/* ************************************************************************** */
/*                                       _____           _                    */
/*  parse/picture.c                     |_   _|__  _   _| |__   ___ _   _     */
/*  | Project: libg1m                     | |/ _ \| | | | '_ \ / _ \ | | |    */
/*                                        | | (_) | |_| | | | |  __/ |_| |    */
/*  By: thomas <thomas@touhey.fr>         |_|\___/ \__,_|_| |_|\___|\__, |.fr */
/*  Last updated: 2016/12/01 13:33:45                               |___/     */
/*                                                                            */
/* ************************************************************************** */
#include <libg1m/internals.h>
#include <zlib.h>

/**
 *	g3p_deobfuscate:
 *	De-obfuscate the image data.
 *
 *	@arg	buf			the buffer.
 *	@arg	n			the buffer size.
 */

static void g3p_deobfuscate(uint8_t *buf, size_t n)
{
	while (n--) {
		int byte = *buf;
		*buf++ = (byte >> 3) | ((byte & 0x7) << 5);
	}
}

/**
 *	g1m_parse_g3p:
 *	Parse a G3P file.
 *
 *	@arg	handle		the handle.
 *	@arg	stream		the stream to parse from.
 *	@arg	std			the standard header.
 *	@return				the error code (0 if ok).
 */

int g1m_parse_g3p(g1m_t *handle, FILE *stream,
	struct standard_header *std)
{
	/* get the G3P global header */
	DREAD(hd, g3p_subheader)
	hd.g3p_size = be32toh(hd.g3p_size);

	/* check magic */
	if (memcmp(hd.magic, "CP", 2)) {
		log_fatal("could not read 'CP'.");
		return (g1m_error_magic);
	}

	/* read the image header */
	DREAD(ihd, g3p_imageheader)

	/* correct endianness */
	ihd.df_size = be32toh(ihd.df_size);
	ihd.width = be16toh(ihd.width);
	ihd.height = be16toh(ihd.height);
	ihd.color_depth = be16toh(ihd.color_depth);
	ihd.data_size = be32toh(ihd.data_size);

	/* check some little things */
	int is_obfuscated =
		((std->obfuscated + 8) & 0xff) != ((std->filesize & 0xff00) >> 8);
	int has_footer = 1; /* might change? */
	size_t deflated_image_size = ihd.data_size - has_footer * 0x4;

	/* log info */
	log_info("Width: %" PRIu16 "px, height: %" PRIu16 "px",
		ihd.width, ihd.height);
	log_info("Pixel depth: %s",
		(ihd.color_depth == g3p_color_4bit) ? "4-bit" : "16-bit");
	log_info("Deflated image length: %" PRIuSIZE "o", deflated_image_size);
	log_info("Is obfuscated: %s", is_obfuscated ? "yes" : "no");

	/* read image */
	uint8_t deflated_image[deflated_image_size];
	READ(deflated_image, deflated_image_size)

	/* read footer and check sum */
	if (has_footer) {
		DREAD(ft, g3p_imagefooter);
		ft.checksum = be32toh(ft.checksum);

		uLong adl = adler32(0, deflated_image, deflated_image_size);
		if (adl != ft.checksum) {
			log_fatal("Incorrect Adler32 checksum!");
			log_fatal("Expected %" PRIu32 ", got %lu",
				ft.checksum, adl);
			return (g1m_error_magic);
		}
	}

	/* unobfuscate if required */
	if (is_obfuscated)
		g3p_deobfuscate(deflated_image, deflated_image_size);

	/* find out length of inflated data */
	uLongf inflated_size = 0L; int z_err;
	if ((z_err = uncompress(Z_NULL, &inflated_size, deflated_image,
		deflated_image_size)) != Z_MEM_ERROR) {
		log_fatal("Zlib error: error #%d", z_err);
		return (g1m_error_magic);
	}
	log_info("Inflated image size is %lu", inflated_size);

	/* allocate space for it, and uncompress */
	uint8_t inflated_image[inflated_size];
	if ((z_err = uncompress(inflated_image, &inflated_size, deflated_image,
		deflated_image_size))) {
		log_fatal("Zlib error: error #%d", z_err);
		return (g1m_error_magic);
	}

	/* allocate picture in handle */
	int w = ihd.width, h = ihd.height;
	handle->width = w;
	handle->height = h;
	handle->pixels = alloc_pixels(w, h);
	if (!handle->pixels) return (g1m_error_alloc);
	prepare_pixels(handle->pixels, w, h)

	/* then store it */
	switch (ihd.color_depth) {
	case g3p_color_4bit:
		g1m_pixels_from_packed4bits(handle->pixels, inflated_image, w, h);
	default: /* case g3p_color_16bit: */
		g1m_pixels_from_16bits(handle->pixels, inflated_image, w, h);
	}

	/* no error */
	return (0);
}

/**
 *	g1m_parse_c2p:
 *	Parse Classpad images.
 *
 *	@arg	handle		the handle.
 *	@arg	stream		the stream to parse from.
 *	@return				the error code (0 if ok).
 */

int g1m_parse_c2p(g1m_t *handle, FILE *stream,
	struct standard_header *std)
{
	(void)std;
	(void)handle;
	(void)stream;
	/* TODO */
	log_info("C2P files are not managed yet.");
	log_info("Size is %" PRIuSIZE " o", sizeof(struct c2p_subheader));

	/* no error */
	return (0);
}