unit KaMResourceInput;

interface

uses
  Classes;

function KaMResourceExists(const aReference: string): Boolean;
function KaMOpenResourceStream(const aReference: string): TStream;
function KaMResolvePackagedResource(const aRelativeIdentity: string): string;

implementation

uses
  CastleUriUtils, CastleDownload;

procedure ValidatePackagedRelativeIdentity(const aRelativeIdentity: string);
var
  I, ComponentStart: Integer;
begin
  if (aRelativeIdentity = '') or (aRelativeIdentity[1] = '/') then
    raise EDownloadError.Create('KaMResourceInput: invalid packaged resource identity');

  ComponentStart := 1;
  for I := 1 to Length(aRelativeIdentity) do
  begin
    if (aRelativeIdentity[I] = '\') or (aRelativeIdentity[I] = ':')
      or (Ord(aRelativeIdentity[I]) < 32) then
      raise EDownloadError.Create('KaMResourceInput: invalid packaged resource identity');
    if aRelativeIdentity[I] = '/' then
    begin
      if (I = ComponentStart)
        or ((I = ComponentStart + 1) and (aRelativeIdentity[ComponentStart] = '.'))
        or ((I = ComponentStart + 2) and (aRelativeIdentity[ComponentStart] = '.')
          and (aRelativeIdentity[ComponentStart + 1] = '.')) then
        raise EDownloadError.Create('KaMResourceInput: invalid packaged resource identity');
      ComponentStart := I + 1;
    end;
  end;
  if (ComponentStart > Length(aRelativeIdentity))
    or ((Length(aRelativeIdentity) = ComponentStart) and (aRelativeIdentity[ComponentStart] = '.'))
    or ((Length(aRelativeIdentity) = ComponentStart + 1) and (aRelativeIdentity[ComponentStart] = '.')
      and (aRelativeIdentity[ComponentStart + 1] = '.')) then
    raise EDownloadError.Create('KaMResourceInput: invalid packaged resource identity');
end;

function KaMResolvePackagedResource(const aRelativeIdentity: string): string;
begin
  ValidatePackagedRelativeIdentity(aRelativeIdentity);
  Result := 'castle-data:/game/' + InternalUriEscape(aRelativeIdentity);
end;

function ResourceProtocol(const aReference: string): string;
begin
  if aReference = '' then
    raise EDownloadError.Create('KaMResourceInput: empty resource reference');

  Result := UriProtocol(aReference);
  if (Result <> '') and (Result <> 'file') and (Result <> 'castle-data') then
    raise EDownloadError.Create('KaMResourceInput: unsupported resource protocol: ' + Result);
end;

function KaMResourceExists(const aReference: string): Boolean;
begin
  ResourceProtocol(aReference);
  case UriExists(aReference) of
    ueFile: Result := True;
    ueNotExists, ueDirectory: Result := False;
    ueUnknown:
      raise EDownloadError.Create('KaMResourceInput: resource existence is unknown: ' + aReference);
  end;
end;

function KaMOpenResourceStream(const aReference: string): TStream;
begin
  if ResourceProtocol(aReference) = '' then
    Result := TFileStream.Create(aReference, fmOpenRead)
  else
    Result := Download(aReference, [soForceMemoryStream]);
end;

end.