unit Myc.Trade.DataServer;

interface

uses
    System.SysUtils,
    System.Generics.Collections,
    Myc.Lazy,
    Myc.Trade.DataPoint,
    Myc.Trade.DataSeries,
    Myc.Signals, // Added for TLatch
    Myc.Futures; // Added for TFuture

type
    IDataServer<T> = interface
        ['{A6E246A2-E84E-49AB-A63E-333E561E488C}']
        function GetIsLiveData: TMutable<Boolean>;
        function GetChunk(var Data: array of T): Integer;
        property IsLiveData: TMutable<Boolean> read GetIsLiveData;
    end;

    TDataServer<T> = class(TInterfacedObject, IDataServer<T>)
    protected
        function GetIsLiveData: TMutable<Boolean>; virtual; abstract;
        function GetChunk(var Data: array of T): Integer; virtual; abstract;
    end;

    IDataServerNode<T> = interface
        ['{DA3531F1-158E-4A63-8E5A-34089C537B1B}']
        function CreateDataServer: IDataServer<T>;
    end;

    TDataServerNode<T> = class(TInterfacedObject, IDataServerNode<T>)
    public
        // Factory method to create the actual data server instance.
        function CreateDataServer: IDataServer<T>; virtual; abstract;
    end;

    TTABFileServer = class(TDataServer<TDataPoint<TAskBidItem>>)

    private
        FFilename: String;
        FIsLiveData: TMutable<Boolean>.IWriteable;

        // Internal state
        FCurrentFileName: string;
        FCurrentData: TFuture<TArray<TAskBid.TTick>>;
        FNextFileName: string;
        FNextData: TFuture<TArray<TAskBid.TTick>>;
        FCurrPosInFile: Int64;
        FCurrentIdx: Int64;
        FLastTimeStamp: TDateTime;

    protected
        function GetChunk(var Data: array of TDataPoint<TAskBidItem>): Integer; override;
        function GetIsLiveData: TMutable<Boolean>; override;
    public
        constructor Create(const AFilename: String);
        procedure AfterConstruction; override;
    end;

implementation

uses
    System.IOUtils;

{ TTABFileServer<T> }

constructor TTABFileServer.Create(const AFilename: String);
begin
    inherited Create;
    FFilename := AFilename;

    FNextData := TFuture<TArray<TAskBid.TTick>>.Null;
    FIsLiveData := TMutable<Boolean>.CreateWriteable(false);
end;

procedure TTABFileServer.AfterConstruction;
begin
    inherited;

    FCurrentFileName := FFilename;
    FCurrentData := TAskBid.LoadDataFile(FCurrentFileName);
    FCurrPosInFile := 0;
    FCurrentIdx := 0;
    FIsLiveData.SetValue(false);
    FLastTimeStamp := 0;
    FFilename := '';

    FNextFileName := FindNextDataFile(FCurrentFileName);
    if FNextFileName <> '' then
        FNextData := TAskBid.LoadDataFile(FNextFileName);
    exit;
end;

function TTABFileServer.GetChunk(var Data: array of TDataPoint<TAskBidItem>): Integer;
begin
    Result := 0;

    if FCurrentData.Done.IsSet then
    begin
        var maxLen := Length(Data);

        var currData := FCurrentData.Value;
        while Result < MaxLen do
        begin
            if FCurrPosInFile >= Length(currData) then
            begin
                // Next File!
                FCurrentData := FNextData;
                FCurrentFileName := FNextFileName;
                FCurrPosInFile := 0;

                FNextFileName := '';
                FNextData := TFuture<TArray<TAskBid.TTick>>.Null;

                if FCurrentFileName <> '' then
                begin
                    FNextFileName := FindNextDataFile(FCurrentFileName);
                    if FNextFileName <> '' then
                        FNextData := TAskBid.LoadDataFile(FNextFileName);

                    if FCurrentData.Done.IsSet then
                    begin
                        currData := FCurrentData.Value;
                        continue;
                    end;
                end
                else
                begin
                    // We're done with this series
                    FIsLiveData.SetValue(true);
                end;
                break;
            end;

            var item := currData[FCurrPosInFile];
            if FLastTimeStamp < item.TimeStamp then
            begin
                FLastTimeStamp := item.TimeStamp;
                Data[Result].Create(FCurrentIdx, FLastTimeStamp, item.Data);
                inc(Result);
                inc(FCurrentIdx);
            end;
            inc(FCurrPosInFile);
        end;
    end;
end;

function TTABFileServer.GetIsLiveData: TMutable<Boolean>;
begin
    Result := FIsLiveData;
end;

end.