/*
 * CDDL HEADER START
 *
 * The contents of this file are subject to the terms of the
 * Common Development and Distribution License (the "License").
 * You may not use this file except in compliance with the License.
 *
 * You can obtain a copy of the license at usr/src/OPENSOLARIS.LICENSE
 * or http://www.opensolaris.org/os/licensing.
 * See the License for the specific language governing permissions
 * and limitations under the License.
 *
 * When distributing Covered Code, include this CDDL HEADER in each
 * file and include the License file at usr/src/OPENSOLARIS.LICENSE.
 * If applicable, add the following below this CDDL HEADER, with the
 * fields enclosed by brackets "[]" replaced with your own identifying
 * information: Portions Copyright [yyyy] [name of copyright owner]
 *
 * CDDL HEADER END
 */

/*
 * Copyright 2009 Sun Microsystems, Inc.  All rights reserved.
 * Use is subject to license terms.
 */

/*      Copyright (c) 1984, 1986, 1987, 1988, 1989 AT&T */
/*        All Rights Reserved   */

/*
 * Copyright 2019 OmniOS Community Edition (OmniOSce) Association.
 */

#include <stdio.h>
#include <err.h>
#include <sys/types.h>
#include <string.h>
#include <stdlib.h>
#include <ctype.h>
#include <assert.h>
#include <libcustr.h>
#include "cron.h"

#ifdef PARSETEST
#define xstrdup(x) strdup((x))
#endif

#define MAX_ELEMENTS 60

#define READNUMBER(x) \
        do { \
                (x) = (x) * 10 + (line[cursor] - '0'); \
                if ((x) > MAX_ELEMENTS) { \
                        err = CFOUTOFBOUND; \
                        goto out; \
                } \
        } while (isdigit(line[++cursor]))

#define ADDELEMENT(x)  \
        do { \
                if (eindex >= MAX_ELEMENTS) { \
                        err = CFEOVERFLOW; \
                        goto out; \
                } \
                elements[eindex++] = (x); \
        } while (0)

/* A more restrictive version of isspace(3C) that only looks for space/tab */
#define ISSPACE(x) \
        ((x) == ' ' || (x) == '\t')

cferror_t
next_field(uint_t lower, uint_t upper, char *line, int *cursorp, char **ret)
{
        uint_t elements[MAX_ELEMENTS];
        uint_t eindex = 0, i;
        int cursor = *cursorp;
        cferror_t err = CFOK;

        assert(upper - lower <= MAX_ELEMENTS);

        if (ret != NULL)
                *ret = NULL;

        while (ISSPACE(line[cursor]))
                cursor++;

        if (line[cursor] == '\0') {
                err = CFEOLN;
                goto out;
        }

        for (;;) {
                uint_t num = 0, num2 = 0, step = 0;

                if (line[cursor] == '*') {
                        cursor++;

                        /* Short circuit for plain '*' */
                        if (ISSPACE(line[cursor])) {
                                if (ret != NULL)
                                        *ret = xstrdup("*");
                                goto out;
                        }

                        /*
                         * '*' is only permitted alongside other elements if
                         * it has an associated step.
                         */

                        if (line[cursor] != '/') {
                                err = CFUNEXPECT;
                                goto out;
                        }

                        /* Treat it as a range covering all values */
                        num = lower;
                        num2 = upper;
                } else {
                        if (!isdigit(line[cursor])) {
                                err = CFUNEXPECT;
                                goto out;
                        }

                        READNUMBER(num);

                        if (num < lower || num > upper) {
                                err = CFOUTOFBOUND;
                                goto out;
                        }

                        if (line[cursor] == '-') {
                                cursor++;
                                if (!isdigit(line[cursor])) {
                                        err = CFUNEXPECT;
                                        goto out;
                                }

                                READNUMBER(num2);

                                if (num2 < lower || num2 > upper) {
                                        err = CFOUTOFBOUND;
                                        goto out;
                                }
                        } else {
                                ADDELEMENT(num);
                                goto next;
                        }
                }

                /* Look for a step definition */
                if (line[cursor] == '/') {
                        cursor++;
                        if (!isdigit(line[cursor])) {
                                err = CFUNEXPECT;
                                goto out;
                        }

                        READNUMBER(step);

                        if (step == 0) {
                                err = CFOUTOFBOUND;
                                goto out;
                        }
                } else {
                        step = 1;
                }

                if (num <= num2) {
                        for (i = num; i <= num2; i += step) {
                                ADDELEMENT(i);
                        }
                } else {
                        /* Wrap-around range */
                        for (i = num; i <= upper; i += step) {
                                ADDELEMENT(i);
                        }

                        i -= (upper - lower + 1);
                        for (; i <= num2; i += step) {
                                ADDELEMENT(i);
                        }
                }

next:

                if (line[cursor] != ',')
                        break;

                cursor++;
        }

        if (line[cursor] == '\0') {
                err = CFEOLN;
                goto out;
        }

        if (!ISSPACE(line[cursor])) {
                err = CFUNEXPECT;
                goto out;
        }

        if (ret != NULL) {
                custr_t *cs = NULL;

                if (custr_alloc(&cs) != 0) {
                        err = CFENOMEM;
                        goto out;
                }

                for (i = 0; i < eindex; i++) {
                        if (custr_len(cs) > 0) {
                                if (custr_appendc(cs, ',') != 0) {
                                        custr_free(cs);
                                        err = CFENOMEM;
                                        goto out;
                                }
                        }
                        if (custr_append_printf(cs, "%u", elements[i]) != 0) {
                                custr_free(cs);
                                err = CFENOMEM;
                                goto out;
                        }
                }

                if (custr_len(cs) != 0)
                        *ret = xstrdup(custr_cstr(cs));
                custr_free(cs);
        }

out:

        *cursorp = cursor;

        return (err);
}

#ifdef PARSETEST
int
main(int argc, char **argv)
{
        int lower, upper, cursor = 0;
        char *ret;

        if (argc != 4)
                errx(1, "<lower> <upper> <string>");

        lower = atoi(argv[1]);
        upper = atoi(argv[2]);

        switch (next_field(lower, upper, argv[3], &cursor, &ret)) {
        case CFOK:
                (void) printf("%s\n", ret);
                break;
        case CFEOLN:
                (void) printf("UnexpectedEOL\n");
                break;
        case CFUNEXPECT:
                (void) printf("UnexpectedChar\n");
                break;
        case CFOUTOFBOUND:
                (void) printf("OutOfBounds\n");
                break;
        case CFEOVERFLOW:
                (void) printf("Overflow\n");
                break;
        case CFENOMEM:
                (void) printf("OutOfMemory\n");
                break;
        default:
                (void) printf("UnknownError\n");
                break;
        }

        return (0);
}
#endif