using System;
using System.Collections.Generic;
using System.Configuration;
using System.IO;
using System.Linq;
using System.Net;
using System.Web;
using HtmlAgilityPack;

public static class DocHelpParcing
{
    public class DocHelpText 
    {
        public string Title { get; set; }
        public string Content { get; set; }
    }

    public static string Title
    {
        get { return GetContent().Title; }
    }

    public static string Content
    {
        get { return GetContent().Content; }
    }

    public static DocHelpText GetContent()
    {
        var result = new DocHelpText();
        var doc = new HtmlDocument();
        var baseDomain = ConfigurationManager.AppSettings["web.doc.teamlab"];
        string mainUrl = "";
        string category = "";
        string filePath = "";
        string mainPath = "";
        List<string> listCategoriesSite = new List<string>
                                              {
                                                  "description-document-editor",
                                                  "description-presentation-editor",
                                                  "description-spreadsheet-editor"
                                              };
        List<string> listCategoriesDocs = new List<string>
                                              {
                                                  "documenteditor",
                                                  "presentationeditor",
                                                  "spreadsheeteditor"
                                              };
        string curUrl = HttpContext.Current.Request.Url.ToString().ToLowerInvariant(); 

        foreach (var item in listCategoriesSite)
        {
            if (curUrl.Contains(item))
            {
                category = listCategoriesDocs[listCategoriesSite.IndexOf(item)];
                curUrl = curUrl.Remove(curUrl.IndexOf(".aspx"));
                filePath = curUrl.Substring(curUrl.IndexOf(item) + item.Length);
            }
        }
        if (baseDomain != null)
        {
            mainPath = baseDomain + "/OfficeWeb/apps/" + category + "/main/resources/help/" + GetLanguage();
            mainUrl = mainPath + filePath + ".htm";
        }
        doc.LoadHtml(SendRequestToDocs(mainUrl));
        var content = doc.DocumentNode.SelectSingleNode("//div[@class='mainpart']");

        if (content == null)
        {
            mainPath = baseDomain + "/OfficeWeb/apps/" + category + "/main/resources/help/en";
            mainUrl = mainPath + filePath + ".htm";        
            doc.LoadHtml(SendRequestToDocs(mainUrl));
            content = doc.DocumentNode.SelectSingleNode("//div[@class='mainpart']");
        }

        if (content != null)
        {
            var images = content.SelectNodes("//img");
            if (images != null)
            {
                foreach (var img in images)
                {
                    var src = img.Attributes["src"];
                    if (src != null)
                    {
                        src.Value = mainPath + src.Value.Substring(src.Value.IndexOf("/images/"));
                    }
                }
            }

            var links = content.SelectNodes("//a[@href]");

            if (links != null)
            {
                foreach (var link in links)
                {
                    var href = link.Attributes["href"];
                    if (href != null && !href.Value.Contains("http"))
                    {
                        if (!String.IsNullOrEmpty(href.Value) && href.Value[0].ToString() != "#")
                        {
                            href.Value = href.Value.Replace(".htm", ".aspx");
                            href.Value = href.Value.Contains("/") ?
                                                                      curUrl.Remove(curUrl.IndexOf(filePath)) + href.Value.Substring(href.Value.IndexOf("/"))
                                             : curUrl.Remove(curUrl.IndexOf(curUrl.Split('/').Last())) + href.Value;
                        }
                    }
                }
            }

            HtmlNode title = content.SelectSingleNode("//h1");
            result.Title = (title != null) ? title.InnerHtml : "";
            content.SelectSingleNode("//h1").Remove();
            result.Content = content.InnerHtml;
        }
        else
        {
            result.Title = "";
            result.Content = "";
        }

        return result;
    }

    private static String SendRequestToDocs(string url)
    {
        try
        {
            var httpWebRequest = (HttpWebRequest)WebRequest.Create(url);

            httpWebRequest.AllowAutoRedirect = false;
            httpWebRequest.Method = "GET";

            using (var httpWebResponse = (HttpWebResponse)httpWebRequest.GetResponse())
            using (var stream = httpWebResponse.GetResponseStream())
            using (var reader = new StreamReader(stream))
            {
                var result = reader.ReadToEnd();

                return result;
            }
        }
        catch (Exception)
        {
            return String.Empty;
        }
    }

    private static String GetLanguage()
    {
        return "ru";
    }
}