xp_WebBrowser_read_amazon_com_UI.linq

// xp_WebBrowser_read_amazon_com_UI.linq - rip book list from the Library page of the Amazon cloud reader
// 2020-09-16
//
// see https://stackoverflow.com/a/63917496/4156577

//<div class="book_container" id="B089DW5DYF">
//    <div class="book_cover">
//        <img title="Il misterioso caso di villa Grada (Le indagini del tenente Roversi Vol. 4) (Italian Edition)" class="book_image book_click_area" src="https://images-na.ssl-images-amazon.com/images/P/B089DW5DYF.01._SX255_SY255_TTXW_SCLZZZZZZZ_.jpg">
//        <div class="alt_title book_click_area"></div>
//    </div>
//    <div class="book_details">
//        <div class="book_title book_click_area">Il misterioso caso di villa Grada (Le indagini del tenente Roversi Vol. 4) (Italian Edition)</div>
//        <div class="book_author book_click_area">Gavino Zucca</div>
//    </div>
//</div>

class KindleBookListProgram
{
    const string FILENAME_TEMPLATE = "x:\\kindle_library_{0:yyyyMMdd}.lst";  // gets DateTime.Now as parameter
    const int TIMER_INTERVAL_MS = 5000;
    const string READ_AMAZON_COM = "https://read.amazon.com/";
    const string USERAGENT = "Mozilla/5.0 (Windows NT 6.3; WOW64; Trident/7.0; rv:11.0) like Gecko";
    const int URLMON_OPTION_USERAGENT = 0x10000001;

    static void Main ()
    {
        // setting the user agent in the Navigate() call works only once;
        // this works for the whole session
        UrlMkSetSessionOption(URLMON_OPTION_USERAGENT, USERAGENT, USERAGENT.Length, 0);

        using (var form = new BrowserForm())
        {
            form.ShowDialog();
        }
    }

    [DllImport("urlmon.dll", CharSet = CharSet.Ansi)]
    private static extern int UrlMkSetSessionOption (
        int dwOption, string pBuffer, int dwBufferLength, int dwReserved );

    class BrowserForm: Form
    {
        WebBrowser m_browser;
        System.Windows.Forms.Timer m_timer;
        string m_text_from_previous_try = null;

        public BrowserForm ()
        {
            Width = 800;
            Height = 600;

            m_timer = new System.Windows.Forms.Timer();
            m_timer.Interval = TIMER_INTERVAL_MS;
            m_timer.Tick += timer_Tick;

            Controls.Add(m_browser = new WebBrowser());
            m_browser.DocumentCompleted += browser_DocumentCompleted;
            m_browser.Dock = DockStyle.Fill;

            KeyPreview = true;
            KeyDown += this_KeyDown;

            m_browser.Navigate(READ_AMAZON_COM);
        }

        string find_book_list_frame_text (WebBrowser browser)
        {
            foreach (HtmlWindow frame in browser.Document.Window.Frames)
            {
                var elt = frame.Document.GetElementById("titles_inner_wrapper");

                if (elt != null)
                {
                    return elt.InnerHtml;
                }
            }

            return null;
        }

        void save_book_list (string text)
        {
            var filename = string.Format(FILENAME_TEMPLATE, DateTime.Now);
#if LINQPAD
            Console.WriteLine("\n##### {0} ######\n\n{1}\n\n", filename, text);
#endif
            File.WriteAllText(filename, text, Encoding.Default);
            this.Text = filename + " saved!";
        }

        void timer_Tick (Object sender, EventArgs e)
        {
            m_timer.Stop();

#if LINQPAD
            Console.WriteLine("{0} Tick event", DateTime.Now);
#endif
            var text = find_book_list_frame_text(m_browser);

            if (!string.IsNullOrEmpty(text))
            {
                if (!string.IsNullOrEmpty(m_text_from_previous_try) && text == m_text_from_previous_try)
                {
                    save_book_list(text);
                    return;
                }

                m_text_from_previous_try = text;
            }

            m_timer.Start();
        }

        void browser_DocumentCompleted (object sender, WebBrowserDocumentCompletedEventArgs e)
        {
#if LINQPAD
            Console.WriteLine("{0} DocumentCompleted event", DateTime.Now);
#endif
            m_timer.Stop();
            m_timer.Start();
        }

        void this_KeyDown (object sender, KeyEventArgs e)
        {
            if (e.Control && e.KeyValue == 17)  // ^S
            {
                e.SuppressKeyPress = true;

                save_book_list(find_book_list_frame_text(m_browser) ?? "");
            }
        }
    }
}