using System;
using System.Collections.Generic;
using System.Text;
using System.Net;
using System.IO;
using System.Web;
using System.Collections.Specialized;

namespace JDFun
{
    public static class YouTubeGetter
    {
        public static Uri GetFlvUri(string viewUri)
        {
            return GetFlvUri(new Uri(viewUri));
        }

        public static Uri GetWatchUri(Uri flvUri)
        {
            NameValueCollection qry = HttpUtility.ParseQueryString(flvUri.Query);

            string videoID = qry["video_id"];
            string watchUri = string.Concat("http://www.youtube.com/watch?v=", HttpUtility.UrlEncode(videoID));

            return new Uri(watchUri);
        }

        public static Uri GetImageUri(Uri flvUri)
        {
            NameValueCollection qry = HttpUtility.ParseQueryString(flvUri.Query);

            string imageUri = qry["iurl"];

            return new Uri(imageUri);
        }

        public static Uri GetFlvUri(Uri viewUri)
        {
            // so either i've got the embed link or the watch link

            //watch link: http://www.youtube.com/watch?v=up-RX_YN7yA
            //embed link: http://www.youtube.com/v/up-RX_YN7yA

            string toQuery = null;

            NameValueCollection queryString = HttpUtility.ParseQueryString(viewUri.Query);

            string videoId = queryString["v"];

            if (null != videoId)
            {
                toQuery = string.Concat("http://www.youtube.com/v/", videoId);
            }
            else
            {
                toQuery = viewUri.ToString();
            }

            if (null == toQuery)
                throw new InvalidOperationException("Not a valid YouTube Uri.");

            Uri queryUri = new Uri(toQuery);
            //ok we have the uri to query, now go there and get redirected.
            HttpWebRequest req = (HttpWebRequest)HttpWebRequest.Create(queryUri);
            req.AllowAutoRedirect = true;

            // make them think we're coming from a direct link
            req.Referer = string.Empty;

            // firefox rules!
            req.UserAgent = "Mozilla/5.0 (Windows; U; Windows NT 5.1; en-GB; rv:1.8.1.3) Gecko/20070309 Firefox/2.0.0.3";
            using (HttpWebResponse resp = (HttpWebResponse)req.GetResponse())
            {
                string absoluteRedirectLocation = resp.ResponseUri.AbsoluteUri;

                //replace the swf with the get_video request
                if (!absoluteRedirectLocation.Contains("/p.swf?"))
                    throw new InvalidOperationException("Unrecognized Uri. YouTube changed something.");

                absoluteRedirectLocation = absoluteRedirectLocation.Replace("/p.swf?", "/get_video?");

                //return the absolute URI for this request
                return new Uri(absoluteRedirectLocation);
            }
        }
    }
}