implement grpc gateway for http api

pkg/ambient/ambientgrpc/grpc.go

@@ -0,0 +1,66 @@
+package ambientgrpc
+
+import (
+	"context"
+
+	"go.opentelemetry.io/otel/attribute"
+	otelcodes "go.opentelemetry.io/otel/codes"
+	"go.opentelemetry.io/otel/trace"
+	"google.golang.org/grpc/codes"
+	"google.golang.org/grpc/status"
+	"google.golang.org/protobuf/types/known/timestamppb"
+
+	"gitea.libretechconsulting.com/rmcguire/go-app/pkg/otel"
+
+	pb "gitea.libretechconsulting.com/rmcguire/ambient-local-exporter/api/v1alpha1/weather"
+	"gitea.libretechconsulting.com/rmcguire/ambient-local-exporter/pkg/weather/recorder"
+)
+
+type GRPCWeather struct {
+	ctx      context.Context
+	recorder *recorder.WeatherRecorder
+	tracer   trace.Tracer
+	*pb.UnimplementedAmbientLocalWeatherServiceServer
+}
+
+func NewGRPCWeather(ctx context.Context, recorder *recorder.WeatherRecorder) *GRPCWeather {
+	return &GRPCWeather{
+		ctx:      ctx,
+		recorder: recorder,
+		tracer:   otel.GetTracer(ctx, "grpcWeather"),
+	}
+}
+
+func (w *GRPCWeather) GetWeather(ctx context.Context, req *pb.GetWeatherRequest) (
+	*pb.GetWeatherResponse, error,
+) {
+	ctx, span := w.tracer.Start(ctx, "getWeather")
+	defer span.End()
+
+	limit := 1
+	if req.Limit != nil {
+		if *req.Limit > 1 {
+			limit = int(*req.Limit)
+		}
+	}
+
+	span.SetAttributes(attribute.Int("limit", limit))
+
+	updates, err := w.recorder.Get(ctx, req)
+	if err != nil {
+		span.RecordError(err)
+		span.SetStatus(otelcodes.Error, err.Error())
+		return nil, status.Error(codes.Internal, err.Error())
+	} else if len(updates) < 1 {
+		return nil, status.Error(codes.OutOfRange, "no weather available")
+	}
+
+	span.SetStatus(otelcodes.Ok, "")
+
+	return &pb.GetWeatherResponse{
+		LastUpdated: &timestamppb.Timestamp{
+			Seconds: updates[0].DateUTC.Unix(),
+		},
+		WeatherUpdates: UpdatesToPbUpdates(updates),
+	}, nil
+}