package promotions

import (
	"testing"
	"time"

	"git.k6n.net/mats/go-cart-actor/pkg/cart"
)

func timeZero() time.Time { return time.Date(2024, 6, 10, 12, 0, 0, 0, time.UTC) }

// volymrabattRule mirrors the seeded data/promotions.json rule so the test
// exercises the same tier configuration shipped to the cart service.
func volymrabattRule() PromotionRule {
	return PromotionRule{
		ID:       "volymrabatt",
		Name:     "Volymrabatt",
		Status:   StatusActive,
		Priority: 100,
		Conditions: Conditions{
			BaseCondition{ID: "min", Type: CondCartTotal, Operator: OpGreaterOrEqual, Value: cvNum(2000000)},
		},
		Actions: []Action{
			{
				ID:   "tiers",
				Type: ActionTieredDiscount,
				Config: map[string]interface{}{
					"tiers": []interface{}{
						map[string]interface{}{"minTotal": 2000000.0, "maxTotal": 4000000.0, "percent": 5.0},
						map[string]interface{}{"minTotal": 4000000.0, "maxTotal": 6000000.0, "percent": 9.0},
						map[string]interface{}{"minTotal": 6000000.0, "maxTotal": 9000000.0, "percent": 14.0},
					},
				},
			},
		},
	}
}

// cartWithTotal builds a grain whose single line item produces the requested
// gross (incl. 25% VAT) total in öre, then runs UpdateTotals.
func cartWithTotal(incVat int64) *cart.CartGrain {
	g := cart.NewCartGrain(1, timeZero())
	g.Items = []*cart.CartItem{
		{Id: 1, Sku: "SKU", Quantity: 1, Price: *cart.NewPriceFromIncVat(incVat, 25)},
	}
	g.UpdateTotals()
	return g
}

func TestVolymrabattTiers(t *testing.T) {
	svc := NewPromotionService(nil)
	rules := []PromotionRule{volymrabattRule()}

	cases := []struct {
		name        string
		total       int64
		wantDiscount int64
		wantNet      int64
	}{
		{"below threshold (19 999 kr)", 1999900, 0, 1999900},
		{"low tier 5% (20 000 kr)", 2000000, 100000, 1900000},
		{"low tier boundary just under 40 000", 3999900, 199995, 3799905},
		{"mid tier 9% at 40 000 boundary", 4000000, 360000, 3640000},
		{"mid tier 9% (50 000 kr)", 5000000, 450000, 4550000},
		{"high tier 14% at 60 000 boundary", 6000000, 840000, 5160000},
		{"high tier 14% (90 000 kr)", 9000000, 1260000, 7740000},
		{"above top tier (100 000 kr) -> no discount", 10000000, 0, 10000000},
	}

	for _, c := range cases {
		t.Run(c.name, func(t *testing.T) {
			g := cartWithTotal(c.total)
			_, actions := svc.EvaluateAll(rules, NewContextFromCart(g, WithNow(timeZero())))
			ApplyActions(g, actions)

			if got := g.TotalDiscount.IncVat; got != c.wantDiscount {
				t.Errorf("discount = %d, want %d", got, c.wantDiscount)
			}
			if got := g.TotalPrice.IncVat; got != c.wantNet {
				t.Errorf("net total = %d, want %d", got, c.wantNet)
			}
		})
	}
}