/* cp437utf8.c : convert DOS ASCII (cp437) to UTF-8
 * PUBLIC DOMAIN - Jon Mayo - November 9, 2007
 */
#define _GNU_SOURCE 1
#include <stdio.h>
#include <stdlib.h>
#include <errno.h>
#include <getopt.h>

unsigned short tab[256] = {
	0x0000, 0x263a, 0x263b, 0x2665, 0x2666, 0x2663, 0x2660, 0x2022,
	0x25d8, 0x25cb, 0x25d9, 0x2642, 0x2640, 0x266a, 0x266b, 0x263c,
	0x25ba, 0x25c4, 0x2195, 0x203c, 0x00b6, 0x00a7, 0x25ac, 0x21a8,
	0x2191, 0x2193, 0x2192, 0x2190, 0x221f, 0x2194, 0x25b2, 0x25bc,
	' ', '!', '"', '#', '$', '%', '&', '\'',
	'(', ')', '*', '+', ',', '-', '.', '/',
	'0', '1', '2', '3', '4', '5', '6', '7',
	'8', '9', ':', ';', '<', '=', '>', '?',
	'@', 'A', 'B', 'C', 'D', 'E', 'F', 'G',
	'H', 'I', 'J', 'K', 'L', 'M', 'N', 'O',
	'P', 'Q', 'R', 'S', 'T', 'U', 'V', 'W',
	'X', 'Y', 'Z', '[', '\\', ']', '^', '_',
	'`', 'a', 'b', 'c', 'd', 'e', 'f', 'g',
	'h', 'i', 'j', 'k', 'l', 'm', 'n', 'o',
	'p', 'q', 'r', 's', 't', 'u', 'v', 'w',
	'x', 'y', 'z', '{', '|', '}', '~', 0x2302,
	0x00c7, 0x00fc, 0x00e9, 0x00e2, 0x00e4, 0x00e0, 0x00e5, 0x00e7,
	0x00ea, 0x00eb, 0x00e8, 0x00ef, 0x00ee, 0x00ec, 0x00c4, 0x00c5,
	0x00c9, 0x00e6, 0x00c6, 0x00f4, 0x00f6, 0x00f2, 0x00fb, 0x00f9,
	0x00ff, 0x00d6, 0x00dc, 0x00a2, 0x00a3, 0x00a5, 0x20a7, 0x0192,
	0x0031, 0x00ed, 0x00f3, 0x00fa, 0x00f1, 0x00d1, 0x00aa, 0x00ba,
	0x00bf, 0x2310, 0x00ac, 0x00bd, 0x00bc, 0x00a1, 0x00ab, 0x00bb,
	0x2591, 0x2592, 0x2593, 0x2502, 0x2524, 0x2561, 0x2562, 0x2556,
	0x2555, 0x2563, 0x2551, 0x2557, 0x255d, 0x255c, 0x255b, 0x2510,
	0x2514, 0x2534, 0x252c, 0x251c, 0x2500, 0x253c, 0x255e, 0x255f,
	0x255a, 0x2554, 0x2569, 0x2566, 0x2560, 0x2550, 0x256c, 0x2567,
	0x2568, 0x2564, 0x2565, 0x2559, 0x2558, 0x2552, 0x2553, 0x256b,
	0x256a, 0x2518, 0x250c, 0x2588, 0x2584, 0x258c, 0x2590, 0x2580,
	0x03b1, 0x00df, 0x0393, 0x03c0, 0x03a3, 0x03c3, 0x00b5, 0x03c4,
	0x03a6, 0x0398, 0x03a9, 0x03b4, 0x221e, 0x03c6, 0x03b5, 0x2229,
	0x2261, 0x00b1, 0x2265, 0x2264, 0x2320, 0x2321, 0x00f7, 0x2248,
	0x00b0, 0x2219, 0x00b7, 0x221a, 0x207f, 0x00b2, 0x25a0, 0x00a0,
};

/* we only support ucs-2 */
static void
writeutf8(unsigned short w)
{
	if(w<0x80) {
		putchar(w);
	} else if(w<0x800) {
		putchar(0xc0|(w>>6));
		putchar(0x80|(w&0x3f));
	} else {
		putchar(0xe0|(w>>12));
		putchar(0x80|((w>>6)&0x3f));
		putchar(0x80|(w&0x3f));
	}
}

static int
do_file(const char *filename, FILE *f)
{
	int c;

	while((c = fgetc(f)) != EOF) {
		/* don't encode control characters */
		writeutf8(c>=' ' ? tab[c] : c);
	}

	return ferror(f) ? -1 : 0;
}

static int
process_one(const char *filename)
{
	if (filename[0] == '-' && !filename[1]) {
		return do_file("<STDIN>", stdin);
	} else {
		FILE *f = fopen(filename, "rb");
		int result = do_file(filename, f);
		fclose(f);
		return result;
	}
}

static void
dump_table(void)
{
	int c;

	for (c=0; c < 256; c++) {
		writeutf8(tab[c]);
		putchar(((c + 1) % 16) ? ' ' : '\n');
	}
}

static int
process_args(int argc, char *argv[])
{
	int opt;

	while ((opt = getopt(argc, argv, "ht")) != -1) {
		switch (opt) {
		case '?':
		case 'h':
			fprintf(stderr, "usage: %s [-ht] [files...]\n", program_invocation_short_name);
			return -1;
		case 't': // dump table of ASCII characters including control characters
			dump_table();
			exit(0);
		}
	}

	return 0;
}

static int
process_files(int argc, char *argv[])
{
        while (optind < argc) {
		if (process_one(argv[optind]))
			return -1;
                optind++;
        }

	return 0;
}

int
main(int argc, char *argv[])
{
	if (process_args(argc, argv))
		return 1;

	if (process_files(argc, argv))
		return 1;

	return 0;
}