Validate precipitation probabilities and ice wording

internal/forecast/derive.go

@@ -192,6 +192,9 @@ func BuildDailySummary(bundle *weatherdata.Bundle, date time.Time, location *tim
 	if bundle.Hourly == nil || len(bundle.Hourly.Periods) == 0 {
 		return nil, fmt.Errorf("hourly forecast data is required")
 	}
+	if err := ValidatePrecipitationProbabilities(bundle.Hourly.Periods); err != nil {
+		return nil, err
+	}
 	day := timeutil.CivilDay(date, location)
 	windows, err := ResolveDayparts(date, location, dayparts)
 	if err != nil {
@@ -247,6 +250,15 @@ func SelectDiscussion(bundle *weatherdata.Bundle) *weatherdata.Discussion {
 	return bundle.Discussion
 }
 
+func ValidatePrecipitationProbabilities(periods []weatherdata.ForecastPeriod) error {
+	for i, period := range periods {
+		if !period.HasValidPrecipitationProbability() {
+			return fmt.Errorf("hourly forecast period %d has an invalid precipitation probability", i+1)
+		}
+	}
+	return nil
+}
+
 func SummarizeDaypart(name string, period timeutil.Period, periods []weatherdata.ForecastPeriod) DaypartSummary {
 	summary := DaypartSummary{
 		Name:          name,
@@ -357,12 +369,24 @@ func indicatorsForText(text string) Indicators {
 	lower := strings.ToLower(text)
 	return Indicators{
 		Snow: strings.Contains(lower, "snow"),
-		Ice:  strings.Contains(lower, "ice") || strings.Contains(lower, "freezing") || strings.Contains(lower, "sleet"),
+		Ice:  mentionsIce(lower),
 		Fog:  strings.Contains(lower, "fog"),
 		Wind: strings.Contains(lower, "wind") || strings.Contains(lower, "gust"),
 	}
 }
 
+func mentionsIce(text string) bool {
+	for _, token := range strings.FieldsFunc(text, func(r rune) bool {
+		return !('a' <= r && r <= 'z')
+	}) {
+		switch token {
+		case "ice", "icy", "freezing", "sleet":
+			return true
+		}
+	}
+	return false
+}
+
 func mentionsThunder(text string) bool {
 	return strings.Contains(strings.ToLower(text), "thunder")
 }