Moved HTTP polling helpers upstream into feedkit, and updated to feedkit v0.8.0

internal/sources/nws/observation.go

@@ -9,6 +9,7 @@ import (
 
 	"gitea.maximumdirect.net/ejr/feedkit/config"
 	"gitea.maximumdirect.net/ejr/feedkit/event"
+	fksources "gitea.maximumdirect.net/ejr/feedkit/sources"
 	nwscommon "gitea.maximumdirect.net/ejr/weatherfeeder/internal/providers/nws"
 	"gitea.maximumdirect.net/ejr/weatherfeeder/internal/sources/common"
 	"gitea.maximumdirect.net/ejr/weatherfeeder/standards"
@@ -16,13 +17,13 @@ import (
 
 // ObservationSource polls an NWS station observation endpoint and emits a RAW observation Event.
 type ObservationSource struct {
-	http *common.HTTPSource
+	http *fksources.HTTPSource
 }
 
 func NewObservationSource(cfg config.SourceConfig) (*ObservationSource, error) {
 	const driver = "nws_observation"
 
-	hs, err := common.NewHTTPSource(driver, cfg, "application/geo+json, application/json")
+	hs, err := fksources.NewHTTPSource(driver, cfg, "application/geo+json, application/json")
 	if err != nil {
 		return nil, err
 	}
@@ -35,10 +36,13 @@ func (s *ObservationSource) Name() string { return s.http.Name }
 func (s *ObservationSource) Kind() event.Kind { return event.Kind("observation") }
 
 func (s *ObservationSource) Poll(ctx context.Context) ([]event.Event, error) {
-	raw, meta, err := s.fetchRaw(ctx)
+	raw, meta, changed, err := s.fetchRaw(ctx)
 	if err != nil {
 		return nil, err
 	}
+	if !changed {
+		return nil, nil
+	}
 
 	// EffectiveAt is optional; for observations it’s naturally the observation timestamp.
 	var effectiveAt *time.Time
@@ -72,16 +76,19 @@ type observationMeta struct {
 	ParsedTimestamp time.Time `json:"-"`
 }
 
-func (s *ObservationSource) fetchRaw(ctx context.Context) (json.RawMessage, observationMeta, error) {
-	raw, err := s.http.FetchJSON(ctx)
+func (s *ObservationSource) fetchRaw(ctx context.Context) (json.RawMessage, observationMeta, bool, error) {
+	raw, changed, err := s.http.FetchJSONIfChanged(ctx)
 	if err != nil {
-		return nil, observationMeta{}, err
+		return nil, observationMeta{}, false, err
+	}
+	if !changed {
+		return nil, observationMeta{}, false, nil
 	}
 
 	var meta observationMeta
 	if err := json.Unmarshal(raw, &meta); err != nil {
 		// If metadata decode fails, still return raw; envelope will fall back to Source:EffectiveAt.
-		return raw, observationMeta{}, nil
+		return raw, observationMeta{}, true, nil
 	}
 
 	tsStr := strings.TrimSpace(meta.Properties.Timestamp)
@@ -91,5 +98,5 @@ func (s *ObservationSource) fetchRaw(ctx context.Context) (json.RawMessage, obse
 		}
 	}
 
-	return raw, meta, nil
+	return raw, meta, true, nil
 }