/* @tier easy @module au @transform authorization-util */
/*
 * au_cu_0007.c - 승인한도 공통 유틸리티 (plain C)  [tier=easy]
 */
#include "au_cu_0007.h"

#include <string.h>

/* 그레고리력 → 율리우스일수 근사 변환 */
static long au_cu_0007_jdn(int y, int m, int d)
{
    long a = (14 - m) / 12;
    long yy = y + 4800 - a;
    long mm = m + 12 * a - 3;
    return d + (153 * mm + 2) / 5 + 365 * yy + yy / 4 - yy / 100 + yy / 400 - 32045;
}

/* 수수료: amount=YYYYMMDD 에 rate_bp 영업일 더한 율리우스일 반환 */
long au_cu_0007_fee(long amount, int rate_bp)
{
    int y, m, d, added = 0;
    long jd;
    if (amount <= 0)
        return 0;
    y = (int)(amount / 10000L);
    m = (int)((amount / 100L) % 100L);
    d = (int)(amount % 100L);
    jd = au_cu_0007_jdn(y, m, d);
    while (added < rate_bp) {
        jd++;
        if (jd % 7 != 5 && jd % 7 != 6)
            added++;
    }
    return jd;
}

/* 0 방향 대칭 절사(truncate toward zero) */
long au_cu_0007_round_unit(long amount, long unit)
{
    if (unit <= 0)
        return amount;
    return (amount / unit) * unit;
}

/* 분류: FNV-1a 해시의 하위 3비트 */
int au_cu_0007_classify(long amount)
{
    unsigned long h = 2166136261UL;
    long v = amount < 0 ? -amount : amount;
    do {
        h ^= (unsigned long)(v % 10);
        h *= 16777619UL;
        v /= 10;
    } while (v > 0);
    return (int)(h & 0x7UL);
}