UrlTokenEncode a GUID

urlTokenEncode.sql

drop function dbo.convertPaddingToCount;
go

create function dbo.convertPaddingToCount(@input varchar(1000))
returns varchar(1000)
as
begin
  if (LEN(@input) < 1)
    return '';

  declare @answer varchar(1000);
  declare @count int;
  declare @ind int;
  
  set @count = 0;
  set @ind = LEN(@input);
  
  while @ind >= 1
  begin
    if SUBSTRING(@input, @ind, 1) = '='
    begin
		set @count = @count + 1;
		set @ind = @ind - 1;
    end
    else
    begin
		break
    end
  end
  
  if (@count > 0)
  begin
	set @answer = SUBSTRING(@input, 1, LEN(@input) - @count) + CONVERT(varchar(5), @count)
  end
  else
  begin
	set @answer = @input;
  end
  
  return @answer;
end;
go

drop function dbo.urlTokenEncode;
go

-- algorithm reverses the steps at http://stackoverflow.com/questions/21657024/is-there-a-java-equivalent-for-cs-httpserverutility-urltokendecode
-- and ports to T-SQL, obviously
create function dbo.urlTokenEncode(@input uniqueidentifier)
returns varchar(3000) 
as 
begin
	declare @answer varchar(3000);
	declare @encoded varchar(3000);

	-- technique due to http://stackoverflow.com/questions/5082345/base64-encoding-in-sql-server-2005-t-sql
	SELECT @encoded =
		CAST(N'' AS XML).value(
			  'xs:base64Binary(xs:hexBinary(sql:column("bin")))'
	        , 'VARCHAR(MAX)'
		)   
	FROM (
	    SELECT CAST(@input AS VARBINARY(MAX)) AS bin
	) AS bin_sql_server_temp;

	set @answer = @encoded;

	-- convert padding characters to a count
	set @answer = dbo.convertPaddingToCount(@encoded);
	
	-- transform url-unsafe characters to url-safe
	set @answer = REPLACE(@answer, '+', '-');
	set @answer = REPLACE(@answer, '=', '');
	set @answer = REPLACE(@answer, '/', '_');

	
	return @answer;
end;
go