using uCalcSoftware;

var uc = new uCalc();

static void URLDecode(uCalc.Callback cb) {
   // In a real application, this would be a full URL decoding implementation.
   // For this example, we'll just handle spaces (%20) and plus signs (+).
   uCalc.String s = cb.ArgStr(1);
   s.Replace("%20", " ").Replace("+", " ");
   cb.ReturnStr(s.Text);
}


// 1. Define the custom URLDecode function in the uCalc engine
uc.DefineFunction("URLDecode(s As String) As String", URLDecode);

// 2. Create the transformer and configure its tokenizer
using (var t = new uCalc.Transformer(uc)) {
   // Treat '&' as a statement separator to process each pair individually
   t.Tokens.Add("&", TokenType.StatementSep);

   // 3. Define the rule to capture key-value pairs and decode the value
   t.FromTo("{@Alphanumeric:key}={value}", "- {key}: '{@Eval: URLDecode(value)}'");

   // 4. Process a real-world query string
   var queryString = "name=John%20Doe&role=user+admin&id=123";

   // Use Filter() to get a clean, newline-separated list of the results
   Console.WriteLine(t.Transform(queryString).Matches);
}