/* *****************************************************************************
 * decode/casemul.c -- decode a Casemul file.
 * Copyright (C) 2017 Thomas "Cakeisalie5" Touhey <thomas@touhey.fr>
 *
 * This file is part of libg1m.
 * libg1m is free software; you can redistribute it and/or modify it
 * under the terms of the GNU Lesser General Public License as published by
 * the Free Software Foundation; either version 3.0 of the License,
 * or (at your option) any later version.
 *
 * libg1m 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 Lesser General Public License for more details.
 *
 * You should have received a copy of the GNU Lesser General Public License
 * along with libg1m; if not, see <http://www.gnu.org/licenses/>.
 *
 * Based on the Casetta project documentation:
 * https://casetta.tuxfamily.org/formats/casemul
 *
 * The support for the subfiles (program, picture, matrix, list) are not added
 * in the specific files in `decode/mcs/` as this is *not* the format they
 * have while in the MCS, but the format CasEmul uses internally.
 * ************************************************************************** */
#include <libg1m/internals.h>
#define e32toh(N) ((big_endian) ? be32toh(N) : le32toh(N))
#define htoe32(N) ((big_endian) ? htobe32(N) : htole32(N))
#define VER htoe32(0x00000100) /* 1.00 */

/* ************************************************************************** */
/*  Utilities                                                                 */
/* ************************************************************************** */
/**
 *	read_internal:
 *	Read the internal headers, and check them.
 *
 *	@arg	buffer		the buffer to read from.
 *	@arg	type		the expected type.
 *	@arg	version		the expected version.
 *	@return				the error (if any).
 */

static int read_internal(g1m_buffer_t *buffer, uint32_t signature,
	uint_fast32_t version)
{
	DREAD(hd, casemul_internal_header)

	/* check type */
	if (signature != hd.signature) {
#if LOGLEVEL <= ll_error
		const char *a = (char*)&signature, *b = (char*)&hd.signature;
		log_error("signature mismatch!");
		log_error("expected '%c%c%c%c', got '%c%c%c%c'",
			a[0], a[1], a[2], a[3], b[0], b[1], b[2], b[3]);
#endif
		return (g1m_error_magic);
	}

	/* check version */
	if (le32toh(hd.version) != version) {
		log_error("version mismatch!");
		log_error("epxected %08" PRIxFAST32 ", got %08" PRIx32,
			version, hd.version);
		return (g1m_error_magic);
	}

	/* nothing wrong :) */
	return (0);
}

/**
 *	read_top:
 *	Read the top of a record.
 *
 *	@arg	buffer		the buffer to read from.
 *	@arg	name		the name buffer (13 bytes including '\0').
 *	@arg	length		the subheader+data length.
 *	@arg	big_endian	big endian?
 *	@return				the error code.
 */

static int read_top(g1m_buffer_t *buffer, char *name, uint_fast32_t *length,
	int big_endian)
{
	/* read and check the name length */
	uint32_t name_length; READ(&name_length, sizeof(uint32_t))
	name_length = e32toh(name_length);

	/* read the raw name */
	uint8_t buf[name_length];
	READ(buf, name_length)

	/* copy to the real name */
	if (name_length > 8) name_length = 8;
	memcpy(name, buf, name_length);
	name[name_length] = 0;

	/* read the length and correct */
	READ(length, sizeof(uint32_t))
	*length = e32toh(*length);

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

/* ************************************************************************** */
/*  Intermediate functions                                                    */
/* ************************************************************************** */
/**
 *	read_picture:
 *	Read a picture record and content.
 *
 *	@arg	pfile		the pointer to the mcsfile to make and fill.
 *	@arg	buffer		the buffer to read from.
 *	@arg	big_endian	whether the file is big endian or not.
 *	@return				the error (if occured).
 */

static int read_picture(g1m_mcsfile_t **pfile, g1m_buffer_t *buffer,
	int big_endian)
{
	int err; *pfile = NULL;
	static const uint32_t colours[256] = {
		[0x00] = 0xFFFFFF, /* white */
		[0x01] = 0xFF8000, /* orange */
		[0x02] = 0x00FF00, /* green */
		[0x03] = 0x0000FF, /* blue */
		/* other colours are black */
	};

	/* general record things */
	char name[13]; uint_fast32_t record_length;
	if ((err = read_top(buffer, name, &record_length, big_endian))
	 || (err = read_internal(buffer, MAKELONG('PI', 'CT'), VER)))
		return (err);

	/* specific things */
	DREAD(pct, casemul_pict_header)
	log_info("picture dimension is %d*%dpx", pct.width, pct.height);

	/* read all of the pixels */
	unsigned int total = pct.width * pct.height;
	uint8_t rawpx[total]; READ(rawpx, total)
	uint8_t *px = rawpx;

	/* make the head and allocate file */
	g1m_mcshead_t head = {
		.g1m_mcshead_type = g1m_mcstype_capture,
		.g1m_mcshead_width = pct.width,
		.g1m_mcshead_height = pct.height,
	};
	memcpy(head.g1m_mcshead_name, name, strlen(name) + 1);
	head.g1m_mcshead_id = name[7] - '0';
	err = g1m_make_mcsfile(pfile, &head);
	if (err) return (err);

	/* set the pixels */
	uint32_t **img = (*pfile)->g1m_mcsfile_pics[0];
	for (int x = 0; x < pct.width; x++) for (int y = 0; y < pct.height; y++)
		img[y][x] = colours[*px++];

	/* finish */
	return (0);
}

/**
 *	read_matrix:
 *	Read a matrix record and content.
 *
 *	@arg	pfile		the pointer to the mcsfile to make and fill.
 *	@arg	buffer		the buffer to read from.
 *	@arg	big_endian	whether the file is big endian encoded or not.
 *	@return				the error that occured.
 */

static int read_matrix(g1m_mcsfile_t **pfile, g1m_buffer_t *buffer,
	int big_endian)
{
	int err; *pfile = NULL;
	/* general record things */
	char name[13]; uint_fast32_t record_length;
	if ((err = read_top(buffer, name, &record_length, big_endian))
	 || (err = read_internal(buffer, MAKELONG('MT', 'RX'), VER)))
		return (err);

	/* read specific things */
	DREAD(mtx, casemul_mtrx_header)
	unsigned int width = e32toh(mtx.lines) & 0x7FFF,
	            height = e32toh(mtx.columns) & 0x7FFF;

	/* read double tab */
	unsigned int total = width * height;
	double tab[total]; READ(tab, total * sizeof(double))
	double *raw = tab;

	/* make the head and allocate file */
	g1m_mcshead_t head = {
		.g1m_mcshead_type = g1m_mcstype_matrix,
		.g1m_mcshead_width = width,
		.g1m_mcshead_height = height,
	};
	memcpy(head.g1m_mcshead_name, name, strlen(name) + 1);
	head.g1m_mcshead_id = name[4] - 'A' + 1;
	err = g1m_make_mcsfile(pfile, &head);
	if (err) return (err);

	/* read the matrix */
	g1m_mcscell_t **cells = (*pfile)->g1m_mcsfile_cells;
	for (unsigned int y = 0; y < height; y++)
	  for (unsigned int x = 0; x < width; x++) {
		/* read the bcd */
		g1m_bcd_t bcd; g1m_bcd_fromdouble(*raw++, &bcd);

#if LOGLEVEL <= ll_info
		/* log the bcd */
		char buf[G1M_BCD_GOODBUFSIZE];
		g1m_bcdtoa(&bcd, buf, G1M_BCD_GOODBUFSIZE);
		log_info("[%d][%d] %s", y, x, buf);
#endif

		/* make the cell */
		cells[y][x] = (g1m_mcscell_t){
			.g1m_mcscell_real = bcd,
			.g1m_mcscell_imgn = {},
			.g1m_mcscell_flags = g1m_mcscellflag_used
		};
	}

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

/**
 *	read_list:
 *	Read a list record and content.
 *
 *	@arg	pfile		the pointer to the mcsfile to make and fill.
 *	@arg	buffer		the buffer to read from.
 *	@arg	big_endian	whether the file is big endian encoded or not.
 *	@return				the error that occured.
 */

static int read_list(g1m_mcsfile_t **pfile, g1m_buffer_t *buffer,
	int big_endian)
{
	int err; *pfile = NULL;
	/* general record things */
	char name[13]; uint_fast32_t record_length;
	if ((err = read_top(buffer, name, &record_length, big_endian))
	 || (err = read_internal(buffer, MAKELONG('LI', 'ST'), VER)))
		return (err);

	/* read specific things */
	DREAD(lst, casemul_list_header)
	int len = le32toh(lst.lines) & 0x7FFF;
	log_info("%d elements in list", len);

	/* read double tab */
	double tab[len]; READ(tab, len * sizeof(double))
	double *raw = tab;

	/* make head */
	g1m_mcshead_t head = {
		.g1m_mcshead_type = g1m_mcstype_list,
		.g1m_mcshead_width = 1,
		.g1m_mcshead_height = len
	};
	memcpy(head.g1m_mcshead_name, name, strlen(name) + 1);
	head.g1m_mcshead_id = name[5] - '0';
	err = g1m_make_mcsfile(pfile, &head);
	if (err) return (err);

	/* read the list */
	g1m_mcscell_t **cells = (*pfile)->g1m_mcsfile_cells;
	for (int x = 0; x < len; x++) {
		/* read bcd */
		g1m_bcd_t bcd; g1m_bcd_fromdouble(*raw++, &bcd);

#if LOGLEVEL <= ll_info
		/* log information */
		char buf[G1M_BCD_GOODBUFSIZE];
		g1m_bcdtoa(&bcd, buf, G1M_BCD_GOODBUFSIZE);
		log_info("[%d] %s", x, buf);
#endif

		/* set the cell */
		cells[x][0] = (g1m_mcscell_t){
			.g1m_mcscell_real = bcd,
			.g1m_mcscell_imgn = {},
			.g1m_mcscell_flags = g1m_mcscellflag_used
		};
	}

	/* no error */
	return (0);
}
/* ************************************************************************** */
/*  Main function                                                             */
/* ************************************************************************** */
/**
 *	g1m_decode_casemul:
 *	Decode a CasEmul file.
 *
 *	@arg	h			the handle to make.
 *	@arg	buffer		the buffer to read from.
 *	@arg	big_endian	whether the file is big endian or not.
 *	@return				the error code (0 if ok).
 */

int g1m_decode_casemul(g1m_handle_t **h, g1m_buffer_t *buffer, int big_endian)
{
	int err;

	/* read the overall header's internal header end */
	struct casemul_internal_header overall_int = {
		.signature = MAKELONG('CA', 'FS')};
	READ(&overall_int.version, 8);
	if (e32toh(overall_int.version) != 0x100)
		return (g1m_error_magic);

	/* read the overall (global) header */
	DREAD(glb, casemul_header)
#if LOGLEVEL <= ll_info
	glb.source_offset = e32toh(glb.source_offset);
	glb.compiled_offset = e32toh(glb.compiled_offset);
	log_info("Header source offset is: 0x%08X", glb.source_offset);
	if (glb.flags & casemul_compiled)
		log_info("Header compiled offset is: 0x%08X", glb.compiled_offset);
	else
		log_info("The file has got no compiled part.");
#endif

	/* read the source header */
	if ((err = read_internal(buffer, MAKELONG('SR', 'CE'), VER)))
		return (err);
	DREAD(src, casemul_source_header)

	/* make the handle */
	err = g1m_make_mcs(h, /* src.programs + */ src.pictures + src.matrixes
		+ src.lists);
	if (err) return (err);
	g1m_handle_t *handle = *h;

	/* read each program; TODO: put this in a function when token parsing
	 * is managed. */
	for (int i = 0; i < src.programs; i++) {
		log_info("Reading program #%d", i + 1);
		log_warn("Program content will be skipped!");
		/* general record things */
		char name[13]; uint_fast32_t record_length;
		if ((err = read_top(buffer, name, &record_length, big_endian))
		 || (err = read_internal(buffer, MAKELONG('PR', 'OG'), VER)))
			goto fail;

		/* specific things */
		GDREAD(prg, casemul_prog_header)
		prg.length = le32toh(prg.length);

		/* TODO: decode using tokens (cf. refc and libfc) */
		SKIP(prg.length)
	}

	/* read each picture */
	for (int i = 0; i < src.pictures; i++) {
		log_info("Reading picture #%d", i + 1);
		err = read_picture(&handle->g1m_handle_files[handle->g1m_handle_count],
			buffer, big_endian);
		if (err) goto fail;
		handle->g1m_handle_count++;
	}

	/* read each matrix */
	for (int i = 0; i < src.matrixes; i++) {
		log_info("Reading matrix #%d", i + 1);
		err = read_matrix(&handle->g1m_handle_files[handle->g1m_handle_count],
			buffer, big_endian);
		if (err) goto fail;
		handle->g1m_handle_count++;
	}

	/* read each list */
	for (int i = 0; i < src.lists; i++) {
		log_info("Reading list #%d", i + 1);
		err = read_list(&handle->g1m_handle_files[handle->g1m_handle_count],
			buffer, big_endian);
		if (err) goto fail;
		handle->g1m_handle_count++;
	}

	/* TODO: skip compiled part? */
	log_warn("Should read compiled part here!");

	/* no error! */
	return (0);
fail:
	g1m_free(handle);
	return (err);
}