chore: acquire-core migration monorepo (legacy C + Spring Boot target skeleton)

TxCore/ECPG legacy 매입·정산 C 슬라이스(빌드검증) + Spring Boot 멀티모듈 골격(mvn test green) + MIGRATION.md 전환룰 + CI(boot 빌드).

legacy/app/common/util_date.c

@@ -0,0 +1,135 @@
+/*
+ * util_date.c - 일자/영업일 유틸리티 (plain C)
+ */
+#include "acq_util.h"
+
+#include <string.h>
+#include <ctype.h>
+#include <stdio.h>
+#include <time.h>
+
+static int is_all_digit(const char *s, int len)
+{
+    int i;
+    for (i = 0; i < len; i++) {
+        if (!isdigit((unsigned char)s[i]))
+            return 0;
+    }
+    return 1;
+}
+
+static int to_int(const char *s, int len)
+{
+    int i, v = 0;
+    for (i = 0; i < len; i++)
+        v = v * 10 + (s[i] - '0');
+    return v;
+}
+
+static int days_in_month(int y, int m)
+{
+    static const int d[] = { 31, 28, 31, 30, 31, 30,
+                             31, 31, 30, 31, 30, 31 };
+    if (m < 1 || m > 12)
+        return 0;
+    if (m == 2) {
+        int leap = (y % 4 == 0 && y % 100 != 0) || (y % 400 == 0);
+        return leap ? 29 : 28;
+    }
+    return d[m - 1];
+}
+
+int date_is_valid(const char *yyyymmdd)
+{
+    int y, m, d;
+
+    if (!yyyymmdd || strlen(yyyymmdd) < 8)
+        return 0;
+    if (!is_all_digit(yyyymmdd, 8))
+        return 0;
+
+    y = to_int(yyyymmdd, 4);
+    m = to_int(yyyymmdd + 4, 2);
+    d = to_int(yyyymmdd + 6, 2);
+
+    if (y < 1900 || y > 2999)
+        return 0;
+    if (m < 1 || m > 12)
+        return 0;
+    if (d < 1 || d > days_in_month(y, m))
+        return 0;
+    return 1;
+}
+
+/* Sakamoto 알고리즘: 0=일요일 ... 6=토요일 */
+int date_weekday(const char *yyyymmdd)
+{
+    static const int t[] = { 0, 3, 2, 5, 0, 3, 5, 1, 4, 6, 2, 4 };
+    int y, m, d;
+
+    if (!date_is_valid(yyyymmdd))
+        return -1;
+
+    y = to_int(yyyymmdd, 4);
+    m = to_int(yyyymmdd + 4, 2);
+    d = to_int(yyyymmdd + 6, 2);
+
+    if (m < 3)
+        y -= 1;
+    return (y + y / 4 - y / 100 + y / 400 + t[m - 1] + d) % 7;
+}
+
+int date_is_weekend(const char *yyyymmdd)
+{
+    int w = date_weekday(yyyymmdd);
+    return (w == 0 || w == 6) ? 1 : 0;
+}
+
+/* YYYYMMDD 를 하루 증가시킨다 (in==out 허용) */
+static void add_one_day(const char *in, char *out)
+{
+    int y = to_int(in, 4);
+    int m = to_int(in + 4, 2);
+    int d = to_int(in + 6, 2);
+
+    d++;
+    if (d > days_in_month(y, m)) {
+        d = 1;
+        m++;
+        if (m > 12) {
+            m = 1;
+            y++;
+        }
+    }
+    snprintf(out, 9, "%04d%02d%02d", y, m, d);
+}
+
+int date_next_business(const char *yyyymmdd, char *out)
+{
+    char cur[9];
+    int guard = 0;
+
+    if (!date_is_valid(yyyymmdd) || !out)
+        return -1;
+
+    memcpy(cur, yyyymmdd, 8);
+    cur[8] = '\0';
+
+    do {
+        add_one_day(cur, cur);
+        if (++guard > 14)      /* 무한루프 방지 */
+            return -1;
+    } while (date_is_weekend(cur));
+
+    memcpy(out, cur, 8);
+    out[8] = '\0';
+    return 0;
+}
+
+void date_today(char *out)
+{
+    time_t     now = time(NULL);
+    struct tm  tmv;
+    localtime_r(&now, &tmv);
+    strftime(out, 9, "%Y%m%d", &tmv);
+}