feat: add percentage loyalti setting mode

internal/processor/earning_calculator.go

@@ -3,6 +3,7 @@ package processor
 import (
 	"math"
 
+	"apskel-pos-be/internal/constants"
 	"apskel-pos-be/internal/entities"
 	"apskel-pos-be/internal/models"
 )
@@ -36,6 +37,10 @@ func (r EarningResult) Metadata(line EarningLine) entities.Metadata {
 		"min_order_amount": line.Settings.MinOrderAmount,
 		"capped":           line.Capped,
 	}
+	if line.Settings.EarnMode == constants.LoyaltyEarnModePercentage {
+		m["earn_mode"] = line.Settings.EarnMode
+		m["earn_percent"] = line.Settings.EarnPercent
+	}
 	if line.Settings.MaxPerOrder != nil {
 		m["max_per_order"] = *line.Settings.MaxPerOrder
 	}
@@ -46,7 +51,8 @@ func (r EarningResult) Metadata(line EarningLine) entities.Metadata {
 //
 //	basis  = subtotal − discount_amount − paid with EnakPoint
 //	amount = 0                                  if basis < min_order_amount
-//	amount = floor(basis / earn_per_amount) × earn_value
+//	amount = floor(basis / earn_per_amount) × earn_value    in PER_AMOUNT mode
+//	amount = floor(basis × earn_percent / 100)              in PERCENTAGE mode
 //	amount = min(amount, max_per_order)         if max_per_order is set
 //
 // The part paid with EnakPoint earns nothing (Q10). Money is handled in whole cents so
@@ -66,13 +72,23 @@ func CalculateEarning(order *entities.Order, pointPaidAmount float64, settings m
 
 func earnLine(basisCents int64, s models.LoyaltyEarnSettings) EarningLine {
 	line := EarningLine{Settings: s}
-	if !s.Enabled || s.EarnPerAmount <= 0 || s.EarnValue <= 0 {
+	if !s.Enabled || basisCents < s.MinOrderAmount*100 {
 		return line
 	}
-	if basisCents < s.MinOrderAmount*100 {
-		return line
+	if s.EarnMode == constants.LoyaltyEarnModePercentage {
+		// The percent has at most two decimals, so in hundredths it is whole and the
+		// product stays in integers: cents × hundredths / (100 × 100 × 100).
+		hundredths := int64(math.Round(s.EarnPercent * 100))
+		if hundredths <= 0 {
+			return line
+		}
+		line.Amount = basisCents * hundredths / 1_000_000
+	} else {
+		if s.EarnPerAmount <= 0 || s.EarnValue <= 0 {
+			return line
+		}
+		line.Amount = basisCents / (s.EarnPerAmount * 100) * s.EarnValue
 	}
-	line.Amount = basisCents / (s.EarnPerAmount * 100) * s.EarnValue
 	if s.MaxPerOrder != nil && line.Amount > *s.MaxPerOrder {
 		line.Amount = *s.MaxPerOrder
 		line.Capped = true