unit Myc.Fmx.Chart;

interface

uses
    System.SysUtils,
    System.Classes,
    System.Types,
    System.Generics.Collections,
    System.UITypes,
    System.UIConsts,
    System.Messaging,
    System.Math.Vectors,
    FMX.Types,
    FMX.Controls,
    FMX.Graphics,
    FMX.Forms,
    Myc.Trade.Types,
    Myc.Trade.DataPoint,
    Myc.Signals,
    Myc.Lazy;

type
    TMycChart = class(TStyledControl)
    public
        type
            TPanel = class;

            // Abstract base for a data series within the chart.
            TSeries = class abstract(TObject)
            protected
                function GetCount: Int64; virtual; abstract;
                function GetTotalCount: Int64; virtual; abstract;
            public
                property Count: Int64 read GetCount;
                property TotalCount: Int64 read GetTotalCount;
            end;

            // Abstract base for a drawable layer in a panel.
            TLayer = class abstract(TObject)
            private
                FParent: TPanel;
                function GetOwner: TMycChart;
            protected
                function GetSeries: TSeries; virtual; abstract;
                procedure Update; virtual; abstract;
                function GetValueRange(First, Last: Int64; out Min, Max: Double): Boolean; virtual; abstract;
                procedure Paint(const Canvas: TCanvas; First, Last: Int64; const XForm, YForm: TFunc<Double, Single>); virtual; abstract;
            public
                constructor Create(AOwner: TPanel);
                procedure Repaint;
                property Owner: TMycChart read GetOwner;
                property Series: TSeries read GetSeries;
            end;

            // A panel is a rectangular area in the chart with its own Y-axis, which can contain multiple layers.
            TPanel = class(TObject)
            private
                FOwner: TMycChart;
                FSeriesList: TObjectList<TMycChart.TLayer>;
            protected
                procedure Paint(const Canvas: TCanvas; const Viewport: TRectF; MasterTotalCount: Int64; ViewStartIndex, ViewCount: Int64);
                procedure UpdateAndCheckChanges(MasterTotalCount: Int64; ViewStartIndex: Int64; out SeriesChanged, SeriesRepaint: Boolean);

            public
                constructor Create(AOwner: TMycChart);
                destructor Destroy; override;

                function AddOhlcSeries(
                    const DataProvider: IMycDataProvider<TOhlcItem>;
                    const AUpColor: TAlphaColor = TAlphaColors.Green;
                    const ADownColor: TAlphaColor = TAlphaColors.Red
                ): TMycChart.TLayer;

                function AddDoubleSeries(
                    const DataProvider: IMycDataProvider<Double>;
                    const ALineColor: TAlphaColor = TAlphaColors.Cornflowerblue;
                    const ALineWidth: Single = 1.5
                ): TMycChart.TLayer;

                property Owner: TMycChart read FOwner;
            end;

    private
        FPanelList: TObjectList<TPanel>;
        FXAxisSeries: TMycChart.TLayer;
        FLookback: TWriteable<Int64>;
        FIdleSubscrId: TMessageSubscriptionId;
        FViewStartIndex: Int64;
        FViewCount: Int64;
        FIsDragging: Boolean;
        FDragStartPoint: TPointF;
        FJumpButtonRect: TRectF;
        FJumpButtonHot: Boolean;
        FJumpButtonPressed: Boolean;
        FNeedRepaint: TFlag;
        function GetPanel(Index: Integer): TPanel;
        function GetPanelCount: Integer;
    protected
        procedure Paint; override;
        procedure DoIdle;
        procedure MouseWheel(Shift: TShiftState; WheelDelta: Integer; var Handled: Boolean); override;
        procedure MouseDown(Button: TMouseButton; Shift: TShiftState; X, Y: Single); override;
        procedure MouseMove(Shift: TShiftState; X, Y: Single); override;
        procedure MouseUp(Button: TMouseButton; Shift: TShiftState; X, Y: Single); override;
    public
        constructor Create(AOwner: TComponent); override;
        destructor Destroy; override;

        // Adds a new, empty panel to the bottom of the chart.
        function AddPanel: TPanel;

        // Sets the master series that defines the time scale (X-axis). This series is not drawn.
        function SetXAxisSeries<T>(const DataProvider: IMycDataProvider<T>): TMycChart.TLayer;

        property Lookback: TWriteable<Int64> read FLookback write FLookback;
        property NeedRepaint: TFlag read FNeedRepaint;
        property PanelCount: Integer read GetPanelCount;
        property Panels[Index: Integer]: TPanel read GetPanel; default;
    end;

implementation

uses
    System.Math,
    Myc.FMX.Chart.Series;

{ TMycChart }

constructor TMycChart.Create(AOwner: TComponent);
begin
    inherited Create(AOwner);
    FPanelList := TObjectList<TPanel>.Create(true);
    FXAxisSeries := nil;

    FLookback := TWriteable<Int64>.CreateWriteable(1000);
    FViewStartIndex := 0;
    FViewCount := 100;
    FIsDragging := false;

    FIdleSubscrId :=
        TMessageManager
            .DefaultManager
            .SubscribeToMessage(TIdleMessage, procedure(const Sender: TObject; const M: TMessage) begin DoIdle; end);

    // Create the default panel.
    AddPanel;
end;

destructor TMycChart.Destroy;
begin
    TMessageManager.DefaultManager.Unsubscribe(TIdleMessage, FIdleSubscrId);

    FXAxisSeries.Free;
    FPanelList.Free;
    inherited;
end;

function TMycChart.AddPanel: TPanel;
begin
    Result := TPanel.Create(Self);
    FPanelList.Add(Result);
    Repaint;
end;

function TMycChart.GetPanel(Index: Integer): TPanel;
begin
    Result := FPanelList[Index];
end;

function TMycChart.GetPanelCount: Integer;
begin
    Result := FPanelList.Count;
end;

function TMycChart.SetXAxisSeries<T>(const DataProvider: IMycDataProvider<T>): TMycChart.TLayer;
begin
    FXAxisSeries.Free;
    // Note: TChartCustomLayer needs its owner to be a TPanel. We use the first panel.
    var counter := TChartSeriesCounter<T>.Create;
    DataProvider.Link(counter);
    FXAxisSeries := TChartCustomLayer<Int64>.Create(Self.Panels[0], counter.Sender);
    Result := FXAxisSeries;
end;

procedure TMycChart.DoIdle;
var
    prevTotalCount, newTotalCount: Int64;
    seriesChanged, seriesRepaint, repaintSignal: Boolean;
    countDelta: Int64;
begin
    if not Assigned(FXAxisSeries) then
        exit;

    prevTotalCount := FXAxisSeries.Series.TotalCount;
    FXAxisSeries.Update;
    newTotalCount := FXAxisSeries.Series.TotalCount;

    seriesChanged := prevTotalCount <> newTotalCount;
    seriesRepaint := (FViewStartIndex = 0);

    for var panel in FPanelList do
    begin
        var panelChanged, panelRepaint: Boolean;
        panel.UpdateAndCheckChanges(prevTotalCount, FViewStartIndex, panelChanged, panelRepaint);
        seriesChanged := seriesChanged or panelChanged;
        seriesRepaint := seriesRepaint or panelRepaint;
    end;

    if (FViewStartIndex > 0) then
    begin
        countDelta := newTotalCount - prevTotalCount;
        if (countDelta > 0) then
        begin
            FViewStartIndex := FViewStartIndex + countDelta;
            if (FViewStartIndex + FViewCount > newTotalCount) then
                FViewStartIndex := newTotalCount - FViewCount;
        end;
    end;

    repaintSignal := FNeedRepaint.Reset;

    if repaintSignal or (seriesRepaint and seriesChanged) then
        Repaint;
end;

procedure TMycChart.Paint;
var
    rect, panelRect: TRectF;
    isButtonVisible: Boolean;
    buttonColor: TAlphaColor;
    path: TPathData;
    masterTotalCount: Int64;
    panelHeight: Single;
begin
    inherited;
    rect := Self.LocalRect;

    if (not Assigned(FXAxisSeries)) or (FXAxisSeries.Series.Count <= 1) or (FViewCount <= 1) or (PanelCount = 0) then
    begin
        Canvas.Fill.Color := TAlphaColors.Gray;
        Canvas.FillText(rect, 'No Data', false, 1, [], TTextAlign.Center, TTextAlign.Center);
        Exit;
    end;

    masterTotalCount := FXAxisSeries.Series.TotalCount;
    panelHeight := rect.Height / PanelCount;

    for var i := 0 to PanelCount - 1 do
    begin
        var panel := Panels[i];
        panelRect := TRectF.Create(rect.Left, rect.Top + (i * panelHeight), rect.Right, rect.Top + ((i + 1) * panelHeight));

        // Draw panel content
        panel.Paint(Self.Canvas, panelRect, masterTotalCount, FViewStartIndex, FViewCount);

        // Draw separator line
        if (i > 0) then
        begin
            Canvas.Stroke.Color := TAlphaColors.Gray;
            Canvas.Stroke.Thickness := 1;
            Canvas.DrawLine(PointF(panelRect.Left, panelRect.Top), PointF(panelRect.Right, panelRect.Top), 1);
        end;
    end;

    // --- Draw the "jump to latest" button (code unchanged) ---
    isButtonVisible := (FViewStartIndex > 0);

    if isButtonVisible then
    begin
        FJumpButtonRect := TRectF.Create(Self.Width - 44, Self.Height - 44, Self.Width - 10, Self.Height - 10);

        if FJumpButtonPressed then
            buttonColor := $FF707070
        else if FJumpButtonHot then
            buttonColor := $FF505050
        else
            buttonColor := $FF303030;

        Canvas.Fill.Color := buttonColor;
        Canvas.FillRect(FJumpButtonRect, 4, 4, AllCorners, 0.7);

        Canvas.Stroke.Color := TAlphaColors.White;
        Canvas.Stroke.Thickness := 1.5;

        path := TPathData.Create;
        try
            var cx := FJumpButtonRect.CenterPoint.X;
            var cy := FJumpButtonRect.CenterPoint.Y;
            path.MoveTo(PointF(cx - 5, cy - 6));
            path.LineTo(PointF(cx, cy));
            path.LineTo(PointF(cx - 5, cy + 6));
            path.MoveTo(PointF(cx + 2, cy - 6));
            path.LineTo(PointF(cx + 7, cy));
            path.LineTo(PointF(cx + 2, cy + 6));
            Canvas.DrawPath(path, 1);
        finally
            path.Free;
        end;
    end
    else
    begin
        FJumpButtonRect := TRectF.Empty;
        FJumpButtonPressed := false;
    end;
end;

procedure TMycChart.MouseDown(Button: TMouseButton; Shift: TShiftState; X, Y: Single);
begin
    // Check for button press first
    if (Button = TMouseButton.mbLeft) and (FViewStartIndex > 0) and FJumpButtonRect.Contains(PointF(X, Y)) then
    begin
        FJumpButtonPressed := true;
        Repaint;
        exit; // Prevent chart dragging
    end;

    inherited MouseDown(Button, Shift, X, Y);
    if (Button = TMouseButton.mbLeft) then
    begin
        FIsDragging := true;
        FDragStartPoint := TPointF.Create(X, Y);
    end;
end;

procedure TMycChart.MouseUp(Button: TMouseButton; Shift: TShiftState; X, Y: Single);
begin
    // Check if a button press was active
    if FJumpButtonPressed then
    begin
        FJumpButtonPressed := false;
        // If mouse is released over the button, trigger the action
        if (FViewStartIndex > 0) and FJumpButtonRect.Contains(PointF(X, Y)) then
        begin
            FViewStartIndex := 0; // Jump to the latest candle
        end;
        Repaint;
        exit;
    end;

    inherited MouseUp(Button, Shift, X, Y);
    if (Button = TMouseButton.mbLeft) then
    begin
        FIsDragging := false;
    end;
end;

procedure TMycChart.MouseMove(Shift: TShiftState; X, Y: Single);
var
    isHot: Boolean;
    dx: Single;
    indexDelta: Int64;
    maxIndex: Int64;
begin
    // Update button hot state
    if (FViewStartIndex > 0) then
    begin
        isHot := FJumpButtonRect.Contains(PointF(X, Y));
        if (isHot <> FJumpButtonHot) then
        begin
            FJumpButtonHot := isHot;
            Repaint;
        end;
    end
    else
    begin
        // Ensure hot state is off when button is not visible
        if FJumpButtonHot then
        begin
            FJumpButtonHot := false;
            Repaint;
        end;
    end;

    // Panning logic
    inherited MouseMove(Shift, X, Y);

    if FIsDragging then
    begin
        dx := X - FDragStartPoint.X;
        if Abs(dx) < 2 then // Threshold to avoid jitter
        begin
            exit;
        end;

        // An X-axis series is required for panning
        if not Assigned(FXAxisSeries) or (FViewCount <= 0) then
        begin
            exit;
        end;

        indexDelta := Round(dx / (Self.Width / FViewCount));

        // To move content left (natural), view must shift to newer data (lower index).
        // Drag left (dx < 0) -> FViewStartIndex must decrease.
        // The formula for that is FViewStartIndex := FViewStartIndex + indexDelta; -> StartIndex + (negative) = decrease.
        FViewStartIndex := FViewStartIndex + indexDelta;

        // Clamp values
        maxIndex := FXAxisSeries.Series.Count - FViewCount;
        if (maxIndex < 0) then
            maxIndex := 0;

        if (FViewStartIndex < 0) then
            FViewStartIndex := 0;
        if (FViewStartIndex > maxIndex) then
            FViewStartIndex := maxIndex;

        FDragStartPoint.X := X;
        FDragStartPoint.Y := Y;

        Repaint;
    end;
end;

procedure TMycChart.MouseWheel(Shift: TShiftState; WheelDelta: Integer; var Handled: Boolean);
var
    mousePos: TPointF;
    anchorIndex: Double;
    zoomFactor: Double;
    newViewCount: Int64;
    ratio: Double;
begin
    Handled := true;

    // An X-axis series is required for zooming
    if not Assigned(FXAxisSeries) then
        exit;

    var xAxisCount := FXAxisSeries.Series.Count;
    if (xAxisCount = 0) or (Width <= 0) then
        exit;

    mousePos := ScreenToLocal(Screen.MousePos);

    // Calculate the anchor index for a right-to-left axis
    anchorIndex := FViewStartIndex + ((Self.Width - mousePos.X) / Self.Width) * FViewCount;

    if (WheelDelta > 0) then
        zoomFactor := 0.8 // Zoom In
    else
        zoomFactor := 1.25; // Zoom Out

    newViewCount := Round(FViewCount * zoomFactor);

    // Clamp zoom level
    if (newViewCount < 10) then
        newViewCount := 10;
    if (newViewCount > xAxisCount) then
        newViewCount := xAxisCount;
    if (newViewCount = FViewCount) then
        exit;

    // Adjust start index to keep anchor point stable
    if (FViewCount > 0) then
        ratio := (anchorIndex - FViewStartIndex) / FViewCount
    else
        ratio := 0;

    FViewStartIndex := Round(anchorIndex - (ratio * newViewCount));
    FViewCount := newViewCount;

    // Clamp start index
    if (FViewStartIndex < 0) then
        FViewStartIndex := 0;
    if (FViewStartIndex + FViewCount > xAxisCount) then
    begin
        FViewStartIndex := xAxisCount - FViewCount;
    end;

    Repaint;
end;

{ TMycChart.TLayer }

constructor TMycChart.TLayer.Create(AOwner: TPanel);
begin
    inherited Create;
    FParent := AOwner;
end;

function TMycChart.TLayer.GetOwner: TMycChart;
begin
    Result := FParent.Owner;
end;

procedure TMycChart.TLayer.Repaint;
begin
    FParent.Owner.Repaint;
end;

{ TMycChart.TPanel }

constructor TMycChart.TPanel.Create(AOwner: TMycChart);
begin
    inherited Create;
    FOwner := AOwner;
    FSeriesList := TObjectList<TMycChart.TLayer>.Create(true);
end;

destructor TMycChart.TPanel.Destroy;
begin
    FSeriesList.Free;
    inherited Destroy;
end;

function TMycChart.TPanel.AddDoubleSeries(
    const DataProvider: IMycDataProvider<Double>;
    const ALineColor: TAlphaColor;
    const ALineWidth: Single
): TMycChart.TLayer;
begin
    Result := TChartLineLayer.Create(Self, DataProvider, ALineColor, ALineWidth);
    FSeriesList.Add(Result);
end;

function TMycChart.TPanel.AddOhlcSeries(
    const DataProvider: IMycDataProvider<TOhlcItem>;
    const AUpColor, ADownColor: TAlphaColor
): TMycChart.TLayer;
begin
    Result :=
        TChartOhlcLayer.Create(Self, DataProvider, TMutable<TAlphaColor>.Constant(AUpColor), TMutable<TAlphaColor>.Constant(ADownColor));
    FSeriesList.Add(Result);
end;

procedure TMycChart.TPanel.Paint(const Canvas: TCanvas; const Viewport: TRectF; MasterTotalCount, ViewStartIndex, ViewCount: Int64);
var
    localMin, localMax, seriesMin, seriesMax, padding: Double;
    rangeInitialized: Boolean;
    seriesFirst, seriesLast: Int64;
    xTransform, yTransform: TFunc<Double, Single>;

    function CalcView(Series: TMycChart.TSeries; out First, Last: Int64): Boolean;
    var
        seriesTotalCount, offset, startIdx: Int64;
    begin
        seriesTotalCount := series.TotalCount;
        offset := MasterTotalCount - seriesTotalCount;
        startIdx := ViewStartIndex - offset;

        First := Max(0, startIdx);
        Last := Min(series.Count, startIdx + ViewCount) - 1;
        Result := First <= Last;
    end;

begin
    rangeInitialized := false;

    // 1. Calculate value range (Y-Axis) for this panel only
    for var series in FSeriesList do
    begin
        if CalcView(series.Series, seriesFirst, seriesLast) then
        begin
            if series.GetValueRange(seriesFirst, seriesLast, seriesMin, seriesMax) then
            begin
                if not rangeInitialized then
                begin
                    localMin := seriesMin;
                    localMax := seriesMax;
                    rangeInitialized := true;
                end
                else
                begin
                    localMin := Min(localMin, seriesMin);
                    localMax := Max(localMax, seriesMax);
                end;
            end;
        end;
    end;

    if not rangeInitialized then
        Exit; // Nothing to draw in this panel

    padding := (localMax - localMin) * 0.1;
    localMin := localMin - padding;
    localMax := localMax + padding;

    if (localMax - localMin) = 0 then
        localMax := localMin + 1; // Avoid division by zero

    // 2. Create transforms for this panel
    yTransform :=
        function(value: Double): Single
        begin
            Result := Viewport.Top + (1 - (value - localMin) / (localMax - localMin)) * Viewport.Height;
        end;

    // 3. Paint all layers in this panel
    for var series in FSeriesList do
    begin
        if CalcView(series.Series, seriesFirst, seriesLast) then
        begin
            var offset := MasterTotalCount - series.Series.TotalCount;
            xTransform :=
                function(index: Double): Single
                begin
                    Result := Viewport.Right - (((index + offset - ViewStartIndex) / (ViewCount - 1)) * Viewport.Width);
                end;

            series.Paint(Canvas, seriesFirst, seriesLast, xTransform, yTransform);
        end;
    end;
end;

procedure TMycChart.TPanel.UpdateAndCheckChanges(MasterTotalCount, ViewStartIndex: Int64; out SeriesChanged, SeriesRepaint: Boolean);
var
    seriesCount: Int64;
begin
    SeriesChanged := false;
    SeriesRepaint := false;
    for var series in FSeriesList do
    begin
        seriesCount := series.Series.TotalCount;

        if (ViewStartIndex <= MasterTotalCount - seriesCount) then
            SeriesRepaint := true;

        series.Update;

        if (seriesCount <> series.Series.TotalCount) then
            SeriesChanged := true;
    end;
end;

end.