program downloader;

uses fphttpclient, base64, opensslsockets, fpjson, jsonparser, SysUtils, process, Classes, libtar, CustApp, Math;

var
  gameId: Integer;
  gameData: TJSONData;
  client: TFPHTTPClient;
  authString, tarFile, errorMsg: String;
  app: TCustomApplication;

procedure createFileDir(filePath: AnsiString);
var
  splitDir: TStringArray;
  s: String;
  newDir: String = '';

begin
  splitDir := filePath.Split(['\', '/']);
  for s in splitDir do
  begin
    if not (s = splitDir[Length(splitDir)-1]) then
    begin
      newDir := newDir + s + '/';
      CreateDir(newDir);
    end;
  end;
end;

procedure copyFile(oldFile, newFile: AnsiString);
var
  source, dest: TFileStream;

begin
  createFileDir(newFile);
  source := TFileStream.Create(oldFile, fmOpenRead);
  dest := TFileStream.Create(newFile, fmCreate);
  dest.CopyFrom(source, source.Size);
  source.Free;
  dest.Free;
end;

function getGameData(var client: TFPHTTPClient; gameId: Integer; out gameData: TJSONData): Boolean;
const
  url = 'https://rpi.narnian.us/games/get_game/';

var
  jData: TJSONData;

begin
  writeln('start get game data');
  client.AllowRedirect := true;
  try
    jData := GetJSON(client.Get(url+IntToStr(gameId)));
    gameData := jData;
    getGameData := true;
  Except
    getGameData := false;
  end;
end;

function downloadGameTar(var client: TFPHTTPClient; gameId: Integer): String;
const
  url = 'https://rpi.narnian.us/games/download/windows/';

var
  tarFile: TFileStream;
  tarFileName: String;

begin
  writeln('start download tar');
  client.AllowRedirect := true;
  tarFileName := gameData.FindPath('title_sanitized').AsString+'.tar';
  tarFile := TFileStream.Create(tarFileName, fmCreate);
  client.Get(url+IntToStr(gameId), tarFile);
  tarFile.Free;
  downloadGameTar := tarFileName;
end;

procedure extractTar(fileName: String);
var
  tarFile: TTarArchive;
  tarContent: TTarDirRec;
  files: TJSONArray;
  firstFile: String;
  i: Integer;

begin
  writeln('start extract tar');
  tarFile := TTarArchive.Create(fileName);
  while tarFile.FindNext(tarContent) do
  begin
    files := TJSONArray(gameData.FindPath('windows.files.'+tarContent.Name));
    firstFile := files.Strings[0];
    createFileDir(firstFile);
    tarFile.ReadFile(firstFile);
    for i := 1 to files.Count-1 do
    begin
      createFileDir(files.Strings[i]);
      copyFile(firstFile, files.Strings[i]);
    end;
  end;
  tarFile.Destroy;
end;

function authenticate(client: TFPHTTPClient): Boolean;
const
  url = 'https://rpi.narnian.us';

var
  username, password: String;

begin
  if app.HasOption('u', 'user') then
  begin
    username := app.GetOptionValue('u', 'username');
  end
  else
  begin
    Write('Enter username: ');
    ReadLn(username);
  end;
  if app.HasOption('p', 'password') then
  begin
    password := app.GetOptionValue('p', 'password');
  end
  else
  begin
    Write('Enter password: ');
    ReadLn(password);
  end;
  authString := username + ':' + password;
  client.AddHeader('Authorization', 'Basic '+base64.EncodeStringBase64(authString));
  client.AllowRedirect := true;
  try
    client.Get(url);
    authenticate := true;
  except
    authenticate := false;
  end;
end;

procedure displayHelp;
const
  optionFlags: TStringArray = (
                '-h, --help',
                '-g, --gameid <game id>',
                '-u, --username <username>',
                '-p, --password <password>');
  optionDescriptions: TStringArray = (
                       'Display help.',
                       'Sets the game id. This is required.',
                       'Sets the username for authentication.',
                       'Sets the password for authentication.');

var
  i, lenFlag, lenDesc, maxLenFlag, maxLenDesc, minLenFlag, minLenDesc: Integer;

begin
  maxLenFlag := 0;
  maxLenDesc := 0;
  minLenFlag := 1000;
  minLenDesc := 1000;
  for i := 0 to Length(optionFlags)-1 do
  begin
    minLenFlag := Min(minLenFlag, Length(optionFlags[i]));
    maxLenFlag := Max(maxLenFlag, Length(optionFlags[i]));
    minLenDesc := Min(minLenDesc, Length(optionDescriptions[i]));
    maxLenDesc := Max(maxLenDesc, Length(optionDescriptions[i]));
  end;
  WriteLn('Usage: downloader.exe [options]');
  WriteLn;
  WriteLn('Options:');
  for i := 0 to Length(optionFLags)-1 do
  begin
    lenFlag := Length(optionFLags[i]);
    lenDesc := Length(optionDescriptions[i]);
    Write(optionFlags[i]:(lenFlag+2));
    WriteLn(optionDescriptions[i]:(lenDesc+maxLenFlag-lenFlag+2))
  end;
end;

begin
  app := TCustomApplication.Create(nil);
  errorMsg := app.checkOptions('hg:u:p:', 'help gameid: username: password:');
  if (errorMsg <> '') or app.HasOption('h', 'help') then
  begin
    WriteLn(errorMsg);
    displayHelp;
  end
  else
  begin
    if app.HasOption('g', 'gameid') then
    begin
      gameId := StrToInt(app.GetOptionValue('g', 'gameid'));
      client := TFPHTTPClient.Create(nil);
      if authenticate(client) then
      begin
        if getGameData(client, gameId, gameData) then
        begin
          tarFile := downloadGameTar(client, gameId);
          extractTar(tarFile);
          DeleteFile(tarFile);
          WriteLn('Download finished');
        end
        else
        begin
          WriteLn('Invalid game id given');
        end;
      end
      else
      begin
        WriteLn('Invalid username or password');
      end;
    end
    else
    begin
      WriteLn('No game id was given');
    end;
  end;
end.