using System;

using System.Text.RegularExpressions;

using System.Linq;

using System.Collections.Generic;

using System.Collections;

​

public class URLParser: UriBuilder

{

    public bool IsPortSet{get;set;}

    public string URL{get;set;}

    public static URLParser Parse(string input)

    {       

        URLParser obj = new URLParser();

        Action<URLParser,int> santitzePort = (obj,port)=>{

            if(port> 65535)//sanitize port

            {

                port = 65535;

            }

            obj.Port = port;

        };

        //parse the input       

        Regex schemeMatcher=new Regex(@"(\w+)(:){1}//", RegexOptions.IgnoreCase);

        //schemeMatcher.Matches(input).Select(x=>x.Value).Dump();

        if(schemeMatcher.IsMatch(input))

        {

            obj.Scheme = schemeMatcher.Matches(input).Select(x=>x.Value).Aggregate("", (str, obj) => str + obj.ToString());

        }

        else

        {

            obj.Scheme = "http://";//inject/correct missing pieces

        }

        Regex hostMatcher = new Regex(@"((\w+)(:))?(www\.)?([^\/]*)(\/.*)?|((\w+)(:)(\w+))$", RegexOptions.IgnoreCase);

        //hostMatcher.Matches(input).Dump();

        if(hostMatcher.IsMatch(input))

        {

            string strHost = string.Empty;

            if(new Regex(@"((\w+)(:)(\w+))$", RegexOptions.IgnoreCase).IsMatch(input))

            {

                var arrURL = input.Split(new char[]{':'},StringSplitOptions.RemoveEmptyEntries);

                strHost = arrURL.First();

                var port = Convert.ToInt32(String.Join("", arrURL.Last().Where(c=>Char.IsDigit(c))));//test:test

                santitzePort(obj, port);//sanitize port

                obj.IsPortSet = true;

                obj.Path ="";

            }

            else

            {

                strHost = hostMatcher.Matches(input).Select(x=>x.Value).Aggregate("", (str, obj) => str + obj.ToString());

            }

            //var proxy = new UriBuilder("test:8888");

            //Console.WriteLine(strHost);

            obj.Host = strHost;

        }

        else

        {

            //obj.Host = "localhost";

        }

        if(!obj.IsPortSet)

        {

            Regex portMatcher = new Regex(@"[:]{1}[\d+]+", RegexOptions.IgnoreCase);

            if(portMatcher.IsMatch(input))

            {

                var port = Convert.ToInt32(String.Join("",hostMatcher.Matches(input).Select(x=>x.Value).Aggregate("", (str, obj) => str + obj.ToString()).ToArray().Where(c=>Char.IsDigit(c))));

                santitzePort(obj, port);//sanitize port

                obj.IsPortSet = true;

            }

            else

            {

                obj.Port = 80;//inject/correct missing pieces

            }

        }

        return obj;

    }

    //cook the url using the parsed ingredients

    public string Cook()

    {

        //form well formed URL, psuedo:

        //return new Uri(this.Scheme+"://"+":8042/over/there?name=ferret#nose");

        this.URL = this.Scheme+"://"+this.Host+":"+this.Port+ this.Path + this.Query + this.Fragment;

        Console.WriteLine(this.URL);

        //return new Uri(this.URL);//forming Uri has so many bugs

        return this.URL;

    }

}

public class Program

{

    public static void Main()

    {

        string[] inputs = new string[]{

            "stackoverflow.com",

            "server:8088",

            "server:8088/func1",

            "server:8088/func1/SubFunc1",

            "http://server",

            "http://server/func1",

            "http://server/func/SubFunc1",

            "http://server:8088",

            "http://server:8088/func1",

            "http://server:8088/func1/SubFunc1",

            "magnet://server",

            "magnet://server/func1",

            "magnet://server/func/SubFunc1",

            "magnet://server:8088",

            "magnet://server:8088/func1",

            "magnet://server:8088/func1/SubFunc1",

            "http://[2001:db8::1]",

            "http://[2001:db8::1]:80"

        };

        /*

              foo://example.com:8042/over/there?name=ferret#nose

              \_/   \_________/ \__/\_________/\__________/ \__/

               |         |        |     |           |        |

            scheme      host    port   path       query   fragment

​

             Expected:

                  stackoverflow.com:3389        

                  \_______________/ \__/

                         |            |

                        host         port

​

             Actual:

                  stackoverflow.com:///3389     

                  \_______________/    \__/

                         |               |

                       scheme           path

        */

        foreach(var userEnteredText in inputs.Take(2))

        {

            try

            {

                //String userEnteredText = "stackoverflow.com:3389";

                URLParser uriBuilder = URLParser.Parse(userEnteredText);

                Console.WriteLine("Scheme: "+uriBuilder.Scheme);

                Console.WriteLine("Host: "+uriBuilder.Host);

                Console.WriteLine("Port: "+uriBuilder.Port);

                Console.WriteLine("Path: "+uriBuilder.Path);

                Console.WriteLine("Query: "+uriBuilder.Query);

                Console.WriteLine("Fragment: "+uriBuilder.Fragment);

                Console.WriteLine("URL usable by HttpWebRequest: "+ uriBuilder.Cook());

            }catch(Exception ex)

            {

                Console.WriteLine("ERROR: "+ex.Message+" - "+ userEnteredText);

            }   

        }

    }

}