Read strings from file and give option to choose installation - inno-setup

Question

I want to make Steam backups installer. However, Steam allow to user make multiple library folders which makes installation difficult.
There are a few tasks that I want to perform.
Installer should identify path from registry to identify where Steam is installed.
The resulting path from registry open file
X:\Steam\config\config.vdf
and read value of "BaseInstallFolder_1", "BaseInstallFolder_2", "BaseInstallFolder_3" and etc.
Example of config.vdf:
"NoSavePersonalInfo" "0"
"MaxServerBrowserPingsPerMin" "0"
"DownloadThrottleKbps" "0"
"AllowDownloadsDuringGameplay" "0"
"StreamingThrottleEnabled" "1"
"AutoUpdateWindowStart" "-1"
"AutoUpdateWindowEnd" "-1"
"LastConfigstoreUploadTime" "1461497849"
"BaseInstallFolder_1" "E:\\Steam_GAMES"
The resulting path or paths of the file config.vdf bring in DirEdit
If user have multiple paths to the folder in different locations then give option select through DirTreeView or Radiobuttons.
How it should look like:
I know how to identify Steam path
WizardForm.DirEdit.Text := ExpandConstant('{reg:HKLM\SOFTWARE\Valve\Steam,InstallPath|{pf}\Steam}')+ '\steamapps\common\gamename';
But it is difficult to perform other tasks
Thanks in advance for your help.

Answer 1

To parse the config.vdf file:
Load the file using LoadStringsFromFile.
And use string functions like Copy, Pos, Delete, CompareText to parse it.
To keep the results use array of string (or predefined TArrayOfString). To allocate the array, use SetArrayLength.
The code may be like:
function ParseSteamConfig(FileName: string; var Paths: TArrayOfString): Boolean;
var
Lines: TArrayOfString;
I: Integer;
Line: string;
P: Integer;
Key: string;
Value: string;
Count: Integer;
begin
Result := LoadStringsFromFile(FileName, Lines);
Count := 0;
for I := 0 to GetArrayLength(Lines) - 1 do
begin
Line := Trim(Lines[I]);
if Copy(Line, 1, 1) = '"' then
begin
Delete(Line, 1, 1);
P := Pos('"', Line);
if P > 0 then
begin
Key := Trim(Copy(Line, 1, P - 1));
Delete(Line, 1, P);
Line := Trim(Line);
Log(Format('Found key "%s"', [Key]));
if (CompareText(
Copy(Key, 1, Length(BaseInstallFolderKeyPrefix)),
BaseInstallFolderKeyPrefix) = 0) and
(Line[1] = '"') then
begin
Log(Format('Found base install folder key "%s"', [Key]));
Delete(Line, 1, 1);
P := Pos('"', Line);
if P > 0 then
begin
Value := Trim(Copy(Line, 1, P - 1));
StringChange(Value, '\\', '\');
Log(Format('Found base install folder "%s"', [Value]));
Inc(Count);
SetArrayLength(Paths, Count);
Paths[Count - 1] := Value;
end;
end;
end;
end;
end;
end;