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

internal/normalizers/nws/metar.go

@@ -0,0 +1,51 @@
+// FILE: ./internal/normalizers/nws/metar.go
+package nws
+
+import (
+	"encoding/json"
+	"strings"
+)
+
+// metarPhenomenon is a typed view of NWS presentWeather objects.
+type metarPhenomenon struct {
+	Intensity  *string `json:"intensity"` // "light", "heavy", or null
+	Modifier   *string `json:"modifier"`  // "freezing", "showers", etc., or null
+	Weather    string  `json:"weather"`   // e.g. "rain", "snow", "fog_mist", ...
+	RawString  string  `json:"rawString"`
+	InVicinity *bool   `json:"inVicinity"`
+}
+
+func decodeMetarPhenomena(raw []map[string]any) []metarPhenomenon {
+	if len(raw) == 0 {
+		return nil
+	}
+
+	out := make([]metarPhenomenon, 0, len(raw))
+	for _, m := range raw {
+		b, err := json.Marshal(m)
+		if err != nil {
+			continue
+		}
+
+		var p metarPhenomenon
+		if err := json.Unmarshal(b, &p); err != nil {
+			continue
+		}
+
+		p.Weather = strings.ToLower(strings.TrimSpace(p.Weather))
+		p.RawString = strings.TrimSpace(p.RawString)
+		out = append(out, p)
+	}
+
+	return out
+}
+
+func containsWeather(phenomena []metarPhenomenon, weather string) bool {
+	weather = strings.ToLower(strings.TrimSpace(weather))
+	for _, p := range phenomena {
+		if p.Weather == weather {
+			return true
+		}
+	}
+	return false
+}