using System;

using System.Collections.Generic;

​

class Program {

    static void Main() {

    }

}

​

​

namespace SharpExtension {

    class Option<T> {

        public static Option<T> Create(T value) { return new Option<T>(value); }

        public static Option<T> CreateEmpty() { return new Option<T>(); }

​

        public bool IsNone() { return (this.GetValue() == null || EqualityComparer<T>.Default.Equals(this.GetValue(), default(T))); }

        public T GetValue() { return m_Value; }

​

        public void Match(Action<T> hasValueDelegate, Action hasNoneDelegate) { if (this.IsNone()) { hasNoneDelegate(); } else { hasValueDelegate(this.GetValue()); } }

        public T UnwrapOrThrow(string msg) { if (this.IsNone()) { throw new Exception(msg); } else return this.GetValue(); }    

​

        private Option() {  }

        private Option(T value) { m_Value = value; }

        private readonly T m_Value;

    }

    class ArgParser {       

        public ArgParser(string program, string description) {

            m_Program = program;

            m_Description = description;

            m_Arguments = new Dictionary<string, Argument>();

            AddArgument("-h", "Display help", false, (parameters) => { DisplayHelp(); });

        }

        public void AddArgument(string option, string description, bool hasParams, Action<string[]> OnArgumentFound) {

            if (m_Arguments.ContainsKey(option)) { return; }

            m_Arguments.Add(option, new Argument() { Arg = option, Description = description, HasParameters = hasParams, OnArgumentFound = OnArgumentFound });

        }

        public void Parse() {

            var args = System.Environment.GetCommandLineArgs();

            for (int i=0; i< args.Length; i++) {

                if (!m_Arguments.ContainsKey(args[i])) { Console.WriteLine("Error: Unknown command \"{0}\" specified!\n\n", args[i]);DisplayHelp(); System.Environment.Exit(0); }

                Argument arg = m_Arguments.GetValueOrDefault(args[i]);

                if (arg.HasParameters) 

                    arg.OnArgumentFound(args[++i].Split(','));  

                else 

                    arg.OnArgumentFound(null);                                      

            }

        }

        public void DisplayHelp() {

            Console.WriteLine("Help for program {0}\n\n{1}\n", m_Program, m_Description);

            Console.WriteLine("Following commands are possible:");

            foreach (var arg in m_Arguments) {

                var option = arg.Key;

                var argument = arg.Value;

                Console.WriteLine("\t{0} : {1}", option, argument.Description);

            }

        }

        //private Dictionary<string, Tuple<string, Action<string[]>>> m_Arguments;

        private Dictionary<string, Argument> m_Arguments;

        private readonly string m_Program;

        private readonly string m_Description;

        private struct Argument {

            public string Arg;

            public string Description;

            public bool HasParameters;

            public string[] Parameters;

            public Action<string[]> OnArgumentFound;

        }

    }

}