fix: register missing Situation endpoint route (#798)

internal/gtfs/realtime.go

@@ -201,6 +201,36 @@ func (manager *Manager) GetAlertsForStop(stopID string) []gtfs.Alert {
 	return out
 }
 
+// GetAllAlerts returns all deduplicated realtime alerts across all feeds.
+// Deduplication is by alert ID, preserving first-seen order by sorted feed ID.
+func (manager *Manager) GetAllAlerts() []gtfs.Alert {
+	manager.realTimeMutex.RLock()
+	defer manager.realTimeMutex.RUnlock()
+
+	feedIDs := make([]string, 0, len(manager.feedAlerts))
+	for feedID := range manager.feedAlerts {
+		feedIDs = append(feedIDs, feedID)
+	}
+	sort.Strings(feedIDs)
+
+	seen := make(map[string]struct{})
+	alerts := make([]gtfs.Alert, 0)
+	for _, feedID := range feedIDs {
+		for _, alert := range manager.feedAlerts[feedID] {
+			if alert.ID == "" {
+				continue
+			}
+			if _, exists := seen[alert.ID]; exists {
+				continue
+			}
+			seen[alert.ID] = struct{}{}
+			alerts = append(alerts, alert)
+		}
+	}
+
+	return alerts
+}
+
 // Fetches GTFS-RT data from a URL with per-feed headers.
 func loadRealtimeData(ctx context.Context, source string, headers map[string]string) (*gtfs.Realtime, error) {
 	req, err := http.NewRequestWithContext(ctx, "GET", source, nil)

internal/restapi/routes.go

@@ -96,6 +96,7 @@ func (api *RestAPI) SetRoutes(mux *http.ServeMux) {
 
 	// Real-time simple ID endpoints (no ETag)
 	mux.Handle("GET /api/where/vehicles-for-agency/{id}", CacheControlMiddleware(models.CacheDurationShort, rateLimitAndValidateAPIKey(api, api.vehiclesForAgencyHandler)))
+	mux.Handle("GET /api/where/situation/{id}", CacheControlMiddleware(models.CacheDurationShort, rateLimitAndValidateAPIKey(api, api.situationHandler)))
 
 	// --- Routes with combined ID validation (agency_id_code format) ---
 	mux.Handle("GET /api/where/trip/{id}", CacheControlMiddleware(models.CacheDurationLong, rateLimitAndValidateAPIKey(api, etagStatic(api, api.tripHandler))))

internal/restapi/situation_handler.go

@@ -0,0 +1,42 @@
+package restapi
+
+import (
+	"fmt"
+	"net/http"
+
+	"github.com/OneBusAway/go-gtfs"
+	"maglev.onebusaway.org/internal/models"
+)
+
+// situationHandler serves a single GTFS-RT service alert (OneBusAway "Situation")
+// by its alert id.
+func (api *RestAPI) situationHandler(w http.ResponseWriter, r *http.Request) {
+	situationID, ok := api.extractAndValidateID(w, r)
+	if !ok {
+		return
+	}
+
+	var alert gtfs.Alert
+	found := false
+	for _, candidate := range api.GtfsManager.GetAllAlerts() {
+		if candidate.ID == situationID {
+			alert = candidate
+			found = true
+			break
+		}
+	}
+	if !found {
+		api.sendNotFound(w, r)
+		return
+	}
+
+	situations := api.BuildSituationReferences([]gtfs.Alert{alert})
+	if len(situations) == 0 {
+		api.serverErrorResponse(w, r, fmt.Errorf("unexpected empty situation build for id %q", situationID))
+		return
+	}
+
+	references := models.NewEmptyReferences()
+	response := models.NewEntryResponse(situations[0], *references, api.Clock)
+	api.sendResponse(w, r, response)
+}

internal/restapi/situation_handler_test.go

@@ -0,0 +1,76 @@
+package restapi
+
+import (
+	"net/http"
+	"testing"
+
+	"github.com/OneBusAway/go-gtfs"
+	"github.com/stretchr/testify/assert"
+	"github.com/stretchr/testify/require"
+)
+
+func TestSituationHandlerRequiresValidAPIKey(t *testing.T) {
+	api := createTestApi(t)
+	defer api.Shutdown()
+
+	resp, model := serveApiAndRetrieveEndpoint(t, api, "/api/where/situation/test-alert.json?key=invalid")
+	assert.Equal(t, http.StatusUnauthorized, resp.StatusCode)
+	assert.Equal(t, http.StatusUnauthorized, model.Code)
+	assert.Equal(t, "permission denied", model.Text)
+}
+
+func TestSituationHandlerNotFound(t *testing.T) {
+	api := createTestApi(t)
+	defer api.Shutdown()
+
+	resp, model := serveApiAndRetrieveEndpoint(t, api, "/api/where/situation/nonexistent-alert.json?key=TEST")
+	assert.Equal(t, http.StatusNotFound, resp.StatusCode)
+	assert.Equal(t, http.StatusNotFound, model.Code)
+	assert.Equal(t, "resource not found", model.Text)
+}
+
+func TestSituationHandlerWithSituation(t *testing.T) {
+	api := createTestApi(t)
+	defer api.Shutdown()
+
+	alert := gtfs.Alert{
+		ID: "test-alert-123",
+		Header: []gtfs.AlertText{
+			{Text: "Service disruption", Language: "en"},
+		},
+		Description: []gtfs.AlertText{
+			{Text: "Detour in effect", Language: "en"},
+		},
+	}
+	api.GtfsManager.AddTestAlert(alert)
+
+	resp, model := serveApiAndRetrieveEndpoint(t, api, "/api/where/situation/test-alert-123.json?key=TEST")
+	assert.Equal(t, http.StatusOK, resp.StatusCode)
+	assert.Equal(t, http.StatusOK, model.Code)
+	assert.Equal(t, "OK", model.Text)
+	assert.Equal(t, 2, model.Version)
+
+	data, ok := model.Data.(map[string]interface{})
+	require.True(t, ok, "response should include data object")
+
+	entry, ok := data["entry"].(map[string]interface{})
+	require.True(t, ok, "response should include data.entry object")
+	assert.Equal(t, "test-alert-123", entry["id"])
+	assert.Equal(t, "UNKNOWN_CAUSE", entry["reason"])
+	assert.Equal(t, "noImpact", entry["severity"])
+
+	references, ok := data["references"].(map[string]interface{})
+	require.True(t, ok, "response should include data.references object")
+
+	agencies, ok := references["agencies"].([]interface{})
+	require.True(t, ok)
+	assert.Len(t, agencies, 0)
+
+	routes, ok := references["routes"].([]interface{})
+	require.True(t, ok)
+	assert.Len(t, routes, 0)
+
+	stops, ok := references["stops"].([]interface{})
+	require.True(t, ok)
+	assert.Len(t, stops, 0)
+}