using System;
using System.Diagnostics;
using System.Linq;
using System.Windows.Forms;
 
using DotNetOpenAuth.OAuth2;
 
using Google.Apis.Authentication.OAuth2;
using Google.Apis.Authentication.OAuth2.DotNetOpenAuth;
using Google.Apis.Services;
using Google.Apis.Util;
 
using Google.Apis.Calendar.v3;
using Google.Apis.Calendar.v3.Data;
 
using GoogleCalendar;
 
 
namespace TestGoogleCalendar
{
    public partial class frmMain : Form
    {
        private Google.Apis.Calendar.v3.CalendarService service;
 
        public frmMain()
        {
            InitializeComponent();
            listView1.Sorting = SortOrder.Ascending;
        }
 
        private void frmMain_Load(object sender, EventArgs e)
        {
            TestMethod1();
        }
 
        private static IAuthorizationState GetAuthorization(NativeApplicationClient arg)
        {
            // Get the auth URL: 
            IAuthorizationState state = new AuthorizationState(new[] { CalendarService.Scopes.Calendar.GetStringValue() });
            state.Callback = new Uri(NativeApplicationClient.OutOfBandCallbackUrl);
            Uri authUri = arg.RequestUserAuthorization(state);
 
            // Request authorization from the user (by opening a browser window): 
            Process.Start(authUri.ToString());
 
            frmGetToken fToken = new frmGetToken();
            fToken.ShowDialog();
            string authCode = fToken.Token;
 
            // Retrieve the access token by using the authorization code: 
            return arg.ProcessUserAuthorization(authCode, state);
        } 
 
        public void TestMethod1()
        {
            var provider = new NativeApplicationClient(GoogleAuthenticationServer.Description)
            {
                ClientIdentifier = "xxxx.apps.googleusercontent.com",
                ClientSecret = "zzzzz"
            };
 
            var auth = new OAuth2Authenticator<NativeApplicationClient>(provider, GetAuthorization);
 
            service = new Google.Apis.Calendar.v3.CalendarService(new BaseClientService.Initializer()
            {
                Authenticator = auth
            });
 
            CalendarList cl = service.CalendarList.List().Fetch();
            comboBox1.Items.Clear();
            foreach (CalendarListEntry cle in cl.Items)
            {
                comboBox1.Items.Add(new CalendarEntry(cle));
            }
        }
 
        private void comboBox1_SelectedIndexChanged(object sender, EventArgs e)
        {
            LoadDay();
        }
 
        private void dateTimePicker1_ValueChanged(object sender, EventArgs e)
        {
            LoadDay();
        }
 
        private void dateTimePicker2_ValueChanged(object sender, EventArgs e)
        {
            LoadDay();
        }
 
        private void LoadDay()
        {
            listView1.Items.Clear();
 
            if (comboBox1.SelectedItem == null) return;
 
            EventsResource.ListRequest lr = service.Events.List((comboBox1.SelectedItem as CalendarEntry).Id);
            Events e = lr.Fetch();
            foreach (Event s in e.Items)
            {
                if (s.Status == "cancelled" ) continue;
                string a = (s.Start.DateTime != null) ? s.Start.DateTime : s.Start.Date;
                DateTime dt = DateTime.Parse(a);
                if (dt >= dateTimePicker1.Value.Date && dt < dateTimePicker2.Value.AddDays(1).Date)
                {
                    ListViewItem i = new ListViewItem(new []{dt.ToString(), s.Summary});
                    i.Tag = s;
                    listView1.Items.Add(i);
                }
            }
        }
 
        private void listView1_DoubleClick(object sender, EventArgs e)
        {
            if (listView1.SelectedItems[0].Tag != null)
            {
                frmCalendarEntry entry = new frmCalendarEntry(listView1.SelectedItems[0].Tag as Event);
                entry.ShowDialog();
                service.Events.Update(entry.evt, (comboBox1.SelectedItem as CalendarEntry).Id, entry.evt.Id);
                LoadDay();
            }
        }
    }
}

frmGetToken fToken = new frmGetToken();
            fToken.ShowDialog();
            string authCode = fToken.Token;