strutils.c

/*
  strutils.c - a collection of useful string utilities

Copyright (c) 2019-2022 Terje Io
All rights reserved.

Redistribution and use in source and binary forms, with or without modification,
are permitted provided that the following conditions are met:

* Redistributions of source code must retain the above copyright notice, this
  list of conditions and the following disclaimer.

* Redistributions in binary form must reproduce the above copyright notice, this
  list of conditions and the following disclaimer in the documentation and/or
  other materials provided with the distribution.

* Neither the name of the copyright holder nor the names of its contributors may
  be used to endorse or promote products derived from this software without
  specific prior written permission.

THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS "AS IS" AND
ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE IMPLIED
WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE ARE
DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT OWNER OR CONTRIBUTORS BE LIABLE FOR
ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES
(INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES;
LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON
ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT
(INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE OF THIS
SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.

*/

#include <string.h>
#include <stdarg.h>
#include <stdlib.h>
#include <stdbool.h>
#include <stdio.h>

#include "strutils.h"

#define CAPS(c) ((c >= 'a' && c <= 'z') ? c & 0x5F : c)

/*! \brief Case insensitive search for first occurrence of a string inside another.
\param s1 pointer to string to search.
\param s2 pointer to string to search for.
\returns pointer to found string or NULL if not found.
*/
char *stristr (const char *s1, const char *s2)
{
    const char *s = s1, *p = s2, *r = NULL;

    if (!s2 || strlen(s2) == 0)
        return (char *)s1;

    while(*s && *p) {

        if(CAPS(*p) == CAPS(*s)) {
            if(!r)
                r = s;
            p++;
        } else {
            p = s2;
            if(r)
                s = r + 1;
            if(CAPS(*p) == CAPS(*s)) {
                r = s;
                p++;
            } else
                r = NULL;
        }
        s++;
    }

    return *p ? NULL : (char *)r;
}

/*! \brief Case insensitive search for first occurrence of a string inside another.
\param s1 pointer to string to search.
\param s2 pointer to string to search for.
\param len max. number of characters to compare.
\returns pointer to found string or NULL if not found.
*/
char *strnistr (const char *s1, const char *s2, size_t len)
{
	size_t slen = len;
    const char *s = s1, *p = s2, *r = NULL;

    if (!s2 || strlen(s2) == 0 || len == 0)
        return (char *)s1;

    while(slen && *s && *p) {

        if(CAPS(*p) == CAPS(*s)) {
            if(!r)
                r = s;
            p++;
        } else {
            p = s2;
            slen = len;
            if(r)
                s = r + 1;
            if(CAPS(*p) == CAPS(*s)) {
                r = s;
                p++;
            } else
                r = NULL;
        }
        s++;
        if(r)
        	slen--;
    }

    return slen == 0 || *p == '\0' ? (char *)r : NULL;
}

// NOTE: ensure buf is large enough to hold concatenated strings!
char *strappend (char *buf, int argc, ...)
{
    char c, *s = buf, *arg;

    va_list list;
    va_start(list, argc);

    while(argc--) {
        arg = va_arg(list, char *);
        do {
            c = *s++ = *arg++;
        } while(c);
        s--;
    }

    va_end(list);

    return buf;
}

uint32_t strnumentries (const char *s, const char delimiter)
{
    char *p = (char *)s;
    uint32_t entries = *s ? 1 : 0;

    while(entries && (p = strchr(p, delimiter))) {
        p++;
        entries++;
    }

    return entries;
}

char *strgetentry (char *res, const char *s, uint32_t entry, const char delimiter)
{
    char *e, *p = (char *)s;

    *res = '\0';
    e = strchr(p, delimiter);

    if(entry == 0 && e == NULL)
        strcpy(res, s);
    else do {
        if(entry) {
            p = e;
            e = strchr(++p, delimiter);
            entry--;
        } else {
            if(e) {
                strncpy(res, p,  e - p);
                res[e - p] = '\0';
            } else
                strcpy(res, p);
            break;
        }
    } while(true);

    return res;
}

int32_t strlookup (const char *s1, const char *s2, const char delimiter)
{
    bool found = false;
    char *e, *p = (char *)s2;
    uint32_t idx = strnumentries(s2, delimiter), len = strlen(s1);
    int32_t entry = 0;

    while(idx--) {

        if((e = strchr(p, delimiter)))
            found = (e - p) == len && !strncmp(p, s1, e - p);
        else
            found = strlen(p) == len && !strcmp(p, s1);

        if(found || e == NULL)
            break;
        else {
            p = e + 1;
            entry++;
        }
    }

    return found ? entry : -1;
}

bool strtotime (char *s, struct tm *time)
{
    char c, *s1 = s;
    uint_fast16_t idx = 0;

    if(s == NULL || time == NULL)
        return false;

    while((c = *s1)) {
        if(c == ':')
            *s1 = ' ';
        s1++;
    }

    if(strchr(s, ',')) { // "text format"

        s1 = strtok(s + 5, " ");
        while(s1) {

            switch(idx) {

                case 0:
                    time->tm_mday = atoi(s1);
                    break;

                case 1:
                    time->tm_mon = strlookup(s1, "Jan,Feb,Mar,Apr,May,Jun,Jul,Aug,Sep,Oct,Nov,Dec", ',');
                    break;

                case 2:
                    time->tm_year = atoi(s1) - 1900;
                    break;

                case 3:
                    time->tm_hour = atoi(s1);
                    break;

                case 4:
                    time->tm_min = atoi(s1);
                    break;

                case 5:
                    time->tm_sec = atoi(s1);
                    break;
            }
            idx++;
            s1 = strtok(NULL, " ");
        }
    } else { // ISO8601 format

        s1 = s;

        while((c = *s1)) {
            if(c == '-' || c == 'T')
                *s1 = ' ';
            else if(c == 'Z')
                *s1 = '\0';
            s1++;
        }

        s1 = strtok(s, " ");
        while(s1) {

            switch(idx) {

                case 0:
                    time->tm_year = atoi(s1) - 1900;
                    break;

                case 1:
                    time->tm_mon = atoi(s1) - 1;
                    break;

                case 2:
                    time->tm_mday = atoi(s1);
                    break;

                case 3:
                    time->tm_hour = atoi(s1);
                    break;

                case 4:
                    time->tm_min = atoi(s1);
                    break;

                case 5:
                    time->tm_sec = atoi(s1);
                    break;
            }
            idx++;
            s1 = strtok(NULL, " ");
        }
    }

    return idx >= 5;
}

char *strtoisodt (struct tm *dt)
{
    static char buf[21];

    if(dt == NULL || snprintf(buf, sizeof(buf), "%04i-%02i-%02iT%02i:%02i:%02i", dt->tm_year < 1000 ? dt->tm_year + 1900 : dt->tm_year, dt->tm_mon + 1, dt->tm_mday, dt->tm_hour, dt->tm_min, dt->tm_sec) > sizeof(buf))
        *buf = '\0';

    return buf;
}

char *strtointernetdt (struct tm *dt)
{
    static const char *month_table[12] = {
        "Jan",
        "Feb",
        "Mar",
        "Apr",
        "May",
        "Jun",
        "Jul",
        "Aug",
        "Sep",
        "Oct",
        "Nov",
        "Dec"
    };

    static const char *day_table[7] = {
        "Sun",
        "Mon",
        "Tue",
        "Wed",
        "Thu",
        "Fri",
        "Sat"
    };

    static char buf[31];

#ifdef __MSP432E401Y__
    return "Thu, 01 Jan 1970 00:00:00 GMT"; // snprintf below crashes the MCU!
#else

    if(dt == NULL || snprintf(buf, sizeof(buf), "%s, %02d %s %04d %02d:%02d:%02d GMT", day_table[dt->tm_wday], dt->tm_mday, month_table[dt->tm_mon], dt->tm_year < 1000 ? dt->tm_year + 1900 : dt->tm_year, dt->tm_hour, dt->tm_min, dt->tm_sec) > sizeof(buf))
        return "Thu, 01 Jan 1970 00:00:00 GMT";

    return buf;

#endif
}