using InnovEnergy.Lib.S3.Metadata;
using InnovEnergy.Lib.S3.Records;
using InnovEnergy.Lib.S3.Records.Operations;
using InnovEnergy.Lib.Utils;

namespace InnovEnergy.Lib.S3.Drivers.Internal.Util;

public class Aggregator
{
    public  AggregationLevel AggregationLevel { get; }

    private Record[] Buffer { get; }
    private UInt32   Index  { get; set; }

    public Aggregator(AggregationLevel thisLevel,
        AggregationLevel levelBelow,
        IEnumerable<Record> initialRecords)
    {
        var ratio = thisLevel.SamplePeriod / levelBelow.SamplePeriod;

        AggregationLevel = thisLevel;

        Index  = 0;
        Buffer = new Record[ratio];

        Clear();

        foreach (var record in initialRecords)
            Aggregate(record);
    }

    public Record? Aggregate(Record r)
    {
        Buffer[Index++] = r;

        return IsFull
            ? ForceAggregation()
            : null;
    }

    public Record? ForceAggregation()
    {
        if (IsEmpty)
            return null;  // nothing to aggregate

        var aggregated = Buffer.Aggregate();
        Clear();
        return aggregated;
    }

    private void Clear()
    {
        Buffer.Fill(Record.Empty);
        Index = 0;
    }

    private Boolean IsFull => Index == Buffer.Length;
    private Boolean IsEmpty => Index == 0;

}