/* See LICENSE file for copyright and license details. */
#include <stdio.h>
#include <stdlib.h>
#include <string.h>

#include "text.h"
#include "util.h"

static void
usage(void)
{
	eprintf("usage: cut -b list [-n] [file...]\n"
	        "       cut -c list [file...]\n"
	        "       cut -f list [-d delim] [-s] [file...]\n");
}

typedef struct Range {
	size_t min, max;
	struct Range *next;
} Range;

static Range *list = NULL;
static char mode = 0;
static char delim = '\t';
static int nflag = 0;
static int sflag = 0;

static void
insert(Range *r)
{
	Range *l, *p, *t;

	for (p = NULL, l = list; l; p = l, l = l->next) {
		if (r->max && r->max + 1 < l->min) {
			r->next = l;
			break;
		} else if (!l->max || r->min < l->max + 2) {
			l->min = MIN(r->min, l->min);
			for (p = l, t = l->next; t; p = t, t = t->next)
				if (r->max && r->max + 1 < t->min)
					break;
			l->max = (p->max && r->max) ? MAX(p->max, r->max) : 0;
			l->next = t;
			return;
		}
	}
	if (p)
		p->next = r;
	else
		list = r;
}

static void
parselist(char *str)
{
	char *s;
	size_t n = 1;
	Range *r;

	for (s = str; *s; s++) {
		if (*s == ' ')
			*s = ',';
		if (*s == ',')
			n++;
	}
	r = emalloc(n * sizeof(Range));
	for (s = str; n; n--, s++) {
		r->min = (*s == '-') ? 1 : strtoul(s, &s, 10);
		r->max = (*s == '-') ? strtoul(s + 1, &s, 10) : r->min;
		r->next = NULL;
		if (!r->min || (r->max && r->max < r->min) || (*s && *s != ','))
			eprintf("cut: bad list value\n");
		insert(r++);
	}
}

static void
freelist(void) {
	Range *l = list, *next;

	while (l) {
		next = l->next;
		free(l);
		l->next = NULL;
		l = next;
	}
}

static size_t
seek(const char *s, size_t pos, size_t *prev, size_t count)
{
	const char *t;
	size_t n = pos - *prev;

	if (mode == 'b') {
		if ((t = memchr(s, 0, n)))
			return t - s;
		if (nflag)
			while (n && !UTF8_POINT(s[n]))
				n--;
		*prev += n;
		return n;
	} else if (mode == 'c') {
		for (n++, t = s; *t; t++)
			if (UTF8_POINT(*t) && !--n)
				break;
	} else {
		for (t = (count < 2) ? s : s + 1; n && *t; t++)
			if (*t == delim && !--n && count)
				break;
	}
	*prev = pos;
	return t - s;
}

static void
cut(FILE *fp)
{
	char *buf = NULL, *s;
	size_t size = 0, i, n, p;
	ssize_t len;
	Range *r;

	while ((len = agetline(&buf, &size, fp)) != -1) {
		if (len && buf[len - 1] == '\n')
			buf[len - 1] = '\0';
		if (mode == 'f' && !strchr(buf, delim)) {
			if (!sflag)
				puts(buf);
			continue;
		}
		for (i = 0, p = 1, s = buf, r = list; r; r = r->next, s += n) {
			s += seek(s, r->min, &p, i++);
			if (!*s)
				break;
			if (!r->max) {
				fputs(s, stdout);
				break;
			}
			n = seek(s, r->max + 1, &p, i++);
			if (fwrite(s, 1, n, stdout) != n)
				eprintf("write error:");
		}
		putchar('\n');
	}
	free(buf);
}

int
main(int argc, char *argv[])
{
	FILE *fp;

	ARGBEGIN {
	case 'b':
	case 'c':
	case 'f':
		mode = ARGC();
		parselist(ARGF());
		break;
	case 'd':
		delim = *ARGF();
		break;
	case 'n':
		nflag = 1;
		break;
	case 's':
		sflag = 1;
		break;
	default:
		usage();
	} ARGEND;

	if (!mode)
		usage();
	if (!argc)
		cut(stdin);
	else {
		for (; argc--; argv++) {
			if (strcmp(*argv, "-"))
				fp = fopen(*argv, "r");
			else
				fp = stdin;
			if (!fp) {
				weprintf("fopen %s:", *argv);
				continue;
			}
			cut(fp);
			if (fp != stdin)
				fclose(fp);
		}
	}
	freelist();
	return 0;
}