using System;
using Upsilon;
using Upsilon.Evaluator;

namespace Ycicle
{
    internal static class Program
    {
        private static void Main()
        {
            Console.WriteLine("Upsilon REPL");
            Script script = null;
            while (true)
            {
                Console.Write("» ");
                var input = Console.ReadLine();
                switch (input)
                {
                    case "exit":
                        return;
                }

                if (script == null)
                    script = new Script(input);
                else
                    script = Script.ContinueWith(script, input);

                if (script.Diagnostics.Messages.Count > 0)
                {
                    Console.ForegroundColor = ConsoleColor.Red;
                    Console.WriteLine("Errors were found during parsing");
                    foreach (var diagnosticsMessage in script.Diagnostics.Messages)
                    {
                        LogError(diagnosticsMessage);
                    }
                    Console.ResetColor();
                    continue;
                }

                var evaluate = script.Evaluate();
                if (script.Diagnostics.Messages.Count > 0)
                {
                    Console.ForegroundColor = ConsoleColor.Red;
                    Console.WriteLine("Errors were found during evaluating");
                    foreach (var diagnosticsMessage in script.Diagnostics.Messages)
                    {
                        LogError(diagnosticsMessage);
                    }
                    Console.ResetColor();
                }
                else
                {
                    if (evaluate == null)
                        continue;
                    Console.ForegroundColor = ConsoleColor.Cyan;
                    Console.WriteLine(evaluate);
                    Console.ResetColor();
                }
            }
        }

        private static void LogError(DiagnosticsMessage message)
        {
            Console.ForegroundColor = ConsoleColor.Red;
            Console.WriteLine(message.Message);

            Console.ForegroundColor = ConsoleColor.Gray;
            Console.Write(message.GetDiagnosticPosition() + " ");
            Console.Write(message.LineBeforeError());

            Console.ForegroundColor = ConsoleColor.Red;
            Console.Write(message.AtError());

            Console.ForegroundColor = ConsoleColor.Gray;
            Console.Write(message.LineAfterError());
            Console.WriteLine();
        }
    }
}