package notify_test

import (
	"bytes"
	"context"
	"encoding/json"
	"errors"
	"io"
	"net/http"
	"net/http/httptest"
	"net/url"
	"sync"
	"testing"
	"time"

	"sneak.berlin/go/dnswatcher/internal/notify"
)

// Color constants used across multiple tests.
const (
	colorError   = "#dc3545"
	colorWarning = "#ffc107"
	colorSuccess = "#28a745"
	colorInfo    = "#17a2b8"
	colorDefault = "#6c757d"
)

// errSimulated is a static error for transport failures.
var errSimulated = errors.New("simulated transport failure")

// failingTransport always returns an error on RoundTrip.
type failingTransport struct {
	err error
}

func (ft *failingTransport) RoundTrip(
	_ *http.Request,
) (*http.Response, error) {
	return nil, ft.err
}

// waitForCondition polls until fn returns true or the test
// times out. This accommodates the goroutine-based dispatch
// in SendNotification.
func waitForCondition(t *testing.T, fn func() bool) {
	t.Helper()

	const (
		maxAttempts = 200
		pollDelay   = 10 * time.Millisecond
	)

	for range maxAttempts {
		if fn() {
			return
		}

		time.Sleep(pollDelay)
	}

	t.Fatal("condition not met within timeout")
}

// slackCapture holds values captured from a Slack/Mattermost
// webhook request, protected by a mutex for goroutine safety.
type slackCapture struct {
	mu      sync.Mutex
	called  bool
	payload notify.SlackPayload
}

func newSlackCaptureServer() (
	*httptest.Server, *slackCapture,
) {
	c := &slackCapture{}

	srv := httptest.NewServer(
		http.HandlerFunc(
			func(w http.ResponseWriter, r *http.Request) {
				c.mu.Lock()
				defer c.mu.Unlock()

				c.called = true

				b, _ := io.ReadAll(r.Body)
				_ = json.Unmarshal(b, &c.payload)

				w.WriteHeader(http.StatusOK)
			}),
	)

	return srv, c
}

// ── ntfyPriority ──────────────────────────────────────────

func TestNtfyPriority(t *testing.T) {
	t.Parallel()

	cases := []struct {
		input string
		want  string
	}{
		{"error", "urgent"},
		{"warning", "high"},
		{"success", "default"},
		{"info", "low"},
		{"", "default"},
		{"unknown", "default"},
		{"critical", "default"},
	}

	for _, tc := range cases {
		t.Run(tc.input, func(t *testing.T) {
			t.Parallel()

			got := notify.NtfyPriority(tc.input)
			if got != tc.want {
				t.Errorf(
					"NtfyPriority(%q) = %q, want %q",
					tc.input, got, tc.want,
				)
			}
		})
	}
}

// ── slackColor ────────────────────────────────────────────

func TestSlackColor(t *testing.T) {
	t.Parallel()

	cases := []struct {
		input string
		want  string
	}{
		{"error", colorError},
		{"warning", colorWarning},
		{"success", colorSuccess},
		{"info", colorInfo},
		{"", colorDefault},
		{"unknown", colorDefault},
		{"critical", colorDefault},
	}

	for _, tc := range cases {
		t.Run(tc.input, func(t *testing.T) {
			t.Parallel()

			got := notify.SlackColor(tc.input)
			if got != tc.want {
				t.Errorf(
					"SlackColor(%q) = %q, want %q",
					tc.input, got, tc.want,
				)
			}
		})
	}
}

// ── newRequest ────────────────────────────────────────────

func TestNewRequest(t *testing.T) {
	t.Parallel()

	target := &url.URL{
		Scheme: "https",
		Host:   "example.com",
		Path:   "/webhook",
	}
	body := bytes.NewBufferString("hello")
	ctx := context.Background()

	req := notify.NewRequestForTest(
		ctx, http.MethodPost, target, body,
	)

	if req.Method != http.MethodPost {
		t.Errorf("Method = %q, want POST", req.Method)
	}

	if req.URL.String() != "https://example.com/webhook" {
		t.Errorf(
			"URL = %q, want %q",
			req.URL.String(),
			"https://example.com/webhook",
		)
	}

	if req.Host != "example.com" {
		t.Errorf(
			"Host = %q, want %q", req.Host, "example.com",
		)
	}

	if req.Header == nil {
		t.Error("Header map should be initialized")
	}

	got, err := io.ReadAll(req.Body)
	if err != nil {
		t.Fatalf("reading body: %v", err)
	}

	if string(got) != "hello" {
		t.Errorf("Body = %q, want %q", string(got), "hello")
	}
}

func TestNewRequestPreservesContext(t *testing.T) {
	t.Parallel()

	type ctxKey string

	ctx := context.WithValue(
		context.Background(),
		ctxKey("k"),
		"v",
	)
	target := &url.URL{Scheme: "https", Host: "example.com"}

	req := notify.NewRequestForTest(
		ctx, http.MethodGet, target, http.NoBody,
	)

	if req.Context().Value(ctxKey("k")) != "v" {
		t.Error("context value not preserved")
	}
}

// ── sendNtfy ──────────────────────────────────────────────

// ntfyCapture holds values captured from an ntfy request.
type ntfyCapture struct {
	method   string
	title    string
	priority string
	body     string
}

func newNtfyCaptureServer() (*httptest.Server, *ntfyCapture) {
	c := &ntfyCapture{}

	srv := httptest.NewServer(
		http.HandlerFunc(
			func(w http.ResponseWriter, r *http.Request) {
				c.method = r.Method
				c.title = r.Header.Get("Title")
				c.priority = r.Header.Get("Priority")

				b, _ := io.ReadAll(r.Body)
				c.body = string(b)

				w.WriteHeader(http.StatusOK)
			}),
	)

	return srv, c
}

func TestSendNtfyHeaders(t *testing.T) {
	t.Parallel()

	srv, captured := newNtfyCaptureServer()
	defer srv.Close()

	svc := notify.NewTestService(srv.Client().Transport)
	topicURL, _ := url.Parse(srv.URL + "/test-topic")

	err := svc.SendNtfy(
		context.Background(),
		topicURL,
		"Test Title",
		"Test message body",
		"error",
	)
	if err != nil {
		t.Fatalf("SendNtfy returned error: %v", err)
	}

	if captured.method != http.MethodPost {
		t.Errorf("method = %q, want POST", captured.method)
	}

	if captured.title != "Test Title" {
		t.Errorf(
			"Title header = %q, want %q",
			captured.title, "Test Title",
		)
	}

	if captured.priority != "urgent" {
		t.Errorf(
			"Priority header = %q, want %q",
			captured.priority, "urgent",
		)
	}

	if captured.body != "Test message body" {
		t.Errorf(
			"body = %q, want %q",
			captured.body, "Test message body",
		)
	}
}

func TestSendNtfyAllPriorities(t *testing.T) {
	t.Parallel()

	priorities := []struct {
		input string
		want  string
	}{
		{"error", "urgent"},
		{"warning", "high"},
		{"success", "default"},
		{"info", "low"},
	}

	for _, tc := range priorities {
		t.Run(tc.input, func(t *testing.T) {
			t.Parallel()

			var gotPriority string

			srv := httptest.NewServer(
				http.HandlerFunc(
					func(w http.ResponseWriter, r *http.Request) {
						gotPriority = r.Header.Get("Priority")

						w.WriteHeader(http.StatusOK)
					}),
			)
			defer srv.Close()

			svc := notify.NewTestService(
				srv.Client().Transport,
			)
			topicURL, _ := url.Parse(srv.URL)

			err := svc.SendNtfy(
				context.Background(),
				topicURL, "t", "m", tc.input,
			)
			if err != nil {
				t.Fatalf("SendNtfy error: %v", err)
			}

			if gotPriority != tc.want {
				t.Errorf(
					"priority %q: got %q, want %q",
					tc.input, gotPriority, tc.want,
				)
			}
		})
	}
}

func TestSendNtfyClientError(t *testing.T) {
	t.Parallel()

	srv := httptest.NewServer(
		http.HandlerFunc(
			func(w http.ResponseWriter, _ *http.Request) {
				w.WriteHeader(http.StatusForbidden)
			}),
	)
	defer srv.Close()

	svc := notify.NewTestService(srv.Client().Transport)
	topicURL, _ := url.Parse(srv.URL)

	err := svc.SendNtfy(
		context.Background(), topicURL, "t", "m", "info",
	)
	if err == nil {
		t.Fatal("expected error for 403 response")
	}

	if !errors.Is(err, notify.ErrNtfyFailed) {
		t.Errorf("error = %v, want ErrNtfyFailed", err)
	}
}

func TestSendNtfyServerError(t *testing.T) {
	t.Parallel()

	srv := httptest.NewServer(
		http.HandlerFunc(
			func(w http.ResponseWriter, _ *http.Request) {
				w.WriteHeader(http.StatusInternalServerError)
			}),
	)
	defer srv.Close()

	svc := notify.NewTestService(srv.Client().Transport)
	topicURL, _ := url.Parse(srv.URL)

	err := svc.SendNtfy(
		context.Background(), topicURL, "t", "m", "info",
	)
	if err == nil {
		t.Fatal("expected error for 500 response")
	}

	if !errors.Is(err, notify.ErrNtfyFailed) {
		t.Errorf("error = %v, want ErrNtfyFailed", err)
	}
}

func TestSendNtfySuccess(t *testing.T) {
	t.Parallel()

	srv := httptest.NewServer(
		http.HandlerFunc(
			func(w http.ResponseWriter, _ *http.Request) {
				w.WriteHeader(http.StatusOK)
			}),
	)
	defer srv.Close()

	svc := notify.NewTestService(srv.Client().Transport)
	topicURL, _ := url.Parse(srv.URL)

	err := svc.SendNtfy(
		context.Background(), topicURL, "t", "m", "info",
	)
	if err != nil {
		t.Fatalf("expected success for 200: %v", err)
	}
}

func TestSendNtfyNetworkError(t *testing.T) {
	t.Parallel()

	transport := &failingTransport{err: errSimulated}

	svc := notify.NewTestService(transport)
	topicURL, _ := url.Parse(
		"http://unreachable.invalid/topic",
	)

	err := svc.SendNtfy(
		context.Background(), topicURL, "t", "m", "info",
	)
	if err == nil {
		t.Fatal("expected error for network failure")
	}
}

// ── sendSlack ─────────────────────────────────────────────

func TestSendSlackPayloadFields(t *testing.T) {
	t.Parallel()

	var (
		gotContentType string
		gotPayload     notify.SlackPayload
		gotMethod      string
	)

	srv := httptest.NewServer(
		http.HandlerFunc(
			func(w http.ResponseWriter, r *http.Request) {
				gotMethod = r.Method
				gotContentType = r.Header.Get("Content-Type")

				b, _ := io.ReadAll(r.Body)
				_ = json.Unmarshal(b, &gotPayload)

				w.WriteHeader(http.StatusOK)
			}),
	)
	defer srv.Close()

	svc := notify.NewTestService(srv.Client().Transport)
	webhookURL, _ := url.Parse(srv.URL + "/hooks/test")

	err := svc.SendSlack(
		context.Background(),
		webhookURL,
		"Alert Title",
		"Alert body text",
		"warning",
	)
	if err != nil {
		t.Fatalf("SendSlack returned error: %v", err)
	}

	assertSlackPayload(
		t,
		gotMethod,
		gotContentType,
		gotPayload,
		"Alert Title",
		"Alert body text",
		colorWarning,
	)
}

func assertSlackPayload(
	t *testing.T,
	method, contentType string,
	payload notify.SlackPayload,
	wantTitle, wantText, wantColor string,
) {
	t.Helper()

	if method != http.MethodPost {
		t.Errorf("method = %q, want POST", method)
	}

	if contentType != "application/json" {
		t.Errorf(
			"Content-Type = %q, want application/json",
			contentType,
		)
	}

	if len(payload.Attachments) != 1 {
		t.Fatalf(
			"attachments length = %d, want 1",
			len(payload.Attachments),
		)
	}

	att := payload.Attachments[0]

	if att.Title != wantTitle {
		t.Errorf(
			"title = %q, want %q", att.Title, wantTitle,
		)
	}

	if att.Text != wantText {
		t.Errorf("text = %q, want %q", att.Text, wantText)
	}

	if att.Color != wantColor {
		t.Errorf(
			"color = %q, want %q", att.Color, wantColor,
		)
	}
}

func TestSendSlackAllColors(t *testing.T) {
	t.Parallel()

	colors := []struct {
		priority string
		want     string
	}{
		{"error", colorError},
		{"warning", colorWarning},
		{"success", colorSuccess},
		{"info", colorInfo},
		{"unknown", colorDefault},
	}

	for _, tc := range colors {
		t.Run(tc.priority, func(t *testing.T) {
			t.Parallel()

			var gotPayload notify.SlackPayload

			srv := httptest.NewServer(
				http.HandlerFunc(
					func(w http.ResponseWriter, r *http.Request) {
						b, _ := io.ReadAll(r.Body)
						_ = json.Unmarshal(b, &gotPayload)

						w.WriteHeader(http.StatusOK)
					}),
			)
			defer srv.Close()

			svc := notify.NewTestService(
				srv.Client().Transport,
			)
			webhookURL, _ := url.Parse(srv.URL)

			err := svc.SendSlack(
				context.Background(),
				webhookURL, "t", "m", tc.priority,
			)
			if err != nil {
				t.Fatalf("SendSlack error: %v", err)
			}

			if len(gotPayload.Attachments) == 0 {
				t.Fatal("no attachments in payload")
			}

			if gotPayload.Attachments[0].Color != tc.want {
				t.Errorf(
					"priority %q: color = %q, want %q",
					tc.priority,
					gotPayload.Attachments[0].Color,
					tc.want,
				)
			}
		})
	}
}

func TestSendSlackClientError(t *testing.T) {
	t.Parallel()

	srv := httptest.NewServer(
		http.HandlerFunc(
			func(w http.ResponseWriter, _ *http.Request) {
				w.WriteHeader(http.StatusBadRequest)
			}),
	)
	defer srv.Close()

	svc := notify.NewTestService(srv.Client().Transport)
	webhookURL, _ := url.Parse(srv.URL)

	err := svc.SendSlack(
		context.Background(), webhookURL, "t", "m", "info",
	)
	if err == nil {
		t.Fatal("expected error for 400 response")
	}

	if !errors.Is(err, notify.ErrSlackFailed) {
		t.Errorf("error = %v, want ErrSlackFailed", err)
	}
}

func TestSendSlackServerError(t *testing.T) {
	t.Parallel()

	srv := httptest.NewServer(
		http.HandlerFunc(
			func(w http.ResponseWriter, _ *http.Request) {
				w.WriteHeader(http.StatusBadGateway)
			}),
	)
	defer srv.Close()

	svc := notify.NewTestService(srv.Client().Transport)
	webhookURL, _ := url.Parse(srv.URL)

	err := svc.SendSlack(
		context.Background(), webhookURL, "t", "m", "error",
	)
	if err == nil {
		t.Fatal("expected error for 502 response")
	}

	if !errors.Is(err, notify.ErrSlackFailed) {
		t.Errorf("error = %v, want ErrSlackFailed", err)
	}
}

func TestSendSlackNetworkError(t *testing.T) {
	t.Parallel()

	transport := &failingTransport{err: errSimulated}

	svc := notify.NewTestService(transport)
	webhookURL, _ := url.Parse(
		"http://unreachable.invalid/hooks",
	)

	err := svc.SendSlack(
		context.Background(), webhookURL, "t", "m", "info",
	)
	if err == nil {
		t.Fatal("expected error for network failure")
	}
}

// ── SendNotification (exported) ───────────────────────────

// endpointResult captures concurrent results from all three
// notification endpoints.
type endpointResult struct {
	mu           sync.Mutex
	ntfyCalled   bool
	ntfyTitle    string
	slackCalled  bool
	slackPayload notify.SlackPayload
	mmCalled     bool
	mmPayload    notify.SlackPayload
}

func newEndpointServers(
	r *endpointResult,
) (*httptest.Server, *httptest.Server, *httptest.Server) {
	ntfy := httptest.NewServer(
		http.HandlerFunc(
			func(w http.ResponseWriter, req *http.Request) {
				r.mu.Lock()
				defer r.mu.Unlock()

				r.ntfyCalled = true
				r.ntfyTitle = req.Header.Get("Title")

				w.WriteHeader(http.StatusOK)
			}),
	)

	slack := httptest.NewServer(
		http.HandlerFunc(
			func(w http.ResponseWriter, req *http.Request) {
				r.mu.Lock()
				defer r.mu.Unlock()

				r.slackCalled = true

				b, _ := io.ReadAll(req.Body)
				_ = json.Unmarshal(b, &r.slackPayload)

				w.WriteHeader(http.StatusOK)
			}),
	)

	mm := httptest.NewServer(
		http.HandlerFunc(
			func(w http.ResponseWriter, req *http.Request) {
				r.mu.Lock()
				defer r.mu.Unlock()

				r.mmCalled = true

				b, _ := io.ReadAll(req.Body)
				_ = json.Unmarshal(b, &r.mmPayload)

				w.WriteHeader(http.StatusOK)
			}),
	)

	return ntfy, slack, mm
}

func assertAllEndpointsResult(
	t *testing.T, r *endpointResult,
) {
	t.Helper()

	if r.ntfyTitle != "DNS Changed" {
		t.Errorf(
			"ntfy Title = %q, want %q",
			r.ntfyTitle, "DNS Changed",
		)
	}

	if len(r.slackPayload.Attachments) == 0 {
		t.Fatal("slack payload has no attachments")
	}

	if r.slackPayload.Attachments[0].Title != "DNS Changed" {
		t.Errorf(
			"slack title = %q, want %q",
			r.slackPayload.Attachments[0].Title,
			"DNS Changed",
		)
	}

	if len(r.mmPayload.Attachments) == 0 {
		t.Fatal("mattermost payload has no attachments")
	}

	wantText := "example.com A record updated"
	if r.mmPayload.Attachments[0].Text != wantText {
		t.Errorf(
			"mattermost text = %q, want %q",
			r.mmPayload.Attachments[0].Text,
			wantText,
		)
	}
}

func TestSendNotificationAllEndpoints(t *testing.T) {
	t.Parallel()

	result := &endpointResult{}
	ntfySrv, slackSrv, mmSrv := newEndpointServers(result)

	defer ntfySrv.Close()
	defer slackSrv.Close()
	defer mmSrv.Close()

	ntfyURL, _ := url.Parse(ntfySrv.URL)
	slackURL, _ := url.Parse(slackSrv.URL)
	mmURL, _ := url.Parse(mmSrv.URL)

	svc := notify.NewTestService(http.DefaultTransport)
	svc.SetNtfyURL(ntfyURL)
	svc.SetSlackWebhookURL(slackURL)
	svc.SetMattermostWebhookURL(mmURL)

	svc.SendNotification(
		context.Background(),
		"DNS Changed",
		"example.com A record updated",
		"warning",
	)

	waitForCondition(t, func() bool {
		result.mu.Lock()
		defer result.mu.Unlock()

		return result.ntfyCalled &&
			result.slackCalled &&
			result.mmCalled
	})

	result.mu.Lock()
	defer result.mu.Unlock()

	assertAllEndpointsResult(t, result)
}

func TestSendNotificationNoWebhooks(t *testing.T) {
	t.Parallel()

	svc := notify.NewTestService(http.DefaultTransport)

	// All URL fields are nil — this should be a no-op.
	svc.SendNotification(
		context.Background(), "Title", "Message", "info",
	)
}

func TestSendNotificationNtfyOnly(t *testing.T) {
	t.Parallel()

	var (
		mu       sync.Mutex
		called   bool
		gotTitle string
	)

	srv := httptest.NewServer(
		http.HandlerFunc(
			func(w http.ResponseWriter, r *http.Request) {
				mu.Lock()
				defer mu.Unlock()

				called = true
				gotTitle = r.Header.Get("Title")

				w.WriteHeader(http.StatusOK)
			}),
	)
	defer srv.Close()

	ntfyURL, _ := url.Parse(srv.URL)

	svc := notify.NewTestService(http.DefaultTransport)
	svc.SetNtfyURL(ntfyURL)

	svc.SendNotification(
		context.Background(), "Only Ntfy", "body", "info",
	)

	waitForCondition(t, func() bool {
		mu.Lock()
		defer mu.Unlock()

		return called
	})

	mu.Lock()
	defer mu.Unlock()

	if gotTitle != "Only Ntfy" {
		t.Errorf(
			"title = %q, want %q", gotTitle, "Only Ntfy",
		)
	}
}

func TestSendNotificationSlackOnly(t *testing.T) {
	t.Parallel()

	var (
		mu      sync.Mutex
		called  bool
		payload notify.SlackPayload
	)

	srv := httptest.NewServer(
		http.HandlerFunc(
			func(w http.ResponseWriter, r *http.Request) {
				mu.Lock()
				defer mu.Unlock()

				called = true

				b, _ := io.ReadAll(r.Body)
				_ = json.Unmarshal(b, &payload)

				w.WriteHeader(http.StatusOK)
			}),
	)
	defer srv.Close()

	slackURL, _ := url.Parse(srv.URL)

	svc := notify.NewTestService(http.DefaultTransport)
	svc.SetSlackWebhookURL(slackURL)

	svc.SendNotification(
		context.Background(),
		"Slack Only", "body", "error",
	)

	waitForCondition(t, func() bool {
		mu.Lock()
		defer mu.Unlock()

		return called
	})

	mu.Lock()
	defer mu.Unlock()

	if len(payload.Attachments) == 0 {
		t.Fatal("no attachments")
	}

	if payload.Attachments[0].Color != colorError {
		t.Errorf(
			"color = %q, want %q",
			payload.Attachments[0].Color, colorError,
		)
	}
}

func TestSendNotificationMattermostOnly(t *testing.T) {
	t.Parallel()

	srv, capture := newSlackCaptureServer()
	defer srv.Close()

	mmURL, _ := url.Parse(srv.URL)

	svc := notify.NewTestService(http.DefaultTransport)
	svc.SetMattermostWebhookURL(mmURL)

	svc.SendNotification(
		context.Background(),
		"MM Only", "body", "success",
	)

	waitForCondition(t, func() bool {
		capture.mu.Lock()
		defer capture.mu.Unlock()

		return capture.called
	})

	capture.mu.Lock()
	defer capture.mu.Unlock()

	if len(capture.payload.Attachments) == 0 {
		t.Fatal("no attachments")
	}

	att := capture.payload.Attachments[0]

	if att.Title != "MM Only" {
		t.Errorf(
			"title = %q, want %q", att.Title, "MM Only",
		)
	}

	if att.Color != colorSuccess {
		t.Errorf(
			"color = %q, want %q", att.Color, colorSuccess,
		)
	}
}

func TestSendNotificationNtfyError(t *testing.T) {
	t.Parallel()

	srv := httptest.NewServer(
		http.HandlerFunc(
			func(w http.ResponseWriter, _ *http.Request) {
				w.WriteHeader(http.StatusInternalServerError)
			}),
	)
	defer srv.Close()

	ntfyURL, _ := url.Parse(srv.URL)

	svc := notify.NewTestService(http.DefaultTransport)
	svc.SetNtfyURL(ntfyURL)

	// Should not panic or block.
	svc.SendNotification(
		context.Background(), "t", "m", "error",
	)

	time.Sleep(100 * time.Millisecond)
}

func TestSendNotificationSlackError(t *testing.T) {
	t.Parallel()

	srv := httptest.NewServer(
		http.HandlerFunc(
			func(w http.ResponseWriter, _ *http.Request) {
				w.WriteHeader(http.StatusForbidden)
			}),
	)
	defer srv.Close()

	slackURL, _ := url.Parse(srv.URL)

	svc := notify.NewTestService(http.DefaultTransport)
	svc.SetSlackWebhookURL(slackURL)

	svc.SendNotification(
		context.Background(), "t", "m", "error",
	)

	time.Sleep(100 * time.Millisecond)
}

func TestSendNotificationMattermostError(t *testing.T) {
	t.Parallel()

	srv := httptest.NewServer(
		http.HandlerFunc(
			func(w http.ResponseWriter, _ *http.Request) {
				w.WriteHeader(http.StatusBadGateway)
			}),
	)
	defer srv.Close()

	mmURL, _ := url.Parse(srv.URL)

	svc := notify.NewTestService(http.DefaultTransport)
	svc.SetMattermostWebhookURL(mmURL)

	svc.SendNotification(
		context.Background(), "t", "m", "warning",
	)

	time.Sleep(100 * time.Millisecond)
}

// ── SlackPayload JSON marshaling ──────────────────────────

func TestSlackPayloadJSON(t *testing.T) {
	t.Parallel()

	payload := notify.SlackPayload{
		Text: "fallback",
		Attachments: []notify.SlackAttachment{
			{
				Color: colorSuccess,
				Title: "Test",
				Text:  "body",
			},
		},
	}

	data, err := json.Marshal(payload)
	if err != nil {
		t.Fatalf("marshal: %v", err)
	}

	var decoded notify.SlackPayload

	err = json.Unmarshal(data, &decoded)
	if err != nil {
		t.Fatalf("unmarshal: %v", err)
	}

	if decoded.Text != "fallback" {
		t.Errorf(
			"Text = %q, want %q", decoded.Text, "fallback",
		)
	}

	if len(decoded.Attachments) != 1 {
		t.Fatalf(
			"Attachments len = %d, want 1",
			len(decoded.Attachments),
		)
	}

	att := decoded.Attachments[0]

	if att.Color != colorSuccess {
		t.Errorf(
			"Color = %q, want %q", att.Color, colorSuccess,
		)
	}

	if att.Title != "Test" {
		t.Errorf("Title = %q, want %q", att.Title, "Test")
	}

	if att.Text != "body" {
		t.Errorf("Text = %q, want %q", att.Text, "body")
	}
}

func TestSlackPayloadEmptyAttachments(t *testing.T) {
	t.Parallel()

	payload := notify.SlackPayload{Text: "no attachments"}

	data, err := json.Marshal(payload)
	if err != nil {
		t.Fatalf("marshal: %v", err)
	}

	var raw map[string]json.RawMessage

	err = json.Unmarshal(data, &raw)
	if err != nil {
		t.Fatalf("unmarshal raw: %v", err)
	}

	if _, exists := raw["attachments"]; exists {
		t.Error(
			"attachments should be omitted when empty",
		)
	}
}