/* ****************************************************************************
 * file/decode/std/eact.c -- decode an e-activity file.
 * Copyright (C) 2017 Thomas "Cakeisalie5" Touhey <thomas@touhey.fr>
 *
 * This file is part of libcasio.
 * libcasio 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.
 *
 * libcasio 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 libcasio; if not, see <http://www.gnu.org/licenses/>.
 * ************************************************************************* */
#include "../decode.h"

/* ---
 * Content parsing.
 * --- */

/* Line content parsing function prototype. */

static int eact_decode_line(casio_line_t *handle, uint8_t *buf, size_t size,
	uint_fast8_t type);

/**
 *	eact_decode_content_eact:
 *	Decodes an EACT in an EACT, from the subheader.
 *
 *	@arg	handle		the handle.
 *	@arg	buf			the buffer.
 *	@arg	bufsize		the buffer size.
 *	@return				the error code (0 if ok).
 */

static int eact_decode_content_eact(casio_line_t *handle, uint8_t *buf,
	size_t bufsize)
{
	int err;
	unsigned long int i;

	/* initialize the handle */
	handle->casio_line_type  = casio_linetype_eact;
	handle->casio_line_count = 0;
	handle->casio_line__size = 0;
	handle->casio_line_lines = NULL;

	/* check if the buffer is non-empty */
	if (!bufsize) return (0);

	/* get e-act subheader */
	if (bufsize < sizeof(casio_eact_content_eact_header_t))
		return (casio_error_eof);
	casio_eact_content_eact_header_t ehd;
	memcpy(&ehd, buf, sizeof(casio_eact_content_eact_header_t));

	/* get the line descriptors
	 *	there is actually a "bonus" line descriptor at the end, but the
	 *	fact that we're using offsets lets us unaware of it. */
	uint32_t count = be32toh(ehd.casio_eact_content_eact_header_line_count);
	if (bufsize < sizeof(casio_eact_content_eact_header_t)
		+ (count + 1) * sizeof(casio_eact_line_descriptor_t))
		return (casio_error_eof);
	casio_eact_line_descriptor_t *lds =
		(void*)&buf[sizeof(casio_eact_content_eact_header_t)];

	/* prepare the handle */
	handle->casio_line_count = 0;
	handle->casio_line__size = count;
	handle->casio_line_lines =
		casio_alloc(handle->casio_line__size, sizeof(casio_line_t*));
	if (!handle->casio_line_lines) return (casio_error_alloc);
	memset(handle->casio_line_lines, 0,
		sizeof(casio_line_t*) * handle->casio_line__size);

	/* browse the lines */
	msg((ll_info, "%" CASIO_PRIu32 " lines to browse", count));
	if (count)
		lds[0].casio_eact_line_descriptor_offset =
			be32toh(lds[0].casio_eact_line_descriptor_offset << 8);
	for (i = 0; i < count; i++) {
		/* allocate line */
		casio_line_t *line = casio_alloc(1, sizeof(casio_line_t));
		err = casio_error_alloc;
		if (!line) goto fail;

		/* get line size
		 *	for this, we'll calculate the distance to the next line offset.
		 *	if there is no next line (last line), then the data left will be
		 *	attributed to the line. */
		size_t linesize;
		if (i == count - 1)
			linesize = bufsize - lds[i].casio_eact_line_descriptor_offset;
		else {
			/* correct endianess of the next element */
			lds[i + 1].casio_eact_line_descriptor_offset =
				be32toh(lds[i + 1].casio_eact_line_descriptor_offset << 8);
			/* then calculate */
			linesize = lds[i + 1].casio_eact_line_descriptor_offset
				- lds[i].casio_eact_line_descriptor_offset;
		}

		/* store current info */
		uint_fast8_t entry_type = lds[i].casio_eact_line_descriptor_type;
		uint_fast32_t entry_offset =
			lds[i].casio_eact_line_descriptor_offset;

		/* check if buffer is big enough */
		err = casio_error_eof;
		if (entry_offset + linesize > bufsize)
			goto loop_fail;

		/* look for the line type */
		err = eact_decode_line(line, &buf[entry_offset], linesize, entry_type);
		if (err) goto loop_fail;

		/* store and continue */
		handle->casio_line_lines[handle->casio_line_count++] = line;
		continue;

	loop_fail:
		casio_free_line_content(line);
		casio_free(line);
		goto fail;
	}

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

/* ---
 * Content Type correspondance list.
 * --- */

/* Correspondance type. */

struct eact_content_type_corresp {
	const char *type;

	int (*decode)(casio_line_t*, uint8_t*, size_t);
};

/* Correspondance list. */

static struct eact_content_type_corresp eact_content_types[] = {
	{"@EACT\0\0", eact_decode_content_eact},
	{}
};

/* ---
 * Line parsing.
 * --- */

/**
 *	eact_decode_line_content:
 *	Decodes an E-Activity content.
 *
 *	@arg	handle		the handle.
 *	@arg	buf			the buffer.
 *	@arg	size		the buffer size.
 *	@return				the error code (0 if ok).
 */

static int eact_decode_line_content(casio_line_t *handle, uint8_t *buf,
	size_t size)
{
	/* read content header */
	size_t could_read = min(size, sizeof(casio_eact_content_header_t));
	if (could_read < 9) return (casio_error_eof);
	casio_eact_content_header_t hd = {};
	memcpy(&hd, buf, could_read);

	/* store info */
	bzero(handle->casio_line_name, 17);
	size_t namesize = max(could_read - 8, 16);
	strncpy(handle->casio_line_name, (char*)hd.casio_eact_content_header_name,
		namesize);

	/* log info */
	msg((ll_info, "Type is '%.8s'", hd.casio_eact_content_header_type));
	msg((ll_info, "Name is '%s'", handle->casio_line_name));

	/* prepare for next */
	buf += could_read;
	size -= could_read;

	/* check for content type */
	struct eact_content_type_corresp *ctype = eact_content_types;
	while (ctype->decode) {
		if (!memcmp(hd.casio_eact_content_header_type, ctype->type, 8))
			break ;
		ctype++;
	}

	/* print the content */
#if !defined(LIBCASIO_DISABLED_LOG)
	if (!ctype->decode)
		msg((ll_error, "Type is unmanaged!"));

	if (!size) log_info("Content was name-only.");
	else if (!ctype->decode) {
		msg((ll_info, "Content was:"));
		mem((ll_info, buf, size));
	}
#endif

	/* then decode */
	return (ctype->decode ? (*ctype->decode)(handle, buf, size) : 0);
}

/**
 *	eact_decode_line_calculation:
 *	Decodes a calculation.
 *
 *	@arg	handle		the handle.
 *	@arg	buf			the buffer.
 *	@arg	size		the buffer size.
 *	@return				the error code (0 if ok).
 */

static int eact_decode_line_calculation(casio_line_t *handle, uint8_t *buf,
	size_t size)
{
	(void)handle;
	(void)buf;
	(void)size;
	/* TODO */
	msg((ll_info, "Calculation raw data is:"));
	mem((ll_info, buf, size));
	return (0);
}

/**
 *	eact_decode_line_result:
 *	Decodes a calculation result.
 *
 *	@arg	handle		the handle.
 *	@arg	buf			the buffer.
 *	@arg	size		the buffer size.
 *	@return				the error code (0 if ok).
 */

static int eact_decode_line_result(casio_line_t *handle,
	uint8_t *buf, size_t size)
{
	(void)handle;
	(void)buf;
	(void)size;
	/* TODO */
	msg((ll_info, "Calculation result raw data is:"));
	mem((ll_info, buf, size));
	return (0);
}

/**
 *	eact_decode_line_stdheading:
 *	Decodes standard heading line.
 *
 *	@arg	handle		the handle.
 *	@arg	buf			the buffer.
 *	@arg	size		the buffer size.
 *	@return				the error code (0 if ok).
 */

static int eact_decode_line_stdheading(casio_line_t *handle, uint8_t *buf,
	size_t size)
{
	(void)size;

	/* log */
	msg((ll_info, "Standard heading raw data is:"));
	mem((ll_info, buf, size));

	/* set handle info */
	handle->casio_line_type = casio_linetype_text;
	handle->casio_line_content = strdup((char*)buf);
	if (!handle->casio_line_content) return (casio_error_alloc);

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

/**
 *	eact_decode_line_picture:
 *	Decodes picture line.
 *
 *	@arg	handle		the handle.
 *	@arg	buf			the buffer.
 *	@arg	size		the buffer size.
 *	@return				the error code (0 if ok).
 */

static int eact_decode_line_picture(casio_line_t *handle, uint8_t *buf,
	size_t size)
{
	(void)size;

	/* log */
	msg((ll_info, "Picture raw data is:"));
	mem((ll_info, buf, size));

	/* big endian to host endianness */
	FONTCHARACTER *s = (FONTCHARACTER*)buf;
	FONTCHARACTER *p = s - 1;
	while (*(++p)) *p = be16toh(*p);

	/* get the size of the multi-byte string */
	size_t sz = casio_wcstombs(NULL, s, 0);
	if (sz == (size_t)-1) return (casio_error_magic);

	/* make the string */
	handle->casio_line_content = casio_alloc(sz + 1, sizeof(FONTCHARACTER));
	if (!handle->casio_line_content) return (casio_error_alloc);
	casio_wcstombs(handle->casio_line_content, s, 0);

	/* don't forget to set the handle type! */
	handle->casio_line_type = casio_linetype_picture;

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

/**
 *	eact_decode_line_text:
 *	Decodes a text line.
 *
 *	@arg	handle		the handle.
 *	@arg	buf			the buffer.
 *	@arg	size		the buffer size.
 *	@return				the error code (0 if ok).
 */

static int eact_decode_line_text(casio_line_t *handle, uint8_t *buf,
	size_t size)
{
	(void)size;

	/* log */
	msg((ll_info, "Text raw data is:"));
	mem((ll_info, buf, size));

	/* set handle info */
	handle->casio_line_type = casio_linetype_text;
	handle->casio_line_content = strdup((char*)buf);
	if (!handle->casio_line_content) return (casio_error_alloc);

	/* TODO: manage text coloration */
	/* no error */
	return (0);
}

/**
 *	eact_decode_line_code:
 *	Decodes code line.
 *
 *	@arg	handle		the handle.
 *	@arg	buf			the buffer.
 *	@arg	size		the buffer size.
 *	@return				the error code (0 if ok).
 */

static int eact_decode_line_code(casio_line_t *handle, uint8_t *buf,
	size_t size)
{
	(void)handle;
	(void)buf;
	(void)size;
	/* TODO */
	msg((ll_info, "Code raw data is:"));
	mem((ll_info, buf, size));
	return (0);
}

/* ---
 * Line Type correspondance list.
 * --- */

/* Correspondance type. */

struct eact_line_type_corresp {
	int rawtype;

	int (*decode)(casio_line_t*, uint8_t*, size_t);
	const char *info;
};

/* All correspondances. */

static struct eact_line_type_corresp eact_line_types[] = {
	{casio_eact_ltype_calc, eact_decode_line_calculation,
		"calculation"},
	{casio_eact_ltype_calc_result, eact_decode_line_result,
		"calculation result"},
	{casio_eact_ltype_content, eact_decode_line_content,
		"content"},
	{casio_eact_ltype_stdheading, eact_decode_line_stdheading,
		"standard heading"},
	{casio_eact_ltype_picture, eact_decode_line_picture,
		"picture"},
	{casio_eact_ltype_text, eact_decode_line_text,
		"pure text"},
	{casio_eact_ltype_code, eact_decode_line_code,
		"text mixed with functions"},
	{0, 0, NULL}
};

/**
 *	eact_decode_line:
 *	decode a line [content].
 *
 *	@arg	handle		the handle.
 *	@arg	buf			the buffer.
 *	@arg	size		the buffer size.
 *	@arg	type		the type.
 *	@return				the error code (0 if ok).
 */

static int eact_decode_line(casio_line_t *handle, uint8_t *buf, size_t size,
	uint_fast8_t type)
{
	/* initialize handle */
	handle->casio_line_type = 0x00;

	/* look for the line type */
	struct eact_line_type_corresp *linetype = eact_line_types;
	while (linetype->decode) {
		if (linetype->rawtype == type)
			break;
		linetype++;
	}
	if (!linetype->decode) {
		msg((ll_error, "unknown line type: %02x", type));
		return (0);
	}

	/* act */
	msg((ll_info, "line type is '%s' (0x%02x)", linetype->info, type));
	return ((*linetype->decode)(handle, buf, size));
}

/* ---
 * Main parsing functions.
 * --- */

/**
 *	casio_decode_std_eact:
 *	Decodes an EACT.
 *
 *	Thanks to Julese50 for his help on e-acts parsing.
 *
 *	@arg	h			the handle to create.
 *	@arg	buffer		the buffer to read from.
 *	@return				the error code (0 if ok).
 */

int CASIO_EXPORT casio_decode_std_eact(casio_file_t **h,
	casio_stream_t *buffer, casio_standard_header_t *std)
{
	(void)std; int err;
	/* decode the header */
	DREAD(hd, casio_eact_header_s)
	hd.casio_eact_header_filesize =
		be32toh(hd.casio_eact_header_filesize);
	hd.casio_eact_header_setup_area_size =
		be32toh(hd.casio_eact_header_setup_area_size);
	hd.casio_eact_header_eact_version =
		be32toh(hd.casio_eact_header_eact_version);
	hd.casio_eact_header_os_version =
		be32toh(hd.casio_eact_header_os_version);

	/* find out the size of the setup area */
	msg((ll_info, "E-Activity version is '%s'.",
		hd.casio_eact_header_eact_version == EACT_G1E ? "g1e" :
		hd.casio_eact_header_eact_version == EACT_G2E ? "g2e" : "g3e"));
	msg((ll_info, "Setup area size is 0x%" PRIx32 " bytes long.",
		hd.casio_eact_header_setup_area_size));

	/* allocate handle */
	*h = casio_alloc(1, sizeof(casio_file_t));
	if (!*h) return (casio_error_alloc);
	casio_file_t *handle = *h;
	memset(handle, 0, sizeof(casio_file_t));

	/* skip the setup area */
	SKIP(hd.casio_eact_header_setup_area_size)

	/* prepare the handle */
	handle->casio_file_type = casio_filetype_eact;
	handle->casio_handle_platform = casio_filefor_fx;
	if (hd.casio_eact_header_eact_version == EACT_G3E) /* check if fx-CG */
		handle->casio_handle_platform = casio_filefor_cg;

	/* get content buffer */
	size_t bufsize = hd.casio_eact_header_filesize
		- sizeof(casio_standard_header_t)
		- sizeof(casio_eact_header_t)
		- hd.casio_eact_header_setup_area_size;
	uint8_t buf[bufsize];
	GREAD(&buf, bufsize)

	/* decode content */
	handle->casio_file_line = &handle->casio_file__linedata;
	return (eact_decode_line_content(handle->casio_file_line, buf, bufsize));
fail:
	casio_free_file(*h); *h = NULL;
	return (err);
}