Share day-style generated text validation

internal/generatedtext/day_style.go

@@ -0,0 +1,63 @@
+package generatedtext
+
+import (
+	"fmt"
+	"strings"
+)
+
+type dayStyleFields struct {
+	Summary             string
+	ForecastDiscussion  []string
+	PrecipitationTiming string
+	Confidence          string
+}
+
+type dayStyleGeneratedText interface {
+	dayStyleFields() dayStyleFields
+	setDayStyleFields(dayStyleFields)
+}
+
+func validateDayStyleGeneratedText[T any, PT interface {
+	*T
+	dayStyleGeneratedText
+}](data []byte, name string) (T, []byte, error) {
+	value, err := decodeGeneratedText[T](data, name)
+	if err != nil {
+		var zero T
+		return zero, nil, err
+	}
+
+	pointer := PT(&value)
+	fields := pointer.dayStyleFields()
+	fields.Summary = strings.TrimSpace(fields.Summary)
+	fields.PrecipitationTiming = strings.TrimSpace(fields.PrecipitationTiming)
+	fields.Confidence = strings.TrimSpace(fields.Confidence)
+	fields.ForecastDiscussion = trimNonEmpty(fields.ForecastDiscussion)
+	if fields.Summary == "" {
+		var zero T
+		return zero, nil, fmt.Errorf("%s generated text summary is required", name)
+	}
+	if len(fields.ForecastDiscussion) == 0 {
+		var zero T
+		return zero, nil, fmt.Errorf("%s generated text forecast discussion is required", name)
+	}
+	pointer.setDayStyleFields(fields)
+
+	normalized, err := normalizeGeneratedText(value, name)
+	if err != nil {
+		var zero T
+		return zero, nil, err
+	}
+	return value, normalized, nil
+}
+
+func trimNonEmpty(values []string) []string {
+	out := make([]string, 0, len(values))
+	for _, value := range values {
+		trimmed := strings.TrimSpace(value)
+		if trimmed != "" {
+			out = append(out, trimmed)
+		}
+	}
+	return out
+}