package order

import (
	"context"
	"testing"

	"github.com/perfect-panel/server/internal/model/promo"
	"github.com/perfect-panel/server/internal/svc"
	"github.com/perfect-panel/server/internal/types"
	"gorm.io/gorm"
)

type fakePromoModel struct {
	rules            []*promo.RuleWithPrice
	lastSubscribeID  int64
	lastQuantity     int64
	requireQuantity  int64
	quantityMismatch []*promo.RuleWithPrice
}

func (m *fakePromoModel) QueryEligibleRules(_ context.Context, subscribeID int64, quantity int64) ([]*promo.RuleWithPrice, error) {
	m.lastSubscribeID = subscribeID
	m.lastQuantity = quantity
	if m.requireQuantity > 0 && quantity != m.requireQuantity {
		return m.quantityMismatch, nil
	}
	return m.rules, nil
}

func (m *fakePromoModel) InsertUsage(context.Context, *promo.Usage, ...*gorm.DB) error {
	return nil
}

func (m *fakePromoModel) InsertRule(context.Context, *promo.Rule) error {
	return nil
}

func (m *fakePromoModel) FindRule(context.Context, int64) (*promo.Rule, error) {
	return nil, gorm.ErrRecordNotFound
}

func (m *fakePromoModel) UpdateRule(context.Context, *promo.Rule) error {
	return nil
}

func (m *fakePromoModel) DeleteRule(context.Context, int64) error {
	return nil
}

func (m *fakePromoModel) QueryRuleList(context.Context, int, int, string, *bool, string) (int64, []*promo.Rule, error) {
	return 0, nil, nil
}

func (m *fakePromoModel) UpsertPrices(context.Context, int64, []*promo.SubscribePromo) error {
	return nil
}

func (m *fakePromoModel) FindPrice(context.Context, int64) (*promo.SubscribePromo, error) {
	return nil, gorm.ErrRecordNotFound
}

func (m *fakePromoModel) DeletePrice(context.Context, int64) error {
	return nil
}

func (m *fakePromoModel) QueryPriceList(context.Context, promo.PriceFilter) (int64, []*promo.SubscribePromo, error) {
	return 0, nil, nil
}

func (m *fakePromoModel) QueryUsageList(context.Context, promo.UsageFilter) (int64, []*promo.Usage, error) {
	return 0, nil, nil
}

func (m *fakePromoModel) Transaction(context.Context, func(*gorm.DB) error) error {
	return nil
}

func TestCalculatePurchasePricePromoUsesQuantityTierTotalPrice(t *testing.T) {
	model := &fakePromoModel{rules: []*promo.RuleWithPrice{
		{
			Rule: promo.Rule{
				Id:      9,
				Name:    "campaign",
				Type:    promo.RuleTypeCampaign,
				Enabled: true,
			},
			PromoPrice: 279,
		},
	}}
	svcCtx := &svc.ServiceContext{
		DB:         &gorm.DB{},
		PromoModel: model,
	}

	result, err := calculatePurchasePrice(
		context.Background(),
		svcCtx,
		1,
		2,
		100,
		7,
		[]types.SubscribeDiscount{{Quantity: 7, Discount: 50}},
		true,
		true,
	)
	if err != nil {
		t.Fatalf("calculatePurchasePrice returned error: %v", err)
	}

	if result.OriginalPrice != 700 {
		t.Fatalf("OriginalPrice = %d, want 700", result.OriginalPrice)
	}
	if result.PayableBase != 279 {
		t.Fatalf("PayableBase = %d, want 279", result.PayableBase)
	}
	if result.DiscountAmount != 0 {
		t.Fatalf("DiscountAmount = %d, want 0", result.DiscountAmount)
	}
	if result.PromoRuleId != 9 {
		t.Fatalf("PromoRuleId = %d, want 9", result.PromoRuleId)
	}
	if result.PromoDiscount != 421 {
		t.Fatalf("PromoDiscount = %d, want 421", result.PromoDiscount)
	}
	if result.PromoPrice != 279 {
		t.Fatalf("PromoPrice = %d, want 279", result.PromoPrice)
	}
	if model.lastQuantity != 7 {
		t.Fatalf("promo query quantity = %d, want 7", model.lastQuantity)
	}
}

func TestCalculatePurchasePriceIgnoresInvalidPromoPrice(t *testing.T) {
	model := &fakePromoModel{rules: []*promo.RuleWithPrice{
		{
			Rule: promo.Rule{
				Id:      10,
				Name:    "invalid campaign",
				Type:    promo.RuleTypeCampaign,
				Enabled: true,
			},
			PromoPrice: 3000,
		},
	}}
	svcCtx := &svc.ServiceContext{
		DB:         &gorm.DB{},
		PromoModel: model,
	}

	result, err := calculatePurchasePrice(
		context.Background(),
		svcCtx,
		1,
		2,
		1000,
		3,
		[]types.SubscribeDiscount{{Quantity: 3, Discount: 50}},
		true,
		true,
	)
	if err != nil {
		t.Fatalf("calculatePurchasePrice returned error: %v", err)
	}

	if result.PayableBase != 1500 {
		t.Fatalf("PayableBase = %d, want 1500", result.PayableBase)
	}
	if result.DiscountAmount != 1500 {
		t.Fatalf("DiscountAmount = %d, want 1500", result.DiscountAmount)
	}
	if result.PromoRuleId != 0 || result.PromoDiscount != 0 {
		t.Fatalf("promo fields = (%d, %d), want (0, 0)", result.PromoRuleId, result.PromoDiscount)
	}
}

func TestCalculatePurchasePricePassesQuantityToPromoEvaluation(t *testing.T) {
	promoModel := &fakePromoModel{
		requireQuantity: 6,
		rules: []*promo.RuleWithPrice{
			{
				Rule: promo.Rule{
					Id:      11,
					Name:    "quantity campaign",
					Type:    promo.RuleTypeCampaign,
					Enabled: true,
				},
				PromoPrice: 3000,
			},
		},
	}
	svcCtx := &svc.ServiceContext{
		DB:         &gorm.DB{},
		PromoModel: promoModel,
	}

	result, err := calculatePurchasePrice(
		context.Background(),
		svcCtx,
		1,
		2,
		1000,
		6,
		[]types.SubscribeDiscount{{Quantity: 6, Discount: 80}},
		true,
		true,
	)
	if err != nil {
		t.Fatalf("calculatePurchasePrice returned error: %v", err)
	}

	if promoModel.lastSubscribeID != 2 {
		t.Fatalf("lastSubscribeID = %d, want 2", promoModel.lastSubscribeID)
	}
	if promoModel.lastQuantity != 6 {
		t.Fatalf("lastQuantity = %d, want 6", promoModel.lastQuantity)
	}
	if result.PayableBase != 3000 {
		t.Fatalf("PayableBase = %d, want 3000", result.PayableBase)
	}
	if result.PromoRuleId != 11 {
		t.Fatalf("PromoRuleId = %d, want 11", result.PromoRuleId)
	}
}

func TestCalculatePurchasePriceCampaignAppliesToReturningUsers(t *testing.T) {
	model := &fakePromoModel{rules: []*promo.RuleWithPrice{
		{
			Rule: promo.Rule{
				Id:      12,
				Name:    "campaign",
				Type:    promo.RuleTypeCampaign,
				Enabled: true,
			},
			PromoPrice: 400,
		},
	}}
	svcCtx := &svc.ServiceContext{DB: &gorm.DB{}, PromoModel: model}

	// isFirstPurchase=false simulates a returning user routed to renewal; the
	// Campaign promo must still apply because it has no first-purchase gate.
	result, err := calculatePurchasePrice(
		context.Background(),
		svcCtx,
		42,
		2,
		1000,
		1,
		nil,
		false,
		false,
	)
	if err != nil {
		t.Fatalf("calculatePurchasePrice returned error: %v", err)
	}
	if result.PromoRuleId != 12 {
		t.Fatalf("PromoRuleId = %d, want 12 (campaign should apply to returning users)", result.PromoRuleId)
	}
	if result.PayableBase != 400 {
		t.Fatalf("PayableBase = %d, want 400", result.PayableBase)
	}
}

func TestCalculatePurchasePriceNewUserGatedByFirstPurchase(t *testing.T) {
	model := &fakePromoModel{rules: []*promo.RuleWithPrice{
		{
			Rule: promo.Rule{
				Id:      13,
				Name:    "new user",
				Type:    promo.RuleTypeNewUser,
				Enabled: true,
				Params:  `{"window_hours": 72}`,
			},
			PromoPrice: 200,
		},
	}}
	svcCtx := &svc.ServiceContext{DB: &gorm.DB{}, PromoModel: model}

	// isFirstPurchase=false → NewUser rule must be skipped, regular discount applies.
	result, err := calculatePurchasePrice(
		context.Background(),
		svcCtx,
		42,
		2,
		1000,
		1,
		[]types.SubscribeDiscount{{Quantity: 1, Discount: 90}},
		true,
		false,
	)
	if err != nil {
		t.Fatalf("calculatePurchasePrice returned error: %v", err)
	}
	if result.PromoRuleId != 0 || result.PromoDiscount != 0 {
		t.Fatalf("promo fields = (%d, %d), want (0, 0) when isFirstPurchase=false", result.PromoRuleId, result.PromoDiscount)
	}
	if result.PayableBase != 900 {
		t.Fatalf("PayableBase = %d, want 900 (regular 90%% discount)", result.PayableBase)
	}
}