//go:build test

package webhooks

import (
	"bytes"
	"context"
	"crypto/hmac"
	"crypto/sha256"
	"encoding/base64"
	"encoding/json"
	"fmt"
	"net/http"
	"net/http/httptest"
	"strings"
	"testing"
)

// =============================================================================
// 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")
	}
}

// =============================================================================
// 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
}

// 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))
}

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())
	}
}

func TestHandleSquareWebhook_UnknownEventType(t *testing.T) {
	event := SquareWebhookEvent{
		Type:      "invoice.created",
		EventID:   "evt_unknown_1",
		CreatedAt: "2025-01-01T00:00:00Z",
		Data:      json.RawMessage(`{"id":"inv_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 unknown event type, got %d. body: %s", w.Code, w.Body.String())
	}
}

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())
	}
}

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) {

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

// =============================================================================
// 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())
	}
}

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")
	}
}