{
    fpGUI IDE - Maximus

    Copyright (C) 2012 - 2013 Graeme Geldenhuys

    See the file COPYING.modifiedLGPL, included in this distribution,
    for details about redistributing fpGUI.

    This program is distributed in the hope that it will be useful,
    but WITHOUT ANY WARRANTY; without even the implied warranty of
    MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.

    Description:
      ---
}

unit filemonitor;

{$mode objfpc}{$H+}

interface

uses
  Classes, SysUtils, fpg_main, fpg_base, contnrs;

type

  TFileMonitorEventType = (fmeFileCreated,
                         fmeFileChanged,
                         fmeFileDeleted,
                         fmeFileRenamed,
                         fmeUnknownChange);

  TFileMonitorEventData = record
    EventType: TFileMonitorEventType;
    FileName: TfpgString;
//    OldFileName: TfpgString;
//    UserData: Pointer;
  end;


  TFileChangedEvent = procedure(Sender: TObject; AData: TFileMonitorEventData) of object;




  TMonitoredFile = class(TObject)
  private
    FName: TfpgString;
    FSize: Int64;
    FDate: TDateTime;
    FSHA1: TfpgString;
    function AsString: TfpgString;
  public
    function GetNewSHA1: TfpgString;
    procedure UpdateInfo;
    property Name: TfpgString read FName write FName;
    property Size: Int64 read FSize write FSize;
    property Date: TDateTime read FDate write FDate;
    property SHA1: TfpgString read FSHA1 write FSHA1;
  end;


  TFileMonitor = class(TThread)
  private
    FInterval: LongWord;
    FFileList: TThreadList;
    FOnFileChanged: TFileChangedEvent;
    FCurrent: TMonitoredFile;
    FCurrentState: TFileMonitorEventType;
    procedure DoFileChangeNotification;
  public
    constructor CreateCustom;
    destructor Destroy; override;
    procedure Execute; override;
    property  Interval: LongWord read FInterval write FInterval;
    procedure AddFile(const AFilename: TfpgString);
    procedure RemoveFile(const AFilename: TfpgString);
    property  OnFileChanged: TFileChangedEvent read FOnFileChanged write FOnFileChanged;
  end;


implementation

uses
  fpg_utils,
  sha1;

function ReadFileDate(const AFileName: string): TDateTime;
var
  fa: LongInt;
begin
  fa := FileAge(AFileName);
  Result := FileDateToDateTime(fa);
end;

function ReadFileSize(const AFileName: string): DWord;
var
  LFileStream: TFileStream;
begin
  LFileStream := TFileStream.Create(AFileName, fmOpenRead or fmShareDenyWrite);
  try
    Result := LFileStream.Size;
  finally
    LFileStream.Free;
  end;
end;

procedure ReadFileDateSize(const AFileName: string; var ADateTime: TDateTime; var AFileSize: Int64);
begin
  ADateTime  := ReadFileDate(AFileName);
  AFileSize := ReadFileSize(AFileName);
end;


{ TMonitoredFile }

function TMonitoredFile.AsString: TfpgString;
const
  OBJ_AS_STRING = '%s %s %d';
begin
  Result := Format(OBJ_AS_STRING, [FName, FormatDateTime('yyyy-mm-dd hh:mm:ss', FDate), FSize]);
end;

function TMonitoredFile.GetNewSHA1: TfpgString;
var
  lFile: TMonitoredFile;
  s: Int64;
  d: TDateTime;
begin
  s := 0;
  d := 0.0;
  lFile := TMonitoredFile.Create;
  try
    lFile.Name := FName;
    ReadFileDateSize(lFile.Name, d, s);
    lFile.Size := s;
    lFile.Date := d;

    Result := SHA1ofStr(lFile.AsString);
  finally
    lFile.Free;
  end;
end;

procedure TMonitoredFile.UpdateInfo;
var
  s: Int64;
  d: TDateTime;
begin
  ReadFileDateSize(Name, d, s);
  Size := s;
  Date := d;
  SHA1 := SHA1ofStr(AsString);
end;

{ TFileMonitor }

procedure TFileMonitor.DoFileChangeNotification;
var
  rec: TFileMonitorEventData;
begin
  if Assigned(FOnFileChanged) then
  begin
    rec.EventType := FCurrentState;
    rec.FileName := FCurrent.Name;
    FOnFileChanged(self, rec);
  end;
end;

constructor TFileMonitor.CreateCustom;
begin
  Create(True);
  FFileList := TThreadList.Create;
  FInterval := 500;
end;

destructor TFileMonitor.Destroy;
var
  f: TMonitoredFile;
  lst: TList;
  i: integer;
begin
  try
    lst := FFileList.LockList;
    for i := lst.Count-1 downto 0 do
    begin
      f := TMonitoredFile(lst[i]);
      lst.Remove(f);
      f.Free;
    end;
  finally
    FFileList.UnlockList;
  end;
  FFileList.Free;
  inherited Destroy;
end;

procedure TFileMonitor.Execute;
var
  i: integer;
  lFile: TMonitoredFile;
  lst: TList;
begin
  while not Terminated do
  begin
    if Assigned(FOnFileChanged) then
    begin
      lst := FFileList.LockList;
      try
        for i := lst.Count-1 downto 0 do
        begin
          lFile := TMonitoredFile(lst[i]);
          if fpgFileExists(lFile.Name) then
          begin
            if lFile.SHA1 <> lFile.GetNewSHA1 then
            begin
              FCurrent := lFile;
              FCurrentState := fmeFileChanged;
              Synchronize(@DoFileChangeNotification);
              lFile.UpdateInfo;
            end;
          end
          else
          begin
            FCurrent := lFile;
            FCurrentState := fmeFileDeleted;
            Synchronize(@DoFileChangeNotification);
            lst.Remove(lFile);
          end;
        end;
      finally
        FFileList.UnlockList;
      end;
    end;
    sleep(FInterval);
  end;
end;

procedure TFileMonitor.AddFile(const AFilename: TfpgString);
var
  lFile: TMonitoredFile;
  s: Int64;
  d: TDateTime;
begin
  s := 0;
  d := 0.0;
  lFile := TMonitoredFile.Create;
  lFile.Name := AFileName;
  ReadFileDateSize(AFileName, d, s);
  lFile.Size := s;
  lFile.Date := d;
  lFile.SHA1 := SHA1ofStr(lFile.AsString);
  FFileList.Add(lFile);
end;

procedure TFileMonitor.RemoveFile(const AFilename: TfpgString);
var
  i: integer;
  lFile: TMonitoredFile;
  lst: TList;
begin
  lst := FFileList.LockList;
  try
    for i := 0 to lst.Count-1 do
    begin
      if AFilename = TMonitoredFile(lst[i]).Name then
      begin
        lFile := TMonitoredFile(lst[i]);
        lst.Delete(i);
        lFile.Free;
        break;
      end;
    end;
  finally
    FFileList.UnlockList;
  end;
end;

end.