using System;
using System.Reflection;
using System.Text;
using System.CodeDom.Compiler;
using Microsoft.CSharp;

namespace Namaah.NetSUUS.Tools.CLI
{
public class Shell
{
    private StringBuilder _code = new StringBuilder();
    ICodeCompiler compiler = new CSharpCodeProvider().CreateCompiler();
    CompilerParameters parameters = new CompilerParameters();

    public static void Main()
    {
        new Shell().Start();
    }

    public Shell()
    {
        parameters.GenerateInMemory = true;
        parameters.ReferencedAssemblies.Add("System.dll");
    }

    public void Start()
    {
        string cmd = ReadCmd();
        while (cmd != null)
        {
            object obj = Run(cmd);
            if (obj != null) Console.WriteLine(obj);
            cmd = ReadCmd();
        }
    }

    private static string ReadCmd()
    {
        Console.Write("shell> ");
        return Console.ReadLine();
    }

    private object Run(string cmd)
    {
        string code;
        string returnline = null;
        bool haserrors = false; 

        if (!cmd.StartsWith("return"))
        {
            returnline = "return null;";
        }

        code = @"
            using System;
            public class Runner
            {
                public object Run()
                {
                    " + _code.ToString() + cmd + returnline + @"
                }
            }";

        CompilerResults compiled = compiler.CompileAssemblyFromSource(parameters, code);

        foreach (CompilerError e in compiled.Errors)
        {
            Console.WriteLine(e.ErrorText);
            if (!e.IsWarning) haserrors = true;
        }    

        if (haserrors) return null;
        
        object obj = compiled.CompiledAssembly.CreateInstance("Runner");
        object returned = compiled.CompiledAssembly.GetType("Runner")
            .InvokeMember(
                "Run",
                BindingFlags.InvokeMethod,
                null, obj, new object[] {}
            );    

        _code.Append(cmd); // All ok so include the line
        if (returnline == null) // A return call means end of the session
            _code = new StringBuilder();
            
        return returned;
    }
}
}