แก้ไขการคำนวนระยะเวลาครองตำแหน่ง

src/utils/tenure.ts

@@ -1,18 +1,37 @@
 /**
- * คำนวณอายุงานจากจำนวนวันรวม
- * ใช้สูตรเดียวกับ Stored Procedure GetProfileSalaryPosition
- * @param totalDays จำนวนวันรวม
- * @returns { year, month, day } ปี เดือน วัน
+ * Normalize a duration sum using calendar arithmetic
+ * Converts excess days to months using average month length (30.4375 days)
+ * and excess months to years. Matches the logic used in stored procedures.
+ *
+ * @param years Total years from sum
+ * @param months Total months from sum
+ * @param days Total days from sum
+ * @returns Normalized { years, months, days }
  */
-export function calculateTenure(totalDays: number) {
-  // Match stored procedure formula:
-  // days_diff / 365.2524               AS Years
-  // (days_diff / 30.4375) % 12         AS Months
-  // days_diff % 30.4375                AS Days
+export function normalizeDurationSumSimple(
+  years: number,
+  months: number,
+  days: number,
+): { years: number; months: number; days: number } {
+  const DAYS_PER_MONTH = 30.4375; // Average days per month in Gregorian calendar
 
-  const year = Math.floor(totalDays / 365.2524);
-  const month = Math.floor((totalDays / 30.4375) % 12);
-  const day = Math.floor(totalDays % 30.4375);
+  let totalMonths = months;
+  let totalDays = days;
 
-  return { year, month, day };
+  // Convert excess days to months
+  if (totalDays >= DAYS_PER_MONTH) {
+    const additionalMonths = Math.floor(totalDays / DAYS_PER_MONTH);
+    totalMonths += additionalMonths;
+    totalDays = totalDays - additionalMonths * DAYS_PER_MONTH;
+  }
+
+  // Convert excess months to years
+  let totalYears = years;
+  if (totalMonths >= 12) {
+    const additionalYears = Math.floor(totalMonths / 12);
+    totalYears += additionalYears;
+    totalMonths = totalMonths % 12;
+  }
+
+  return { years: totalYears, months: Math.floor(totalMonths), days: Math.floor(totalDays) };
 }