#include <png.h>

#include "types.h"
#include "action.h"
#include "canvas.h"
#include "debug.h"

#define COORD(x,y)  ((x) + (y) * c->w)

uint8
canvas_export_png(Canvas *c, const char *path)
{
	/* TODO: use a defer */
	uint xcnt, ycnt, cnt, w, h, i, j, k, l, col;
	FILE *file;
	png_structp png_ptr;
	png_infop info_ptr;
	uint *data, **row_ptr;

	if (c == NULL)
		return 1;

	if (c->layer_arr_cnt == 0 || c->frame_arr_cnt == 0)
		return 1;

	file = fopen(path, "wb");
	if (!file)
		return 1;

	cnt = xcnt = ycnt = 0;

	for (i = 0; i < c->frame_arr_cnt; i++) {
		cnt++;
		if (c->frames[i].state || i+1 == c->frame_arr_cnt) {
			++ycnt;
			xcnt = (cnt > xcnt) ? cnt : xcnt;
			cnt = 0;
		}
	}
	w = xcnt * c->w;
	h = ycnt * c->h;

	data = malloc(h*w*sizeof *data);
	if (data == NULL) {
		fclose(file);
		return 1;
	}
	row_ptr = malloc(h*sizeof *row_ptr);
	if (row_ptr == NULL) {
		fclose(file);
		free(data);
		return 1;
	}

	png_ptr = png_create_write_struct(PNG_LIBPNG_VER_STRING, NULL, NULL, NULL);
	if (!png_ptr) {
		fclose(file);
		free(data);
		free(row_ptr);
		return 1;
	}

	info_ptr = png_create_info_struct(png_ptr);
	if (!info_ptr) {
		png_destroy_write_struct(&png_ptr, NULL);
		fclose(file);
		free(data);
		free(row_ptr);
		return 1;
	}

	if (setjmp(png_jmpbuf(png_ptr))) {
		png_destroy_write_struct(&png_ptr, &info_ptr);
		fclose(file);
		free(data);
		free(row_ptr);
		return 1;
	}

	png_init_io(png_ptr, file);
	png_set_IHDR(png_ptr, info_ptr, w, h,
	    8, PNG_COLOR_TYPE_RGBA, PNG_INTERLACE_NONE,
	    PNG_COMPRESSION_TYPE_DEFAULT, PNG_FILTER_TYPE_DEFAULT);
/*	png_set_invert_alpha(png_ptr);*/
	png_write_info(png_ptr, info_ptr);
/*	png_set_swap(png_ptr);*/

	for (i = 0; i < w * h; i++)
		data[i] = 0;

	for (i = 0; i < h; i++)
		row_ptr[i] = &data[i * w];

	ycnt = cnt = 0;
	for (i = 0; i < c->frame_arr_cnt; i++) {
		for (k = 0; k < c->h; k++) {
			for (j = 0; j < c->w; j++) {
				col = 0;
				for (l = 0; l < c->layer_arr_cnt; l++)
					if (c->layers[l].visible)
						col = canvas_blend_color(col,
						    c->cells[c->layer_arr_cnt * i + l][COORD(j, k)]);
				data[(ycnt * c->h + k) * w + cnt * c->w + j] =
					((col&255)<<24) | (((col>>8)&255)<<16) | (((col>>16)&255)<<8) | (((col>>24)&255));
			}
		}

		if (c->frames[i].state || i+1 == c->frame_arr_cnt) {
			++ycnt;
			cnt = 0;
		} else {
			cnt++;
		}
	}

	png_write_image(png_ptr, row_ptr);
	png_write_end(png_ptr, info_ptr);
	png_destroy_write_struct(&png_ptr, &info_ptr);
	fclose(file);
	free(data);
	free(row_ptr);

	return 0;
}