efrilmandClaude Opus 5.5
5baed18b22
Adds CalculateEarning (docs/prd-point-coin.md F1, Q1, Q10, PC-202), a pure
function returning, per currency, the amount an order earns and the
settings that produced it, plus the basis:
basis = subtotal − discount − paid with EnakPoint (never negative)
amount = 0 below min_order_amount, else
floor(basis / earn_per_amount) × earn_value, capped by max_per_order
Tax and anything added on top of the subtotal are not part of the basis,
and the part paid with EnakPoint earns nothing. Money is handled in whole
cents: in float64 some baskets divide to 4956.999… and a naive floor would
lose a point, which a test reproduces. Metadata() gives the snapshot the
EARN row will freeze.
Co-Authored-By: Claude Opus 5.5 <noreply@anthropic.com>
86 lines
2.8 KiB
Go
86 lines
2.8 KiB
Go
package processor
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import (
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"math"
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"apskel-pos-be/internal/entities"
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"apskel-pos-be/internal/models"
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)
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// EarningLine is what an order earns in one currency, and the settings that produced
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// it. The settings are kept so the ledger row can freeze them: a later change of
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// setting must not change what an earning meant, and a reversal is computed with the
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// same numbers (docs/prd-point-coin.md F3).
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type EarningLine struct {
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Amount int64
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Settings models.LoyaltyEarnSettings
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// True when max_per_order cut the amount down.
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Capped bool
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}
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// EarningResult is what an order earns.
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type EarningResult struct {
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// subtotal − discount − the part paid with EnakPoint, in rupiah, never negative.
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// Tax and anything else added on top of the subtotal are not part of it (Q1).
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Basis float64
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Point EarningLine
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Coin EarningLine
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}
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// Metadata is the snapshot stored on the currency's EARN ledger row.
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func (r EarningResult) Metadata(line EarningLine) entities.Metadata {
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m := entities.Metadata{
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"basis": r.Basis,
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"earn_per_amount": line.Settings.EarnPerAmount,
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"earn_value": line.Settings.EarnValue,
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"min_order_amount": line.Settings.MinOrderAmount,
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"capped": line.Capped,
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}
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if line.Settings.MaxPerOrder != nil {
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m["max_per_order"] = *line.Settings.MaxPerOrder
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}
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return m
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}
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// CalculateEarning applies the earning formula of docs/prd-point-coin.md F1:
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//
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// basis = subtotal − discount_amount − paid with EnakPoint
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// amount = 0 if basis < min_order_amount
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// amount = floor(basis / earn_per_amount) × earn_value
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// amount = min(amount, max_per_order) if max_per_order is set
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//
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// The part paid with EnakPoint earns nothing (Q10). Money is handled in whole cents so
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// floor never lands one short on a value like 87500.00 that float64 cannot hold
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// exactly. It has no side effects.
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func CalculateEarning(order *entities.Order, pointPaidAmount float64, settings models.OutletLoyaltySettings) EarningResult {
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basisCents := toCents(order.Subtotal) - toCents(order.DiscountAmount) - toCents(pointPaidAmount)
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if basisCents < 0 {
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basisCents = 0
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}
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return EarningResult{
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Basis: float64(basisCents) / 100,
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Point: earnLine(basisCents, settings.Point),
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Coin: earnLine(basisCents, settings.Coin),
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}
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}
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func earnLine(basisCents int64, s models.LoyaltyEarnSettings) EarningLine {
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line := EarningLine{Settings: s}
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if !s.Enabled || s.EarnPerAmount <= 0 || s.EarnValue <= 0 {
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return line
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}
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if basisCents < s.MinOrderAmount*100 {
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return line
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}
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line.Amount = basisCents / (s.EarnPerAmount * 100) * s.EarnValue
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if s.MaxPerOrder != nil && line.Amount > *s.MaxPerOrder {
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line.Amount = *s.MaxPerOrder
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line.Capped = true
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}
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return line
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}
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func toCents(rupiah float64) int64 {
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return int64(math.Round(rupiah * 100))
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}
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