@page "/Account/Manage/ExternalLogins"
@using Microsoft.AspNetCore.Authentication
@using Microsoft.AspNetCore.Identity

@inject UserManager<IdentityUser>   UserManager
@inject SignInManager<IdentityUser> SignInManager
@inject IdentityUserAccessor        UserAccessor
@inject IUserStore<IdentityUser>    UserStore
@inject IdentityRedirectManager     RedirectManager

<PageTitle>Manage your external logins</PageTitle>

<StatusMessage/>
@if(currentLogins?.Count > 0)
{
    <h3>Registered Logins</h3>
    <table class="table">
        <tbody>
        @foreach(UserLoginInfo login in currentLogins)
        {
            <tr>
                <td>@login.ProviderDisplayName</td>
                <td>
                    @if(showRemoveButton)
                    {
                        <form @formname="@($"remove-login-{login.LoginProvider}")" method="post" @onsubmit="OnSubmitAsync">
                            <AntiforgeryToken/>
                            <div>
                                <input name="@nameof(LoginProvider)" type="hidden" value="@login.LoginProvider"/>
                                <input name="@nameof(ProviderKey)" type="hidden" value="@login.ProviderKey"/>
                                <button class="btn btn-primary" title="Remove this @login.ProviderDisplayName login from your account" type="submit">Remove</button>
                            </div>
                        </form>
                    }
                    else
                    {
                        @: &nbsp;
                    }
                </td>
            </tr>
        }
        </tbody>
    </table>
}
@if(otherLogins?.Count > 0)
{
    <h4>Add another service to log in.</h4>
    <hr/>
    <form action="Account/Manage/LinkExternalLogin" class="form-horizontal" method="post">
        <AntiforgeryToken/>
        <div>
            <p>
                @foreach(AuthenticationScheme provider in otherLogins)
                {
                    <button class="btn btn-primary" name="Provider" title="Log in using your @provider.DisplayName account" type="submit" value="@provider.Name">
                        @provider.DisplayName
                    </button>
                }
            </p>
        </div>
    </form>
}

@code {
    public const string LinkLoginCallbackAction = "LinkLoginCallback";

    private IdentityUser                 user = default!;
    private IList<UserLoginInfo>?        currentLogins;
    private IList<AuthenticationScheme>? otherLogins;
    private bool                         showRemoveButton;

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

    [SupplyParameterFromForm]
    private string? LoginProvider { get; set; }

    [SupplyParameterFromForm]
    private string? ProviderKey { get; set; }

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

    protected override async Task OnInitializedAsync()
    {
        user          = await UserAccessor.GetRequiredUserAsync(HttpContext);
        currentLogins = await UserManager.GetLoginsAsync(user);
        otherLogins   = (await SignInManager.GetExternalAuthenticationSchemesAsync()).Where(auth => currentLogins.All(ul => auth.Name != ul.LoginProvider)).ToList();

        string? passwordHash = null;

        if(UserStore is IUserPasswordStore<IdentityUser> userPasswordStore)
        {
            passwordHash = await userPasswordStore.GetPasswordHashAsync(user, HttpContext.RequestAborted);
        }

        showRemoveButton = passwordHash is not null || currentLogins.Count > 1;

        if(HttpMethods.IsGet(HttpContext.Request.Method) && Action == LinkLoginCallbackAction)
        {
            await OnGetLinkLoginCallbackAsync();
        }
    }

    private async Task OnSubmitAsync()
    {
        IdentityResult result = await UserManager.RemoveLoginAsync(user, LoginProvider!, ProviderKey!);

        if(!result.Succeeded)
        {
            RedirectManager.RedirectToCurrentPageWithStatus("Error: The external login was not removed.", HttpContext);
        }

        await SignInManager.RefreshSignInAsync(user);
        RedirectManager.RedirectToCurrentPageWithStatus("The external login was removed.", HttpContext);
    }

    private async Task OnGetLinkLoginCallbackAsync()
    {
        string             userId = await UserManager.GetUserIdAsync(user);
        ExternalLoginInfo? info   = await SignInManager.GetExternalLoginInfoAsync(userId);

        if(info is null)
        {
            RedirectManager.RedirectToCurrentPageWithStatus("Error: Could not load external login info.", HttpContext);
        }

        IdentityResult result = await UserManager.AddLoginAsync(user, info);

        if(!result.Succeeded)
        {
            RedirectManager.RedirectToCurrentPageWithStatus("Error: The external login was not added. External logins can only be associated with one account.", HttpContext);
        }

        // Clear the existing external cookie to ensure a clean login process
        await HttpContext.SignOutAsync(IdentityConstants.ExternalScheme);

        RedirectManager.RedirectToCurrentPageWithStatus("The external login was added.", HttpContext);
    }

}