package processor

import (
	"testing"

	"github.com/stretchr/testify/assert"

	"apskel-pos-be/internal/constants"
	"apskel-pos-be/internal/entities"
	"apskel-pos-be/internal/models"
)

// 1 EnakPoint per Rp 100 and 1 EnakCoin per Rp 25.000, as in the F1 example.
func prdEarningSettings() models.OutletLoyaltySettings {
	return models.OutletLoyaltySettings{
		Point: models.LoyaltyEarnSettings{Enabled: true, EarnPerAmount: 100, EarnValue: 1},
		Coin:  models.LoyaltyEarnSettings{Enabled: true, EarnPerAmount: 25000, EarnValue: 1},
	}
}

func TestCalculateEarning_PRDExample(t *testing.T) {
	// Subtotal after discount Rp 87.500, paid in full in cash.
	order := &entities.Order{Subtotal: 97500, DiscountAmount: 10000, TaxAmount: 9625, TotalAmount: 97125}

	got := CalculateEarning(order, prdEarningSettings())
	assert.Equal(t, 87500.0, got.Basis)
	assert.Equal(t, int64(875), got.Point.Amount)
	assert.Equal(t, int64(3), got.Coin.Amount)
}

func TestCalculateEarning_TaxIsNotPartOfTheBasis(t *testing.T) {
	withoutTax := &entities.Order{Subtotal: 50000}
	withTax := &entities.Order{Subtotal: 50000, TaxAmount: 5500, TotalAmount: 55500}
	assert.Equal(t, CalculateEarning(withoutTax, prdEarningSettings()), CalculateEarning(withTax, prdEarningSettings()))
	assert.Equal(t, int64(500), CalculateEarning(withTax, prdEarningSettings()).Point.Amount)
}

func TestCalculateEarning_BelowMinimum(t *testing.T) {
	s := prdEarningSettings()
	s.Point.MinOrderAmount = 50000

	assert.Equal(t, int64(0), CalculateEarning(&entities.Order{Subtotal: 49999}, s).Point.Amount)
	assert.Equal(t, int64(500), CalculateEarning(&entities.Order{Subtotal: 50000}, s).Point.Amount, "the minimum itself earns")
	// The minimum applies to the basis, after discount.
	assert.Equal(t, int64(0), CalculateEarning(&entities.Order{Subtotal: 60000, DiscountAmount: 15000}, s).Point.Amount)
	// Coin has its own minimum.
	assert.Equal(t, int64(1), CalculateEarning(&entities.Order{Subtotal: 49999}, s).Coin.Amount)
}

func TestCalculateEarning_MaxPerOrder(t *testing.T) {
	s := prdEarningSettings()
	max := int64(300)
	s.Point.MaxPerOrder = &max

	got := CalculateEarning(&entities.Order{Subtotal: 87500}, s)
	assert.Equal(t, int64(300), got.Point.Amount)
	assert.True(t, got.Point.Capped)
	assert.Equal(t, int64(300), got.Metadata(got.Point)["max_per_order"])

	got = CalculateEarning(&entities.Order{Subtotal: 20000}, s)
	assert.Equal(t, int64(200), got.Point.Amount)
	assert.False(t, got.Point.Capped)

	zero := int64(0)
	s.Point.MaxPerOrder = &zero
	assert.Equal(t, int64(0), CalculateEarning(&entities.Order{Subtotal: 87500}, s).Point.Amount)
}

func TestCalculateEarning_DisabledEarnsNothing(t *testing.T) {
	s := prdEarningSettings()
	s.Point.Enabled = false
	got := CalculateEarning(&entities.Order{Subtotal: 87500}, s)
	assert.Equal(t, int64(0), got.Point.Amount)
	assert.Equal(t, int64(3), got.Coin.Amount, "each currency is switched on its own")

	s.Coin.Enabled = false
	got = CalculateEarning(&entities.Order{Subtotal: 87500}, s)
	assert.Equal(t, int64(0), got.Coin.Amount)
	assert.Equal(t, 87500.0, got.Basis, "the basis is still reported")

	// The defaults of an outlet that never set anything earn nothing.
	var defaults models.OutletLoyaltySettings
	loadLoyaltyFields(outletLoyaltyFields(&defaults), nil, "test")
	got = CalculateEarning(&entities.Order{Subtotal: 87500}, defaults)
	assert.Equal(t, int64(0), got.Point.Amount)
	assert.Equal(t, int64(0), got.Coin.Amount)
}

func TestCalculateEarning_EdgeCases(t *testing.T) {
	s := prdEarningSettings()

	// floor, not round.
	assert.Equal(t, int64(875), CalculateEarning(&entities.Order{Subtotal: 87599.99}, s).Point.Amount)
	// Values float64 cannot hold exactly do not lose a point: computed in float64 this
	// basis divides to 4956.999…, which a naive floor turns into 4956.
	per250 := prdEarningSettings()
	per250.Point.EarnPerAmount = 250
	assert.Equal(t, int64(4957), CalculateEarning(&entities.Order{Subtotal: 1240155.48, DiscountAmount: 905.48}, per250).Point.Amount)
	// A discount larger than the subtotal leaves nothing, never a negative amount.
	got := CalculateEarning(&entities.Order{Subtotal: 10000, DiscountAmount: 15000}, s)
	assert.Equal(t, 0.0, got.Basis)
	assert.Equal(t, int64(0), got.Point.Amount)
	// earn_value multiplies.
	s.Point.EarnValue = 5
	assert.Equal(t, int64(4375), CalculateEarning(&entities.Order{Subtotal: 87500}, s).Point.Amount)
	// A zero earn_value earns nothing even when enabled.
	s.Point.EarnValue = 0
	assert.Equal(t, int64(0), CalculateEarning(&entities.Order{Subtotal: 87500}, s).Point.Amount)
}

func TestCalculateEarning_Percentage(t *testing.T) {
	s := prdEarningSettings()
	s.Point.EarnMode = constants.LoyaltyEarnModePercentage
	s.Point.EarnPercent = 1

	// 1% of the basis; the per-amount settings are ignored, and coin keeps its own mode.
	got := CalculateEarning(&entities.Order{Subtotal: 97500, DiscountAmount: 10000}, s)
	assert.Equal(t, int64(875), got.Point.Amount)
	assert.Equal(t, int64(3), got.Coin.Amount)

	// Decimals, and floor, not round: 2.5% of 87.500 is 2187.5.
	s.Point.EarnPercent = 2.5
	assert.Equal(t, int64(2187), CalculateEarning(&entities.Order{Subtotal: 87500}, s).Point.Amount)
	s.Point.EarnPercent = 0.01
	assert.Equal(t, int64(8), CalculateEarning(&entities.Order{Subtotal: 87599.99}, s).Point.Amount)

	// The minimum and the cap apply as in the other mode.
	s.Point.EarnPercent = 10
	s.Point.MinOrderAmount = 50000
	max := int64(6000)
	s.Point.MaxPerOrder = &max
	assert.Equal(t, int64(0), CalculateEarning(&entities.Order{Subtotal: 49999}, s).Point.Amount)
	assert.Equal(t, int64(5000), CalculateEarning(&entities.Order{Subtotal: 50000}, s).Point.Amount)
	got = CalculateEarning(&entities.Order{Subtotal: 87500}, s)
	assert.Equal(t, int64(6000), got.Point.Amount)
	assert.True(t, got.Point.Capped)

	// The mode and percent are frozen on the ledger row.
	assert.Equal(t, constants.LoyaltyEarnModePercentage, got.Metadata(got.Point)["earn_mode"])
	assert.Equal(t, 10.0, got.Metadata(got.Point)["earn_percent"])

	// A zero percent earns nothing even when enabled.
	s.Point.EarnPercent = 0
	assert.Equal(t, int64(0), CalculateEarning(&entities.Order{Subtotal: 87500}, s).Point.Amount)
}

func TestCalculateEarning_MetadataSnapshot(t *testing.T) {
	got := CalculateEarning(&entities.Order{Subtotal: 87500}, prdEarningSettings())
	assert.Equal(t, entities.Metadata{
		"basis": 87500.0, "earn_per_amount": int64(100), "earn_value": int64(1), "min_order_amount": int64(0), "capped": false,
	}, got.Metadata(got.Point))
}