using System;
using System.Collections.Generic;
using System.Drawing;
using System.Linq;
using System.Threading;
using System.Windows.Forms;

using AshMind.Web.Snapshots.Sizing;

// This code was built using information from an article
// "Build A Self-Caching ASP.NET Web Site Thumbnail Control" by Peter Bromberg
// http://www.eggheadcafe.com/tutorials/aspnet/b7cce396-e2b3-42d7-9571-cdc4eb38f3c1/build-a-selfcaching-asp.aspx

namespace AshMind.Web.Snapshots {
    public static class WebSnapshot {
        public static Image Create(Uri url, IWebSnapshotSize size) {
            if (Thread.CurrentThread.GetApartmentState() != ApartmentState.STA) {
                Image image = null;
                RunInSTAThread(() => image = RequestSnapshot(url, size));
                return image;
            }

            return RequestSnapshot(url, size);
        }

        private static void RunInSTAThread(ThreadStart action) {
            var thread = new Thread(action) {
                Name = "WebSnapshot.BrowserThread",
                IsBackground = true
            };
            thread.SetApartmentState(ApartmentState.STA);
            thread.Start();
            thread.Join();
        }

        private static Image RequestSnapshot(Uri url, IWebSnapshotSize size) {
            Image result = null;

            using (var completed = new AutoResetEvent(false)) 
            using (var browser = new WebBrowser()) {
                browser.ScrollBarsEnabled = false;
                browser.DocumentCompleted += delegate {
                    result = ExtractSnapshot(browser, size);
                    completed.Set();
                };
                browser.Navigate(url);
                
                //completed.WaitOne();
                while (result == null) {
                    Thread.Sleep(0);
                    Application.DoEvents();
                }
            }

            return result;
        }

        private static Image ExtractSnapshot(WebBrowser browser, IWebSnapshotSize size) {
            browser.ScrollBarsEnabled = false;
            var bounds = size.Resize(browser);

            var bitmap = new Bitmap(bounds.Width, bounds.Height);
            browser.BringToFront();
            browser.DrawToBitmap(bitmap, bounds);

            return bitmap;
        }
    }
}