nws: update `GetForecastHourly`

Add handling to error out when weather data returned by NWS is stale.

1 files changed, 16 insertions, 1 deletions

diff --git a/nws/nws.go b/nws/nws.go
index 0a456d9..c5dfe19 100644
--- a/nws/nws.go
+++ b/nws/nws.go
@@ -53,7 +53,8 @@ type ForecastPeriod struct {
 }
 
 type ForecastProperties struct {
-	Periods []ForecastPeriod
+	GeneratedAt string
+	Periods     []ForecastPeriod
 }
 
 type Forecast struct {
@@ -262,6 +263,20 @@ func GetForecastHourly(point *Point) (*Forecast, error) {
 	if len(forecast.Properties.Periods) == 0 {
 		return nil, fmt.Errorf("forecast hourly: periods empty")
 	}
+
+	// Check for staleness.
+	genAt, tErr := time.Parse(time.RFC3339, forecast.Properties.GeneratedAt)
+	if tErr != nil {
+		return nil, fmt.Errorf("forecast hourly: unable to check staleness")
+	}
+	if time.Since(genAt).Seconds() > 86400 {
+		fhCache.Set(point.Properties.ForecastHourly,
+			[]byte{}, time.Now()) // Invalidate cache.
+		return nil, fmt.Errorf(
+			"forecast hourly: stale data from weather.gov from %v",
+			forecast.Properties.GeneratedAt,
+		)
+	}
 	return forecast, nil
 }