feat: add go realtime redis api

go/vehicle-gateway/internal/realtime/http.go

@@ -0,0 +1,69 @@
+package realtime
+
+import (
+	"encoding/json"
+	"errors"
+	"net/http"
+	"strings"
+
+	"github.com/redis/go-redis/v9"
+
+	"lingniu-vehicle-ingest/go/vehicle-gateway/internal/envelope"
+)
+
+type Handler struct {
+	repository *Repository
+}
+
+func NewHandler(repository *Repository) *Handler {
+	if repository == nil {
+		panic("realtime repository must not be nil")
+	}
+	return &Handler{repository: repository}
+}
+
+func (h *Handler) ServeHTTP(w http.ResponseWriter, r *http.Request) {
+	if r.Method != http.MethodGet {
+		writeError(w, http.StatusMethodNotAllowed, "method not allowed")
+		return
+	}
+	path := strings.Trim(strings.TrimPrefix(r.URL.Path, "/api/realtime/vehicles/"), "/")
+	parts := strings.Split(path, "/")
+	if len(parts) == 0 || strings.TrimSpace(parts[0]) == "" {
+		writeError(w, http.StatusNotFound, "vehicle not found")
+		return
+	}
+	vin := parts[0]
+	switch {
+	case len(parts) == 1:
+		snapshot, err := h.repository.GetMerged(r.Context(), vin)
+		writeResult(w, snapshot, err)
+	case len(parts) == 2 && parts[1] == "online":
+		status, err := h.repository.IsOnline(r.Context(), vin)
+		writeResult(w, status, err)
+	case len(parts) == 3 && parts[1] == "protocols":
+		snapshot, err := h.repository.GetProtocol(r.Context(), vin, envelope.Protocol(strings.ToUpper(parts[2])))
+		writeResult(w, snapshot, err)
+	default:
+		writeError(w, http.StatusNotFound, "route not found")
+	}
+}
+
+func writeResult(w http.ResponseWriter, value any, err error) {
+	if err != nil {
+		if errors.Is(err, redis.Nil) {
+			writeError(w, http.StatusNotFound, "not found")
+			return
+		}
+		writeError(w, http.StatusInternalServerError, err.Error())
+		return
+	}
+	w.Header().Set("Content-Type", "application/json")
+	_ = json.NewEncoder(w).Encode(value)
+}
+
+func writeError(w http.ResponseWriter, status int, message string) {
+	w.Header().Set("Content-Type", "application/json")
+	w.WriteHeader(status)
+	_ = json.NewEncoder(w).Encode(map[string]any{"error": message})
+}