public async Task<ActionResult> ExternalLoginConfirmation(ExternalLoginConfirmationViewModel model, string returnUrl)
        {
            if (User.Identity.IsAuthenticated)
            {
                return RedirectToAction("Index", "Manage");
            }

            if (ModelState.IsValid)
            {
                // Get the information about the user from the external login provider
                var info = await AuthenticationManager.GetExternalLoginInfoAsync();
                if (info == null)
                {
                    return View("ExternalLoginFailure");
                }
                var user = new ApplicationUser { UserName = model.Email, Email = model.Email, Hometown = model.Hometown };
                var result = await UserManager.CreateAsync(user);
                if (result.Succeeded)
                {
                    result = await UserManager.AddLoginAsync(user.Id, info.Login);
                    if (result.Succeeded)
                    {
                        await SignInManager.SignInAsync(user, isPersistent: false, rememberBrowser: false);
                        return RedirectToLocal(returnUrl);
                    }
                }
                AddErrors(result);
            }

            ViewBag.ReturnUrl = returnUrl;
            return View(model);
        }
        public async Task<ActionResult> ExternalLoginCallback(string returnUrl)
        {
            var loginInfo = await AuthenticationManager.GetExternalLoginInfoAsync();
            if (loginInfo == null)
            {
                return RedirectoToLogin();
            }

            // ユーザーが既にログインを持っている場合、この外部ログイン プロバイダーを使用してユーザーをサインインします
            var result = await SignInManager.ExternalSignInAsync(loginInfo, isPersistent: false);
            switch (result)
            {
                case SignInStatus.Success:
                    return RedirectToLocal(returnUrl);
                case SignInStatus.LockedOut:
                    return LockoutView();
                case SignInStatus.RequiresVerification:
                    return RedirectToSendCode(returnUrl);
                case SignInStatus.Failure:
                default:
                    // ユーザーがアカウントを持っていない場合、ユーザーにアカウントを作成するよう求めます
                    ViewBag.ReturnUrl = returnUrl;
                    ViewBag.LoginProvider = loginInfo.Login.LoginProvider;
                    var model = new ExternalLoginConfirmationViewModel { Email = loginInfo.Email };
                    return ExternalLoginConfirmationView(model);
            }
        }
        public async Task<ActionResult> ExternalLoginConfirmation(ExternalLoginConfirmationViewModel model, string returnUrl)
        {
            if (User.Identity.IsAuthenticated)
            {
                return RedirectToManageIndex();
            }

            if (!ModelState.IsValid)
            {
                ViewBag.ReturnUrl = returnUrl;
                return ExternalLoginConfirmationView(model);
            }

            // 外部ログイン プロバイダーからユーザーに関する情報を取得します
            var info = await AuthenticationManager.GetExternalLoginInfoAsync();
            if (info == null)
            {
                return ExternalLoginFailureView();
            }
            var user = new ApplicationUser { UserName = model.Email, Email = model.Email };
            var result = await UserManager.CreateAsync(user);
            if (result.Succeeded)
            {
                result = await UserManager.AddLoginAsync(user.Id, info.Login);
                if (result.Succeeded)
                {
                    await SignInManager.SignInAsync(user, isPersistent: false, rememberBrowser: false);
                    return RedirectToLocal(returnUrl);
                }
            }
            AddErrors(result);
            ViewBag.ReturnUrl = returnUrl;
            return ExternalLoginConfirmationView(model);
        }
 private ActionResult ExternalLoginConfirmationView(ExternalLoginConfirmationViewModel model)
 {
     return View(ViewNames.ExternalLoginConfirmation, model);
 }