#include <sys/types.h>
#include <time.h>
#include "plugin.h"
#ifdef PLUGIN
#define mktime(t) rb->mktime(t)
#endif

static const char   sweekdays [7] [4] = {
    "Sun", "Mon", "Tue", "Wed", "Thu", "Fri", "Sat"
};
static const char   weekdays [7] [10] = {
    "Sunday", "Monday", "Tuesday", "Wednesday", "Thursday", "Friday", "Saturday"
};
static const char   smonths [12] [4] = {
    "Jan", "Feb", "Mar", "Apr", "May", "Jun",
    "Jul", "Aug", "Sep", "Oct", "Nov", "Dec"
};
static const char*  months [12] = {
    "January", "February", "March", "April", smonths[5-1], "June",
    "July", "August", "September", "October", "November", "December"
};
static const char   ampm [4] [3] = {
    "am", "pm",
    "AM", "PM"
};

static void i2a ( char* dest,unsigned long x )
{
    int  div = 10;
    *dest++ = x/div + '0';
    *dest++ = x%div + '0';
    *dest++ = '\0';
}

size_t  strftime ( char* dst, size_t max, const char* format, const struct tm* tm )
{
    char*         p = dst;
    const char*   src;
    unsigned long no;
    char          buf [5];
#if CONFIG_RTC
    char sbuf[101];
#endif

    if (!max) return 0;
    for ( ; *format != '\0'; format++ ) {
    if (*format == '%') {
        if (*++format == '%') {
            *p++ = '%';
        }
        else
again:
        switch (*format) {
//          case '%': *p++ = '%';                  break;            // reduce size of jump table
        case 'n': *p++ = '\n';                 break;
        case 't': *p++ = '\t';                 break;
        case 'O': case 'E': ++format; goto again;
        case 'c': src = "%b %a %d %k:%M:%S %Z %Y";            goto _strf;
        case 'r': src = "%I:%M:%S %p";                        goto _strf;
        case 'R': src = "%H:%M";                  goto _strf;
        case 'x': src = "%b %a %d";               goto _strf;
        case 'X': src = "%k:%M:%S";               goto _strf;
        case 'D': src = "%m/%d/%y";               goto _strf;
        case 'F': src = "%Y-%m-%d";               goto _strf;
        case 'T': src = "%H:%M:%S";
           _strf: p  += strftime (p, (size_t)(dst+max-p), src, tm);      break;
        case 'a': src = sweekdays [tm->tm_wday];         goto _str;
        case 'A': src = weekdays  [tm->tm_wday];         goto _str;
        case 'h':
        case 'b': src = smonths   [tm->tm_mon];          goto _str;
        case 'B': src = months    [tm->tm_mon];          goto _str;
        case 'p': src = ampm [tm->tm_hour > 12 ? 3 : 2]; goto _str;
        case 'P': src = ampm [tm->tm_hour > 12 ? 1 : 0]; goto _str;
        case 'C': no  = tm->tm_year/100 + 19;         goto _no;
        case 'd': no  = tm->tm_mday;                  goto _no;
        case 'e': no  = tm->tm_mday;                  goto _nos;
        case 'H': no  = tm->tm_hour;                  goto _no;
        case 'I': no  = tm->tm_hour % 12;             goto _no;
        case 'j': no  = tm->tm_yday;                  goto _no;
        case 'k': no  = tm->tm_hour;                  goto _nos;
        case 'l': no  = tm->tm_hour % 12;             goto _nos;
        case 'm': no  = tm->tm_mon + 1;               goto _no;
        case 'M': no  = tm->tm_min;                   goto _no;
        case 'S': no  = tm->tm_sec;                   goto _no;
        case 'u': no  = tm->tm_wday ? tm->tm_wday : 7;       goto _no;
        case 'w': no  = tm->tm_wday;                         goto _no;
        case 'U': no  = (tm->tm_yday - tm->tm_wday + 7) / 7; goto _no;
        case 'W': no  = (tm->tm_yday - (tm->tm_wday - 1 + 7) % 7 + 7) / 7; goto _no;
        case 's': {
#if CONFIG_RTC
            time_t t = mktime((struct tm*)tm);
            char* c;
            sbuf[100]=0;
            for (c=sbuf+99; c>sbuf; --c) {
              *c=(t%10)+'0';
              t/=10;
              if (!t) break;
            }
#else
            char* c = "0";
#endif
            src=c;
            goto _str;
              }
        case 'Z':
#ifdef WANT_TZFILE_PARSER
              tzset(); src = tzname[0];
#else
              src = "[unknown timezone]";
#endif
              goto _str;
        case 'Y': i2a ( buf+0, (unsigned int)(tm->tm_year / 100 + 19) );
              i2a ( buf+2, (unsigned int)(tm->tm_year % 100) );
              src = buf;
              goto _str;
        case 'y': no  = tm->tm_year % 100;              goto _no;
         _no: i2a ( buf, no );                 /* append number 'no' */
              src = buf;
              goto _str;
        _nos: i2a ( buf, no );                 /* the same, but '0'->' ' */
              if (buf[0] == '0')
              buf[0] = ' ';
              src = buf;
        _str: while (*src  &&  p < dst+max)         /* append string */
              *p++ = *src++;
              break;
        };
    } else {
        *p++ = *format;
    }

    if (p >= dst+max)
        break;
    }

    if ((size_t)(p-dst)>=max) {
      if (max) p[-1]=0;
    } else
      *p = '\0';
    return p - dst;
}