/*
 * Image output functions
 *
 * Copyright (C) 2019  Patrick McDermott
 *
 * This file is part of fbcon2png.
 *
 * fbcon2png 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.
 *
 * fbcon2png 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 fbcon2png.  If not, see <http://www.gnu.org/licenses/>.
 */

#include "image.h"

#include <stdlib.h>
#include <stdio.h>

#include <png.h>

#include "i18n.h"

#define BIT_DEPTH    4
#define PALETTE_SIZE (1 << BIT_DEPTH)
#define PIXEL_SIZE   ((BIT_DEPTH + 7) / 8)

struct image {
	png_structp  png_ptr;
	png_infop    info_ptr;
	png_bytepp   rows;
};

static png_color palette[PALETTE_SIZE];

struct image *
image_new(const char *file_name)
{
	struct image *image;
	FILE         *fp;
	size_t        i;
	size_t        width  = 32;
	size_t        height = 32;

	image = calloc(1, sizeof(*image));
	if (!image) {
		return NULL;
	}

	fp = fopen(file_name, "wb");
	if (!fp) {
		printf(_("Error: Cannot open \"%s\" for writing\n"), file_name);
		return image_destroy(&image);
	}

	image->png_ptr = png_create_write_struct(PNG_LIBPNG_VER_STRING,
			NULL, NULL, NULL);
	if (!image->png_ptr) {
		return image_destroy(&image);
	}

	image->info_ptr = png_create_info_struct(image->png_ptr);
	if (!image->info_ptr) {
		return image_destroy(&image);
	}

	png_init_io(image->png_ptr, fp);

	png_set_IHDR(image->png_ptr, image->info_ptr, width, height,
			BIT_DEPTH, PNG_COLOR_TYPE_PALETTE, PNG_INTERLACE_NONE,
			PNG_COMPRESSION_TYPE_DEFAULT, PNG_FILTER_TYPE_DEFAULT);
	png_set_PLTE(image->png_ptr, image->info_ptr, palette, PALETTE_SIZE);

	image->rows = png_malloc(image->png_ptr, height * sizeof(*image->rows));
	for (i = 0; i < height; ++i) {
		image->rows[i] = png_malloc(image->png_ptr, width * PIXEL_SIZE);
	}
	png_set_rows(image->png_ptr, image->info_ptr, image->rows);

	return image;
}

void
image_render(struct image *image)
{
	png_write_png(image->png_ptr, image->info_ptr, PNG_TRANSFORM_IDENTITY,
			NULL);
}

struct image *
image_destroy(struct image **image_p)
{
	struct image *image;
	size_t        i;

	image = *image_p;

	for (i = 0; i < 32; ++i) {
		png_free(image->png_ptr, image->rows[i]);
	}
	png_free(image->png_ptr, image->rows);
	png_destroy_write_struct(&image->png_ptr, &image->info_ptr);
	free(image);
	return image = NULL;
}