#include <u.h>
#include <libc.h>
#include <utffold.h>
#include <utfunfold.h>

static Rune*
bsearch(Rune c, Rune *t, int n, int ne)
{
	Rune *p;
	int m;

	while(n > 1) {
		m = n/2;
		p = t + m*ne;
		if(c >= p[0]) {
			t = p;
			n = n-m;
		} else
			n = m;
	}
	if(n && c >= t[0])
		return t;
	return 0;
}

static Rune*
bsearchs(Rune c, Rune **t, int n, int ne)
{
	Rune **p;
	int m;

	while(n > 1) {
		m = n/2;
		p = t + m*ne;
		if(c >= p[0][0]) {
			t = p;
			n = n-m;
		} else
			n = m;
	}
	if(n && c >= t[0][0])
		return t[0];
	return 0;
}

Rune
tobaserune(Rune c)
{
	Rune *p;

	p = bsearch(c, __base2, nelem(__base2)/2, 2);
	if(p && *p == c)
		c = p[1];
	return c;
}

Rune*
equivrune(Rune c)
{
	Rune *p;

	p = bsearchs(c, __unfoldbase, nelem(__unfoldbase), 1);
	if(p && *p == c)
		return p;
	return nil;
}

#include <bio.h>

void
unfold(Biobuf *b, char *re)
{
	Rune r, r0, *s;

	for(; *re != 0; ){
		if(*re == '\\'){
			Bputc(b, '\\');
			if(re[1] == 0)
				break;
		}
		re += chartorune(&r, re);
		r0 = tobaserune(r);
		if(s = equivrune(r0))
			Bprint(b, "[%S]", s);
		else
			Bputrune(b, r);
	}
}

void
usage(void)
{
	fprint(2, "usage: unfoldre\n");
	exits("usage");
}

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

	ARGBEGIN{
	default:
		usage();
	}ARGEND
	Binit(&b, 1, OWRITE);
	for(i = 0; i < argc; i++)
		unfold(&b, argv[i]);
	Bterm(&b);
	exits("");
}