/* See LICENSE file for copyright and license details. */
#include "liblss16.h"
#include <errno.h>
#include <stdio.h>
#include <stdlib.h>
#include <string.h>
#include <unistd.h>

#if defined(__clang__)
# pragma clang diagnostic ignored "-Wunsafe-buffer-usage"
#endif


static const char *argv0 = "lss16toppm";


static void
writeall(char *buf, size_t n)
{
	ssize_t r;

	while (n) {
		r = write(STDOUT_FILENO, buf, n);
		if (r < 0) {
			if (errno == EINTR)
				continue;
			fprintf(stderr, "%s: write <stdout>: %s\n", argv0, strerror(errno));
			exit(2);
		}
		buf += (size_t)r;
		n -= (size_t)r;
	}
}


int
main(int argc, char *argv[])
{
	char buf[1024], wbuf[1024];
	uint8_t pixels[1024];
	struct liblss16_decoder decoder;
	enum liblss16_decode_state state;
	ssize_t r;
	size_t n, off, consumed, npixels, pending;
	enum liblss16_decode_error error;
	int head_printed = 0;
	int print_colour_map = 0;
	int have_stdout = 0, len;
	size_t i;

	/* cmdline syntax is inherited from the SYSLINUX implementation,
	 * it's bad, but it's the way it is, and the way it will remain */

	if (argc) {
		argv0 = *argv++;
		argc--;
	}

	for (; argc--; argv++) {
		if (!strcmp(*argv, "-map")) {
			print_colour_map = 1;
		} else {
			fprintf(stderr, "%s: Unknown option: %s\n", argv0, *argv);
			return 2;
		}
	}

	liblss16_decoder_init(&decoder);

	pending = 0;
	for (;;) {
		r = read(STDIN_FILENO, buf, sizeof(buf));
		if (r <= 0) {
			if (!r)
				break;
			if (errno == EINTR)
				continue;
			fprintf(stderr, "%s: read <stdin>: %s\n", argv0, strerror(errno));
			return 2;
		}
		n = (size_t)r;

		for (off = 0; off < n;) {
			state = liblss16_decode_to_colour_index(&decoder, &buf[off], n - off, &consumed,
								pixels, sizeof(pixels) / sizeof(*pixels), &npixels, &error);
			off += consumed;
			if (state == LIBLSS16_DECODE_ERROR) {
				goto error;
			} else if (state == LIBLSS16_DECODE_END_OF_IMAGE) {
				if (off != n) {
					fprintf(stderr, "%s: image file contains extraneous data\n", argv0);
					return 1;
				}
			}
			if (!npixels)
				continue;

			if (!head_printed) {
				head_printed = 1;
				len = sprintf(wbuf, "P6\n%u %u\n255\n", decoder.image.width, decoder.image.height);
				if (len < 0 || (size_t)len >= sizeof(wbuf))
					abort();
				pending = (size_t)len;
				if (print_colour_map) {
					for (i = 0; i < sizeof(decoder.image.colour_map) / sizeof(*decoder.image.colour_map); i++) {
						fprintf(stderr, "#%02x%02x%02x=%zu\n", decoder.image.colour_map[i].r,
						        decoder.image.colour_map[i].g, decoder.image.colour_map[i].b, i);
					}
				}
			}
			for (i = 0; i < npixels; i++) {
				if (3U > sizeof(wbuf) - pending) {
					writeall(wbuf, pending);
					pending = 0;
				}
				wbuf[pending++] = (char)decoder.image.colour_map[pixels[i]].r;
				wbuf[pending++] = (char)decoder.image.colour_map[pixels[i]].g;
				wbuf[pending++] = (char)decoder.image.colour_map[pixels[i]].b;
			}
		}
	}
	if (pending)
		writeall(wbuf, pending);

	state = liblss16_decode_to_colour_index(&decoder, NULL, 0, &consumed, pixels,
						sizeof(pixels) / sizeof(*pixels), &npixels, &error);
	if (state == LIBLSS16_DECODE_ERROR) {
	error:
		fprintf(stderr, "%s: %s\n", argv0, liblss16_decode_strerror(error));
		return 1;
	} else if (state != LIBLSS16_DECODE_END_OF_IMAGE) {
		fprintf(stderr, "%s: image file truncated\n", argv0);
		return 1;
	}

	while (close(STDOUT_FILENO)) {
		if (have_stdout && errno == EBADF)
			break;
		if (errno == EINTR) {
			have_stdout = 1;
		} else {
			fprintf(stderr, "%s: write <stdout>: %s\n", argv0, strerror(errno));
			return 2;
		}
	}
	return 0;
}