using InnovEnergy.Time.Unix;

namespace InnovEnergy.S3.Metadata;

public record AggregationLevel
{
    public UnixTimeSpan RetentionPeriod     { get; }
    public UnixTimeSpan SamplePeriod        { get; }
    public UInt32       RetentionBufferSize { get; }

    public AggregationLevel(UnixTimeSpan samplePeriod, UnixTimeSpan retentionPeriod)
    {
        SamplePeriod        = samplePeriod;
        RetentionPeriod     = retentionPeriod;
        RetentionBufferSize = retentionPeriod / samplePeriod;
    }

    public IEnumerable<UnixTime> RangeExclusive(UnixTime from, UnixTime to)
    {
        if (from > to)
            throw new ArgumentOutOfRangeException(nameof(to));

        for (var t = GetPeriodStartTime(from); t < to; t += SamplePeriod)
            yield return t;
    }


    // TODO:
    public IEnumerable<UnixTime> RangeInclusive(UnixTime from, UnixTime to)
    {
        if (from >= to)
            throw new ArgumentOutOfRangeException(nameof(to));

        from = GetPeriodStartTime(from);
        to   = GetPeriodStartTime(to) + SamplePeriod;

        for (var t = GetPeriodStartTime(from); t < to; t += SamplePeriod)
            yield return t;
    }

    public UInt32 GetRetentionIndex(UnixTime t)
    {
        return t / SamplePeriod % RetentionBufferSize;
    }

    public UnixTime GetPeriodStartTime(UnixTime t)
    {
        return UnixTime.Epoch + t / SamplePeriod * SamplePeriod;  // integer division!
    }

    public override String ToString() => SamplePeriod.ToString();
}