/* @tier easy @module st @transform settlement-online */
/*
 * st_ol_0028.pgc - 프로모션 할인 정산 (ST_OL_0028)  [tier=easy]
 *
 * 프로모션 할인요율(만분율)을 매출에 적용하여 할인액을 산출하되,
 * 프로모션 예산 한도(cap)를 상한으로 실 청구금액을 계산한다.
 */
#include <stdio.h>
#include <string.h>

#include "txcore.h"
#include "acq_util.h"
#include "st_core.h"

EXEC SQL INCLUDE sqlca;


static long st_fee_round(long amount, long rate_bp)
{
    /* 요율(만분율, basis point) x 금액 -> 원단위 반올림 (BigDecimal HALF_UP 대응) */
    if (amount < 0)
        return -(((-amount) * rate_bp + 5000) / 10000);
    return (amount * rate_bp + 5000) / 10000;
}

TX_SERVICE(ST_OL_0028, ctx)
{
    char merch[16], promo[12];
    long amount = 0, promo_bp = 0, cap = 0, discount, charged;

    tx_log(TX_LOG_INFO, "[ST_OL_0028] 프로모션 할인 정산 진입");

    if (tx_buf_get(ctx->in, "MERCHID", merch, sizeof(merch)) != TX_OK) {
        tx_return(ctx, TX_EINVAL, ctx->out);
        return;
    }
    if (tx_buf_get(ctx->in, "PROMO", promo, sizeof(promo)) != TX_OK)
        strncpy(promo, "DEFAULT", sizeof(promo) - 1);
    tx_buf_getlong(ctx->in, "AMOUNT", &amount);
    tx_buf_getlong(ctx->in, "PROMOBP", &promo_bp);
    tx_buf_getlong(ctx->in, "CAP", &cap);
    if (promo_bp <= 0) promo_bp = 500;   /* 5% 할인 */
    if (cap <= 0) cap = 10000;           /* 프로모션 상한 1만원 */

    if (!amount_is_valid(amount)) {
        tx_buf_reset(ctx->out);
        tx_buf_sets(ctx->out, "RESPCODE", RESP_INVALID);
        tx_return(ctx, TX_EINVAL, ctx->out);
        return;
    }

    discount = st_fee_round(amount, promo_bp);
    if (discount > cap) discount = cap;
    charged  = amount - discount;

    tx_buf_reset(ctx->out);
    tx_buf_sets(ctx->out, "RESPCODE", RESP_OK);
    tx_buf_sets(ctx->out, "MERCHID", merch);
    tx_buf_sets(ctx->out, "PROMO", promo);
    tx_buf_setlong(ctx->out, "DISCOUNT", discount);
    tx_buf_setlong(ctx->out, "CHARGED", charged);
    tx_log(TX_LOG_INFO, "[ST_OL_0028] 프로모션 %s amount=%ld 할인=%ld 청구=%ld",
           promo, amount, discount, charged);
    tx_return(ctx, TX_OK, ctx->out);
}
