#include <wchar.h>
#include <time.h>
#include <string.h>
#include <locale.h>
#include "libc.h"

const char *__strftime_fmt_1(char (*s)[100], size_t *l, int f, const struct tm *tm, locale_t loc);

size_t __wcsftime_l(wchar_t *restrict s, size_t n, const wchar_t *restrict f, const struct tm *restrict tm, locale_t loc)
{
	size_t l, k;
	char buf[100];
	wchar_t wbuf[100];
	wchar_t *p;
	const char *t_mb;
	const wchar_t *t;
	int plus;
	unsigned long width;
	for (l=0; l+1<n; f++) {
		if (!*f) {
			s[l] = 0;
			return l;
		}
		if (*f != '%') {
			s[l++] = *f;
			continue;
		}
		f++;
		if ((plus = (*f == '+'))) f++;
		width = wcstoul(f, &p, 10);
		if (*p == 'C' || *p == 'F' || *p == 'G' || *p == 'Y') {
			if (!width && p!=f) width = 1;
			if (width >= n-l) return 0;
		} else {
			width = 0;
		}
		f = p;
		if (*f == 'E' || *f == 'O') f++;
		t_mb = __strftime_fmt_1(&buf, &k, *f, tm, loc);
		if (!t_mb) return 0;
		k = mbstowcs(wbuf, t_mb, sizeof wbuf / sizeof *wbuf);
		if (k == (size_t)-1) return 0;
		t = wbuf;
		if (width) {
			for (; *t=='+' || *t=='-' || (*t=='0'&&t[1]); t++, k--);
			width--;
			if (plus && tm->tm_year >= 10000-1900)
				s[l++] = '+';
			else if (tm->tm_year < -1900)
				s[l++] = '-';
			else
				width++;
			if (width >= n-l) return 0;
			for (; width > k; width--)
				s[l++] = '0';
		}
		if (k >= n-l) return 0;
		wmemcpy(s+l, t, k);
		l += k;
	}
	return 0;
}

size_t wcsftime(wchar_t *restrict wcs, size_t n, const wchar_t *restrict f, const struct tm *restrict tm)
{
	return __wcsftime_l(wcs, n, f, tm, 0);
}

weak_alias(__wcsftime_l, wcsftime_l);