//go:build test && dev

package payments

import (
	"context"
	"encoding/json"
	"net/http"
	"testing"
	"time"

	"crussell/clock"
	"crussell/db"
	"crussell/internal/square"
	"crussell/testutils"
	"crussell/testutils/fixtures"
	"crussell/testutils/jwt"

	"github.com/stretchr/testify/assert"
	"github.com/stretchr/testify/require"
)

// =============================================================================
// Finding 2 — the A6 deposit clamp can produce chargeAmount=0 with no guard:
// the handler then charged £0 at Square (invalid in prod, minted a completed
// £0 deposit in the dev mock that consumed the discount). A deposit whose
// eligible campaign credit covers the ENTIRE remaining obligation must skip the
// Square call and report deposit_covered_by_discount.
// =============================================================================

// seedActiveCampaign inserts an active time-based campaign with the given
// discount percent and returns its id.
func seedActiveCampaign(t *testing.T, ctx context.Context, q db.Querier, percent int) string {
	t.Helper()
	now := clock.Now()
	var id string
	err := q.QueryRow(ctx, `
		INSERT INTO discount_campaigns (name, campaign_type, discount_percent, status, start_date, end_date, times_redeemed)
		VALUES ($1, 'time_based', $2, 'active', $3, $4, 0)
		RETURNING id
	`, "Money-Fix Campaign", percent, now.Add(-24*time.Hour), now.Add(24*time.Hour)).Scan(&id)
	require.NoError(t, err)
	return id
}

// failOnChargeClient fails the test if a Square charge is attempted. Proves a
// discount-covered deposit skips the Square call entirely (finding 2).
type failOnChargeClient struct {
	square.SquareClient
	t *testing.T
}

func (c *failOnChargeClient) CreatePayment(ctx context.Context, req square.CreatePaymentReq) (*square.PaymentResult, error) {
	c.t.Fatalf("Square CreatePayment must NOT be called for a discount-covered deposit (amount=%d)", req.Amount)
	return nil, nil
}

// TestBookingPayment_DepositFullyCoveredByDiscount_SkipsSquareCharge pins the
// A6 skip path: a deposit whose eligible campaign credit covers the ENTIRE
// remaining obligation skips the Square charge (never charges £0) AND applies
// the eligible campaign discount rows IMMEDIATELY (finding: deferring the
// discount to the next real charge let the booking complete at full price with
// no discount row — the customer overpaid the promised discount). The
// discount row is a completed payments row (payment_method='discount'), the
// response reports deposit_covered_by_discount only because a discount was
// actually applied, and a fully-covered booking completes like the real charge
// path.
func TestBookingPayment_DepositFullyCoveredByDiscount_SkipsSquareCharge(t *testing.T) {
	ctx, tx := testutils.SetupTestTx(t)

	userID, bookingID, _ := setupTestData(t, ctx, tx)
	userToken := jwt.GenerateUserToken(userID)
	// 100% time-based campaign = £50 discount on the £50 fixture booking, which
	// fully covers the £25 deposit request (chargeAmount clamps to £0).
	seedActiveCampaign(t, ctx, tx, 100)

	origClient := SquareClient
	SquareClient = &failOnChargeClient{SquareClient: square.NewDevClient(), t: t}
	defer func() { SquareClient = origClient }()

	cardToken := "cnon:deposit-covered"
	req := CreateBookingPaymentRequest{
		Amount:         2500, // £25 deposit
		PaymentType:    "deposit",
		NewCardToken:   &cardToken,
		IdempotencyKey: "deposit-covered-" + bookingID,
	}

	handler := CreateBookingPayment
	w := makePaymentRequest(handler, "POST", "/api/bookings/"+bookingID+"/payment", req, userToken, ctx)
	require.Equal(t, http.StatusOK, w.Code, "a discount-covered deposit must complete without a Square charge, body: %s", w.Body.String())

	var body map[string]any
	require.NoError(t, json.Unmarshal(w.Body.Bytes(), &body))
	assert.Equal(t, true, body["deposit_covered_by_discount"], "the response must signal the discount-covered deposit")

	// The discount rows are now applied AT the skip path (never deferred to a
	// later charge that F1-skips them — the overcharge bug). The single
	// payments row IS the completed discount row.
	var payCount int
	require.NoError(t, tx.QueryRow(ctx, `SELECT COUNT(*) FROM payments WHERE booking_id = $1`, bookingID).Scan(&payCount))
	assert.Equal(t, 1, payCount, "exactly one discount payment row must be recorded for the discount-covered deposit")

	var discountCount int
	require.NoError(t, tx.QueryRow(ctx, `SELECT COUNT(*) FROM booking_discounts WHERE booking_id = $1`, bookingID).Scan(&discountCount))
	assert.Equal(t, 1, discountCount, "the eligible campaign discount must be recorded at the skip path")

	var discountAmount float64
	require.NoError(t, tx.QueryRow(ctx, `SELECT amount FROM payments WHERE booking_id = $1 AND payment_method = 'discount'`, bookingID).Scan(&discountAmount))
	assert.Equal(t, 50.00, discountAmount, "the £50 campaign discount must be recorded in full")

	// The discount fully covers the booking — it completes exactly like a fully
	// paid booking on the real charge path.
	var bookingStatus string
	require.NoError(t, tx.QueryRow(ctx, `SELECT status FROM bookings WHERE id = $1`, bookingID).Scan(&bookingStatus))
	assert.Equal(t, "completed", bookingStatus, "a booking whose entire obligation is discount-covered must complete")
}

// TestBookingPayment_DepositCoveredDiscount_RecordsDiscount_NoOvercharge is the
// exact A6 scenario from the finding: £100 booking, 50% campaign, post-start
// partial £50 already paid, then a £50 deposit whose eligible credit covers the
// ENTIRE remaining obligation. The skip path must record the £50 discount row
// IMMEDIATELY so the promised discount is never lost — before the fix the
// deposit returned deposit_covered_by_discount with NO discount row, the later
// balance charge F1-skipped the discount (headroom already spent by the real
// money) and the booking completed at the full £100 with the customer overpaying
// the promised £50.
func TestBookingPayment_DepositCoveredDiscount_RecordsDiscount_NoOvercharge(t *testing.T) {
	ctx, tx := testutils.SetupTestTx(t)

	userID, bookingID, _ := setupTestDataPast(t, ctx, tx)
	userToken := jwt.GenerateUserToken(userID)
	_, err := tx.Exec(ctx, `UPDATE bookings SET total_amount = 100.00 WHERE id = $1`, bookingID)
	require.NoError(t, err)
	// 50% time-based campaign = £50 eligible credit on the £100 booking.
	seedActiveCampaign(t, ctx, tx, 50)
	// Post-start partial £50 already paid — remaining obligation is £50.
	_, err = fixtures.CreateTestPayment(tx, bookingID, 50.00, "online_square", "partial", "completed")
	require.NoError(t, err)

	origClient := SquareClient
	SquareClient = &failOnChargeClient{SquareClient: square.NewDevClient(), t: t}
	defer func() { SquareClient = origClient }()

	// £50 deposit — the eligible £50 credit covers the ENTIRE remaining £50,
	// so chargeAmount clamps to £0 and the skip path runs.
	cardToken := "cnon:deposit-covered-partial"
	req := CreateBookingPaymentRequest{
		Amount:         5000,
		PaymentType:    "deposit",
		NewCardToken:   &cardToken,
		IdempotencyKey: "deposit-covered-partial-" + bookingID,
	}

	w := makePaymentRequest(CreateBookingPayment, "POST", "/api/bookings/"+bookingID+"/payment", req, userToken, ctx)
	require.Equal(t, http.StatusOK, w.Code, "a discount-covered deposit must complete without a Square charge, body: %s", w.Body.String())

	var body map[string]any
	require.NoError(t, json.Unmarshal(w.Body.Bytes(), &body))
	assert.Equal(t, true, body["deposit_covered_by_discount"], "the response must signal the discount-covered deposit")

	// The £50 campaign discount row is recorded AT the skip path.
	var discountAmount float64
	require.NoError(t, tx.QueryRow(ctx, `SELECT amount FROM payments WHERE booking_id = $1 AND payment_method = 'discount'`, bookingID).Scan(&discountAmount))
	assert.Equal(t, 50.00, discountAmount, "the promised £50 discount must be recorded at the skip path")

	// Ledger: real £50 + discount £50 = £100 = total. The customer pays the
	// discounted £50, never the full £100. GetBookingRemainingBalancePence
	// counts only REAL money — a discount row is a ledger entry, not a payment
	// toward the balance (the real-money convention every other paid
	// computation applies) — so the remaining balance reports the full £50 even
	// though the booking auto-completed (bookingIsFullyPaid counts the discount
	// row toward completion).
	var remainingPence int64
	remainingPence, err = NewPaymentService().GetBookingRemainingBalancePence(ctx, bookingID)
	require.NoError(t, err)
	assert.Equal(t, int64(5000), remainingPence, "the remaining balance counts real money only — the discount row is not 'paid'")

	// A later unconfirmed balance charge of £50 must be REJECTED — the booking
	// auto-completed when the deposit + discount settled it, so the completed-
	// booking guard refuses the charge outright. The booking can never be
	// silently overcharged the remaining £50 (the old bug: the balance charge
	// completed at full price with no discount row).
	w = makePaymentRequest(CreateBookingPayment, "POST", "/api/bookings/"+bookingID+"/payment", CreateBookingPaymentRequest{
		Amount:         5000,
		PaymentType:    "balance",
		NewCardToken:   &cardToken,
		IdempotencyKey: "balance-after-covered-deposit-" + bookingID,
	}, userToken, ctx)
	require.Equal(t, http.StatusConflict, w.Code, "a balance charge on a completed discounted booking must be rejected, body: %s", w.Body.String())
}

// TestGetBookingPaymentSummary_ExcludesTipsFromRemaining pins finding 4: the
// payment summary must not count tip rows as "paid" — a tip is gratuity paid
// beyond the booking total and must not reduce the balance owed. Before the
// fix PaidAmount included the tip and RemainingAmount (total - paid + refunded)
// understated the authoritative tip-excluded balance, so an admin relying on
// the summary could under-collect.
func TestGetBookingPaymentSummary_ExcludesTipsFromRemaining(t *testing.T) {
	ctx, tx := testutils.SetupTestTx(t)

	userID, err := fixtures.CreateTestUser(tx)
	require.NoError(t, err)
	serviceID, err := fixtures.CreateTestService(tx)
	require.NoError(t, err)
	bookingID, err := fixtures.CreateTestBooking(tx, userID, serviceID)
	require.NoError(t, err)

	svc := NewPaymentService()
	// Pay the full £50 booking + a £20 tip.
	_, err = svc.CreatePaymentRecord(ctx, PaymentRecord{
		BookingID:     bookingID,
		PaymentType:   "full",
		PaymentMethod: "online_square",
		Status:        "completed",
		Amount:        50.00,
	}, nil)
	require.NoError(t, err)
	_, err = svc.CreatePaymentRecord(ctx, PaymentRecord{
		BookingID:     bookingID,
		PaymentType:   "tip",
		PaymentMethod: "online_square",
		Status:        "completed",
		Amount:        20.00,
	}, nil)
	require.NoError(t, err)

	summary, err := svc.GetBookingPaymentSummary(ctx, bookingID)
	require.NoError(t, err)

	require.Equal(t, 50.00, summary.PaidAmount, "PaidAmount must exclude the £20 tip row")
	require.Equal(t, 0.00, summary.RemainingAmount, "RemainingAmount must exclude the £20 tip row (the £50 booking is fully paid)")

	// Cross-check against the authoritative charge-guard balance.
	remaining, err := svc.GetBookingRemainingBalancePence(ctx, bookingID)
	require.NoError(t, err)
	require.Equal(t, remaining, int64(summary.RemainingAmount*100), "RemainingAmount must match GetBookingRemainingBalancePence")
}

// =============================================================================
// Finding 7 — remaining-balance capacity ignored PENDING refunds: service.go
// counted only completed refunds in GetBookingRemainingBalancePence while
// GetBookingPaymentInfo counts completed + pending. An in-flight refund
// understated the remaining balance and blocked a legitimate retry.
// =============================================================================

func TestGetBookingRemainingBalancePence_PendingRefundsReopenCapacity(t *testing.T) {
	t.Parallel()
	ctx, tx := testutils.SetupTestTx(t)

	userID, err := fixtures.CreateTestUser(tx)
	require.NoError(t, err)

	serviceID, err := fixtures.CreateTestService(tx)
	require.NoError(t, err)

	bookingID, err := fixtures.CreateTestBooking(tx, userID, serviceID)
	require.NoError(t, err)

	var bookingTotal int64
	require.NoError(t, tx.QueryRow(ctx, `SELECT ROUND(total_amount * 100)::bigint FROM bookings WHERE id = $1`, bookingID).Scan(&bookingTotal))

	svc := NewPaymentService()

	// Pay the full booking amount.
	_, err = svc.CreatePaymentRecord(ctx, PaymentRecord{
		BookingID:     bookingID,
		PaymentType:   "full",
		PaymentMethod: "online_square",
		Status:        "completed",
		Amount:        float64(bookingTotal) / 100.0,
	}, nil)
	require.NoError(t, err)

	remaining, err := svc.GetBookingRemainingBalancePence(ctx, bookingID)
	require.NoError(t, err)
	require.Equal(t, int64(0), remaining, "a fully-paid booking must have 0 remaining")

	// A PENDING refund is money in flight that will come back — it must re-open
	// capacity by its amount exactly like a completed refund.
	var payRowID string
	require.NoError(t, tx.QueryRow(ctx, `SELECT id FROM payments WHERE booking_id = $1 AND payment_type = 'full' ORDER BY created_at DESC LIMIT 1`, bookingID).Scan(&payRowID))

	refundAmount := bookingTotal / 2
	_, err = tx.Exec(ctx, `
		INSERT INTO refunds (payment_id, booking_id, amount, status, reason, origin)
		VALUES ($1, $2, $3, 'pending', 'in-flight test refund', 'manual')
	`, payRowID, bookingID, float64(refundAmount)/100.0)
	require.NoError(t, err)

	remaining, err = svc.GetBookingRemainingBalancePence(ctx, bookingID)
	require.NoError(t, err)
	require.Equal(t, refundAmount, remaining, "a pending refund must re-open the remaining balance by its amount")
}