first commit of restructured project

trahn-trade-backend/internal/repository/tradingday.go

@@ -0,0 +1,22 @@
+package repository
+
+import "time"
+
+// TradingDay returns the trading day (YYYY-MM-DD) for a given timestamp.
+// Trading day boundary is 12:00 EST (17:00 UTC).
+func TradingDay(ts time.Time) string {
+	utc := ts.UTC()
+	cutoff := 17 * 60 // 17:00 UTC in minutes
+	utcMinutes := utc.Hour()*60 + utc.Minute()
+
+	day := utc
+	if utcMinutes < cutoff {
+		day = day.AddDate(0, 0, -1)
+	}
+	return day.Format("2006-01-02")
+}
+
+// TradingDayNow returns the trading day for the current moment.
+func TradingDayNow() string {
+	return TradingDay(time.Now())
+}