#define _GNU_SOURCE
#include <stdio.h>
#include <stdlib.h>
#include <string.h>
#include <limits.h>
#include <assert.h>
#include <getopt.h>
#include <errno.h>

#include <png.h>

#include "image.h"
#include "lbx.h"

/* Global flags */
static int verbose = 0;
static char *outname = "out";
static int usepalette = 1;

static const char *progname;
#define errmsg(fmt, ...) (\
	fprintf(stderr, "%s: " fmt, progname, __VA_ARGS__)\
)

enum {
	MODE_NONE,
	MODE_DECODE,
	MODE_IDENT,
};

int parserange(struct lbx_imginfo *info, char *str, unsigned char *bits)
{
	unsigned long start, end;
	unsigned int i;
	char *endptr;

	start = strtoul(str, &endptr, 0);
	if (start >= info->nframes) {
		errmsg("frame %lu out of range.\n", start);
		return -1;
	}

	if (endptr == str) {
		errmsg("invalid frame range: %s.\n", str);
		return -1;
	}

	switch (*endptr) {
	case '\0':
		end = start;
		break;
	case '-':
		end = strtoul(endptr+1, &endptr, 0);
		if (end >= info->nframes) {
			errmsg("frame %lu out of range.\n", end);
			return -1;
		}

		if (endptr == str)
			end = info->nframes - 1;
		break;
	default:
		errmsg("invalid frame range: %s.\n", str);
		return -1;
	}

	if (end < start) {
		errmsg("invalid frame range: %s.\n", str);
		return -1;
	}

	for (i = start; i <= end; i++) {
		bits[i / CHAR_BIT] |= 1 << (i % CHAR_BIT);
	}

	return 0;
}

int outpng(unsigned int frameno, unsigned char **framedata,
           unsigned int width,   unsigned int height,
           struct lbx_colour palette[static 256])
{
	char name[strlen(outname) + sizeof ".65535.png"];
	FILE *of;

	png_structp png;
	png_infop   info;

	assert(frameno < 65536);
	snprintf(name, sizeof name, "%s.%03d.png", outname, frameno);
	
	of = fopen(name, "wb");
	if (!of) {
		errmsg("failed to open %s: %s.\n", name, strerror(errno));
		return -1;
	}

	png = png_create_write_struct(PNG_LIBPNG_VER_STRING, NULL, NULL, NULL);
	if (!png) {
		errmsg("failed to init libpng.\n", 0);
		goto err;
	}

	info = png_create_info_struct(png);
	if (!info) {
		errmsg("failed to init libpng.\n", 0);
		png_destroy_write_struct(&png, NULL);
		goto err;
	}

	if (setjmp(png_jmpbuf(png))) {
		png_destroy_write_struct(&png, &info);
		goto err;
	}

		
	png_set_IHDR(png, info, width, height, 8,
	             usepalette ? PNG_COLOR_TYPE_PALETTE : PNG_COLOR_TYPE_GRAY,
	             PNG_INTERLACE_NONE, PNG_COMPRESSION_TYPE_DEFAULT,
	             PNG_FILTER_TYPE_DEFAULT);

	if (usepalette)
		png_set_PLTE(png, info, (png_colorp)palette, 256);
	png_set_rows(png, info, framedata);

	png_init_io(png, of);
	png_write_png(png, info, PNG_TRANSFORM_IDENTITY, NULL);

	png_destroy_write_struct(&png, &info);
	fclose(of);

	if (verbose)
		printf("wrote %s\n", name);

	return 0;
err:
	fclose(of);
	remove(name);
	return -1;
}

static int loadpalette(LBX_IMG *img, struct lbx_imginfo *info,
                       FILE *palf, struct lbx_colour palette[static 256])
{
	int i;

	for (i = 0; i < 256; i++)
		palette[i] = (struct lbx_colour){0xff, 0x00, 0xff};

	if (palf) {
		if (lbximg_loadpalette(palf, palette) == -1) {
			errmsg("error reading palette: %s\n", lbx_strerror());
			return -1;
		}
	} else if (!info->haspalette) {
		errmsg("no palette available.\n", 0);
		return -1;
	}

	if (lbximg_getpalette(img, palette) == -1) {
		errmsg("error reading embedded palette: %s\n", lbx_strerror());
		return -1;
	}

	return 0;
}

int decode(LBX_IMG *img, FILE *palf, FILE *override, char **argv)
{
	unsigned char *framebits;
	struct lbx_colour palette[256];
	struct lbx_imginfo info;
	int extracted = 0;
	unsigned int i;

	lbximg_getinfo(img, &info);

	framebits = malloc(info.nframes / CHAR_BIT + 1);
	if (!framebits) {
		return EXIT_FAILURE;
	}

	/* Figure out what images we're extracting. */
	if (!argv[0]) {
		/* extract all images by default. */
		memset(framebits, -1, info.nframes / CHAR_BIT + 1);
	} else {
		for (i = 0; argv[i]; i++) {
			parserange(&info, argv[i], framebits);
		}
	}

	if (usepalette && loadpalette(img, &info, palf, palette) == -1) {
		goto err;
	}

	if (override) {
		LBX_IMG *overimg = lbximg_fopen(override);
		struct lbx_imginfo info;

		if (!overimg) {
			errmsg("failed to open override image: %s\n",
			       lbx_strerror());
			goto err;
		}
		lbximg_getinfo(overimg, &info);

		if (!info.haspalette) {
			errmsg("override image has no palette.\n", 0);
			lbximg_close(overimg);
			goto err;
		}

		if (lbximg_getpalette(overimg, palette) == -1) {
			errmsg("error reading override palette: %s\n",
			       lbx_strerror());
			lbximg_close(overimg);
			goto err;
		}

		lbximg_close(overimg);
	}

	/* Extract the images, in order. */
	for (i = 0; i < info.nframes; i++) {
		unsigned char **framedata;

		if (!(framebits[i / CHAR_BIT] & (1 << (i % CHAR_BIT))))
			continue;

		framedata = lbximg_getframe(img, i);
		if (!framedata) {
			errmsg("error in frame %u: %s\n", i, lbx_strerror());
			continue;
		}

		if (!outpng(i, framedata, info.width, info.height, palette)) {
			extracted = 1;
		}
	}

	if (!extracted) {
		errmsg("no frames extracted.\n", 0);
		goto err;
	}
	
	free(framebits);
	return EXIT_SUCCESS;
err:
	free(framebits);
	return EXIT_FAILURE;
}

int main(int argc, char **argv)
{
	int mode = MODE_NONE;
	FILE *inf = stdin, *palf = NULL, *overf = NULL;
	const char *name = "stdin";
	LBX_IMG *img;
	int opt;

	static const char *sopts = "idvf:p:O:";
	static const struct option lopts[] = {
		{ "info",     0, NULL, 'i' },
		{ "decode",   0, NULL, 'd' },
		{ "verbose",  0, NULL, 'v' },
		{ "file",     1, NULL, 'f' },
		{ "palette",  1, NULL, 'p' },
		{ "override", 1, NULL, 'p' },

		{ "nopalette", 0, &usepalette, 0 },

		{ 0 }
	};

	progname = "lbximg"; /* argv[0]; */
	while ((opt = getopt_long(argc, argv, sopts, lopts, NULL)) != -1) {
		switch(opt) {
		case 'i':
			mode = MODE_IDENT;
			break;
		case 'd':
			mode = MODE_DECODE;
			break;
		case 'v':
			verbose = 1;
			break;
		case 'f':
			if (strcmp(optarg, "-") == 0)
				break;

			name = strrchr(optarg, '/');
			name = name ? name+1 : optarg;

			inf = fopen(optarg, "rb");
			if (!inf) {
				errmsg("failed to open %s: %m\n", optarg);
				return EXIT_FAILURE;
			}
			break;
		case 'p':
			palf = fopen(optarg, "rb");
			if (!palf) {
				errmsg("failed to open %s: %m\n", optarg);
				return EXIT_FAILURE;
			}

			break;
		case 'O':
			overf = fopen(optarg, "rb");
			if (!overf) {
				errmsg("failed to open %s: %m\n", optarg);
				return EXIT_FAILURE;
			}
			break;
		case '?':
		case ':':
			return EXIT_FAILURE;
		}
	}

	if (mode == MODE_NONE) {
		errmsg("you must specify a mode.\n", 0);
		return EXIT_FAILURE;
	}

	img = lbximg_fopen(inf);
	if (!img) {
		errmsg("failed to open image: %s.\n", lbx_strerror());
		return EXIT_FAILURE;
	}

	if (verbose || mode == MODE_IDENT) {
		struct lbx_imginfo info;
		lbximg_getinfo(img, &info);

		printf("%s is %ux%u LBX image, %u frame(s)%s%s\n",
		       name, info.width, info.height, info.nframes,
		       info.haspalette ? ", embedded palette" : "",
		       info.looping    ? ", loops" : "");
	}

	switch (mode) {
	case MODE_DECODE:
		if (decode(img, palf, overf, &argv[optind])) {
			lbximg_close(img);
			return EXIT_FAILURE;
		}
		break;
	}

	lbximg_close(img);
	return EXIT_SUCCESS;
}