using System;
using System.IO;
using System.Net;
using System.Text;
using System.Text.RegularExpressions;

namespace ZapTheDingbat
{
    public static class Facebook
    {
        //Make a request to login.facebook.com to get a session cookie.
        private CookieCollection login(String password, String username)
        {
            HttpWebRequest request = (HttpWebRequest)WebRequest.Create("https://login.facebook.com/login.php?m&next=http%3A%2F%2Fm.facebook.com%2Fhome.php");
            request.CookieContainer = new CookieContainer();
            request.AllowAutoRedirect = false;
            request.Method = "POST";
            request.ContentType = "application/x-www-form-urlencoded";
            request.UserAgent = "Mozilla/1";

            String postData = "";
            postData += "pass=" + password;
            postData += "&email=" + username;
            UTF8Encoding encoding = new UTF8Encoding();
            byte[] postBytes = encoding.GetBytes(postData);
            request.ContentLength = postBytes.Length;

            Stream requestStream = request.GetRequestStream();
            requestStream.Write(postBytes, 0, postBytes.Length);
            requestStream.Close();

            HttpWebResponse response = (HttpWebResponse)request.GetResponse();
            return response.Cookies;
        }

        //pull the markup of the Status update form and parse the post_form_id value
        private String getPostId(CookieCollection cookies)
        {
            HttpWebRequest request = (HttpWebRequest)WebRequest.Create("http://m.facebook.com/home.php");
            request.CookieContainer = new CookieContainer();
            request.CookieContainer.Add(cookies);
            request.AllowAutoRedirect = false;
            request.Method = "GET";
            request.UserAgent = "Mozilla/1";

            HttpWebResponse response = (HttpWebResponse)request.GetResponse();
            StreamReader reader = new StreamReader(response.GetResponseStream());
            String responseString = reader.ReadToEnd();

            Match match = Regex.Match(responseString, @"name=""post_form_id"" value=""([0-9a-f]+)""");
            if (match.Success) return match.Groups[1].Value;
            return "";
        }

        //post the status update
        private Boolean postUpdate(String postId, String status, CookieCollection cookies)
        {
            HttpWebRequest request = (HttpWebRequest)WebRequest.Create("http://m.facebook.com/home.php");
            request.CookieContainer = new CookieContainer();
            request.CookieContainer.Add(cookies);
            request.AllowAutoRedirect = false;

            request.Method = "POST";
            request.ContentType = "application/x-www-form-urlencoded";
            request.UserAgent = "Mozilla/1";

            String postData = "";
            postData += "post_form_id=" + postId;
            postData += "&status=" + status;
            postData += "&update=Update";
            UTF8Encoding encoding = new UTF8Encoding();
            byte[] postBytes = encoding.GetBytes(postData);
            request.ContentLength = postBytes.Length;

            Stream requestStream = request.GetRequestStream();
            requestStream.Write(postBytes, 0, postBytes.Length);
            requestStream.Close();

            HttpWebResponse response = (HttpWebResponse)request.GetResponse();
            return (response.StatusCode == HttpStatusCode.OK);
        }

        // public update method
        public bool updateStatus(String password, String username, String status)
        {
            //create a CookieCollection to store the session/auth cookies in.
            CookieCollection loginCookies = login(password, username);
            //use the session to get the PostId
            String postId = getPostId(loginCookies);
            //use the session and postID to post the status update
            return postUpdate(postId, status, loginCookies);
        }
    }
}