getDailyTotalPrecipitation method

Implementation

Map<DateTime, double> getDailyTotalPrecipitation() {
  final dailyPrecipitation = <DateTime, List<double>>{};

  for (final point in data) {
    // Include 0 values, skip only null.
    if (point.precipitation == null) continue;
    final date = DateTime(point.time.year, point.time.month, point.time.day);
    dailyPrecipitation.putIfAbsent(date, () => []).add(point.precipitation!);
  }

  // Return empty map ONLY if no precipitation data exists at all
  // If all values are 0, we still return the data (not empty map)

  if (dailyPrecipitation.isEmpty) return {};

  return dailyPrecipitation.map(
    (date, precipitations) => MapEntry(
      date,
      precipitations.reduce((a, b) => a + b), // Sum all hourly values
    ),
  );
}