(*
 * Licensed to the Apache Software Foundation (ASF) under one
 * or more contributor license agreements. See the NOTICE file
 * distributed with this work for additional information
 * regarding copyright ownership. The ASF licenses this file
 * to you under the Apache License, Version 2.0 (the
 * "License"); you may not use this file except in compliance
 * with the License. You may obtain a copy of the License at
 *
 *   http://www.apache.org/licenses/LICENSE-2.0
 *
 * Unless required by applicable law or agreed to in writing,
 * software distributed under the License is distributed on an
 * "AS IS" BASIS, WITHOUT WARRANTIES OR CONDITIONS OF ANY
 * KIND, either express or implied. See the License for the
 * specific language governing permissions and limitations
 * under the License.
 *)

unit ConsoleHelper;

interface

uses Classes, SysUtils, SyncObjs;

type
  TThriftConsole = class
  strict private
    FLock : TCriticalSection;
  strict protected
    procedure Lock;
    procedure UnLock;
  public
    constructor Create;
    destructor Destroy; override;

    procedure Write( const S: string); virtual;
    procedure WriteLine( const S: string); virtual;
  end;


  TGUIConsole = class( TThriftConsole )
  strict private
    FLineBreak : Boolean;
    FMemo : TStrings;

    procedure InternalWrite( const S: string; bWriteLine: Boolean);
  public
    constructor Create( AMemo: TStrings);

    procedure Write( const S: string); override;
    procedure WriteLine( const S: string); override;
  end;


function Console: TThriftConsole;
procedure ChangeConsole( AConsole: TThriftConsole );
procedure RestoreConsoleToDefault;


implementation

var
  FDefaultConsole : TThriftConsole;
  FConsole : TThriftConsole;

function Console: TThriftConsole;
begin
  Result := FConsole;
end;

{ TThriftConsole }

constructor TThriftConsole.Create;
begin
  inherited Create;
  FLock := TCriticalSection.Create;
end;

destructor TThriftConsole.Destroy;
begin
  FreeAndNil( FLock);
  inherited Destroy;
end;

procedure TThriftConsole.Lock;
begin
  FLock.Enter;
end;

procedure TThriftConsole.UnLock;
begin
  FLock.Leave;
end;

procedure TThriftConsole.Write(const S: string);
begin
  Lock;
  try
    System.Write( S );
  finally
    Unlock;
  end;
end;

procedure TThriftConsole.WriteLine(const S: string);
begin
  Lock;
  try
    System.Writeln( S );
  finally
    Unlock;
  end;
end;

procedure ChangeConsole( AConsole: TThriftConsole );
begin
  FConsole := AConsole;
end;

procedure RestoreConsoleToDefault;
begin
  FConsole := FDefaultConsole;
end;

{ TGUIConsole }

constructor TGUIConsole.Create( AMemo: TStrings);
begin
  inherited Create;
  FMemo := AMemo;
  FLineBreak := True;
end;

procedure TGUIConsole.InternalWrite(const S: string; bWriteLine: Boolean);
var idx : Integer;
begin
  Lock;
  try

    if FLineBreak then begin
      FMemo.Add( S )
    end
    else begin
      idx := FMemo.Count - 1;
      if idx < 0
      then FMemo.Add( S )
      else FMemo[idx] := FMemo[idx] + S;
    end;
    FLineBreak := bWriteLine;

  finally
    Unlock;
  end;
end;

procedure TGUIConsole.Write(const S: string);
begin
  InternalWrite( S, False);
end;

procedure TGUIConsole.WriteLine(const S: string);
begin
  InternalWrite( S, True);
end;

initialization
  FDefaultConsole := TThriftConsole.Create;
  FConsole := FDefaultConsole;

finalization
  FDefaultConsole.Free;
  FDefaultConsole := nil;

end.