unit ApprovedClientsStorage;

interface

uses Classes, SyncObjs;

type
  TApprovedClientsStorage = class(TObject)
  private
    fStorageFile: string;
    fGuidList: TStringList;
    fLock: TCriticalSection;
    procedure SetStorageFile(aName: string);
  protected
    procedure Initialize;
    procedure FlushStorage;
  public
    constructor Create;
    destructor Destroy; override;
    procedure AddClient(aClientGuid: string);
    function IsClientKnown(aClientGuid: string): boolean;
    property StorageFile: string read fStorageFile write SetStorageFile;
  end;

var
  StorageInstance: TApprovedClientsStorage;

implementation

uses SysUtils, uROClasses;

{ TApprovedClientsStorage }

procedure TApprovedClientsStorage.AddClient(aClientGuid: string);
var s: AnsiString;
begin
  s := AnsiUpperCase({$IFDEF UNICODE}WideStringToAnsiString{$ENDIF}(aClientGuid));
  if fGuidList.IndexOf(s) = -1 then begin
    fLock.Enter;
    try
      if fGuidList.IndexOf(s) = -1 then begin
        fGuidList.Add(s);
        FlushStorage;
      end;
    finally
      fLock.Leave;
    end;
  end;
end;

constructor TApprovedClientsStorage.Create;
begin
  inherited;
  fGuidList := TStringList.Create;
  fLock := TCriticalSection.Create;
end;

destructor TApprovedClientsStorage.Destroy;
begin
  fGuidList.Free;
  fLock.Free;
  inherited;
end;

procedure TApprovedClientsStorage.FlushStorage;
var
  f: Text;
  s: AnsiString;
  i: integer;
begin
  {$I-}
  AssignFile(f, fStorageFile);
  try
    Rewrite(f);
    for i := 0 to fGuidList.Count - 1 do begin
      s := {$IFDEF UNICODE}WideStringToAnsiString{$ENDIF}(fGuidList[i]);
      WriteLn(f, s);
      if IOResult <> 0 then raise Exception.Create('Approved clients file write error.');
    end;
  finally
    CloseFile(f);
  end;
end;

procedure TApprovedClientsStorage.Initialize;
var
  f: Text;
  s: AnsiString;
begin
  {$I-}
  AssignFile(f, fStorageFile);
  try
    fGuidList.Clear;
    Reset(f);
    if IOResult <> 0 then Rewrite(f)
    else
      while not Eof(f) do begin
        ReadLn(f, s);
        if IOResult <> 0 then raise Exception.Create('Approved clients file read error.');
        fGuidList.Append({$IFDEF UNICODE}AnsiStringToWideString{$ENDIF}(s));
      end;
  finally
    CloseFile(f);
  end;
end;

function TApprovedClientsStorage.IsClientKnown(aClientGuid: string): boolean;
var s: AnsiString;
begin
  s := AnsiUpperCase({$IFDEF UNICODE}WideStringToAnsiString{$ENDIF}(aClientGuid));
  fLock.Enter;
  try
    Result := fGuidList.IndexOf(s) > -1;
  finally
    fLock.Leave;
  end;
end;

procedure TApprovedClientsStorage.SetStorageFile(aName: string);
var needInit: boolean;
begin
  fLock.Enter;
  try
    needInit := fStorageFile = '';
    fStorageFile := aName;
    if needInit then Initialize;
  finally
    fLock.Leave;
  end;    
end;

initialization
  StorageInstance := TApprovedClientsStorage.Create;
finalization
  StorageInstance.Free;
end.