@page "/Account/ConfirmEmailChange"
@using System.Text
@using Microsoft.AspNetCore.Identity
@using Microsoft.AspNetCore.WebUtilities

@inject UserManager<IdentityUser>   UserManager
@inject SignInManager<IdentityUser> SignInManager
@inject IdentityRedirectManager     RedirectManager

<PageTitle>Confirm email change</PageTitle>

<h1>Confirm email change</h1>

<StatusMessage Message="@message"/>

@code {
    private string? message;

    [CascadingParameter]
    private HttpContext HttpContext { get; set; } = default!;

    [SupplyParameterFromQuery]
    private string? UserId { get; set; }

    [SupplyParameterFromQuery]
    private string? Email { get; set; }

    [SupplyParameterFromQuery]
    private string? Code { get; set; }

    protected override async Task OnInitializedAsync()
    {
        if(UserId is null || Email is null || Code is null)
        {
            RedirectManager.RedirectToWithStatus("Account/Login", "Error: Invalid email change confirmation link.", HttpContext);
        }

        IdentityUser? user = await UserManager.FindByIdAsync(UserId);

        if(user is null)
        {
            message = "Unable to find user with Id '{userId}'";

            return;
        }

        string         code   = Encoding.UTF8.GetString(WebEncoders.Base64UrlDecode(Code));
        IdentityResult result = await UserManager.ChangeEmailAsync(user, Email, code);

        if(!result.Succeeded)
        {
            message = "Error changing email.";

            return;
        }

        // In our UI email and user name are one and the same, so when we update the email
        // we need to update the user name.
        IdentityResult setUserNameResult = await UserManager.SetUserNameAsync(user, Email);

        if(!setUserNameResult.Succeeded)
        {
            message = "Error changing user name.";

            return;
        }

        await SignInManager.RefreshSignInAsync(user);
        message = "Thank you for confirming your email change.";
    }

}