program LiveLogViewer;

// Atlas Log viewer: a TAtlasLogView shows a TAtlasMemorySink live while the
// main thread and worker threads log. A level box and a text box filter the
// rows, Copy puts rows on the clipboard, Clear empties the sink. The form is
// built in code; no .dfm is needed.
//
// Run with a file name argument to save a PNG of the window instead of
// showing it:  LiveLogViewer.exe window.png

uses
  System.SysUtils, System.Classes, System.Generics.Collections, Vcl.Forms, Vcl.Controls,
  Vcl.StdCtrls, Vcl.ExtCtrls, Atlas.Log, Atlas.LogSinks, Atlas.LogView, Atlas.TestVcl;

type
  TViewerForm = class(TForm)
  private
    FLogger: TAtlasLogger;
    FMemory: TAtlasMemorySink;
    FView: TAtlasLogView;
    FLevel: TComboBox;
    FFilter: TEdit;
    FStatus: TLabel;
    FStatusTimer: TTimer;
    FWorkers: TObjectList<TThread>;
    procedure AddButton(Parent: TWinControl; var Left: Integer; const Caption: string; Handler: TNotifyEvent);
    procedure LogBatchClicked(Sender: TObject);
    procedure FailureClicked(Sender: TObject);
    procedure ThreadsClicked(Sender: TObject);
    procedure CopyClicked(Sender: TObject);
    procedure ClearClicked(Sender: TObject);
    procedure LevelChanged(Sender: TObject);
    procedure FilterChanged(Sender: TObject);
  public
    constructor Create(AOwner: TComponent); override;
    destructor Destroy; override;
    procedure LogBatch;
    procedure UpdateStatus(Sender: TObject);
    property View: TAtlasLogView read FView;
  end;

constructor TViewerForm.Create(AOwner: TComponent);
var Bar: TPanel; X: Integer;
begin
  inherited CreateNew(AOwner);
  Caption := 'Atlas Log: live viewer';
  Width := 1000;
  Height := 560;
  Position := poScreenCenter;
  FWorkers := TObjectList<TThread>.Create;

  FLogger := TAtlasLogger.Create(Self);
  FLogger.MinLevel := llTrace;
  FMemory := TAtlasMemorySink.Create(Self);
  FMemory.Capacity := 2000;
  FMemory.Logger := FLogger;

  Bar := TPanel.Create(Self);
  Bar.Parent := Self;
  Bar.Align := alTop;
  Bar.Height := 40;
  Bar.BevelOuter := bvNone;
  X := 8;
  AddButton(Bar, X, 'Log a batch', LogBatchClicked);
  AddButton(Bar, X, 'Log a failure', FailureClicked);
  AddButton(Bar, X, 'Four threads', ThreadsClicked);
  AddButton(Bar, X, 'Copy', CopyClicked);
  AddButton(Bar, X, 'Clear', ClearClicked);
  FLevel := TComboBox.Create(Self);
  FLevel.Parent := Bar;
  FLevel.SetBounds(X, 8, 100, 24);
  FLevel.Style := csDropDownList;
  FLevel.Items.CommaText := 'Trace,Debug,Info,Warning,Error,Fatal';
  FLevel.ItemIndex := 0;
  FLevel.OnChange := LevelChanged;
  Inc(X, 110);
  FFilter := TEdit.Create(Self);
  FFilter.Parent := Bar;
  FFilter.SetBounds(X, 8, 200, 24);
  FFilter.TextHint := 'Filter';
  FFilter.OnChange := FilterChanged;

  FStatus := TLabel.Create(Self);
  FStatus.Parent := Self;
  FStatus.Align := alBottom;
  FStatus.AlignWithMargins := True;

  FView := TAtlasLogView.Create(Self);
  FView.Parent := Self;
  FView.Align := alClient;
  FView.Font.Name := 'Consolas';
  FView.RefreshInterval := 100;
  FView.Sink := FMemory;

  FStatusTimer := TTimer.Create(Self);
  FStatusTimer.Interval := 250;
  FStatusTimer.OnTimer := UpdateStatus;
  UpdateStatus(nil);
end;

destructor TViewerForm.Destroy;
var Worker: TThread;
begin
  // Workers log through FLogger, so they must finish before the form frees it.
  for Worker in FWorkers do Worker.WaitFor;
  FWorkers.Free;
  inherited;
end;

procedure TViewerForm.AddButton(Parent: TWinControl; var Left: Integer; const Caption: string; Handler: TNotifyEvent);
var Button: TButton;
begin
  Button := TButton.Create(Self);
  Button.Parent := Parent;
  Button.SetBounds(Left, 7, 100, 26);
  Button.Caption := Caption;
  Button.OnClick := Handler;
  Inc(Left, 106);
end;

procedure TViewerForm.LogBatch;
var Orders: TAtlasLogChannel; Scope, Timer: IInterface;
begin
  Timer := FLogger.Time('batch', llDebug);
  Orders := FLogger.Channel('orders');
  FLogger.Info('Batch started');
  FLogger.Trace('Reading {count} rows', [3]);
  Scope := FLogger.BeginScope('checkout');
  Orders.Info('Order {id} placed by {customer} for {total}', [1042, 'Contoso', 1250.5]);
  Orders.Warning('Stock for {sku} is low: {left} left', ['AX-7', 3]);
  Orders.Error('Payment {id} was declined', [77]);
  Scope := nil;
  FLogger.Fatal('Batch aborted');
end;

procedure TViewerForm.LogBatchClicked(Sender: TObject);
begin
  LogBatch;
end;

procedure TViewerForm.FailureClicked(Sender: TObject);
begin
  try
    StrToInt('not a number');
  except
    on E: Exception do FLogger.Failure(E, 'Parsing user input failed');
  end;
end;

procedure TViewerForm.ThreadsClicked(Sender: TObject);
var I: Integer; Logger: TAtlasLogger; Worker: TThread;
begin
  Logger := FLogger;
  for I := 1 to 4 do
  begin
    Worker := TThread.CreateAnonymousThread(
      procedure
      var Step: Integer; Log: TAtlasLogChannel;
      begin
        Log := Logger.Channel('worker');
        for Step := 1 to 500 do Log.Trace('Step {step} of 500', [Step]);
        Log.Info('Worker finished');
      end);
    // Kept, not self-freeing, so the form can wait for them when it closes.
    Worker.FreeOnTerminate := False;
    FWorkers.Add(Worker);
    Worker.Start;
  end;
end;

procedure TViewerForm.CopyClicked(Sender: TObject);
begin
  FView.CopyToClipboard;
end;

procedure TViewerForm.ClearClicked(Sender: TObject);
begin
  // The view notices the sink's Version changing on its next timer tick.
  FMemory.Clear;
end;

procedure TViewerForm.LevelChanged(Sender: TObject);
begin
  FView.MinLevel := TAtlasLogLevel(FLevel.ItemIndex);
end;

procedure TViewerForm.FilterChanged(Sender: TObject);
begin
  FView.FilterText := FFilter.Text;
end;

procedure TViewerForm.UpdateStatus(Sender: TObject);
begin
  FStatus.Caption := Format('%d of %d events shown, %d pushed out of the ring buffer',
    [FView.ShownCount, FMemory.Count, FMemory.Discarded]);
end;

var
  Form: TViewerForm;
begin
  Application.Initialize;
  Application.MainFormOnTaskbar := True;
  if ParamCount >= 1 then
  begin
    Form := TViewerForm.Create(nil);
    try
      Form.LogBatch;
      Form.View.Reload;
      Form.UpdateStatus(nil);
      SaveFormImage(Form, ParamStr(1));
    finally
      Form.Free;
    end;
  end
  else
  begin
    Application.CreateForm(TViewerForm, Form);
    Application.Run;
  end;
end.