/*
 * gui.c - Graphical output for ubb-la
 *
 * Written 2013 by Werner Almesberger
 * Copyright 2013 Werner Almesberger
 *
 * 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 2 of the License, or
 * (at your option) any later version.
 */

#include <stdint.h>
#include <stdlib.h>

#include "SDL.h"
#include "SDL_gfxPrimitives.h"

#include "gui.h"


#define XRES	320	/* canvas width */
#define YRES	240	/* canvas height */

#define	LEVEL_RGBA	0xffff00ff
#define	BOUNCE_RGBA	0xff8080ff

#define	CH_XOFF		30
#define	CH_YOFF		30
#define	CH_SKIP		16
#define	CH_HEIGHT	8

#define	MAX_ZOOM	8


static SDL_Surface *surf;


void gui_init(void)
{
	if (SDL_Init(SDL_INIT_VIDEO) < 0) {
		fprintf(stderr, "SDL_init: %s\n", SDL_GetError());
		exit(1);
	}
	atexit(SDL_Quit);

	surf = SDL_SetVideoMode(XRES, YRES, 0, SDL_SWSURFACE);
	if (!surf) {
		fprintf(stderr, "SDL_SetVideoMode: %s\n", SDL_GetError());
		exit(1);
	}
}


static void clear(void)
{
	SDL_LockSurface(surf);
	SDL_FillRect(surf, NULL, SDL_MapRGB(surf->format, 0, 0, 0));
}


static inline int ch_y(int ch, int v)
{
	return CH_YOFF+CH_SKIP*ch+(v ? 0 : CH_HEIGHT);
}


static void bounce(int x, int ch)
{
	vlineColor(surf, x, ch_y(ch, 0), ch_y(ch, 1), BOUNCE_RGBA);
}


static void change(int x, int ch)
{
	vlineColor(surf, x, ch_y(ch, 0), ch_y(ch, 1), LEVEL_RGBA);
}


static void level(int x, int ch, int v)
{
	pixelColor(surf, x, ch_y(ch, v), LEVEL_RGBA);
}


static void show_buffer(const uint8_t *buf, int skip, int nibbles,
    int x0, int x1)
{
	double f = (nibbles-skip)/(x1-x0+1.0);
	int x;
	int i = skip-1, n, j;
	int changes[4], last[4] = { -1, -1, -1, -1}, next[4];
	uint8_t v, bit;

	for (x = x0; x != x1+1; x++) {
		n = (x-x0)*f+skip;
		if (i == n) {
			for (j = 0; j != 4; j++)
				level(x, j, last[j]);
			continue;
		}
		for (j = 0; j != 4; j++) {
			next[j] = last[j];
			changes[j] = 0;
		}
		while (i != n) {
			i++;
			v = (buf[i >> 1] >> 4*(~i & 1)) & 0xf;
			for (j = 0; j != 4; j++) {
				bit = (v >> j) & 1;
				if (bit != next[j]) {
					changes[j]++;
					next[j] = bit;
				}
			}
		}
		for (j = 0; j != 4; j++) {
			if (changes[j] > 1)
				bounce(x, j);
			else if (!changes[j] || last[j] == -1)
				level(x, j, next[j]);
			else
				change(x, j);
			last[j] = next[j];
		}
	}
}


static void update(void)
{
	SDL_UnlockSurface(surf);
	SDL_UpdateRect(surf, 0, 0, 0, 0);
}


void gui(const uint8_t *buf, int skip, int nibbles)
{
	SDL_Event event;
	int zoom = 0;
	int m, w;

	while (1) {
		m = (nibbles-skip) >> 1;
		w = (nibbles-skip) >> zoom;
		clear();
		show_buffer(buf, m-(w >> 1), m+(w >> 1), CH_XOFF, XRES-1);
		update();

		do {
			SDL_WaitEvent(&event);
			switch (event.type) {
			case SDL_KEYDOWN:
				switch (event.key.keysym.sym) {
				case SDLK_UP:
					if (zoom < MAX_ZOOM)
						zoom++;
					break;
				case SDLK_DOWN:
					if (zoom)
						zoom--;
					break;
				case SDLK_RETURN:
				case SDLK_q:
					return;
				default:
					printf("%x\n", event.key.keysym.sym);
					continue;
				}
				break;
			case SDL_QUIT:
				return;
			default:
				continue;
			}	
		}
		while (0);
	}
}