terdut-server/internal/api/api_test.go

package api_test

import (
	"bytes"
	"context"
	"database/sql"
	"encoding/json"
	"fmt"
	"io"
	"net/http"
	"net/http/httptest"
	"testing"
	"time"

	"github.com/yeniklas/terdut-server/internal/api"
	"github.com/yeniklas/terdut-server/internal/db"
)

// ts wraps httptest.Server with a pre-bootstrapped API key. db is exposed so
// tests can age rows directly — the sweeper's inputs are wall-clock timestamps.
type ts struct {
	*httptest.Server
	key    string
	db     *sql.DB
	notify api.NotifyConfig
}

// newTS builds a server over a fresh in-memory database. Notifications are off
// unless a NotifyConfig is passed, so tests that predate them are unaffected.
func newTS(t *testing.T, notify ...api.NotifyConfig) *ts {
	t.Helper()
	var cfg api.NotifyConfig
	if len(notify) > 0 {
		cfg = notify[0]
	}

	database, err := db.Open(":memory:")
	if err != nil {
		t.Fatalf("open db: %v", err)
	}
	if err := db.Migrate(database); err != nil {
		t.Fatalf("migrate: %v", err)
	}
	srv := httptest.NewServer(api.NewRouter(database, cfg))
	t.Cleanup(func() { srv.Close(); database.Close() })

	body, _ := json.Marshal(map[string]string{"username": "admin", "email": "admin@test.com"})
	resp, err := http.Post(srv.URL+"/api/bootstrap", "application/json", bytes.NewReader(body))
	if err != nil {
		t.Fatalf("bootstrap: %v", err)
	}
	defer resp.Body.Close()
	if resp.StatusCode != http.StatusCreated {
		t.Fatalf("bootstrap returned %d", resp.StatusCode)
	}
	var result map[string]any
	json.NewDecoder(resp.Body).Decode(&result)
	key := result["api_key"].(map[string]any)["key"].(string)

	return &ts{Server: srv, key: key, db: database, notify: cfg}
}

// exec runs a statement against the test database.
func (s *ts) exec(t *testing.T, query string, args ...any) {
	t.Helper()
	if _, err := s.db.Exec(query, args...); err != nil {
		t.Fatalf("exec %q: %v", query, err)
	}
}

// alertRow reads the sweeper-relevant columns of one alert straight from the DB.
func (s *ts) alertRow(t *testing.T, fingerprint string) (status string, source *string, archivedAt *int64) {
	t.Helper()
	err := s.db.QueryRow(
		"SELECT status, resolution_source, archived_at FROM alerts WHERE fingerprint = ?",
		fingerprint).Scan(&status, &source, &archivedAt)
	if err != nil {
		t.Fatalf("read alert %s: %v", fingerprint, err)
	}
	return status, source, archivedAt
}

// alertTimes reads the timestamp columns that make up the received_at contract.
func (s *ts) alertTimes(t *testing.T, fingerprint string) (startsAt, receivedAt int64) {
	t.Helper()
	err := s.db.QueryRow(
		"SELECT starts_at, received_at FROM alerts WHERE fingerprint = ?",
		fingerprint).Scan(&startsAt, &receivedAt)
	if err != nil {
		t.Fatalf("read alert times %s: %v", fingerprint, err)
	}
	return startsAt, receivedAt
}

// alertEndsAt reads the nullable ends_at column of one alert.
func (s *ts) alertEndsAt(t *testing.T, fingerprint string) *int64 {
	t.Helper()
	var endsAt *int64
	if err := s.db.QueryRow(
		"SELECT ends_at FROM alerts WHERE fingerprint = ?", fingerprint).Scan(&endsAt); err != nil {
		t.Fatalf("read ends_at %s: %v", fingerprint, err)
	}
	return endsAt
}

// req sends an authenticated request, optionally with a JSON body.
func (s *ts) req(t *testing.T, method, path string, body any) *http.Response {
	t.Helper()
	var r io.Reader
	if body != nil {
		data, _ := json.Marshal(body)
		r = bytes.NewReader(data)
	}
	req, _ := http.NewRequest(method, s.URL+path, r)
	req.Header.Set("Authorization", "Bearer "+s.key)
	if body != nil {
		req.Header.Set("Content-Type", "application/json")
	}
	resp, err := http.DefaultClient.Do(req)
	if err != nil {
		t.Fatalf("%s %s: %v", method, path, err)
	}
	return resp
}

func decode(t *testing.T, resp *http.Response, v any) {
	t.Helper()
	defer resp.Body.Close()
	if err := json.NewDecoder(resp.Body).Decode(v); err != nil {
		t.Fatalf("decode response: %v", err)
	}
}

// ---------------------------------------------------------------------------
// Auth middleware
// ---------------------------------------------------------------------------

func TestAuthMiddleware_MissingToken(t *testing.T) {
	s := newTS(t)
	req, _ := http.NewRequest(http.MethodGet, s.URL+"/api/users", nil)
	resp, _ := http.DefaultClient.Do(req)
	if resp.StatusCode != http.StatusUnauthorized {
		t.Errorf("expected 401, got %d", resp.StatusCode)
	}
}

func TestAuthMiddleware_InvalidToken(t *testing.T) {
	s := newTS(t)
	req, _ := http.NewRequest(http.MethodGet, s.URL+"/api/users", nil)
	req.Header.Set("Authorization", "Bearer notavalidkey")
	resp, _ := http.DefaultClient.Do(req)
	if resp.StatusCode != http.StatusUnauthorized {
		t.Errorf("expected 401, got %d", resp.StatusCode)
	}
}

func TestAuthMiddleware_ValidToken(t *testing.T) {
	s := newTS(t)
	resp := s.req(t, http.MethodGet, "/api/users", nil)
	if resp.StatusCode != http.StatusOK {
		t.Errorf("expected 200, got %d", resp.StatusCode)
	}
}

// ---------------------------------------------------------------------------
// Bootstrap idempotency
// ---------------------------------------------------------------------------

func TestBootstrap_SecondCallForbidden(t *testing.T) {
	s := newTS(t) // already bootstrapped
	body, _ := json.Marshal(map[string]string{"username": "x", "email": "x@x.com"})
	resp, _ := http.Post(s.URL+"/api/bootstrap", "application/json", bytes.NewReader(body))
	if resp.StatusCode != http.StatusForbidden {
		t.Errorf("expected 403, got %d", resp.StatusCode)
	}
}

// ---------------------------------------------------------------------------
// Alert upsert by fingerprint
// ---------------------------------------------------------------------------

// postWebhook sends an Alertmanager v4 payload. groupKey is optional: omitting
// it exercises the fallback for senders that do not group, which is what most of
// these tests want.
func postWebhook(t *testing.T, s *ts, alerts []map[string]any, groupKey ...string) {
	t.Helper()
	payload := map[string]any{"version": "4", "status": "firing", "alerts": alerts}
	if len(groupKey) > 0 {
		payload["groupKey"] = groupKey[0]
		// Alertmanager groups by alertname by default, so the group labels echo
		// the first alert's name.
		if len(alerts) > 0 {
			if labels, ok := alerts[0]["labels"].(map[string]string); ok {
				payload["groupLabels"] = map[string]string{"alertname": labels["alertname"]}
			}
		}
	}
	data, _ := json.Marshal(payload)
	resp, err := http.Post(s.URL+"/api/alertmanager/webhook", "application/json", bytes.NewReader(data))
	if err != nil {
		t.Fatalf("post webhook: %v", err)
	}
	resp.Body.Close()
	if resp.StatusCode != http.StatusOK {
		t.Fatalf("webhook returned %d", resp.StatusCode)
	}
}

func TestAlertUpsert_SameFingerprintUpdates(t *testing.T) {
	s := newTS(t)

	alert := map[string]any{
		"status":       "firing",
		"labels":       map[string]string{"alertname": "HighCPU"},
		"annotations":  map[string]string{},
		"startsAt":     "2026-05-20T10:00:00Z",
		"endsAt":       "0001-01-01T00:00:00Z",
		"generatorURL": "",
		"fingerprint":  "fp-upsert",
	}
	postWebhook(t, s, []map[string]any{alert})

	// Same fingerprint, now resolved.
	alert["status"] = "resolved"
	alert["endsAt"] = "2026-05-20T11:00:00Z"
	postWebhook(t, s, []map[string]any{alert})

	resp := s.req(t, http.MethodGet, "/api/alerts", nil)
	var list []map[string]any
	decode(t, resp, &list)

	if len(list) != 1 {
		t.Fatalf("expected 1 alert (upsert), got %d", len(list))
	}
	if list[0]["status"] != "resolved" {
		t.Errorf("expected status resolved, got %s", list[0]["status"])
	}
	if list[0]["ends_at"] == nil {
		t.Error("expected ends_at to be set after resolve")
	}
}

func TestAlertUpsert_DifferentFingerprintsStored(t *testing.T) {
	s := newTS(t)

	for i := range 3 {
		alert := map[string]any{
			"status":       "firing",
			"labels":       map[string]string{"alertname": fmt.Sprintf("Alert%d", i)},
			"annotations":  map[string]string{},
			"startsAt":     "2026-05-20T10:00:00Z",
			"endsAt":       "0001-01-01T00:00:00Z",
			"generatorURL": "",
			"fingerprint":  fmt.Sprintf("fp-%d", i),
		}
		postWebhook(t, s, []map[string]any{alert})
	}

	resp := s.req(t, http.MethodGet, "/api/alerts", nil)
	var list []map[string]any
	decode(t, resp, &list)
	if len(list) != 3 {
		t.Errorf("expected 3 alerts, got %d", len(list))
	}
}

// ---------------------------------------------------------------------------
// Schedule conflict
// ---------------------------------------------------------------------------

func TestSchedule_ConflictOnSameDate(t *testing.T) {
	s := newTS(t)

	first := s.req(t, http.MethodPost, "/api/schedule",
		map[string]any{"user_id": 1, "dates": []string{"2026-06-01"}})
	if first.StatusCode != http.StatusCreated {
		t.Fatalf("first assignment returned %d", first.StatusCode)
	}
	first.Body.Close()

	second := s.req(t, http.MethodPost, "/api/schedule",
		map[string]any{"user_id": 1, "dates": []string{"2026-06-01"}})
	if second.StatusCode != http.StatusConflict {
		t.Errorf("expected 409 on duplicate date, got %d", second.StatusCode)
	}
	second.Body.Close()
}

func TestSchedule_MultiDateRollbackOnConflict(t *testing.T) {
	s := newTS(t)

	// Claim 2026-06-10 first.
	s.req(t, http.MethodPost, "/api/schedule",
		map[string]any{"user_id": 1, "dates": []string{"2026-06-10"}}).Body.Close()

	// Try to assign two dates in one request where the second conflicts.
	resp := s.req(t, http.MethodPost, "/api/schedule",
		map[string]any{"user_id": 1, "dates": []string{"2026-06-09", "2026-06-10"}})
	if resp.StatusCode != http.StatusConflict {
		t.Fatalf("expected 409, got %d", resp.StatusCode)
	}
	resp.Body.Close()

	// 2026-06-09 must NOT have been committed (transaction rolled back).
	listResp := s.req(t, http.MethodGet, "/api/schedule?from=2026-06-09&to=2026-06-09", nil)
	var entries []any
	decode(t, listResp, &entries)
	if len(entries) != 0 {
		t.Errorf("expected rollback to leave 2026-06-09 unassigned, got %d entries", len(entries))
	}
}

// ---------------------------------------------------------------------------
// Stats
// ---------------------------------------------------------------------------

func TestStats_Totals(t *testing.T) {
	s := newTS(t)

	alerts := []map[string]any{
		{"status": "firing", "labels": map[string]string{"alertname": "A"}, "annotations": map[string]string{}, "startsAt": "2026-05-20T10:00:00Z", "endsAt": "0001-01-01T00:00:00Z", "generatorURL": "", "fingerprint": "s1"},
		{"status": "resolved", "labels": map[string]string{"alertname": "B"}, "annotations": map[string]string{}, "startsAt": "2026-05-20T10:00:00Z", "endsAt": "2026-05-20T11:00:00Z", "generatorURL": "", "fingerprint": "s2"},
	}
	postWebhook(t, s, alerts)

	resp := s.req(t, http.MethodGet, "/api/stats/alerts", nil)
	var stats map[string]any
	decode(t, resp, &stats)

	if int(stats["total"].(float64)) != 2 {
		t.Errorf("expected total=2, got %v", stats["total"])
	}
	if int(stats["firing"].(float64)) != 1 {
		t.Errorf("expected firing=1, got %v", stats["firing"])
	}
	if int(stats["resolved"].(float64)) != 1 {
		t.Errorf("expected resolved=1, got %v", stats["resolved"])
	}
}

func TestStats_ByHourReturnsTwentyFourSlots(t *testing.T) {
	s := newTS(t)
	resp := s.req(t, http.MethodGet, "/api/stats/alerts/by-hour", nil)
	var slots []any
	decode(t, resp, &slots)
	if len(slots) != 24 {
		t.Errorf("expected 24 hour slots, got %d", len(slots))
	}
}

// ---------------------------------------------------------------------------
// Archive
// ---------------------------------------------------------------------------

// Alert archiving is sweeper-only housekeeping now — nobody archives an alert by
// hand — but the list filter it drives is still part of the API.
func TestArchive_AlertListFilter(t *testing.T) {
	s := newTS(t)

	postWebhook(t, s, []map[string]any{{
		"status": "resolved", "fingerprint": "arch1",
		"labels":       map[string]string{"alertname": "Archivable"},
		"annotations":  map[string]string{},
		"startsAt":     "2026-05-20T10:00:00Z",
		"endsAt":       "2026-05-20T11:00:00Z",
		"generatorURL": "",
	}})

	// 1. Alert appears in the default list.
	var alerts []map[string]any
	decode(t, s.req(t, http.MethodGet, "/api/alerts", nil), &alerts)
	if len(alerts) != 1 {
		t.Fatalf("expected 1 alert in default list, got %d", len(alerts))
	}

	// 2. Let the sweeper archive it: ends_at is already well past archiveAfter.
	api.Sweep(context.Background(), s.db, time.Hour, 6*time.Hour)

	// 3. Default list excludes it.
	decode(t, s.req(t, http.MethodGet, "/api/alerts", nil), &alerts)
	if len(alerts) != 0 {
		t.Errorf("expected archived alert to be hidden, got %d results", len(alerts))
	}

	// 4. archived=true shows it.
	decode(t, s.req(t, http.MethodGet, "/api/alerts?archived=true", nil), &alerts)
	if len(alerts) != 1 {
		t.Fatalf("expected 1 archived alert, got %d", len(alerts))
	}
}

// ---------------------------------------------------------------------------
// Stale-alert expiry
// ---------------------------------------------------------------------------

// noArchive is long enough that archiving never interferes with expiry tests.
const noArchive = 365 * 24 * time.Hour

// zeroTime is Alertmanager's "no end known" sentinel, which stores ends_at NULL.
const zeroTime = "0001-01-01T00:00:00Z"

// postAlert sends a single-alert webhook.
func postAlert(t *testing.T, s *ts, fingerprint, status, startsAt, endsAt string) {
	t.Helper()
	postWebhook(t, s, []map[string]any{{
		"status":       status,
		"labels":       map[string]string{"alertname": "Stale"},
		"annotations":  map[string]string{},
		"startsAt":     startsAt,
		"endsAt":       endsAt,
		"generatorURL": "",
		"fingerprint":  fingerprint,
	}})
}

func sweep(t *testing.T, s *ts, staleAfter time.Duration) {
	t.Helper()
	api.Sweep(context.Background(), s.db, noArchive, staleAfter)
}

// A firing alert Alertmanager stopped refreshing is resolved via the
// received_at heartbeat, even with no ends_at watermark to go on.
func TestExpiry_StaleFiringAlert(t *testing.T) {
	s := newTS(t)
	postAlert(t, s, "stale1", "firing", time.Now().Add(-24*time.Hour).Format(time.RFC3339), zeroTime)

	// Age the last-seen timestamp past the staleness window.
	s.exec(t, "UPDATE alerts SET received_at = ? WHERE fingerprint = 'stale1'",
		time.Now().Add(-10*time.Hour).Unix())

	sweep(t, s, 6*time.Hour)

	status, source, _ := s.alertRow(t, "stale1")
	if status != "resolved" {
		t.Errorf("expected status resolved, got %q", status)
	}
	if source == nil || *source != "expiry" {
		t.Errorf("expected resolution_source=expiry, got %v", source)
	}
}

// A fresh webhook whose ends_at watermark has already passed is expired without
// waiting out the full staleness window.
func TestExpiry_PastEndsAt(t *testing.T) {
	s := newTS(t)
	postAlert(t, s, "stale2", "firing",
		time.Now().Add(-2*time.Hour).Format(time.RFC3339),
		time.Now().Add(-30*time.Minute).Format(time.RFC3339))

	sweep(t, s, 6*time.Hour) // received_at is fresh; only ends_at can trigger

	status, source, _ := s.alertRow(t, "stale2")
	if status != "resolved" {
		t.Errorf("expected status resolved, got %q", status)
	}
	if source == nil || *source != "expiry" {
		t.Errorf("expected resolution_source=expiry, got %v", source)
	}
}

// The regression that matters most: a genuinely firing alert must survive a
// sweep untouched.
func TestExpiry_LeavesFreshAlertsAlone(t *testing.T) {
	s := newTS(t)
	postAlert(t, s, "fresh1", "firing",
		time.Now().Add(-10*time.Minute).Format(time.RFC3339),
		time.Now().Add(1*time.Hour).Format(time.RFC3339))

	sweep(t, s, 6*time.Hour)

	status, source, _ := s.alertRow(t, "fresh1")
	if status != "firing" {
		t.Errorf("expected fresh alert to stay firing, got %q", status)
	}
	if source != nil {
		t.Errorf("expected no resolution_source, got %q", *source)
	}
}

// An ends_at only just past must not trip expiry — that grace absorbs clock skew.
func TestExpiry_RespectsGraceOnEndsAt(t *testing.T) {
	s := newTS(t)
	postAlert(t, s, "grace1", "firing",
		time.Now().Add(-time.Hour).Format(time.RFC3339),
		time.Now().Add(-1*time.Minute).Format(time.RFC3339))

	sweep(t, s, 6*time.Hour)

	if status, _, _ := s.alertRow(t, "grace1"); status != "firing" {
		t.Errorf("expected alert within grace period to stay firing, got %q", status)
	}
}

// ---------------------------------------------------------------------------
// Webhook resolution bookkeeping
// ---------------------------------------------------------------------------

func TestWebhook_ResolvedSetsSource(t *testing.T) {
	s := newTS(t)
	start := time.Now().Add(-time.Hour).Format(time.RFC3339)
	postAlert(t, s, "src1", "firing", start, zeroTime)

	if _, source, _ := s.alertRow(t, "src1"); source != nil {
		t.Errorf("expected firing alert to have no resolution_source, got %q", *source)
	}

	postAlert(t, s, "src1", "resolved", start, time.Now().Format(time.RFC3339))

	status, source, _ := s.alertRow(t, "src1")
	if status != "resolved" {
		t.Errorf("expected status resolved, got %q", status)
	}
	if source == nil || *source != "alertmanager" {
		t.Errorf("expected resolution_source=alertmanager, got %v", source)
	}
}

// A re-fire under the same fingerprint must leave the archive and clear the
// stale expiry marker, otherwise the alert stays invisible in the default list.
func TestWebhook_RefireUnarchivesAndClearsSource(t *testing.T) {
	s := newTS(t)
	postAlert(t, s, "refire1", "firing", time.Now().Add(-24*time.Hour).Format(time.RFC3339), zeroTime)

	// Expire it, then archive it.
	s.exec(t, "UPDATE alerts SET received_at = ? WHERE fingerprint = 'refire1'",
		time.Now().Add(-10*time.Hour).Unix())
	sweep(t, s, 6*time.Hour)
	s.exec(t, "UPDATE alerts SET archived_at = unixepoch() WHERE fingerprint = 'refire1'")

	var alerts []map[string]any
	decode(t, s.req(t, http.MethodGet, "/api/alerts", nil), &alerts)
	if len(alerts) != 0 {
		t.Fatalf("expected archived alert to be hidden, got %d", len(alerts))
	}

	// Fires again: a new alert instance, so a newer startsAt.
	postAlert(t, s, "refire1", "firing", time.Now().Format(time.RFC3339), zeroTime)

	status, source, archivedAt := s.alertRow(t, "refire1")
	if status != "firing" {
		t.Errorf("expected status firing after re-fire, got %q", status)
	}
	if source != nil {
		t.Errorf("expected resolution_source cleared on re-fire, got %q", *source)
	}
	if archivedAt != nil {
		t.Errorf("expected archived_at cleared on re-fire, got %d", *archivedAt)
	}

	decode(t, s.req(t, http.MethodGet, "/api/alerts", nil), &alerts)
	if len(alerts) != 1 {
		t.Errorf("expected re-fired alert back in default list, got %d", len(alerts))
	}
}

// Alertmanager retries failed notifications, so a firing payload for an
// already-resolved instance can arrive late. It must not resurrect the alert.
func TestWebhook_IgnoresOutOfOrderRetry(t *testing.T) {
	s := newTS(t)
	start := time.Now().Add(-time.Hour).Format(time.RFC3339)
	end := time.Now().Format(time.RFC3339)

	postAlert(t, s, "ooo1", "firing", start, zeroTime)
	postAlert(t, s, "ooo1", "resolved", start, end)
	postAlert(t, s, "ooo1", "firing", start, zeroTime) // stale retry, same instance

	status, source, _ := s.alertRow(t, "ooo1")
	if status != "resolved" {
		t.Errorf("expected alert to stay resolved after stale retry, got %q", status)
	}
	if source == nil || *source != "alertmanager" {
		t.Errorf("expected resolution_source=alertmanager, got %v", source)
	}
}

// An expiry resolve writes ends_at as an upper bound, not an observed end: an
// Alertmanager watermark already on the row is preserved, and a row that never
// carried one is stamped at sweep time. Clients are told to read it that way —
// see "resolution_source says how much to trust ends_at" in the README.
func TestExpiry_EndsAtIsUpperBound(t *testing.T) {
	s := newTS(t)

	// No watermark: expires on the received_at heartbeat, so the sweeper has
	// nothing to go on but its own clock.
	postAlert(t, s, "ub-none", "firing", time.Now().Add(-24*time.Hour).Format(time.RFC3339), zeroTime)
	s.exec(t, "UPDATE alerts SET received_at = ? WHERE fingerprint = 'ub-none'",
		time.Now().Add(-10*time.Hour).Unix())

	// Stale watermark: expires on the ends_at branch, and that reported time
	// must survive the resolve rather than be overwritten with sweep time.
	watermark := time.Now().Add(-90 * time.Minute).Truncate(time.Second)
	postAlert(t, s, "ub-mark", "firing",
		time.Now().Add(-3*time.Hour).Format(time.RFC3339), watermark.Format(time.RFC3339))

	sweep(t, s, 6*time.Hour)

	if _, source, _ := s.alertRow(t, "ub-none"); source == nil || *source != "expiry" {
		t.Fatalf("expected resolution_source=expiry for heartbeat expiry, got %v", source)
	}
	stamped := s.alertEndsAt(t, "ub-none")
	if stamped == nil {
		t.Fatal("expected expiry to stamp ends_at when no watermark was known")
	}
	if skew := time.Now().Unix() - *stamped; skew < 0 || skew > 5 {
		t.Errorf("expected stamped ends_at at sweep time, off by %ds", skew)
	}

	if _, source, _ := s.alertRow(t, "ub-mark"); source == nil || *source != "expiry" {
		t.Fatalf("expected resolution_source=expiry for watermark expiry, got %v", source)
	}
	switch kept := s.alertEndsAt(t, "ub-mark"); {
	case kept == nil:
		t.Errorf("expected reported watermark %d preserved, got NULL", watermark.Unix())
	case *kept != watermark.Unix():
		t.Errorf("expected reported watermark %d preserved, got %d", watermark.Unix(), *kept)
	}
}

// ---------------------------------------------------------------------------
// received_at heartbeat contract
//
// received_at is documented as a public liveness signal, so these lock the
// behaviour clients are told they may rely on. See "received_at is a liveness
// heartbeat" in the README and the comment on models.Alert.ReceivedAt.
// ---------------------------------------------------------------------------

// The heartbeat itself: an unchanged firing notification — what Alertmanager
// re-sends every repeat_interval — must advance received_at, while leaving
// starts_at, which identifies the alert instance, untouched.
func TestWebhook_ResendBumpsReceivedAt(t *testing.T) {
	s := newTS(t)
	start := time.Now().Add(-24 * time.Hour).Format(time.RFC3339)
	postAlert(t, s, "beat1", "firing", start, zeroTime)

	startsBefore, _ := s.alertTimes(t, "beat1")

	// received_at has one-second granularity, so back-date it to make the bump
	// observable instead of sleeping out a second.
	aged := time.Now().Add(-2 * time.Hour).Unix()
	s.exec(t, "UPDATE alerts SET received_at = ? WHERE fingerprint = 'beat1'", aged)

	// Identical re-send: same fingerprint, same startsAt, still firing.
	postAlert(t, s, "beat1", "firing", start, zeroTime)

	startsAfter, receivedAfter := s.alertTimes(t, "beat1")
	if receivedAfter <= aged {
		t.Errorf("expected re-send to advance received_at past %d, got %d", aged, receivedAfter)
	}
	if skew := time.Now().Unix() - receivedAfter; skew < 0 || skew > 5 {
		t.Errorf("expected received_at to track the server clock, off by %ds", skew)
	}
	if startsAfter != startsBefore {
		t.Errorf("expected starts_at unchanged by re-send, got %d want %d", startsAfter, startsBefore)
	}
}

// received_at tracks accepted payloads, not delivery attempts: a retry
// describing an already-resolved instance is discarded, so it must not register
// as a heartbeat and revive the alert's apparent liveness.
func TestWebhook_DiscardedRetryLeavesReceivedAtAlone(t *testing.T) {
	s := newTS(t)
	start := time.Now().Add(-time.Hour).Format(time.RFC3339)

	postAlert(t, s, "beat2", "firing", start, zeroTime)
	postAlert(t, s, "beat2", "resolved", start, time.Now().Format(time.RFC3339))

	aged := time.Now().Add(-2 * time.Hour).Unix()
	s.exec(t, "UPDATE alerts SET received_at = ? WHERE fingerprint = 'beat2'", aged)

	postAlert(t, s, "beat2", "firing", start, zeroTime) // stale retry, discarded

	if _, receivedAfter := s.alertTimes(t, "beat2"); receivedAfter != aged {
		t.Errorf("expected discarded retry to leave received_at at %d, got %d", aged, receivedAfter)
	}
}

func TestStats_ByDayReturnsSevenSlots(t *testing.T) {
	s := newTS(t)
	resp := s.req(t, http.MethodGet, "/api/stats/alerts/by-day", nil)
	var slots []any
	decode(t, resp, &slots)
	if len(slots) != 7 {
		t.Errorf("expected 7 day slots, got %d", len(slots))
	}
}