<%@ WebHandler Language="C#" Class="getMeta" %>

using System;
using System.Web;
using System.Runtime.Serialization.Json;
using Newtonsoft.Json;
using Newtonsoft.Json.Linq;
using System.Web.Services.Protocols;
using System.Security.Cryptography;
using System.Text;
using System.Web.SessionState;
using System.Data;
using System.Collections.Generic;
using System.IO.Compression;
using System.Drawing;
using System.Drawing.Imaging;
using System.IO;
using System.Linq;
using System.Text.RegularExpressions;

public class getMeta : IHttpHandler, IReadOnlySessionState {
    private string _baseurl = HttpContext.Current.Request.Url.Scheme + "://" + HttpContext.Current.Request.Url.Authority + HttpContext.Current.Request.ApplicationPath.TrimEnd('/');

    public void ProcessRequest (HttpContext context) {
        result objRet = new result();
        DataContractJsonSerializer json = new DataContractJsonSerializer(objRet.GetType());
        context.Response.ContentType = "application/json;charset=utf-8";
        context.Response.AddHeader("Access-Control-Allow-Origin", "*");

        string acceptEncoding = context.Request.Headers["Accept-Encoding"].ToString().ToUpperInvariant();
        if (!String.IsNullOrEmpty(acceptEncoding))
        {
            if (acceptEncoding.Contains("GZIP"))
            {
                //输出流头部GZIP压缩
                context.Response.AppendHeader("Content-encoding", "gzip");
                context.Response.Filter = new GZipStream(context.Response.Filter, CompressionMode.Compress);
            }
            else if (acceptEncoding.Contains("DEFLATE"))
            {
                //输出流头部DEFLATE压缩
                context.Response.AppendHeader("Content-encoding", "deflate");
                context.Response.Filter = new DeflateStream(context.Response.Filter, CompressionMode.Compress);
            }
        }

        authPermission objAuth = new authPermission();
        if (!objAuth.isLogin())
        {
            objRet.ret = "no";
            objRet.err_code = "0001";
            objRet.message = "尚未登入，請登入後使用";
            json.WriteObject(context.Response.OutputStream, objRet);
            return;
        }

        string url = (context.Request["url"] == null) ? "" : context.Request["url"].ToString();

        if (url == "") {
            objRet.ret = "no";
            objRet.err_code = "0001";
            objRet.message = "無傳入網址!\n";
            json.WriteObject(context.Response.OutputStream, objRet);
            return;
        }

        string htmlData = globalClass.getPageData(url);
        //htmlData = htmlData.Replace("\n", "");

        Match ogTitleMatch = Regex.Match(htmlData, "<meta.*?property=\"og:title\".*?content=\"([^<]*)\".*?([^<]*)>", RegexOptions.IgnoreCase | RegexOptions.Multiline);
        Match ogDescMatch = Regex.Match(htmlData, "<meta.*?property=\"og:description\" content=\"([^<]*)\".*?([^<]*)>", RegexOptions.IgnoreCase | RegexOptions.Multiline);
        Match ogImageMatch = Regex.Match(htmlData, "<meta.*?property=\"og:image\".*?content=\"([^<]*)\".*?([^<]*)>", RegexOptions.IgnoreCase | RegexOptions.Multiline);
        string ogTitle = ogTitleMatch.Groups[1].Value;
        string ogDesc = ogDescMatch.Groups[1].Value;
        string ogImage = ogImageMatch.Groups[1].Value;

        if (ogTitle == "") {
            ogTitleMatch = Regex.Match(htmlData, "<meta.*?name=\"og:title\".*?content=\"([^<]*)\".*?([^<]*)>", RegexOptions.IgnoreCase | RegexOptions.Multiline);
            ogDescMatch = Regex.Match(htmlData, "<meta.*?name=\"og:description\" content=\"([^<]*)\".*?([^<]*)>", RegexOptions.IgnoreCase | RegexOptions.Multiline);
            ogImageMatch = Regex.Match(htmlData, "<meta.*?name=\"og:image\".*?content=\"([^<]*)\".*?([^<]*)>", RegexOptions.IgnoreCase | RegexOptions.Multiline);
            ogTitle = ogTitleMatch.Groups[1].Value;
            ogDesc = ogDescMatch.Groups[1].Value;
            ogImage = ogImageMatch.Groups[1].Value;
        }

        objRet.ret = "yes";
        objRet.ogTitle = ogTitle;
        objRet.ogDescript = ogDesc;

        if (objRet.ogDescript.Length > 100) {
            objRet.ogDescript = objRet.ogDescript.Substring(0, 95) + "...";
        }

        string imageName = "";

        if (ogImage != "") {
            imageName = globalClass.CreateRandomCode(24);
            string filePath = string.Format("/downloads/{0}.png", imageName);
            string path = System.Web.HttpContext.Current.Server.MapPath("~/");

            try
            {
                globalClass.getUrlPic(ogImage).Save(path + filePath.Replace("/", "\\"), ImageFormat.Png);
                objRet.ogImage = _baseurl + "/downloads/" + imageName + ".png";
            }
            catch (Exception ex)
            {
                objRet.ogImage = "";
            }
        }

        
        json.WriteObject(context.Response.OutputStream, objRet);
        return;
    }

    public class result
    {
        public string ret = "no";
        public string err_code = "0000";
        public string message = "";
        public string ogTitle = "";
        public string ogDescript = "";
        public string ogImage = "";
    }

    public bool IsReusable {
        get {
            return false;
        }
    }

}