nws: refactored the NWS source files to relocate normalization logic to internal/normalizers.

internal/normalizers/nws/observation.go

@@ -0,0 +1,145 @@
+// FILE: ./internal/normalizers/nws/observation.go
+package nws
+
+import (
+	"context"
+	"encoding/json"
+	"fmt"
+	"strings"
+	"time"
+
+	"gitea.maximumdirect.net/ejr/feedkit/event"
+	"gitea.maximumdirect.net/ejr/weatherfeeder/internal/model"
+	normcommon "gitea.maximumdirect.net/ejr/weatherfeeder/internal/normalizers/common"
+	"gitea.maximumdirect.net/ejr/weatherfeeder/internal/standards"
+)
+
+// ObservationNormalizer converts:
+//
+//	standards.SchemaRawNWSObservationV1 -> standards.SchemaWeatherObservationV1
+//
+// It interprets NWS GeoJSON station observations and maps them into the
+// canonical model.WeatherObservation representation.
+//
+// Precedence for determining ConditionCode (WMO):
+//  1. presentWeather (METAR phenomena objects) — strongest signal
+//  2. textDescription keyword fallback — reusable across providers
+//  3. cloudLayers sky-only fallback — NWS/METAR-specific
+type ObservationNormalizer struct{}
+
+func (ObservationNormalizer) Match(e event.Event) bool {
+	return strings.TrimSpace(e.Schema) == standards.SchemaRawNWSObservationV1
+}
+
+func (ObservationNormalizer) Normalize(ctx context.Context, in event.Event) (*event.Event, error) {
+	_ = ctx // normalization is pure/CPU; keep ctx for future expensive steps
+
+	rawBytes, err := normcommon.PayloadBytes(in)
+	if err != nil {
+		return nil, fmt.Errorf("nws observation normalize: %w", err)
+	}
+
+	var parsed nwsObservationResponse
+	if err := json.Unmarshal(rawBytes, &parsed); err != nil {
+		return nil, fmt.Errorf("nws observation normalize: decode raw payload: %w", err)
+	}
+
+	obs, effectiveAt, err := buildObservation(parsed)
+	if err != nil {
+		return nil, err
+	}
+
+	out := in
+	out.Schema = standards.SchemaWeatherObservationV1
+	out.Payload = obs
+
+	// EffectiveAt is optional; for observations it is naturally the observation timestamp.
+	if !effectiveAt.IsZero() {
+		t := effectiveAt.UTC()
+		out.EffectiveAt = &t
+	}
+
+	if err := out.Validate(); err != nil {
+		return nil, err
+	}
+	return &out, nil
+}
+
+// buildObservation contains the domain mapping logic (provider -> canonical model).
+func buildObservation(parsed nwsObservationResponse) (model.WeatherObservation, time.Time, error) {
+	// Timestamp (RFC3339)
+	var ts time.Time
+	if s := strings.TrimSpace(parsed.Properties.Timestamp); s != "" {
+		t, err := time.Parse(time.RFC3339, s)
+		if err != nil {
+			return model.WeatherObservation{}, time.Time{}, fmt.Errorf("nws observation normalize: invalid timestamp %q: %w", s, err)
+		}
+		ts = t
+	}
+
+	cloudLayers := make([]model.CloudLayer, 0, len(parsed.Properties.CloudLayers))
+	for _, cl := range parsed.Properties.CloudLayers {
+		cloudLayers = append(cloudLayers, model.CloudLayer{
+			BaseMeters: cl.Base.Value,
+			Amount:     cl.Amount,
+		})
+	}
+
+	// Preserve raw presentWeather objects (for troubleshooting / drift analysis).
+	present := make([]model.PresentWeather, 0, len(parsed.Properties.PresentWeather))
+	for _, pw := range parsed.Properties.PresentWeather {
+		present = append(present, model.PresentWeather{Raw: pw})
+	}
+
+	// Decode presentWeather into typed METAR phenomena for mapping.
+	phenomena := decodeMetarPhenomena(parsed.Properties.PresentWeather)
+
+	providerDesc := strings.TrimSpace(parsed.Properties.TextDescription)
+
+	// Determine canonical WMO condition code.
+	wmo := mapNWSToWMO(providerDesc, cloudLayers, phenomena)
+
+	// Canonical condition text comes from our WMO table.
+	// NWS observation responses typically do not include a day/night flag -> nil.
+	canonicalText := standards.WMOText(wmo, nil)
+
+	obs := model.WeatherObservation{
+		StationID:   parsed.Properties.StationID,
+		StationName: parsed.Properties.StationName,
+		Timestamp:   ts,
+
+		ConditionCode: wmo,
+		ConditionText: canonicalText,
+		IsDay:         nil,
+
+		ProviderRawDescription: providerDesc,
+
+		// Transitional / human-facing:
+		// keep output consistent by populating TextDescription from canonical text.
+		TextDescription: canonicalText,
+		IconURL:         parsed.Properties.Icon,
+
+		TemperatureC: parsed.Properties.Temperature.Value,
+		DewpointC:    parsed.Properties.Dewpoint.Value,
+
+		WindDirectionDegrees: parsed.Properties.WindDirection.Value,
+		WindSpeedKmh:         parsed.Properties.WindSpeed.Value,
+		WindGustKmh:          parsed.Properties.WindGust.Value,
+
+		BarometricPressurePa: parsed.Properties.BarometricPressure.Value,
+		SeaLevelPressurePa:   parsed.Properties.SeaLevelPressure.Value,
+		VisibilityMeters:     parsed.Properties.Visibility.Value,
+
+		RelativeHumidityPercent: parsed.Properties.RelativeHumidity.Value,
+		WindChillC:              parsed.Properties.WindChill.Value,
+		HeatIndexC:              parsed.Properties.HeatIndex.Value,
+
+		ElevationMeters: parsed.Properties.Elevation.Value,
+		RawMessage:      parsed.Properties.RawMessage,
+
+		PresentWeather: present,
+		CloudLayers:    cloudLayers,
+	}
+
+	return obs, ts, nil
+}