/*
 * VBSF - generate C file with codepage -> unicode tables based on uni*.tbl files
 * Copyright (C) 2022 Javier S. Pedro
 *
 * This program is free software; you can redistribute it and/or
 * modify it under the terms of the GNU General Public License
 * as published by the Free Software Foundation; either version 2
 * of the License, or (at your option) any later version.

 * This program 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 General Public License for more details.
 *
 * You should have received a copy of the GNU General Public License
 * along with this program; if not, write to the Free Software
 * Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA  02110-1301, USA.
 */

#include <stdio.h>
#include <stdlib.h>
#include <stdint.h>
#include <libgen.h>
#include <ctype.h>
#include <string.h>

/** size of codepage -> unicode table */
#define TBL_SIZE 128   /* in 16bit words */
/** maximum number of codepages in the same C file */
#define MAX_CPS 32

static FILE *fout;
static unsigned all_cps[MAX_CPS] = {0};
static unsigned num_cps = 0;

static void print_table(const uint16_t *table, unsigned cp)
{
	int i;
	int col = 0;

	fprintf(fout, "static const uint16_t cp%utbl[%u] = {\n  ", cp, TBL_SIZE);

	for (i = 0; i < TBL_SIZE; i++)
	{
		if (col)
		{
			fprintf(fout, ", ");
		}
		if (col >= 8)
		{
			fprintf(fout, "\n  ");
			col = 0;
		}
		fprintf(fout, "0x%04X", table[i]);
		col++;
	}

	fprintf(fout, "\n};\n\n");
}

static int process_table(FILE *fp, const char *base, unsigned cp)
{
	char buffer[TBL_SIZE*2];
	int err;

	// Read "Description of table" (terminated by \r\n)
	if (!fgets(buffer, sizeof(buffer), fp)) {
		return -1;
	}

	fprintf(fout, "// %s", buffer);

	// Read "Table format designator" (currently only format 1 is supported)
	err = fread(buffer, 1, 1, fp);
	if (err != 1 || buffer[0] != 1) {
		return -1;
	}

	// Now read the actual table (256 bytes in format 1)
	if ((err = fread(buffer, 1, sizeof(buffer), fp)) != sizeof(buffer)) {
		return -1;
	}

	print_table((const uint16_t *)buffer, cp);

	all_cps[num_cps++] = cp;

	return 0;
}

static int process_file(char *filename)
{
	FILE *fp = fopen(filename, "rb");
	char *base = basename(filename);
	unsigned cp = 0;

	if (!fp) {
		fprintf(stderr, "Cannot open file '%s'\n", filename);
		return -1;
	}

	if (strnicmp(&base[0], "CP", 2) == 0
	        && isdigit(base[2]) && isdigit(base[3]) && isdigit(base[4])
	        && strnicmp(&base[5], "UNI.TBL", 7) == 0) {
		cp = atoi(&base[2]);
	} else if (strnicmp(&base[0], "C", 2) == 0
	           && isdigit(base[1]) && isdigit(base[2]) && isdigit(base[3]) && isdigit(base[4])
	           && strnicmp(&base[5], "UNI.TBL", 7) == 0) {
		cp = atoi(&base[1]);
	}

	if (!cp) {
		fprintf(stderr, "Cannot guess codepage number from filename '%s'\n", base);
		fclose(fp);
		return -1;
	}

	if (process_table(fp, base, cp) != 0) {
		fprintf(stderr, "Cannot read table format from '%s'\n", base);
		fclose(fp);
		return -1;
	}

	fclose(fp);
	return 0;
}

#ifdef __UNIX__
// no need to process wildcards on UNIX
static int process_arg(char *arg)
{
	return process_file(arg);
}
#else
#include <io.h>

static int process_arg(char *arg)
{
	struct _finddata_t fileinfo;
	intptr_t fh = _findfirst(arg, &fileinfo);

	if (!fh) {
		fprintf(stderr, "Cannot find '%s'\n", arg);
		return -1;
	}

	do {
		// Name of file in fileinfo will be without path
		// If so copy the path from the arg
		char namebuf[_MAX_PATH];
		char *s;

		if ((s = strrchr(arg, '\\')) || (s = strrchr(arg, '/')) || (s = strrchr(arg, ':'))) {
			memcpy(namebuf, arg, s-arg+1);
			strcpy(namebuf + (s-arg) +1, fileinfo.name);
		} else {
			strcpy(namebuf, fileinfo.name);
		}

		if (process_file(namebuf) != 0) {
			return -1;
		}
	} while (_findnext(fh, &fileinfo) == 0);

	return 0;
}
#endif

int main(int argc, char **argv)
{
	int i;

	if (argc < 3)
	{
		fprintf(stderr,
		        "Usage: bin2c <output c file> <unitbl/*.tbl>\n");
		return 1;
	}

	fout = fopen(argv[1], "wt");
	fprintf(fout, "#include <stdint.h>\n");

	for (i = 2; i < argc; i++) {
		if (process_arg(argv[i])) {
			return EXIT_FAILURE;
		}
	}

	fprintf(fout, "static const uint16_t * get_uni_tbl(unsigned cp) {\n");
	fprintf(fout, " switch (cp) {\n");
	for (i = 0; i < num_cps; i++) {
		unsigned cp = all_cps[i];
		fprintf(fout, "  case %u:\n", cp);
		fprintf(fout, "   return cp%utbl;\n", cp);
	}
	fprintf(fout, "  default:\n");
	fprintf(fout, "   return 0;\n");
	fprintf(fout, " }\n");
	fprintf(fout, "}\n\n");

	fclose(fout);

	printf("Processed %u tables\n", num_cps);

	return EXIT_SUCCESS;
}