1 files changed, 49 insertions, 0 deletions
diff --git a/internal/openmeteo/openmeteo.go b/internal/openmeteo/openmeteo.go
index b5220f4..b1596e0 100644
--- a/internal/openmeteo/openmeteo.go
+++ b/internal/openmeteo/openmeteo.go
@@ -383,3 +383,52 @@ func presentSlice(v any) []bool {
 	}
 	return out
 }
+
+// AirHourly fetches per-hour values for air-quality fields, keyed by the local
+// timestamp the API reports ("2006-01-02T15:04") and then by field.
+//
+// Keyed by time rather than by index because this is a different endpoint from
+// the forecast: nothing guarantees the two arrays start at the same hour, and
+// merging by position would silently shift a column by an hour.
+//
+// A field the API withholds is absent rather than zero, so a column shows blank
+// instead of a confident wrong number.
+func AirHourly(lat, lon float64, hours int, fields []string) (map[string]map[string]float64, error) {
+	out := map[string]map[string]float64{}
+	if len(fields) == 0 {
+		return out, nil
+	}
+	days := hours/24 + 2
+	if days > MaxAirDays {
+		days = MaxAirDays
+	}
+	var r struct {
+		Hourly map[string]any `json:"hourly"`
+	}
+	err := get(airURL, url.Values{
+		"latitude":      {strconv.FormatFloat(lat, 'f', 4, 64)},
+		"longitude":     {strconv.FormatFloat(lon, 'f', 4, 64)},
+		"hourly":        {strings.Join(fields, ",")},
+		"forecast_days": {strconv.Itoa(days)},
+		"timezone":      {"auto"},
+	}, &r)
+	if err != nil {
+		return nil, err
+	}
+
+	times := stringSlice(r.Hourly["time"])
+	for _, f := range fields {
+		vals := floatSlice(r.Hourly[f])
+		have := presentSlice(r.Hourly[f])
+		for i, t := range times {
+			if i >= len(vals) || (i < len(have) && !have[i]) {
+				continue
+			}
+			if out[t] == nil {
+				out[t] = map[string]float64{}
+			}
+			out[t][f] = vals[i]
+		}
+	}
+	return out, nil
+}