PTT crawler

HtmlAgilityPack

using HtmlAgilityPack;
using System;
using System.Collections.Generic;
using System.Linq;
using System.Text;
using System.Threading.Tasks;
using NEO_Crawler_PTT.Model;
using ZapLib;
using System.CodeDom;

namespace NEO_Crawler_PTT.Main
{
    class Crawler
    {
        public void Run()
        {
            /* Set Target Website URL */
            string uri = "https://www.ptt.cc";
            int page = Int32.Parse(Config.get("page"));
            var baseUrl = Config.get("pttUri");/* Send HTTP Request and Get Result */
            HtmlWeb web = new HtmlWeb();

            string next = "https://www.ptt.cc/bbs/C_Chat/index.html";
            
            for (int a = 0; a < page; a++)  //爬 ? 頁
            {
                int s=1; //第一頁 預設

                var htmlDoc = web.Load(next);

                if (htmlDoc == null)
                    Console.WriteLine("fail");
                else
                    Console.WriteLine("成功");

                /* Save HTML to File */
                //string s = htmlDoc.DocumentNode.OuterHtml;
                //System.IO.StreamWriter file = new System.IO.StreamWriter(@"D:\res.html");

                /* Find Element in DOM Tree by XPath */
                
                ModelPost m_post = new ModelPost();

               
                var content = htmlDoc.DocumentNode.SelectSingleNode("//div[@class=\"r-ent\"]"); //文章內容
                var link = content.SelectNodes("//div[@class=\"title\"]//a");

                var btn = htmlDoc.DocumentNode.SelectSingleNode("//div[@class=\"action-bar\"]"); //標題內容
                var nex = btn.SelectNodes("//div[@class=\"btn-group btn-group-paging\"]//a[2]");

                foreach (var n in link) //取得文章與連結
                {
                    m_post.name = n.InnerText;
                    m_post.link = uri + n.Attributes["href"].Value;

                    Console.WriteLine("\n -----第 "+s+" 篇開始-----");
                    s++;
                    Console.WriteLine(m_post.name + "\n" + m_post.link);

                    enter(m_post.link); // 副程式進入點
                    
                }
                foreach (var n in nex) //取得下一頁
                {
                    if (n.NodeType == HtmlNodeType.Element)
                    {
                        m_post.next = uri + n.Attributes["href"].Value; 
                        Console.WriteLine("Next: " + uri + n.Attributes["href"].Value);
                    }
                }

                next = m_post.next; //取得一頁

            }

        }
        public static string enter(string link)
        {
            string a, b, c, d, e, f = null;
            
            HtmlWeb web = new HtmlWeb();
            var htmlDoc = web.Load(link);

            if (htmlDoc == null)
                Console.WriteLine("fail");
            else
                Console.WriteLine(" ");

            //Console.WriteLine(link);
            var content =htmlDoc.DocumentNode.SelectSingleNode("//div[@id=\"main-container\"]"); //取得文章\

            var top = htmlDoc.DocumentNode.SelectSingleNode("//div[@id=\"main-content\"]"); //文章ALL

            var other = htmlDoc.DocumentNode.SelectNodes("//div[@id=\"main-content\"]");

            var maker = top.SelectNodes("//div[@class=\"article-metaline\"]"); //取得標題列表

            var titler =top.SelectNodes("//div[@class=\"article-metaline-right\"]"); //標題開頭


            var recall = top.SelectNodes("//div[@class=\"push\"]"); //取得回覆留言
           
            ModelComment m_comment = new ModelComment();
            if(other != null) //fixing
            {
                foreach(var n in other)
                { 
                 //content.RemoveChild(n); //無法移除 top階層 :main-content
                                           //卻可以移除content階層 :main-container

                 a=n.SelectSingleNode("span[1]").InnerText;
                 b=n.SelectSingleNode("span[2]").InnerText;
                // Console.WriteLine(a +" "+ b+" ");    
                }
            }

            if (maker != null)
            {
                foreach (var n in maker)
                {
                     if (n.NodeType == HtmlNodeType.Element)
                    {
                        top.RemoveChild(n);

                        switch (n.SelectSingleNode("span[1]").InnerText)
                        {
                            case "作者":
                               //Console.WriteLine("作者: " +n.SelectSingleNode("span[2]").InnerText); 
                                m_comment.maker=n.SelectSingleNode("span[2]").InnerText;

                                break;
                            case "標題":
                              // Console.WriteLine("標題: " +n.SelectSingleNode("span[2]").InnerText);
                                m_comment.title=n.SelectSingleNode("span[2]").InnerText;

                                break;
                            case "時間":
                              // Console.WriteLine("時間: " +n.SelectSingleNode("span[2]").InnerText);
                                m_comment.date=n.SelectSingleNode("span[2]").InnerText;
                                break;
                         }
                     }
                };
            }
            else
            {
                Console.WriteLine("-----此頁為公告 因此為空值-----");
            }

            if (recall != null)
            {
                foreach(var n in recall)
                {
                    if (n.NodeType == HtmlNodeType.Element)
                    {
                        top.RemoveChild(n); //移除留言者 內容 時間

                        a=n.SelectSingleNode("span[2]").InnerText;
                        b=n.SelectSingleNode("span[3]").InnerText;
                        c=n.SelectSingleNode("span[4]").InnerText;

                        m_comment.recall=a+b+c;

                        //Console.WriteLine(a +b +c );
                    }
                    
                }
            }
            if (titler != null)
            {
                foreach (var n in titler)
                {
                    if (n.NodeType == HtmlNodeType.Element)
                    {
                        top.RemoveChild(n); //移除 看板 + C_CHAT

                        a=n.SelectSingleNode("span[1]").InnerText;
                        b=n.SelectSingleNode("span[2]").InnerText;
                        //Console.WriteLine(a+" "+b);
                    }
                }
            }
            Console.WriteLine(" 作者:"+m_comment.maker+"\n 標題:"+m_comment.title+"\n 日期:"+m_comment.date);

            Console.WriteLine(top.InnerText);

            Console.WriteLine(m_comment.recall);

            Console.WriteLine("-----此篇已結束-----");
            

            return f;
        }

    }
}