/* *****************************************************************************
 * decode/mcs/spreadsheet.c -- decode an MCS spreadsheet.
 * 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/>.
 * ************************************************************************** */
#include <libg1m/internals.h>

/**
 *	g1m_decode_mcs_spreadsheet:
 *	Decode a spreadsheet.
 *
 *	@arg	handle		the handle to make.
 *	@arg	buffer		the buffer to read from.
 *	@arg	head		the pre-filled head to complete and use.
 *	@return				the error code (0 if ok).
 */

int g1m_decode_mcs_spreadsheet(g1m_mcsfile_t **handle, g1m_buffer_t *buffer,
	g1m_mcshead_t *head)
{
	/* read header */
	DREAD(hd, g1m_mcs_spreadsheet_header_s)
	if (hd.g1m_mcs_spreadsheet_header_has_subheader != 0x01)
		return (0);

	/* read subheader */
	DREAD(shd, g1m_mcs_spreadsheet_subheader_s)
	uint_fast32_t colcount = hd.g1m_mcs_spreadsheet_header_column_count;
	colcount = be32toh(colcount << 8);
	shd.g1m_mcs_spreadsheet_subheader_defs_size =
		be32toh(shd.g1m_mcs_spreadsheet_subheader_defs_size);

	/* prepare */
	g1m_mcscell_t cells[1000 * colcount];
	bzero(cells, sizeof(g1m_mcscell_t) * 1000 * colcount);
	int cells_count = 0;
	uint_fast32_t rows = 0;
	uint_fast32_t cols = 0;

	/* log some info */
	log_info("%" PRIuFAST32 " columns to read!", colcount);

	if (colcount) {
		/* get the column directory */
		uint32_t column_directory[colcount];
		READ(&column_directory, sizeof(uint32_t) * colcount)

		/* browse columns */
		for (uint_fast32_t c = 0; c < colcount; c++) {
			/* check if column is empty */
			if (!column_directory[c])
				continue;

			/* get the row directory */
			uint8_t row_directory[0x80];
			READ(&row_directory, (size_t)0x80)

			/* initialize loop values */
			uint8_t *rd = row_directory;
			int bit = 1 << 7;

			/* explore each cell */
			for (uint_fast32_t i = 0; i < 1000; i++) {
				/* check if used */
				if (*rd & bit) {
					/* get cell */
					g1m_bcd_t cell;
					DREAD(rawcell, g1m_mcsbcd_s)
					g1m_bcd_frommcs(&rawcell, &cell);

					/* store it */
					cells[c * 1000 + i] = (g1m_mcscell_t){
						.g1m_mcscell_real = cell,
						.g1m_mcscell_imgn = (g1m_bcd_t){},
						.g1m_mcscell_flags = g1m_mcscellflag_used
					};

					/* check things (max row, max col, cells count) */
					rows = max(rows, i);
					cols = c;
					cells_count++;
				}

				/* iterate bit and rd */
				rd += (bit & 1);
				bit = (bit >> 1) | ((bit & 1) << 7);
			}
		}
	}

	/* we have max rows and columns, increment to have sizes */
	rows++, cols++;

	/* create final tab */
	head->g1m_mcshead_width = 0; head->g1m_mcshead_height = 0;
	if (cells_count) {
		head->g1m_mcshead_width = cols;
		head->g1m_mcshead_height = rows;
	}
	int err = g1m_make_mcsfile(handle, head);
	if (err) return (err);

	/* main copying loop */
	g1m_mcscell_t **tab = (*handle)->g1m_mcsfile_cells;
	for (uint_fast32_t y = 0; y < head->g1m_mcshead_height; y++)
	  for (uint_fast32_t x = 0; x < head->g1m_mcshead_width; x++)
		tab[y][x] = cells[x * 1000 + y];

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