/*
	Software License Agreement (BSD License)
	
	Copyright (c) 1997-2008, David Lindauer, (LADSoft).
	All rights reserved.
	
	Redistribution and use of this software 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 LADSoft nor the names of its
	  contributors may be used to endorse or promote products
	  derived from this software without specific prior
	  written permission of LADSoft.
	
	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 <time.h> 
#include <stdio.h>
#include <string.h>
#include <locale.h>
#include <wchar.h>
#include "_locale.h"
#include <limits.h>

static int weekbasedoffset(struct tm *t)
{
    struct tm t2 = *t;
    time_t tt;
    t2.tm_mon = 0; // january 1
    t2.tm_mday = 1 ;
    tt = mktime(&t2);
    if (tt == -1)
        return INT_MAX;
    if (t2.tm_wday <= 1)
        return t2.tm_wday - 1 ;
    if (t2.tm_wday >= 5)
        return t2.tm_wday - 8;
    return t2.tm_wday - 1;
}
static int weekbasedyear(struct tm *t)
{
    int n = weekbasedoffset(t);
    int ydays = 365;
    if (n == INT_MAX)
        return 0 ;
    n += t->tm_yday;
    if (n < 0)
        return t->tm_year+1900-1;
    if (n >= ydays)
        return t->tm_year +1900+ 1;
    return t->tm_year + 1900;    
}
static int weekbasedyearweek(struct tm *t)
{
    int n = weekbasedoffset(t);
    if (n == INT_MAX)
        return 0 ;
    n += t->tm_yday;
    if (n < 0)
        return 53;
    return n / 7 ;
}
static int weeknum(struct tm *t, int startday)
{
    struct tm t2 = *t;
    int rv;
    time_t tt;
    t2.tm_mon = 0; // january 1
    t2.tm_mday = 1 ;
    tt = mktime(&t2);
    if (tt == -1)
        return 0;
    if (t2.tm_wday == 0)
        rv = t->tm_yday-startday;
    else if (t2.tm_wday == 1)
        rv = t->tm_yday - (1- startday);
    else
        rv = t->tm_yday-(7 + startday - t2.tm_wday);    
    if (rv < 0)
        return 52;
    return rv/7;
}
static int pstr(wchar_t *str,wchar_t *astr, int maxsize, int mode, int *cursize)
{
	int l;
	if (*cursize > maxsize)
		return 1;
	l = wcslen(astr);
	str += *cursize;
	while (*cursize < maxsize-1 && l) {
		*str++ = *astr++;
		(*cursize)++;
		l--;
	}
	*str = 0;
	if (l)
		return 1;
	return 0;
}
static int pchar(wchar_t *str,char astr, int maxsize, int mode, int *cursize)
{
	if (*cursize > maxsize)
		return 1;
	str += *cursize;
	*str++ = astr;
	(*cursize)++;
	*str = 0;
	return 0;
}
static int pnum(wchar_t *str, int num, int fwidth, int maxsize, int mode, int *cursize)
{
	wchar_t buf[11],*p = &buf[9], *nm;
	int i;
    TIME_DATA *td = __locale_data[LC_TIME];
    nm = td->ths;
    buf[0] = 0;
    if (mode == 'O') {
        for (i=0; i < num; i++) {
            if (*nm == 0)
                break ;
            nm += wcslen(nm);
        }
        if (*nm)
        	return(pstr(str,nm,maxsize,mode,cursize));
    }
	for (i=0; i < 10; i++)
    	buf[i] = '0';
    buf[10] = 0;
    while (num) {
    	*p-- = (char)(num %10)+'0';
	    num = num / 10;
    }
	return(pstr(str,buf+10-fwidth,maxsize,mode,cursize));
}
static int basic_format(wchar_t *restrict format, const struct tm * restrict t,
        wchar_t *restrict str, size_t maxsize, int mode, int *restrict cursize)
{
        int temp ;
        TIME_DATA *td = __locale_data[LC_TIME];
			switch(*format) {
				case 'a':
					if (pstr(str,td->shortdays[t->tm_wday],maxsize,mode,cursize))
						return 0;
					break;
				case 'A':
					if (pstr(str,td->longdays[t->tm_wday],maxsize,mode,cursize))
						return 0;
					break;
				case 'b':
                case 'h':
					if (pstr(str,td->shortmonths[t->tm_mon],maxsize,mode,cursize))
						return 0;
					break;
				case 'B':
					if (pstr(str,td->longmonths[t->tm_mon],maxsize,mode,cursize))
						return 0;
					break;
                case 'C':
					if (pnum(str,(t->tm_year+1900)/100,2,maxsize,mode,cursize))
						return 0;
                    break;
				case 'd':
					if (pnum(str,t->tm_mday,2,maxsize,mode,cursize))
						return 0;
					break;
                case 'e':
                    if (t->tm_mday < 10) {
    					if (pstr(str," ",maxsize,mode,cursize))
	    					return 0;
    					if (pnum(str,t->tm_mday,1,maxsize,mode,cursize))
	    					return 0;
                    } else
    					if (pnum(str,t->tm_mday,2,maxsize,mode,cursize))
	    					return 0;
                    break;
                case 'g':
    			    if (pnum(str,weekbasedyear(t)%100,2,maxsize,mode,cursize))
	    					return 0;
                    break ;
                case 'G':
    			    if (pnum(str,weekbasedyear(t),4,maxsize,mode,cursize))
	    					return 0;
                    break ;                    
				case 'H':
					if (pnum(str,t->tm_hour,2,maxsize,mode,cursize))
						return 0;
					break;
				case 'I':
                case 'i':
                    temp = t->tm_hour % 12;
                    if (temp == 0) temp = 12;
					if (pnum(str,temp,2,maxsize,mode,cursize))
						return 0;
					break;
				case 'j':
					if (pnum(str,t->tm_yday,3,maxsize,mode,cursize))
						return 0;
					break;
				case 'm':
					if (pnum(str,t->tm_mon+1,2,maxsize,mode,cursize))
						return 0;
					break;
				case 'M':
					if (pnum(str,t->tm_min,2,maxsize,mode,cursize))
						return 0;
					break;
                case 'n':
					if (pchar(str,'\n',maxsize,mode,cursize))
						return 0;
                    break;
				case 'P':
                case 'p':
					if (pstr(str,td->am + (t->tm_hour/12) * sizeof(td->am),maxsize,mode,cursize))
						return 0;
					break;
				case 'S':
					if (pnum(str,t->tm_sec,2,maxsize,mode,cursize))
						return 0;
					break;
                case 't':
					if (pchar(str,'\t',maxsize,mode,cursize))
						return 0;
                    break ;
				case 'U':
					if (pnum(str,weeknum(t,0),2,maxsize,mode,cursize))
						return 0;
					break;
                case 'u':
                    if (t->tm_wday == 0)
                        temp = 6 ;
                    else
                        temp = t->tm_wday-1;
					if (pnum(str,temp,1,maxsize,mode,cursize))
						return 0;
					break;
                case  'V':
					if (pnum(str,weekbasedyearweek(t),2,maxsize,mode,cursize))
						return 0;
					break;
				case 'w':
					if (pnum(str,t->tm_wday,1,maxsize,mode,cursize))
						return 0;
					break;
				case 'W':
					if (pnum(str,weeknum(t,1),2,maxsize,mode,cursize))
						return 0;
					break;
				case 'y':
					if (pnum(str,t->tm_year %100,2,maxsize,mode,cursize))
						return 0;
					break;
				case 'Y':
					if (pnum(str,t->tm_year+1900,4,maxsize,mode,cursize))
						return 0;
					break;
				case 'z':
					if (pstr(str,__getTzName(),maxsize,mode,cursize))
						return 0;
					break;
                case 'Z':
                    temp = *__getTimezone()/60;
                    if (temp > 0)
    					if (pchar(str,'-',maxsize,mode,cursize))
	    					return 0;
					if (pnum(str,temp/60,2,maxsize,mode,cursize))
						return 0;
					if (pnum(str,temp%60,2,maxsize,mode,cursize))
						return 0;
					break;
				default: // also catch %%
					if (pchar(str,*format,maxsize,mode,cursize))
						return 0;
                    break;
					
			}
        return 1;
}
static int advanced_format(wchar_t *restrict format, const struct tm * restrict t,
        wchar_t *restrict str, size_t maxsize, int *restrict cursize)
{
	int i,size,xsize;
    int mode,index ;
    TIME_DATA *td = __locale_data[LC_TIME];
	for (i=0; i < wcslen(format); i++) {
		if (format[i] == '%') {
            if (!format[++i])
                return cursize;
            mode = 0;
            if (format[i] == 'O' || format[i] == 'E') {
                mode = format[i];
                if (!format[++i])
                    return cursize;
            }
            switch(format[i]) {
				case 'c':
                    index = mode == 'E';
                    if (!wcscmp(td->qualname,"C")) {
                        if (!advanced_format("%A %B %d %T %y",t,str,maxsize,cursize))
                            return 0;                    
                    } else {
                        if (!advanced_format(td->dates[index],t,str,maxsize,cursize))
                            return 0;                    
    					if (pchar(str,' ',maxsize,mode,cursize))
	    					return 0;
                        if (!advanced_format(td->times[index],t,str,maxsize,cursize))
                            return 0;                    
                    }
                    break ;
                case 'D':
                    if (!advanced_format("%m/%d/%y",t,str,maxsize,cursize))
                        return 0;                    
                    break ;
                case 'F':
                    if (!advanced_format("%Y-%m-%d",t,str,maxsize,cursize))
                        return 0;                    
                    break ;                    
                case 'r':
                    if (!advanced_format(td->times[1],t,str,maxsize,cursize))
                        return 0;                    
                    break ;                    
                case 'R':
                    if (!advanced_format("%H:%M",t,str,maxsize,cursize))
                        return 0;                    
                    break ;                    
                case 'T':
                    if (!advanced_format("%H:%M:%S",t,str,maxsize,cursize))
                        return 0;                    
                    break ;                    
				case 'x':
                    index = mode == 'E';
                    if (!advanced_format(td->dates[index],t,str,maxsize,cursize))
                        return 0;                    
					break;
				case 'X':
                    index = mode == 'E';
                    if (!advanced_format(td->times[index],t,str,maxsize,cursize))
                        return 0;                    
					break;
                default:
                    if (!basic_format(format + i,t,str,maxsize,mode,cursize))
                        return 0;
                    break ;					
			}
		}
		else {
			if (pchar(str,format[i],maxsize,mode,cursize))
				return 0;
		}
	}
	return 1;
}
size_t _RTL_FUNC wcsftime(wchar_t *restrict str, size_t maxsize, 
                const wchar_t *restrict format, const struct tm * restrict t)
{
	int rv = 0;
    str[0] = 0;
    if (!advanced_format(format,t,str,maxsize,&rv))
        return 0;                    
	return rv;
}