#include "libc.h"
#include "locale_impl.h"
#include <locale.h>
#include <time.h>
#include <wchar.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 < 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;
        } else {
            width = 0;
        }
        f = p;
        if (*f == 'E' || *f == 'O')
            f++;
        t_mb = __strftime_fmt_1(&buf, &k, *f, tm, loc);
        if (!t_mb)
            break;
        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++;
            for (; width > k && l < n; width--)
                s[l++] = '0';
        }
        if (k >= n - l)
            k = n - l;
        wmemcpy(s + l, t, k);
        l += k;
    }
    if (n) {
        if (l == n)
            l = n - 1;
        s[l] = 0;
    }
    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, CURRENT_LOCALE);
}

weak_alias(__wcsftime_l, wcsftime_l);