using System;
using System.Collections.Generic;
using System.Linq;
using System.Web;
using System.Web.UI;
using System.Web.UI.WebControls;
using System.Data.SqlClient;
using System.Data;
using System.Net;

public partial class Ajax_Writer : System.Web.UI.Page
{
    protected void Page_Load(object sender, EventArgs e)
    {
        string connStr = System.Web.Configuration.WebConfigurationManager.ConnectionStrings["skiveConnectionString1"].ToString();

        if (Request.QueryString["type"] != null)
        {
            string qstring = Request.QueryString["type"].ToString().ToUpper();

            switch (qstring)
            {
                case "ALLFEEDS":
                    writeAllFeeds(connStr);
                    break;
                case "ADDFEED":
                    if (Request.QueryString["uri"] != null)
                        saveFeed(connStr, Request.QueryString["uri"].ToString());
                    else
                        Response.Write("Query string when adding 'uri' is null");
                    break;
                case "DELETEFEED":
                    if (Request.QueryString["feed_id"] != null)
                        deleteFeed(connStr, Request.QueryString["feed_id"].ToString());
                    else
                        Response.Write("Query string when deleting 'feed_id' is null");
                    break;
                default:
                    Response.Write("Incorrect query string param:" + Request.QueryString["type"].ToString());
                    break;
            }
        }
        else
            Response.Write("Query string 'type' was null");

        
    }

    private void deleteFeed(string connStr, string feed_id)
    {
        bool successful = true;

        try
        {
            using (SqlConnection connection = new SqlConnection(connStr))
            {
                string commandText = "DeleteURI";
                SqlCommand command = new SqlCommand(commandText, connection);
                
                command.CommandType = CommandType.StoredProcedure;

                command.Parameters.AddWithValue("feed_id", feed_id);
                
                connection.Open();
                command.ExecuteNonQuery();
                connection.Close();
            }
        }

        catch (Exception ex)
        {
            successful = false;
            Response.Write("Sorry your feed could not be Feed deleted " + ex.ToString());
        }
        if (successful)
            Response.Write("Feed deleted");
    }


    private void saveFeed(string connStr, string url)
    {
        bool succussful = true;
        if (!feedIsValid(url))
        {
            Response.Write("Please check if the feed url is valid");
        }
        else
        {
        try
        {
            using (SqlConnection connection = new SqlConnection(connStr))
            {

                string commandText = "SaveURI";
                SqlCommand command = new SqlCommand(commandText, connection);

                command.CommandType = CommandType.StoredProcedure;
                //generate a random id for each feed
                
                int ticks = Convert.ToInt32(DateTime.Now.Ticks.GetHashCode());
                Random feed_id = new Random(ticks);
                int int_feed_id = feed_id.Next() * ticks;

                command.Parameters.AddWithValue("hash_id", int_feed_id);
                command.Parameters.AddWithValue("uri", url);
                command.Parameters.AddWithValue("title", "no title");
                command.Parameters.AddWithValue("updated", DateTime.Now);
                
                connection.Open();
                command.ExecuteNonQuery();
                connection.Close();
            }
        }

        catch (Exception ex)
        {
            if (ex.ToString().IndexOf("Violation of UNIQUE KEY constraint") > 0)
                Response.Write("This feed has already been added to your reader");
            else
                Response.Write(ex.Message);

            succussful = false;
        }
            if(succussful)
                Response.Write(url + " Saved");
        }
    }

    /// <summary>
    /// Returns true if url returns an http 20x status code with 2.5 secs, otherwise returns false
    /// Modified version of example on: http://carso-owen.blogspot.com/2008/02/check-if-url-is-valid-and-accessible.html
    /// </summary>
    /// <param name="url"></param>
    /// <returns></returns>
    private bool feedIsValid(string url)
    {
        HttpWebRequest httpReq =(HttpWebRequest)WebRequest.Create(url);
        httpReq.AllowAutoRedirect =false;
        httpReq.Method = "HEAD";
        httpReq.KeepAlive = false;
        httpReq.Timeout = 10000;
        HttpWebResponse httpRes;
        bool exists = false;
        try
        {
            httpRes = (HttpWebResponse)httpReq.GetResponse();
            if(httpRes.StatusCode == HttpStatusCode.OK || httpRes.StatusCode == HttpStatusCode.Found)
            {
                exists = true;
            }
        }
        catch (Exception ex)
        {/*Silent expection is permissable in this instance*/}
        return exists;
    }
    
    
    
    

    /// <summary>
    /// Outputs a list of the rss feeds in html
    /// </summary>
    /// <param name="connStr">Connection string to use to connect to DB</param>
    private void writeAllFeeds(string connStr)
    {
        try
        {
            using (SqlConnection connection = new SqlConnection(connStr))
            {

                string commandText = "getAllURIs";

                SqlCommand command = new SqlCommand(commandText, connection);

                command.CommandType = CommandType.StoredProcedure;

                connection.Open();

                using (SqlDataReader dataReader = command.ExecuteReader())
                {

                    while (dataReader.Read())
                    {

                        Response.Write("<b>" + dataReader["feed_uri"] + "</b>" + ", " +
                        dataReader["title"] + ", " + dataReader["updated"] + "<a href='#' OnClick='deleteURI("
                        + dataReader["feed_id"].ToString().Trim() 
                        + ");'title='Delete'>Delete</a><br />");
                    }
                }
                connection.Close();
            }
        }

        catch (Exception ex)
        {
            Response.Write(ex.Message);
        }
    }
}