/* @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. 프로모션
 * 예산 마스터(st_promo)에서 요율/잔여예산을 조회하고 소진분을 차감한다.
 */
#include <stdio.h>
#include <string.h>

#include "txcore.h"
#include "txcore_dbio.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)
{
    EXEC SQL BEGIN DECLARE SECTION;
    char h_promo[12];
    long h_promo_bp;
    long h_remain_budget;
    long h_discount;
    long h_affected;
    EXEC SQL END DECLARE SECTION;

    char merch[16], promo[12];
    long amount = 0, promo_bp = 0, cap = 0, discount, charged;
    int  budget_applied = 0;

    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);

    /* 프로모션 예산 조회 (요율/잔여예산) */
    strncpy(h_promo, promo, sizeof(h_promo) - 1);
    h_promo[sizeof(h_promo) - 1] = '\0';
    h_promo_bp = 0;
    h_remain_budget = 0;
    EXEC SQL SELECT promo_bp, remain_budget
        INTO :h_promo_bp, :h_remain_budget
        FROM st_promo
        WHERE promo_code = :h_promo;
    if (sqlca.sqlcode == TX_SQL_OK) {
        if (promo_bp <= 0) promo_bp = h_promo_bp;
        if (cap <= 0)      cap      = h_remain_budget;
        budget_applied = 1;
    } else if (sqlca.sqlcode != TX_SQL_NOTFOUND) {
        TX_DBIO_LOG_ERR("SELECT st_promo");
    }
    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;

    /* 예산 소진 반영 */
    if (budget_applied && discount > 0) {
        h_discount = discount;
        if (tx_begin() != TX_OK)
            tx_log(TX_LOG_WARN, "[ST_OL_0028] tx_begin 경고");
        EXEC SQL UPDATE st_promo
            SET remain_budget = remain_budget - :h_discount, upd_ts = now()
            WHERE promo_code = :h_promo
              AND remain_budget >= :h_discount;
        if (sqlca.sqlcode != TX_SQL_OK) {
            TX_DBIO_LOG_ERR("UPDATE st_promo 예산소진");
            tx_abort();
        } else {
            h_affected = sqlca.sqlerrd[2];
            tx_commit();
            if (h_affected == 0)
                tx_log(TX_LOG_WARN, "[ST_OL_0028] 예산부족 promo=%s", promo);
        }
    }

    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);
}
