/*
 * 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 <assert.h>
#include <stdlib.h>
#include <stdio.h>

#include <png.h>

#include "font.h"
#include "i18n.h"
#include "output.h"
#include "text.h"

struct image {
	FILE        *fp;
	png_structp  png_ptr;
	png_infop    info_ptr;
};

struct image *
image_new(const char *file_name)
{
	struct image *image;

	assert(file_name && *file_name);

	image = calloc(1, sizeof(*image));
	if (!image) {
		error(_("Cannot allocate memory for image object"));
		return NULL;
	}

	if (strcmp(file_name, "-") != 0) {
		image->fp = fopen(file_name, "wb");
		if (!image->fp) {
			error(_("Cannot open \"%s\" for writing"), file_name);
			return image_destroy(&image);
		}
	}

	image->png_ptr = png_create_write_struct(PNG_LIBPNG_VER_STRING,
			NULL, NULL, NULL);
	if (!image->png_ptr) {
		error(_("Failed to create PNG structure"));
		return image_destroy(&image);
	}

	image->info_ptr = png_create_info_struct(image->png_ptr);
	if (!image->info_ptr) {
		error(_("Failed to create PNG info structure"));
		return image_destroy(&image);
	}

	if (image->fp) {
		png_init_io(image->png_ptr, image->fp);
	} else {
		png_init_io(image->png_ptr, stdout);
	}

	return image;
}

void
image_render(struct image *image, const struct text *text,
		const struct font *font)
{
	size_t     width;
	size_t     height;
	png_byte **rows;
	size_t     i;

	assert(image);
	assert(text);
	assert(font);

	width  = text_get_width(text)  * font_get_width(font);
	height = text_get_height(text) * font_get_height(font);

	png_set_IHDR(image->png_ptr, image->info_ptr, width, height,
			IMAGE_BIT_DEPTH, PNG_COLOR_TYPE_RGB, PNG_INTERLACE_NONE,
			PNG_COMPRESSION_TYPE_DEFAULT, PNG_FILTER_TYPE_DEFAULT);

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

	text_render(text, font, rows);

	png_write_png(image->png_ptr, image->info_ptr, PNG_TRANSFORM_IDENTITY,
			NULL);

	for (i = 0; i < height; ++i) {
		png_free(image->png_ptr, rows[i]);
	}
	png_free(image->png_ptr, rows);
}

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

	assert(image_p && *image_p);

	image = *image_p;

	if (image->fp) {
		fclose(image->fp);
	}
	png_destroy_write_struct(&image->png_ptr, &image->info_ptr);
	free(image);
	return image = NULL;
}