Crussell/backend/handlers/webhooks/webhooks_test.go

//go:build test

package webhooks

import (
	"bytes"
	"context"
	"crypto/hmac"
	"crypto/sha256"
	"encoding/base64"
	"encoding/json"
	"fmt"
	"log"
	"net/http"
	"net/http/httptest"
	"os"
	"strings"
	"sync"
	"sync/atomic"
	"testing"
	"time"
	"unicode/utf8"

	"crussell/db"
	"github.com/jackc/pgx/v5/pgxpool"
)

// =============================================================================
// Unit tests — verifySquareSignature (pure function)
// =============================================================================

func TestVerifySquareSignature_ValidSignature(t *testing.T) {
	t.Parallel()
	body := []byte(`{"type":"payment.updated","event_id":"evt_1"}`)
	key := "test-signing-key"
	notificationURL := "http://localhost:8080/webhooks/square"

	payload := notificationURL + string(body)
	mac := hmac.New(sha256.New, []byte(key))
	mac.Write([]byte(payload))
	expectedSig := base64.StdEncoding.EncodeToString(mac.Sum(nil))

	if !verifySquareSignature(body, expectedSig, key, notificationURL) {
		t.Error("expected valid signature to verify")
	}
}

func TestVerifySquareSignature_InvalidSignature(t *testing.T) {
	t.Parallel()
	body := []byte(`{"type":"payment.updated"}`)
	key := "test-signing-key"
	notificationURL := "http://localhost:8080/webhooks/square"

	if verifySquareSignature(body, "invalid-signature", key, notificationURL) {
		t.Error("expected invalid signature to fail")
	}
}

func TestVerifySquareSignature_WrongKey(t *testing.T) {
	t.Parallel()
	body := []byte(`{"type":"payment.updated"}`)
	notificationURL := "http://localhost:8080/webhooks/square"

	payload := notificationURL + string(body)
	mac := hmac.New(sha256.New, []byte("correct-key"))
	mac.Write([]byte(payload))
	sig := base64.StdEncoding.EncodeToString(mac.Sum(nil))

	// Verify with a different key
	if verifySquareSignature(body, sig, "wrong-key", notificationURL) {
		t.Error("expected wrong key to produce failing verification")
	}
}

func TestVerifySquareSignature_EmptyBody(t *testing.T) {
	t.Parallel()
	key := "test-signing-key"
	notificationURL := "http://localhost:8080/webhooks/square"

	payload := notificationURL + string([]byte{})
	mac := hmac.New(sha256.New, []byte(key))
	mac.Write([]byte(payload))
	expectedSig := base64.StdEncoding.EncodeToString(mac.Sum(nil))

	if !verifySquareSignature([]byte{}, expectedSig, key, notificationURL) {
		t.Error("expected empty body verification to succeed with matching signature")
	}
}

func TestVerifySquareSignature_TamperedBody(t *testing.T) {
	t.Parallel()
	body := []byte(`{"type":"payment.updated","event_id":"evt_1"}`)
	key := "test-signing-key"
	notificationURL := "http://localhost:8080/webhooks/square"

	payload := notificationURL + string(body)
	mac := hmac.New(sha256.New, []byte(key))
	mac.Write([]byte(payload))
	sig := base64.StdEncoding.EncodeToString(mac.Sum(nil))

	// Verify with a tampered body
	tamperedBody := []byte(`{"type":"payment.updated","event_id":"evt_2"}`)
	if verifySquareSignature(tamperedBody, sig, key, notificationURL) {
		t.Error("expected tampered body to fail verification")
	}
}

func TestTruncateDisputeReason_RuneSafe(t *testing.T) {
	// 191 ASCII bytes + a 4-byte emoji: byte-slicing at 192 would split the
	// emoji into an incomplete rune (invalid UTF-8). Rune-safe truncation must
	// keep the whole emoji and stay valid UTF-8.
	edge := strings.Repeat("a", 191) + "\U0001F600"
	got := truncateDisputeReason(edge)
	if !utf8.ValidString(got) {
		t.Errorf("expected valid UTF-8 after truncation, got %q", got)
	}
	if !strings.HasSuffix(got, "\U0001F600") {
		t.Errorf("expected the 4-byte rune to be preserved intact, got %q", got)
	}
	if len(got) != 195 { // 191 ASCII + 4-byte emoji
		t.Errorf("expected 195 bytes (191 ASCII + 4-byte emoji), got %d", len(got))
	}

	// An over-long multi-byte reason truncates to exactly 192 runes.
	got = truncateDisputeReason(strings.Repeat("界", 300))
	if r := []rune(got); len(r) != 192 {
		t.Errorf("expected exactly 192 runes after truncation, got %d", len(r))
	}
	if !utf8.ValidString(got) {
		t.Errorf("expected valid UTF-8 after truncation, got %q", got)
	}

	// Short and ASCII reasons pass through untouched.
	if got := truncateDisputeReason("NO_KNOWLEDGE"); got != "NO_KNOWLEDGE" {
		t.Errorf("expected short reason unchanged, got %q", got)
	}
}

// =============================================================================
// Integration tests — HandleSquareWebhook
// =============================================================================

func makeWebhookRequest(body []byte, signature string, ctx context.Context) *httptest.ResponseRecorder {
	w := httptest.NewRecorder()
	req := httptest.NewRequest("POST", "/webhooks/square", bytes.NewReader(body))
	req = req.WithContext(ctx)
	req.Header.Set("Content-Type", "application/json")
	if signature != "" {
		req.Header.Set("x-square-hmacsha256-signature", signature)
	}
	HandleSquareWebhook(w, req)
	return w
}

// makeWebhookRequestWithEnv is makeWebhookRequest plus an explicit
// square-environment header (Square sends one on every real delivery).
func makeWebhookRequestWithEnv(body []byte, signature, env string, ctx context.Context) *httptest.ResponseRecorder {
	w := httptest.NewRecorder()
	req := httptest.NewRequest("POST", "/webhooks/square", bytes.NewReader(body))
	req = req.WithContext(ctx)
	req.Header.Set("Content-Type", "application/json")
	if signature != "" {
		req.Header.Set("x-square-hmacsha256-signature", signature)
	}
	if env != "" {
		req.Header.Set("square-environment", env)
	}
	HandleSquareWebhook(w, req)
	return w
}

// webhookTestEnv sets a signing key and returns a valid signature for the body
// (the fail-closed handler requires a verifiable signature on every request).
func webhookTestEnv(t *testing.T, body []byte) (signature string) {
	t.Helper()
	tKey := "test-signing-key"
	tURL := "http://localhost:8080/webhooks/square"
	mac := hmac.New(sha256.New, []byte(tKey))
	mac.Write([]byte(tURL))
	mac.Write(body)
	t.Setenv("SQUARE_WEBHOOK_SIGNATURE_KEY", tKey)
	return base64.StdEncoding.EncodeToString(mac.Sum(nil))
}

// countWebhookEvents returns how many dedup rows exist for an event_id. The
// handler commits its dedup insert to the pool (no per-test transaction), so a
// fresh query sees it.
func countWebhookEvents(t *testing.T, eventID string) int {
	t.Helper()
	var n int
	if err := db.Conn.QueryRow(context.Background(),
		"SELECT COUNT(*) FROM square_webhook_events WHERE event_id = $1", eventID).Scan(&n); err != nil {
		t.Fatalf("failed to count square_webhook_events rows: %v", err)
	}
	return n
}

// testDBHost mirrors testdb.dbHost so the broken-pool test can reach the same
// Postgres instance without importing testdb internals.
func testDBHost() string {
	if h := os.Getenv("TEST_DB_HOST"); h != "" {
		return h
	}
	if h := os.Getenv("POSTGRES_HOST"); h != "" {
		return h
	}
	return "localhost"
}

func TestHandleSquareWebhook_PaymentUpdated(t *testing.T) {
	event := SquareWebhookEvent{
		Type:      "payment.updated",
		EventID:   "evt_payment_1",
		CreatedAt: "2025-01-01T00:00:00Z",
		Data:      json.RawMessage(`{"id":"payment_1"}`),
	}
	body, _ := json.Marshal(event)
	sig := webhookTestEnv(t, body)
	w := makeWebhookRequest(body, sig, context.Background())
	if w.Code != http.StatusOK {
		t.Errorf("expected 200, got %d. body: %s", w.Code, w.Body.String())
	}
	if w.Body.String() != "ok" {
		t.Errorf("expected body 'ok', got %q", w.Body.String())
	}
}

func TestHandleSquareWebhook_RefundUpdated(t *testing.T) {
	event := SquareWebhookEvent{
		Type:      "refund.updated",
		EventID:   "evt_refund_1",
		CreatedAt: "2025-01-01T00:00:00Z",
		Data:      json.RawMessage(`{"id":"refund_1"}`),
	}
	body, _ := json.Marshal(event)
	sig := webhookTestEnv(t, body)
	w := makeWebhookRequest(body, sig, context.Background())
	if w.Code != http.StatusOK {
		t.Errorf("expected 200, got %d. body: %s", w.Code, w.Body.String())
	}
}

func TestHandleSquareWebhook_DisputeCreated(t *testing.T) {
	event := SquareWebhookEvent{
		Type:      "dispute.created",
		EventID:   "evt_dispute_1",
		CreatedAt: "2025-01-01T00:00:00Z",
		Data:      json.RawMessage(`{"id":"dispute_1"}`),
	}
	body, _ := json.Marshal(event)
	sig := webhookTestEnv(t, body)
	w := makeWebhookRequest(body, sig, context.Background())
	if w.Code != http.StatusOK {
		t.Errorf("expected 200 for dispute.created, got %d. body: %s", w.Code, w.Body.String())
	}
}

// TestHandleSquareWebhook_UnknownEventType verifies a signed event whose type
// prefix matches NEITHER the handled switch cases NOR a known family
// (e.g. frobnicator.created) is NOT acknowledged 200. The handler returns 501
// Not Implemented with body "unhandled webhook event type", so Square's retry
// policy re-delivers the event and it stays visible in the delivery history —
// the event is surfaced and retried, never silently acked. No dedup row is
// written on the 501 path, so a retry (or a future code path supporting the
// type) is always re-dispatched.
func TestHandleSquareWebhook_UnknownEventType(t *testing.T) {
	event := SquareWebhookEvent{
		Type:      "frobnicator.created",
		EventID:   "evt_unknown_1",
		CreatedAt: "2025-01-01T00:00:00Z",
		Data:      json.RawMessage(`{"id":"frob_1"}`),
	}
	body, _ := json.Marshal(event)
	sig := webhookTestEnv(t, body)
	notifBefore := countCriticalNotifications(t)
	w := makeWebhookRequest(body, sig, context.Background())
	if w.Code != http.StatusNotImplemented {
		t.Errorf("expected 501 Not Implemented for unknown event type, got %d. body: %s", w.Code, w.Body.String())
	}
	if got := strings.TrimSpace(w.Body.String()); got != "unhandled webhook event type" {
		t.Errorf("expected body 'unhandled webhook event type', got %q", w.Body.String())
	}
	// The 501 path returns before the dedup commit (like the dispatch-error
	// path): Square must be allowed to retry, so no dedup row may be persisted.
	if n := countWebhookEvents(t, event.EventID); n != 0 {
		t.Errorf("expected no dedup row for an unhandled event type (Square must retry), got %d", n)
	}
	// A19: the event must still surface in the admin notification centre —
	// without it, after Square's ~24h retry window the event is silently gone.
	// The notification is a SEPARATE table, so the no-dedup-row assertion above
	// still holds.
	if n := countCriticalNotifications(t) - notifBefore; n != 1 {
		t.Errorf("expected exactly 1 critical_payment_log admin notification for the unknown event (A19), got %d", n)
	}
}

// TestHandleSquareWebhook_KnownNonMoneyEvent_Acknowledged verifies a signed
// event from a KNOWN NON-MONEY family this app will never process
// (e.g. customer.created) is deliberately acknowledged 200 WITH a committed
// dedup row so Square stops retrying it. These events carry no money state the
// app tracks, so acking loses nothing — and retrying them would fill the
// subscription's retry queue until Square suspends it, silently killing
// money-event delivery (payment.created/updated). The ack is logged at WARN.
func TestHandleSquareWebhook_KnownNonMoneyEvent_Acknowledged(t *testing.T) {
	event := SquareWebhookEvent{
		Type:      "customer.created",
		EventID:   "evt_nonmoney_1",
		CreatedAt: "2025-01-01T00:00:00Z",
		Data:      json.RawMessage(`{"id":"cust_1"}`),
	}
	body, _ := json.Marshal(event)
	sig := webhookTestEnv(t, body)

	var buf bytes.Buffer
	oldOutput := log.Writer()
	log.SetOutput(&buf)
	defer log.SetOutput(oldOutput)

	w := makeWebhookRequest(body, sig, context.Background())
	if w.Code != http.StatusOK {
		t.Errorf("expected 200 for acknowledged non-money event, got %d. body: %s", w.Code, w.Body.String())
	}
	if w.Body.String() != "ok" {
		t.Errorf("expected body 'ok', got %q", w.Body.String())
	}
	// Exactly one dedup row is committed so Square stops retrying.
	if n := countWebhookEvents(t, event.EventID); n != 1 {
		t.Errorf("expected exactly 1 dedup row for an acknowledged non-money event (Square stops retrying), got %d", n)
	}
	out := buf.String()
	if !strings.Contains(out, "WARNING: acknowledged unhandled non-money event") {
		t.Errorf("expected WARN ack log for non-money event, got:\n%s", out)
	}
}

// TestHandleSquareWebhook_UnhandledMoneyEvent_NotAcknowledged verifies a
// MONEY-STATE family event that is NOT one of the explicitly handled switch
// cases (e.g. payment.checkout_offer_created) is NOT acknowledged 200: the
// handler returns 501 with body "unhandled webhook event type" and writes NO
// dedup row, so Square's retry re-delivers it. A money event this app does not
// yet handle is never a safe 200-ack — the caller would commit the dedup row
// and the event would be dropped forever.
func TestHandleSquareWebhook_UnhandledMoneyEvent_NotAcknowledged(t *testing.T) {
	event := SquareWebhookEvent{
		Type:      "payment.checkout_offer_created",
		EventID:   "evt_money_unhandled_1",
		CreatedAt: "2025-01-01T00:00:00Z",
		Data:      json.RawMessage(`{"id":"pco_1"}`),
	}
	body, _ := json.Marshal(event)
	sig := webhookTestEnv(t, body)
	notifBefore := countCriticalNotifications(t)
	w := makeWebhookRequest(body, sig, context.Background())
	if w.Code != http.StatusNotImplemented {
		t.Errorf("expected 501 Not Implemented for unhandled money-family event, got %d. body: %s", w.Code, w.Body.String())
	}
	if got := strings.TrimSpace(w.Body.String()); got != "unhandled webhook event type" {
		t.Errorf("expected body 'unhandled webhook event type', got %q", w.Body.String())
	}
	// The 501 path returns before the dedup commit: the event must be retried,
	// so no dedup row may be persisted.
	if n := countWebhookEvents(t, event.EventID); n != 0 {
		t.Errorf("expected no dedup row for an unhandled money-family event (Square must retry), got %d", n)
	}
	// A19: the unhandled money event must still surface in the admin
	// notification centre before the retry window closes.
	if n := countCriticalNotifications(t) - notifBefore; n != 1 {
		t.Errorf("expected exactly 1 critical_payment_log admin notification for the unhandled money-family event (A19), got %d", n)
	}
}

func TestHandleSquareWebhook_InvalidJSON(t *testing.T) {
	body := []byte(`{invalid json}`)
	sig := webhookTestEnv(t, body)
	w := makeWebhookRequest(body, sig, context.Background())
	if w.Code != http.StatusBadRequest {
		t.Errorf("expected 400 for invalid JSON, got %d. body: %s", w.Code, w.Body.String())
	}
}

// TestHandleSquareWebhook_EmptyEventID_Rejected verifies a signed event with an
// empty event_id is rejected with 400 — fail-safe: no dispatch, no dedup row.
// Square's retry policy treats 4xx as non-retryable, so the malformed event is
// dropped without side effects.
func TestHandleSquareWebhook_EmptyEventID_Rejected(t *testing.T) {
	body := []byte(`{"type":"payment.updated","event_id":"","data":{"id":"payment_empty_id"}}`)
	sig := webhookTestEnv(t, body)

	var buf bytes.Buffer
	oldOutput := log.Writer()
	log.SetOutput(&buf)
	defer log.SetOutput(oldOutput)

	w := makeWebhookRequest(body, sig, context.Background())
	if w.Code != http.StatusBadRequest {
		t.Fatalf("expected 400 for empty event_id, got %d. body: %s", w.Code, w.Body.String())
	}

	out := buf.String()
	if !strings.Contains(out, "Rejecting event with empty event_id (400)") {
		t.Errorf("expected empty event_id rejection log, got:\n%s", out)
	}
	if strings.Contains(out, "Received event: payment.updated") {
		t.Errorf("expected empty event_id to skip dispatch, got:\n%s", out)
	}

	// No dedup row may be written for an empty event_id.
	if n := countWebhookEvents(t, ""); n != 0 {
		t.Errorf("expected no dedup row for empty event_id, got %d", n)
	}
}

func TestHandleSquareWebhook_BodyTooLarge(t *testing.T) {
	// 600KB body exceeds the 512KB limit
	largeBody := []byte(strings.Repeat("a", 600*1024))
	sig := webhookTestEnv(t, largeBody)
	w := makeWebhookRequest(largeBody, sig, context.Background())
	if w.Code != http.StatusRequestEntityTooLarge {
		t.Errorf("expected 413 for oversized body, got %d. body: %s", w.Code, w.Body.String())
	}
}

func TestHandleSquareWebhook_ValidSignatureWithEnvKey(t *testing.T) {
	// Well-formed payment.updated event carrying the full nested payment object
	// (data.object.payment with id/status) so handlePaymentUpdated can parse
	// and dispatch it — a known money event whose payload fails to parse
	// returns 503 without a dedup row (Square retries), which is NOT this
	// test's intent. The unique event_id and square_payment_id avoid colliding
	// with the other tests' dedup rows and payment fixtures.
	body := []byte(`{"type":"payment.updated","event_id":"evt_envkey_1","created_at":"2025-01-01T00:00:00Z","data":{"object":{"payment":{"id":"sqp_env_key_1","status":"COMPLETED","amount_money":{"amount":5000,"currency":"GBP"},"updated_at":"2025-01-01T00:00:00Z"}}}}`)
	key := "env-signing-key"
	notificationURL := "http://localhost:8080/webhooks/square"

	payload := notificationURL + string(body)
	mac := hmac.New(sha256.New, []byte(key))
	mac.Write([]byte(payload))
	sig := base64.StdEncoding.EncodeToString(mac.Sum(nil))

	t.Setenv("SQUARE_WEBHOOK_SIGNATURE_KEY", key)

	w := makeWebhookRequest(body, sig, context.Background())
	if w.Code != http.StatusOK {
		t.Errorf("expected 200 with valid signature, got %d. body: %s", w.Code, w.Body.String())
	}
}

func TestHandleSquareWebhook_InvalidSignatureWithEnvKey(t *testing.T) {

	body := []byte(`{"type":"payment.updated","event_id":"evt_1"}`)

	t.Setenv("SQUARE_WEBHOOK_SIGNATURE_KEY", "env-signing-key")

	w := makeWebhookRequest(body, "bad-signature", context.Background())
	if w.Code != http.StatusForbidden {
		t.Errorf("expected 403 with invalid signature, got %d. body: %s", w.Code, w.Body.String())
	}
}

func TestHandleSquareWebhook_NoSignatureWhenKeySet(t *testing.T) {

	body := []byte(`{"type":"payment.updated","event_id":"evt_1"}`)

	t.Setenv("SQUARE_WEBHOOK_SIGNATURE_KEY", "env-signing-key")

	// No x-square-signature header at all
	w := makeWebhookRequest(body, "", context.Background())
	if w.Code != http.StatusForbidden {
		t.Errorf("expected 403 when signature key is set but header missing, got %d. body: %s", w.Code, w.Body.String())
	}
}

func TestHandleSquareWebhook_RejectedWhenKeyEmpty(t *testing.T) {

	t.Setenv("SQUARE_WEBHOOK_SIGNATURE_KEY", "")

	body := []byte(`{"type":"payment.updated","event_id":"evt_1"}`)
	// Fail-closed: an unset signing key means the webhook cannot be verified,
	// so the request is rejected rather than accepted with a bad signature.
	w := makeWebhookRequest(body, "some-signature", context.Background())
	if w.Code != http.StatusServiceUnavailable {
		t.Errorf("expected 503 when no key configured (fail-closed), got %d. body: %s", w.Code, w.Body.String())
	}
}

func TestHandleSquareWebhook_NoRawPayloadInLogs(t *testing.T) {
	event := SquareWebhookEvent{
		Type:      "payment.updated",
		EventID:   "evt_pii_1",
		CreatedAt: "2025-01-01T00:00:00Z",
		Data: json.RawMessage(`{"id":"payment_pii_1","buyer_email_address":"secret@example.com",
			"card_details":{"card":{"brand":"VISA","last_4":"1234","cardholder_name":"Jane Doe"}}}`),
	}
	body, _ := json.Marshal(event)
	sig := webhookTestEnv(t, body)

	var buf bytes.Buffer
	oldOutput := log.Writer()
	log.SetOutput(&buf)
	defer log.SetOutput(oldOutput)

	w := makeWebhookRequest(body, sig, context.Background())
	if w.Code != http.StatusOK {
		t.Fatalf("expected 200, got %d. body: %s", w.Code, w.Body.String())
	}

	out := buf.String()
	for _, pii := range []string{"secret@example.com", "VISA", "1234", "Jane Doe", "payment_pii_1_full"} {
		if strings.Contains(out, pii) {
			t.Errorf("log output leaked PII %q:\n%s", pii, out)
		}
	}
	if !strings.Contains(out, "data.id=payment_pii_1") {
		t.Errorf("expected log to include object id, got:\n%s", out)
	}
	if !strings.Contains(out, "Received event: payment.updated") {
		t.Errorf("expected log to reference event type, got:\n%s", out)
	}
}

// =============================================================================
// Dedup — event_id replay protection
// =============================================================================

func TestHandleSquareWebhook_DuplicateEventID(t *testing.T) {
	event := SquareWebhookEvent{
		Type:      "payment.updated",
		EventID:   "evt_http_dup_1",
		CreatedAt: "2025-01-01T00:00:00Z",
		Data:      json.RawMessage(`{"id":"payment_dup_1"}`),
	}
	body, _ := json.Marshal(event)
	sig := webhookTestEnv(t, body)

	// First delivery processes the event.
	w := makeWebhookRequest(body, sig, context.Background())
	if w.Code != http.StatusOK {
		t.Fatalf("expected first delivery 200, got %d. body: %s", w.Code, w.Body.String())
	}

	// Replay of the same signed event returns 200 but skips dispatch.
	w2 := makeWebhookRequest(body, sig, context.Background())
	if w2.Code != http.StatusOK {
		t.Fatalf("expected replay 200, got %d. body: %s", w2.Code, w2.Body.String())
	}
	if w2.Body.String() != "ok" {
		t.Errorf("expected replay body 'ok', got %q", w2.Body.String())
	}

	// The persistent dedup row is written exactly once despite both deliveries.
	if n := countWebhookEvents(t, event.EventID); n != 1 {
		t.Errorf("expected exactly 1 persisted dedup row, got %d", n)
	}
}

func TestHandleSquareWebhook_DistinctEventIDs(t *testing.T) {
	for _, id := range []string{"evt_distinct_1", "evt_distinct_2"} {
		event := SquareWebhookEvent{
			Type:      "payment.updated",
			EventID:   id,
			CreatedAt: "2025-01-01T00:00:00Z",
			Data:      json.RawMessage(`{"id":"p"}`),
		}
		body, _ := json.Marshal(event)
		sig := webhookTestEnv(t, body)
		w := makeWebhookRequest(body, sig, context.Background())
		if w.Code != http.StatusOK {
			t.Fatalf("expected 200 for %s, got %d. body: %s", id, w.Code, w.Body.String())
		}
	}
}

func TestSquareWebhookDedup_FirstThenDuplicate(t *testing.T) {
	d := newSquareWebhookDedup(1000)
	if d.register("evt_dedup_1") {
		t.Error("expected first occurrence to register as new")
	}
	if !d.register("evt_dedup_1") {
		t.Error("expected second occurrence to register as duplicate")
	}
}

func TestSquareWebhookDedup_CapEvictsOldest(t *testing.T) {
	d := newSquareWebhookDedup(3)
	for i := 0; i < 3; i++ {
		if d.register(fmt.Sprintf("evt_cap_%d", i)) {
			t.Errorf("expected evt_cap_%d to register as new", i)
		}
	}
	// The 4th distinct ID pushes out the oldest (evt_cap_0).
	if d.register("evt_cap_3") {
		t.Errorf("expected evt_cap_3 to register as new")
	}
	// Survivors still dedupe (register returns true without mutating the set).
	for _, id := range []string{"evt_cap_1", "evt_cap_2", "evt_cap_3"} {
		if !d.register(id) {
			t.Errorf("expected %s to still be a duplicate", id)
		}
	}
	// The evicted ID is treated as new again.
	if d.register("evt_cap_0") {
		t.Errorf("expected evt_cap_0 to be evicted and treated as new")
	}
}

func TestSquareWebhookDedup_HasDoesNotRecord(t *testing.T) {
	d := newSquareWebhookDedup(3)
	if d.has("evt_has_1") {
		t.Error("expected has() on empty set to return false")
	}
	if d.register("evt_has_1") {
		t.Error("expected first register to report new")
	}
	if !d.has("evt_has_1") {
		t.Error("expected has() to observe a registered id")
	}
}

// TestHandleSquareWebhook_DedupDispatchOnce verifies the handler body runs
// exactly once across a delivery + replay, with a single persisted dedup row.
func TestHandleSquareWebhook_DedupDispatchOnce(t *testing.T) {
	event := SquareWebhookEvent{
		Type:      "payment.updated",
		EventID:   "evt_dispatch_once_1",
		CreatedAt: "2025-01-01T00:00:00Z",
		Data:      json.RawMessage(`{"id":"payment_dispatch_once_1"}`),
	}
	body, _ := json.Marshal(event)
	sig := webhookTestEnv(t, body)

	var buf bytes.Buffer
	oldOutput := log.Writer()
	log.SetOutput(&buf)
	defer log.SetOutput(oldOutput)

	w1 := makeWebhookRequest(body, sig, context.Background())
	if w1.Code != http.StatusOK {
		t.Fatalf("expected first delivery 200, got %d. body: %s", w1.Code, w1.Body.String())
	}
	w2 := makeWebhookRequest(body, sig, context.Background())
	if w2.Code != http.StatusOK {
		t.Fatalf("expected replay 200, got %d. body: %s", w2.Code, w2.Body.String())
	}
	if w2.Body.String() != "ok" {
		t.Errorf("expected replay body 'ok', got %q", w2.Body.String())
	}

	out := buf.String()
	if got := strings.Count(out, "Received event: payment.updated"); got != 1 {
		t.Errorf("expected dispatch to run exactly once, saw %d 'Received event' log lines:\n%s", got, out)
	}
	if n := countWebhookEvents(t, event.EventID); n != 1 {
		t.Errorf("expected exactly 1 persisted dedup row, got %d", n)
	}
}

// TestHandleSquareWebhook_DedupPersistsAcrossRestart simulates a restart: the
// event was handled by a previous process whose in-memory cache is gone, but
// the dedup row survived in the DB. The dedup row now commits AFTER dispatch
// (at-least-once delivery), so a replayed delivery is re-dispatched — the
// idempotent status-guarded handlers are a no-op the second time — and is
// acknowledged 200 without duplicating the persisted dedup row.
func TestHandleSquareWebhook_DedupPersistsAcrossRestart(t *testing.T) {
	event := SquareWebhookEvent{
		Type:      "payment.updated",
		EventID:   "evt_restart_1",
		CreatedAt: "2025-01-01T00:00:00Z",
		Data:      json.RawMessage(`{"id":"payment_restart_1"}`),
	}
	body, _ := json.Marshal(event)
	sig := webhookTestEnv(t, body)

	if _, err := db.Conn.Exec(context.Background(),
		"INSERT INTO square_webhook_events (event_id) VALUES ($1) ON CONFLICT (event_id) DO NOTHING", event.EventID); err != nil {
		t.Fatalf("failed to seed dedup row: %v", err)
	}

	var buf bytes.Buffer
	oldOutput := log.Writer()
	log.SetOutput(&buf)
	defer log.SetOutput(oldOutput)

	w := makeWebhookRequest(body, sig, context.Background())
	if w.Code != http.StatusOK {
		t.Fatalf("expected 200 for replayed event, got %d. body: %s", w.Code, w.Body.String())
	}
	if w.Body.String() != "ok" {
		t.Errorf("expected body 'ok', got %q", w.Body.String())
	}
	if out := buf.String(); !strings.Contains(out, "Received event: payment.updated") {
		t.Errorf("expected replayed event to be re-dispatched (at-least-once), got:\n%s", out)
	}
	if n := countWebhookEvents(t, event.EventID); n != 1 {
		t.Errorf("expected still exactly 1 dedup row, got %d", n)
	}
}

// webhookConcurrentTestSeq gives each invocation of
// TestHandleSquareWebhook_ConcurrentSameEvent_Serialized a distinct
// square_payment_id + event_id, so repeated in-process runs (-count>1, or a
// replay in the same suite) cannot collide on the process-global dedup cache
// or the shared test DB — the suite is order-independent.
var webhookConcurrentTestSeq atomic.Int64

// TestHandleSquareWebhook_ConcurrentSameEvent_Serialized verifies the in-memory
// fast-path dedup (squareWebhookEventsSeen) plus the DB ON CONFLICT (event_id)
// insert serialize CONCURRENT delivery of the same signed event_id. Two
// goroutines hitting the handler with the same payload must produce exactly one
// persisted dedup row, exactly one "already processed" short-circuit (either
// the in-memory 'skipping' fast-path or the DB-conflict 'acknowledging'
// branch), and exactly one state mutation — the status-guarded UPDATE applies
// once and the second delivery's UPDATE is a 0-row no-op.
func TestHandleSquareWebhook_ConcurrentSameEvent_Serialized(t *testing.T) {
	seq := webhookConcurrentTestSeq.Add(1)
	squarePaymentID := fmt.Sprintf("sqp_concurrent_same_%d", seq)
	eventID := fmt.Sprintf("evt_concurrent_same_%d", seq)
	payID := createWebhookTestPayment(t, squarePaymentID, "pending")

	event := SquareWebhookEvent{
		Type:      "payment.updated",
		EventID:   eventID,
		CreatedAt: "2025-01-01T00:00:00Z",
		Data: json.RawMessage(`{
			"type": "payment",
			"id": "` + squarePaymentID + `",
			"object": {
				"payment": {
					"id": "` + squarePaymentID + `",
					"status": "COMPLETED"
				}
			}
		}`),
	}
	body, err := json.Marshal(event)
	if err != nil {
		t.Fatalf("failed to marshal webhook event: %v", err)
	}
	sig := webhookTestEnv(t, body)

	var buf bytes.Buffer
	oldOutput := log.Writer()
	log.SetOutput(&buf)
	defer log.SetOutput(oldOutput)

	var wg sync.WaitGroup
	codes := make([]int, 2)
	for i := range codes {
		wg.Add(1)
		go func(idx int) {
			defer wg.Done()
			codes[idx] = makeWebhookRequest(body, sig, context.Background()).Code
		}(i)
	}
	wg.Wait()

	for i, code := range codes {
		if code != http.StatusOK {
			t.Errorf("delivery %d: expected 200, got %d", i, code)
		}
	}
	if got := getPaymentStatus(t, payID); got != "completed" {
		t.Errorf("expected payment 'completed' after concurrent delivery, got %q", got)
	}
	if n := countWebhookEvents(t, event.EventID); n != 1 {
		t.Errorf("expected exactly 1 persisted dedup row after concurrent delivery, got %d", n)
	}
	out := buf.String()
	// Exactly one of the two deliveries hit an "already processed" path; the
	// other processed fresh (both may still return 200).
	if got := strings.Count(out, "already processed"); got != 1 {
		t.Errorf("expected exactly 1 'already processed' short-circuit, got %d:\n%s", got, out)
	}
	// The status-guarded UPDATE applied exactly once — the second delivery's
	// UPDATE matched 0 rows (already 'completed') and logged nothing.
	if got := strings.Count(out, "→ local status completed"); got != 1 {
		t.Errorf("expected exactly 1 state-mutation log line, got %d:\n%s", got, out)
	}
}

// TestHandleSquareWebhook_DedupCacheEviction_Redispatches documents why the
// 500-slot in-memory dedup cache cannot permanently hide an event across the
// test suite (or a long-lived process): once an event_id is evicted from the
// bounded cache, a replayed delivery is treated as NEW and re-dispatched — the
// DB dedup row is what actually absorbs it. Concretely: process the event
// (registers it + writes the dedup row), flood the cache past its 500-entry
// cap so the event is evicted, then replay it — the handler re-dispatches (the
// "Received event" log appears again) and the DB ON CONFLICT keeps the dedup
// row at exactly 1.
func TestHandleSquareWebhook_DedupCacheEviction_Redispatches(t *testing.T) {
	resetSquareWebhookEventsSeen()
	defer resetSquareWebhookEventsSeen()

	const squarePaymentID = "sqp_dedup_eviction"
	payID := createWebhookTestPayment(t, squarePaymentID, "pending")

	event := SquareWebhookEvent{
		Type:      "payment.updated",
		EventID:   "evt_dedup_eviction_target",
		CreatedAt: "2025-01-01T00:00:00Z",
		Data: json.RawMessage(`{
			"type": "payment",
			"id": "` + squarePaymentID + `",
			"object": {
				"payment": {
					"id": "` + squarePaymentID + `",
					"status": "COMPLETED"
				}
			}
		}`),
	}
	body, _ := json.Marshal(event)
	sig := webhookTestEnv(t, body)

	var buf bytes.Buffer
	oldOutput := log.Writer()
	log.SetOutput(&buf)
	defer log.SetOutput(oldOutput)

	w := makeWebhookRequest(body, sig, context.Background())
	if w.Code != http.StatusOK {
		t.Fatalf("expected first delivery 200, got %d. body: %s", w.Code, w.Body.String())
	}
	if n := countWebhookEvents(t, event.EventID); n != 1 {
		t.Fatalf("expected 1 dedup row after first delivery, got %d", n)
	}

	// Flood the 500-slot cache so the target event_id is evicted.
	for i := 0; i < squareWebhookEventsSeen.max; i++ {
		squareWebhookEventsSeen.register(fmt.Sprintf("evt_eviction_fill_%d", i))
	}
	if squareWebhookEventsSeen.has(event.EventID) {
		t.Fatal("expected target event_id to be evicted from the 500-slot cache")
	}

	// Replay: evicted from the fast-path cache, so it is re-dispatched. The DB
	// row already exists, so the ON CONFLICT insert keeps the count at 1.
	w2 := makeWebhookRequest(body, sig, context.Background())
	if w2.Code != http.StatusOK {
		t.Fatalf("expected replay 200, got %d. body: %s", w2.Code, w2.Body.String())
	}
	if w2.Body.String() != "ok" {
		t.Errorf("expected replay body 'ok', got %q", w2.Body.String())
	}
	out := buf.String()
	if got := strings.Count(out, "Received event: payment.updated"); got != 2 {
		t.Errorf("expected the evicted event to be re-dispatched (2 'Received event' lines), got %d:\n%s", got, out)
	}
	if n := countWebhookEvents(t, event.EventID); n != 1 {
		t.Errorf("expected still exactly 1 dedup row after re-dispatch, got %d", n)
	}
	if got := getPaymentStatus(t, payID); got != "completed" {
		t.Errorf("expected payment 'completed', got %q", got)
	}
}

// TestHandleSquareWebhook_DedupInsertFails_FailsClosed verifies the handler
// rejects (503) when the dedup INSERT cannot be persisted, so Square retries.
func TestHandleSquareWebhook_DedupInsertFails_FailsClosed(t *testing.T) {
	event := SquareWebhookEvent{
		Type:      "payment.updated",
		EventID:   "evt_db_down_1",
		CreatedAt: "2025-01-01T00:00:00Z",
		Data:      json.RawMessage(`{"id":"payment_db_down_1"}`),
	}
	body, _ := json.Marshal(event)
	sig := webhookTestEnv(t, body)

	orig := db.Conn
	defer func() { db.Conn = orig }()
	// A pool whose database does not exist fails every Exec — simulating a DB
	// that is unreachable or down.
	badDSN := fmt.Sprintf("postgres://myuser:mypassword@%s:5432/crussell_test_webhooks_nonexistent?sslmode=disable", testDBHost())
	badPool, err := pgxpool.New(context.Background(), badDSN)
	if err != nil {
		t.Fatalf("failed to create broken pool: %v", err)
	}
	defer badPool.Close()
	db.Conn = db.NewPoolProxy(badPool)

	w := makeWebhookRequest(body, sig, context.Background())
	if w.Code != http.StatusServiceUnavailable {
		t.Fatalf("expected 503 when dedup write fails, got %d. body: %s", w.Code, w.Body.String())
	}
}

// TestHandleSquareWebhook_DedupNilConn_FailsClosed verifies the handler also
// rejects (503) when the DB was never wired at all (defensive fail-closed).
func TestHandleSquareWebhook_DedupNilConn_FailsClosed(t *testing.T) {
	event := SquareWebhookEvent{
		Type:      "payment.updated",
		EventID:   "evt_nil_conn_1",
		CreatedAt: "2025-01-01T00:00:00Z",
		Data:      json.RawMessage(`{"id":"payment_nil_conn_1"}`),
	}
	body, _ := json.Marshal(event)
	sig := webhookTestEnv(t, body)

	orig := db.Conn
	db.Conn = nil
	defer func() { db.Conn = orig }()

	w := makeWebhookRequest(body, sig, context.Background())
	if w.Code != http.StatusServiceUnavailable {
		t.Fatalf("expected 503 when DB is not wired, got %d. body: %s", w.Code, w.Body.String())
	}
}

// =============================================================================
// square-environment header validation (finding a)
// =============================================================================

// TestHandleSquareWebhook_EnvMismatch_Rejected verifies fail-closed behavior: a
// correctly-signed event carrying a square-environment header that contradicts
// the configured SQUARE_ENVIRONMENT (e.g. a sandbox subscription mis-pointed at
// the production URL + key) is rejected with 403. 403 is correct here because
// the mismatch is a permanent configuration error — Square treats 4xx as
// non-retryable, so the retry loop stops instead of hammering a condition no
// retry can fix. No dispatch and no dedup row.
func TestHandleSquareWebhook_EnvMismatch_Rejected(t *testing.T) {
	t.Setenv("SQUARE_ENVIRONMENT", "production")
	event := SquareWebhookEvent{
		Type:      "payment.updated",
		EventID:   "evt_env_mismatch_1",
		CreatedAt: "2025-01-01T00:00:00Z",
		Data:      json.RawMessage(`{"id":"payment_env_mismatch_1"}`),
	}
	body, _ := json.Marshal(event)
	sig := webhookTestEnv(t, body)

	w := makeWebhookRequestWithEnv(body, sig, "sandbox", context.Background())
	if w.Code != http.StatusForbidden {
		t.Fatalf("expected 403 on environment mismatch, got %d. body: %s", w.Code, w.Body.String())
	}
	if n := countWebhookEvents(t, event.EventID); n != 0 {
		t.Errorf("expected no dedup row for a rejected event, got %d", n)
	}
}

// TestHandleSquareWebhook_EnvMatch_Accepted verifies a matching environment
// header passes the check and dispatches normally.
func TestHandleSquareWebhook_EnvMatch_Accepted(t *testing.T) {
	t.Setenv("SQUARE_ENVIRONMENT", "production")
	event := SquareWebhookEvent{
		Type:      "payment.updated",
		EventID:   "evt_env_match_1",
		CreatedAt: "2025-01-01T00:00:00Z",
		Data:      json.RawMessage(`{"id":"payment_env_match_1"}`),
	}
	body, _ := json.Marshal(event)
	sig := webhookTestEnv(t, body)

	w := makeWebhookRequestWithEnv(body, sig, "production", context.Background())
	if w.Code != http.StatusOK {
		t.Fatalf("expected 200 on matching environment, got %d. body: %s", w.Code, w.Body.String())
	}
	if n := countWebhookEvents(t, event.EventID); n != 1 {
		t.Errorf("expected 1 dedup row after successful dispatch, got %d", n)
	}
}

// TestHandleSquareWebhook_EnvHeaderAbsent_Allowed verifies an absent header is
// allowed through (local mock/dev posting), even in an enforced deployment —
// the signature check remains the authentication gate.
func TestHandleSquareWebhook_EnvHeaderAbsent_Allowed(t *testing.T) {
	t.Setenv("SQUARE_ENVIRONMENT", "production")
	event := SquareWebhookEvent{
		Type:      "payment.updated",
		EventID:   "evt_env_absent_1",
		CreatedAt: "2025-01-01T00:00:00Z",
		Data:      json.RawMessage(`{"id":"payment_env_absent_1"}`),
	}
	body, _ := json.Marshal(event)
	sig := webhookTestEnv(t, body)

	w := makeWebhookRequestWithEnv(body, sig, "", context.Background())
	if w.Code != http.StatusOK {
		t.Fatalf("expected 200 when the environment header is absent, got %d. body: %s", w.Code, w.Body.String())
	}
}

// TestHandleSquareWebhook_EnvMismatch_DevNotEnforced verifies the header check
// is NOT enforced when the configured SQUARE_ENVIRONMENT is a dev/mock value
// (the same interpretation IsExplicitDevOrMockEnv uses elsewhere), so a header
// carrying "sandbox" against an explicit "mock" config still dispatches.
func TestHandleSquareWebhook_EnvMismatch_DevNotEnforced(t *testing.T) {
	t.Setenv("SQUARE_ENVIRONMENT", "mock")
	event := SquareWebhookEvent{
		Type:      "payment.updated",
		EventID:   "evt_env_dev_1",
		CreatedAt: "2025-01-01T00:00:00Z",
		Data:      json.RawMessage(`{"id":"payment_env_dev_1"}`),
	}
	body, _ := json.Marshal(event)
	sig := webhookTestEnv(t, body)

	w := makeWebhookRequestWithEnv(body, sig, "sandbox", context.Background())
	if w.Code != http.StatusOK {
		t.Fatalf("expected 200 in dev mode (check not enforced), got %d. body: %s", w.Code, w.Body.String())
	}
}

// =============================================================================
// Bounded post-dispatch DB contexts (finding b)
// =============================================================================

// TestWebhookDBContext_HasTimeout verifies webhookDBContext returns a
// Background-derived context with a deadline, so a hung DB call cannot hold a
// pgx pool connection forever while still surviving a client disconnect.
func TestWebhookDBContext_HasTimeout(t *testing.T) {
	ctx, cancel := webhookDBContext()
	defer cancel()
	deadline, ok := ctx.Deadline()
	if !ok {
		t.Fatal("expected webhookDBContext to carry a deadline")
	}
	if remaining := time.Until(deadline); remaining <= 0 || remaining > webhookDBTimeout {
		t.Errorf("expected remaining budget within (0, %v], got %v", webhookDBTimeout, remaining)
	}
	if got := ctx.Err(); got != nil {
		t.Errorf("expected a fresh context to be active, got %v", got)
	}
}