/* vi: set sw=4 ts=4: */
/*
 * cut.c - minimalist version of cut
 *
 * Copyright (C) 1999,2000,2001 by Lineo, inc.
 * Written by Mark Whitley <markw@codepoet.org>
 * debloated by Bernhard Reutner-Fischer
 *
 * Licensed under GPLv2 or later, see file LICENSE in this tarball for details.
 */

#include "libbb.h"

/* This is a NOEXEC applet. Be very careful! */


/* option vars */
static const char optstring[] ALIGN1 = "b:c:f:d:sn";
#define CUT_OPT_BYTE_FLGS     (1 << 0)
#define CUT_OPT_CHAR_FLGS     (1 << 1)
#define CUT_OPT_FIELDS_FLGS   (1 << 2)
#define CUT_OPT_DELIM_FLGS    (1 << 3)
#define CUT_OPT_SUPPRESS_FLGS (1 << 4)

struct cut_list {
        int startpos;
        int endpos;
};

enum {
        BOL = 0,
        EOL = INT_MAX,
        NON_RANGE = -1
};

static int cmpfunc(const void *a, const void *b)
{
        return (((struct cut_list *) a)->startpos -
                        ((struct cut_list *) b)->startpos);

}

static void cut_file(FILE *file, char delim, const struct cut_list *cut_lists, unsigned nlists)
{
        char *line;
        unsigned linenum = 0;   /* keep these zero-based to be consistent */

        /* go through every line in the file */
        while ((line = xmalloc_fgetline(file)) != NULL) {

                /* set up a list so we can keep track of what's been printed */
                int linelen = strlen(line);
                char *printed = xzalloc(linelen + 1);
                char *orig_line = line;
                unsigned cl_pos = 0;
                int spos;

                /* cut based on chars/bytes XXX: only works when sizeof(char) == byte */
                if (option_mask32 & (CUT_OPT_CHAR_FLGS | CUT_OPT_BYTE_FLGS)) {
                        /* print the chars specified in each cut list */
                        for (; cl_pos < nlists; cl_pos++) {
                                spos = cut_lists[cl_pos].startpos;
                                while (spos < linelen) {
                                        if (!printed[spos]) {
                                                printed[spos] = 'X';
                                                putchar(line[spos]);
                                        }
                                        spos++;
                                        if (spos > cut_lists[cl_pos].endpos
                                        /* NON_RANGE is -1, so if below is true,
                                         * the above was true too (spos is >= 0) */
                                        /* || cut_lists[cl_pos].endpos == NON_RANGE */
                                        ) {
                                                break;
                                        }
                                }
                        }
                } else if (delim == '\n') {     /* cut by lines */
                        spos = cut_lists[cl_pos].startpos;

                        /* get out if we have no more lists to process or if the lines
                         * are lower than what we're interested in */
                        if (((int)linenum < spos) || (cl_pos >= nlists))
                                goto next_line;

                        /* if the line we're looking for is lower than the one we were
                         * passed, it means we displayed it already, so move on */
                        while (spos < (int)linenum) {
                                spos++;
                                /* go to the next list if we're at the end of this one */
                                if (spos > cut_lists[cl_pos].endpos
                                 || cut_lists[cl_pos].endpos == NON_RANGE
                                ) {
                                        cl_pos++;
                                        /* get out if there's no more lists to process */
                                        if (cl_pos >= nlists)
                                                goto next_line;
                                        spos = cut_lists[cl_pos].startpos;
                                        /* get out if the current line is lower than the one
                                         * we just became interested in */
                                        if ((int)linenum < spos)
                                                goto next_line;
                                }
                        }

                        /* If we made it here, it means we've found the line we're
                         * looking for, so print it */
                        puts(line);
                        goto next_line;
                } else {                /* cut by fields */
                        int ndelim = -1;        /* zero-based / one-based problem */
                        int nfields_printed = 0;
                        char *field = NULL;
                        const char delimiter[2] = { delim, 0 };

                        /* does this line contain any delimiters? */
                        if (strchr(line, delim) == NULL) {
                                if (!(option_mask32 & CUT_OPT_SUPPRESS_FLGS))
                                        puts(line);
                                goto next_line;
                        }

                        /* process each list on this line, for as long as we've got
                         * a line to process */
                        for (; cl_pos < nlists && line; cl_pos++) {
                                spos = cut_lists[cl_pos].startpos;
                                do {
                                        /* find the field we're looking for */
                                        while (line && ndelim < spos) {
                                                field = strsep(&line, delimiter);
                                                ndelim++;
                                        }

                                        /* we found it, and it hasn't been printed yet */
                                        if (field && ndelim == spos && !printed[ndelim]) {
                                                /* if this isn't our first time through, we need to
                                                 * print the delimiter after the last field that was
                                                 * printed */
                                                if (nfields_printed > 0)
                                                        putchar(delim);
                                                fputs(field, stdout);
                                                printed[ndelim] = 'X';
                                                nfields_printed++;      /* shouldn't overflow.. */
                                        }

                                        spos++;

                                        /* keep going as long as we have a line to work with,
                                         * this is a list, and we're not at the end of that
                                         * list */
                                } while (spos <= cut_lists[cl_pos].endpos && line
                                                && cut_lists[cl_pos].endpos != NON_RANGE);
                        }
                }
                /* if we printed anything at all, we need to finish it with a
                 * newline cuz we were handed a chomped line */
                putchar('\n');
 next_line:
                linenum++;
                free(printed);
                free(orig_line);
        }
}

int cut_main(int argc, char **argv) MAIN_EXTERNALLY_VISIBLE;
int cut_main(int argc UNUSED_PARAM, char **argv)
{
        /* growable array holding a series of lists */
        struct cut_list *cut_lists = NULL;
        unsigned nlists = 0;    /* number of elements in above list */
        char delim = '\t';      /* delimiter, default is tab */
        char *sopt, *ltok;
        unsigned opt;

        opt_complementary = "b--bcf:c--bcf:f--bcf";
        opt = getopt32(argv, optstring, &sopt, &sopt, &sopt, &ltok);
//      argc -= optind;
        argv += optind;
        if (!(opt & (CUT_OPT_BYTE_FLGS | CUT_OPT_CHAR_FLGS | CUT_OPT_FIELDS_FLGS)))
                bb_error_msg_and_die("expected a list of bytes, characters, or fields");

        if (opt & CUT_OPT_DELIM_FLGS) {
                if (ltok[0] && ltok[1]) { /* more than 1 char? */
                        bb_error_msg_and_die("the delimiter must be a single character");
                }
                delim = ltok[0];
        }

        /*  non-field (char or byte) cutting has some special handling */
        if (!(opt & CUT_OPT_FIELDS_FLGS)) {
                static const char _op_on_field[] ALIGN1 = " only when operating on fields";

                if (opt & CUT_OPT_SUPPRESS_FLGS) {
                        bb_error_msg_and_die
                                ("suppressing non-delimited lines makes sense%s",
                                 _op_on_field);
                }
                if (delim != '\t') {
                        bb_error_msg_and_die
                                ("a delimiter may be specified%s", _op_on_field);
                }
        }

        /*
         * parse list and put values into startpos and endpos.
         * valid list formats: N, N-, N-M, -M
         * more than one list can be separated by commas
         */
        {
                char *ntok;
                int s = 0, e = 0;

                /* take apart the lists, one by one (they are separated with commas) */
                while ((ltok = strsep(&sopt, ",")) != NULL) {

                        /* it's actually legal to pass an empty list */
                        if (!ltok[0])
                                continue;

                        /* get the start pos */
                        ntok = strsep(&ltok, "-");
                        if (!ntok[0]) {
                                s = BOL;
                        } else {
                                s = xatoi_u(ntok);
                                /* account for the fact that arrays are zero based, while
                                 * the user expects the first char on the line to be char #1 */
                                if (s != 0)
                                        s--;
                        }

                        /* get the end pos */
                        if (ltok == NULL) {
                                e = NON_RANGE;
                        } else if (!ltok[0]) {
                                e = EOL;
                        } else {
                                e = xatoi_u(ltok);
                                /* if the user specified and end position of 0,
                                 * that means "til the end of the line" */
                                if (e == 0)
                                        e = EOL;
                                e--;    /* again, arrays are zero based, lines are 1 based */
                                if (e == s)
                                        e = NON_RANGE;
                        }

                        /* add the new list */
                        cut_lists = xrealloc_vector(cut_lists, 4, nlists);
                        /* NB: startpos is always >= 0,
                         * while endpos may be = NON_RANGE (-1) */
                        cut_lists[nlists].startpos = s;
                        cut_lists[nlists].endpos = e;
                        nlists++;
                }

                /* make sure we got some cut positions out of all that */
                if (nlists == 0)
                        bb_error_msg_and_die("missing list of positions");

                /* now that the lists are parsed, we need to sort them to make life
                 * easier on us when it comes time to print the chars / fields / lines
                 */
                qsort(cut_lists, nlists, sizeof(struct cut_list), cmpfunc);
        }

        {
                int retval = EXIT_SUCCESS;

                if (!*argv)
                        *--argv = (char *)"-";

                do {
                        FILE *file = fopen_or_warn_stdin(*argv);
                        if (!file) {
                                retval = EXIT_FAILURE;
                                continue;
                        }
                        cut_file(file, delim, cut_lists, nlists);
                        fclose_if_not_stdin(file);
                } while (*++argv);

                if (ENABLE_FEATURE_CLEAN_UP)
                        free(cut_lists);
                fflush_stdout_and_exit(retval);
        }
}