using KumiScript.Reader;

namespace KumiScript.Interpreter
{
    public class ReadEvalPrintLoop
    {
        Stream _stdin;
        Stream _stdout;
        public ReadEvalPrintLoop(Stream stdin, Stream stdout)
        {
            _stdin = stdin;
            _stdout = stdout;
        }

        public void Loop()
        {
            Lexer lexer = new Lexer(_stdin);
            Parser parser = new Parser(lexer);
            StreamWriter streamWriter = new StreamWriter(_stdout);
            Environment top = LispPrimitives.RegisterPrimitives();

            while (true) //this thing is ugly but it's just a little test
            {
                Expression expr = parser.NextTopLevelExpression();
                try
                {
                Expression result = expr.Eval(top);
                streamWriter.Write(string.Format("{0}\n", result.ToString()));
                streamWriter.Flush();
                } catch (Exception ex) {
                    if (ex is InterpreterInvalidApplicationException
                        or InterpreterInvalidDefinitionException
                        or InterpreterInvalidInvocationException
                        or InterpreterTypingException
                        or InterpreterUnboundSymbolException)
                        {
                            streamWriter.WriteLine(ex);
                            streamWriter.Flush();
                            continue;
                        }
                    throw;
                }
            }
        }
    }
}