using InnovEnergy.Lib.S3.Drivers.Internal;
using InnovEnergy.Lib.S3.Drivers.Internal.Delegates;
using InnovEnergy.Lib.S3.Metadata;
using InnovEnergy.Lib.S3.Records.Specialized;
using InnovEnergy.Lib.Time.Unix;

namespace InnovEnergy.Lib.S3.Drivers;

using Levels = IReadOnlyList<AggregationLevel>;
using Memory = Dictionary<String, TimeStampedRecord>;

public class MemoryDriver : Writer
{

    public MemoryDriver(Levels levels, UnixTime startTime, Memory memory) :
        base(
            startTime,
            levels,
            ReadRecord(memory),
            WriteRecord(memory)
        )
    {
    }

    private static String GetKey(AggregationLevel level, UInt32 index)
    {
        return $"{level}/{index}";
    }

    private static ReadRecord ReadRecord(Memory memory)
    {
        Task<TimeStampedRecord> Read(AggregationLevel level, UInt32 index)
        {
            var key = GetKey(level, index);

            var result = memory.TryGetValue(key, out var tsRecord)
                ? tsRecord
                : TimeStampedRecord.Empty();

            return Task.FromResult(result);
        }

        return Read;
    }

    private static WriteRecord WriteRecord(Memory memory)
    {
        Task Write(TimeStampedRecord record, AggregationLevel level, UInt32 index)
        {
            var key = GetKey(level, index);
            memory[key] = record;
            return Task.CompletedTask;
        }

        return Write;
    }
}