = 0.0;
		strcpy(timestr, frozenstr);
	}

	if ( (cues[gc->cue].type == GLITCH)
	  && (seconds_elapsed < cues[gc->cue].parameter) )
	{
		duty = 0.5;
		glitch = 1;
	}

	if ( cues[gc->cue].type == GLITCH_STOP ) {
		glitch = 1;
		duty = 0.5 + seconds_elapsed / cues[gc->cue].parameter;
		if ( duty > 1.0 ) duty = 1.0;
	}

	if ( cues[gc->cue].type == GLITCH_BACK ) {
		if ( !gc->flag ) {
			duty = 0.5 + seconds_elapsed / 4;
			glitch = 1;
			if ( duty > 1.0 ) {
				duty = 1.0;
				gc->real_time_last_reset += cues[gc->cue].parameter * 60;

				/* The real_time_elapsed will now probably be
				 * negative (unless the clock glitched back by
				 * less than real_time_elapsed).  To avoid
				 * negative numbers appearing, go back a whole
				 * day.  Yes, I'm a dirty cheat. */
				gc->real_time_last_reset -= 24*60*60;
				gc->flag = 1;
			}
		} else {
			glitch = 0;
		}
	}

	if ( glitch ) {
		if ( fmod(seconds_elapsed, 0.05) > duty*0.05 ) {
			strcpy(timestr, "Tz:Yi");
		} else {
			strcpy(timestr, frozenstr);
		}
	}

	pango_layout_set_text(layout, "88:88", -1);
	pango_cairo_update_layout(cr, layout);
	pango_layout_get_size(layout, &ilw, &ilh);
	lw = (double)ilw / PANGO_SCALE;
	lh = (double)ilh / PANGO_SCALE;
	cairo_scale(cr, gc->clock_w/lw, gc->clock_h/lh);

	pango_cairo_update_layout(cr, layout);
	cairo_set_source_rgb(cr, gc->brightness*0.20, 0.0, 0.0);
	pango_cairo_show_layout(cr, layout);

	pango_layout_set_text(layout, timestr, -1);
	cairo_set_source_rgb(cr, gc->brightness*0.95, gc->brightness*0.0, gc->brightness*0.05);
	pango_cairo_show_layout(cr, layout);

	return FALSE;
}


static gboolean configure_sig(GtkWidget *da, GdkEventConfigure *event, struct glitchyclock *gc)
{
	gc->clock_w = screen_w_frac * event->width;
	gc->clock_h = clock_aspect * gc->clock_w;
	gc->clock_x = (event->width - gc->clock_w)/2.0;
	gc->clock_y = event->height * screen_y_offset;

	return FALSE;
}


static gboolean redraw_cb(gpointer data)
{
	struct glitchyclock *gc = data;
	gtk_widget_queue_draw_area(GTK_WIDGET(gc->da), gc->clock_x, gc->clock_y,
	                                               gc->clock_w, gc->clock_h);
	return G_SOURCE_CONTINUE;
}


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

	if ( event->keyval == GDK_KEY_BackSpace ) {
		back_cue(gc);
		redraw_cb(gc);
		return TRUE;
	}

	if ( event->keyval == GDK_KEY_q ) {
		gtk_main_quit();
	}

	return FALSE;
}


static gint realise_sig(GtkWidget *da, struct glitchyclock *gc)
{
	GdkCursor *cursor;
	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 24");

	cursor = gdk_cursor_new_for_display(gtk_widget_get_display(da), GDK_BLANK_CURSOR);
	gdk_window_set_cursor(gtk_widget_get_window(da), cursor);

	return FALSE;
}


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

	gc.cue = 0;
	gc.brightness = 0.0;
	gc.real_time_last_cue = get_monotonic_seconds();
	gc.real_time_last_reset = get_monotonic_seconds();
	gc.base_hours = cues[gc.cue].hours;
	gc.base_minutes = cues[gc.cue].minutes;
	gc.base_seconds = cues[gc.cue].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);
	g_signal_connect(G_OBJECT(gc.da), "configure-event", G_CALLBACK(configure_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;
}