A Really Vain "How are my articles doing" Web Spider

using System;
using System.Collections.Generic;
using System.ComponentModel;
using System.Data;
using System.Drawing;
using System.Text;
using System.Windows.Forms;
using Microsoft.Win32;

namespace VainWebSpider
{
    #region frmMain CLASS
    /// <summary>
    /// Creates a new BackGroundWorker which creates a new 
    /// <see cref="WebScreenScraper">WebScreenScraper </see>
    /// and subscribe to its StartParse/EndParse events. If the  WebScreenScraper
    /// data signifies that the currently selected codeproject user has some
    /// articles, get the article data out of the WebScreenScraper, and display
    /// the data in a DataGridView.
    /// </summary>
    /// <param name="sender">BackgroundWorker</param>
    /// <param name="e">DoWorkEventArgs</param>
    public partial class frmMain : Form
    {
        #region Instance Fields
        //instance fields
        private Boolean formShown = true;
        private WebScreenScraper wss;
        private DataTable dt;
        #endregion
        #region Contructor
        /// <summary>
        /// Constructs a new frmMain object
        /// </summary>
        public frmMain()
        {
            InitializeComponent();
        }
        #endregion

        #region Private Methods

        /// <summary>
        /// User double clicked the system tray icon, so if the form
        /// is shown it is hidden, if its hidden its shown
        /// </summary>
        /// <param name="sender">The notify icon</param>
        /// <param name="e">The event arguments</param>
        private void nfIcon_DoubleClick(object sender, EventArgs e)
        {
            if (formShown)
            {
                this.Hide();
                formShown = false;
            }
            else
            {
                this.Show();
                formShown = true;
            }
        }

        /// <summary>
        /// Shows the form
        /// </summary>
        /// <param name="sender">The show menu</param>
        /// <param name="e">The event arguments</param>
        private void showFormToolStripMenuItem_Click(object sender, EventArgs e)
        {
            this.Show();
        }

        /// <summary>
        /// Hides the form
        /// </summary>
        /// <param name="sender">The hide menu</param>
        /// <param name="e">The event arguments</param>
        private void hideFormToolStripMenuItem_Click(object sender, EventArgs e)
        {
            this.Hide();
        }

        /// <summary>
        /// Calls the ClearRemoteObjectReference() method if the user confirms they
        /// wish to quit.
        /// </summary>
        /// <param name="sender">The exit menu</param>
        /// <param name="e">The event arguments</param>
        private void exitToolStripMenuItem_Click(object sender, EventArgs e)
        {
            DialogResult dr = MessageBox.Show("Are you sure you want to quit.\r\n" +
                "There may be client connected at present", "Exit", MessageBoxButtons.YesNo, MessageBoxIcon.Question);
            if (dr.Equals(DialogResult.Yes))
            {
                Application.Exit();
            }
        }
        
        /// <summary>
        /// Creates a new <see cref="WebScreenScraper">WebScreenScraper </see>
        /// and subscribe to its StartParse/EndParse events. If the  WebScreenScraper
        /// data signifies that the currently selected codeproject user has some
        /// articles, get the article data out of the WebScreenScraper, and display
        /// the data in a DataGridView.
        /// </summary>
        /// <param name="sender">BackgroundWorker</param>
        /// <param name="e">DoWorkEventArgs</param>
        private void bgw_DoWork(object sender, DoWorkEventArgs e)
        {
            //create a new WebScreenScraper and subscribe to its events
            wss = new WebScreenScraper(Program.UserID);
            wss.StartParse += wss_StartParse;
            //get the initial article summary area only, discard the other 
            //text that doesnt hold any text we need to parse
            wss.getInitialData();
            if (wss.HasArticles)
            {
                dt = wss.getWebData();
            }
        }


        private void bgw_RunWorkerCompleted(object sender, RunWorkerCompletedEventArgs e)
        {

            //need to test for an invoke initially, as the BackgroundWorker
            //that is run to do the web site parsing is on a different handle
            //to that of this forms controls, so will need to be marshalled to
            //the correct thread handle, on order to change properties
            //are there any articles for the current user
            if (wss.HasArticles)
            {

                lblProgress.Visible = false;
                prgBar.Visible = false;
                pnlUser.Visible = true;
                pnlGridMainFill.Visible = true;
                this.Invalidate();
                Application.DoEvents();



                lblCurrentUser.Text = wss.AuthorName + ": " + wss.NoOfArticles + " articles available";

                //check there is at least 1 article, before showing the 
                //article DataGridView
                if (dt.Rows.Count > 0)
                {
                    dgArticles.Columns.Clear();
                    dgArticles.DataSource = dt;
                    alterColumns();
                    resizeColumns();
                    dgArticles.Visible = true;
                    pnlResults.Visible = true;
                    this.Invalidate();
                    Application.DoEvents();
                }
                    //known author, but no articles to show
                else
                {
                    dgArticles.Visible = false;
                    pnlResults.Visible = false;
                    this.Invalidate();
                    Application.DoEvents();
                }
            }
                //there are no articles to show, so update GUI to show this
            else
            {
                pnlResults.Visible = false;
                lblCurrentUser.Text = "Unknown Or Unpublished Author";
                lblProgress.Visible = false;
                prgBar.Visible = false;
                dgArticles.Visible = false;
                pnlResults.Visible = false;
                pnlUser.Visible = true;
                this.Invalidate();
                Application.DoEvents();
                Program.InfoBox("There are no CodeProject articles avaialble for user ("
                                + Program.UserID + ")");
            }
        }
    



        /// <summary>
        /// Alter the article DataGridView columns, by firstly adding an image column
        /// which will be a new column index of 4. And then Delete the auto mapped
        /// "ArticleURL" column, and create a new DataGridViewLinkColumn column for
        /// the "ArticleURL" column, which will be column index 5.
        /// </summary>
        private void alterColumns()
        {

            //need to catch this, as this column may not be in existence
            //when the request to remove it is made.
            try
            {
                //remove existing ArticleURL column
                dgArticles.Columns.Remove("ArticleURL");
            }
            catch (Exception)
            {
                //cant do much about the removal of a non-existent column
            }
            //create a new image column
            DataGridViewImageColumn imgs = new DataGridViewImageColumn();
            imgs.Image = global::VaneWebSpider.FormResources.LinkIcon;
            imgs.DisplayIndex = 0;
            imgs.Width = 40;
            dgArticles.Columns.Add(imgs);
            //create a new hyperlink column
            DataGridViewLinkColumn links = new DataGridViewLinkColumn();
            links.HeaderText = "ArticleURL";
            links.DataPropertyName = "ArticleURL";
            links.ActiveLinkColor = Color.Blue;
            links.LinkBehavior = LinkBehavior.SystemDefault;
            links.LinkColor = Color.Blue;
            links.SortMode = DataGridViewColumnSortMode.Automatic;
            links.TrackVisitedState = true;
            links.VisitedLinkColor = Color.Blue;
            links.DisplayIndex = 1;
            links.Width = 300;
            dgArticles.Columns.Add(links);
        }

        /// <summary>
        /// Resize all article DataGridView columns to fixed sizes
        /// </summary>
        private void resizeColumns()
        {
            //resize all other columns to have default width of 60
            dgArticles.Columns[0].Width = 60; //Views column
            dgArticles.Columns[1].Width = 60; //Ratings column
            dgArticles.Columns[2].Width = 60; //Votes column
            dgArticles.Columns[3].Width = 60; //Popularity column
        }

        ///// <summary>
        ///// Puts all the GUI components into a EndParse state
        ///// </summary>
        ///// <param name="sender"><see cref="WebScreenScraper">
        ///// The WebScreenScraper</param>
        ///// <param name="e">EventArgs</param>
        //private void wss_EndParse(object sender, EventArgs e)
        //{
        //    lblProgress.Visible = false;
        //    prgBar.Visible = false;
        //    pnlUser.Visible = true;
        //    pnlGridMainFill.Visible = true;
        //    this.Invalidate();
        //    Application.DoEvents();
        //}

        /// <summary>
        /// Puts all the GUI components into a StartParse state
        /// </summary>
        /// <param name="sender"><see cref="WebScreenScraper">
        /// The WebScreenScraper</param>
        /// <param name="e">EventArgs</param>
        private void wss_StartParse(object sender, EventArgs e)
        {
            //need to test for an invoke initially, as the BackgroundWorker
            //that is run to do the web site parsing is on a different handle
            //to that of this forms controls, so will need to be marshalled to
            //the correct thread handle, on order to change properties
            if (this.InvokeRequired)
            {
                this.Invoke(new EventHandler(delegate
                {
                    lblProgress.Visible = true;
                    prgBar.Visible = true;
                    this.Invalidate();
                    Application.DoEvents();
                }));
            }
        }

        /// <summary>
        /// If the column of the DataridView clicked was the link column
        /// call the startProcess, passing it the correct URL to navigate to
        /// </summary>
        /// <param name="sender"></param>
        /// <param name="e"></param>
        private void dgArticles_CellContentClick(object sender, DataGridViewCellEventArgs e)
        {
            int LINK_COLUMN_INDEX = 5;
            //the link column is index 5, as it was created at index 5, as there were
            //originally 5 auto generated columns created by the WebScreenScraper.createDataSet() 
            //method, but then we deleted that auto-generated column, and swapped it for a hyperlink
            //column which was added to the end of teh existing auto-generated columns. Thats why its
            //at index 5 which is a little strange, but there you go.
            if (e.ColumnIndex == LINK_COLUMN_INDEX)
            {
                startProcess(@"http://www.codeproject.com" +
                    dgArticles[e.ColumnIndex, e.RowIndex].Value.ToString());
            }
        }

        /// <summary>
        /// Attempts to start the process which has the name of the parameter supplied, So
        /// long as the process is a URL. Must start with www or http, as we are attempting
        /// to start a web browser
        /// </summary>
        /// <param name="target">The process to start</param>
        private void startProcess(string target)
        {
            // If the value looks like a URL, navigate to it.
            if (null != target && (target.StartsWith("www") || target.StartsWith("http")))
            {
                try
                {
                    System.Diagnostics.Process.Start(target);
                }
                catch (Exception)
                {
                    Program.ErrorBox("Problem with starting process " + target);
                }
            }
        }

        /// <summary>
        /// Creates a new BackgroundWorker thread and calls the 
        /// BackgroundWorkers bgw_DoWork(..) method, where the 
        /// argument is the value of the <see cref="Program">
        /// Program classes </see>UserID
        /// </summary>
        /// <param name="sender">frmMain</param>
        /// <param name="e">EventArgs</param>
        private void frmMain_Load(object sender, EventArgs e)
        {
            pnlUser.Visible = false;
            pnlGridMainFill.Visible = false;
            BackgroundWorker bgw = new BackgroundWorker();
            bgw.DoWork += bgw_DoWork;
            bgw.RunWorkerCompleted += bgw_RunWorkerCompleted;
            bgw.RunWorkerAsync(Program.UserID);
        }

        /// <summary>
        /// Allows the user to specify a new UserId to fetch codeproject articles for by the
        /// use of a <see cref="InputBoxDialog">InputBoxDialog </see>
        /// The value entered must be a postive number
        /// </summary>
        /// <param name="sender">lnkChangeUser</param>
        /// <param name="e">LinkLabelLinkClickedEventArgs</param>
        private void lnkChangeUser_LinkClicked(object sender, LinkLabelLinkClickedEventArgs e)
        {
            //get the new userId
            string stringEntered = Program.InputBox("Enter a new user ID to examine", "Enter a new user ID", "");
            //check for empty
            if (stringEntered.Equals(string.Empty)) 
            {
                Program.ErrorBox("You must enter a value for the userId");
            }
            else 
            {
                try 
                {
                    //make sure its a positive number, then update the Program
                    //held property
                    long uId = long.Parse(stringEntered);
                    if (uId > 0)
                    {
                        Program.UserID = uId;
                        BackgroundWorker bgw = new BackgroundWorker();
                        bgw.DoWork += new DoWorkEventHandler(bgw_DoWork);
                        bgw.RunWorkerAsync(Program.UserID);
                    }
                    else
                    {
                        Program.ErrorBox("User ID must be a postive value");
                    }
                }
                //its not a number that was entered, tell them off
                catch(Exception) 
                {
                    Program.ErrorBox("The value you entered was not valid\r\n" +
                                    "The user ID must be a number");
                }
            }
        }

        /// <summary>
        /// Hide the notify icon, and shutdown the application
        /// </summary>
        /// <param name="sender">frmMain</param>
        /// <param name="e">FormClosedEventArgs</param>
        private void frmMain_FormClosed(object sender, FormClosedEventArgs e)
        {
            nfIcon.Visible = false;
            Application.Exit();
        }

        /// <summary>
        /// Create and show a new <see cref="frmPie">frmPie</see> object, and hide this form
        /// </summary>
        /// <param name="sender">lnkResults</param>
        /// <param name="e">LinkLabelLinkClickedEventArgs</param>
        private void lnkResults_LinkClicked(object sender, LinkLabelLinkClickedEventArgs e)
        {
            frmPie fPie = new frmPie();
            fPie.GridIsUse = dgArticles;
            fPie.AuthorString = lblCurrentUser.Text;
            this.Hide();
            fPie.ShowDialog(this);
            this.Show();
        }
        #endregion
    }
    #endregion
}