EnvelopeGenerator/EnvelopeGenerator.Server/EnvelopeGenerator.Server.Client/Layout/LanguageControls.razor

@using EnvelopeGenerator.Server.Client.Services
@using EnvelopeGenerator.Application.Resources
@using Microsoft.Extensions.Localization
@rendermode InteractiveWebAssembly

@inject LocalizationService LocalizationService
@inject NavigationManager Navigation
@inject IStringLocalizer<Resource> UiLocalizer

<div class="sf-lang-combo">
    <button type="button"
            class="sf-lang-trigger"
            @onclick="ToggleMenu"
            aria-label="@L("Language", "Language")"
            aria-expanded="@_isOpen">
        <span class="fi @_selected.FlagClass"></span>
    </button>

    @if (_isOpen)
    {
        <button type="button"
                class="sf-lang-backdrop"
                aria-label="@L("CloseLanguageMenu", "Close language menu")"
                @onclick="CloseMenu">
        </button>

        <div class="sf-lang-menu" role="listbox" aria-label="@L("Languages", "Languages")">
            @foreach (var option in _options)
            {
                <button type="button"
                        class="sf-lang-option @(_selected.Code == option.Code ? "sf-lang-option--active" : string.Empty)"
                        role="option"
                        aria-selected="@(_selected.Code == option.Code)"
                        @onmousedown:preventDefault="true"
                        @onclick="() => SelectLanguageAsync(option)">
                    <span class="fi @option.FlagClass"></span>
                    <span>@option.ShortName</span>
                </button>
            }
        </div>
    }
</div>

@code {
    private readonly IReadOnlyList<LanguageOption> _options =
    [
        new("de-DE", "fi-de", "DE"),
        new("en-US", "fi-us", "EN"),
        new("fr-FR", "fi-fr", "FR")
    ];

    private LanguageOption _selected = new("de-DE", "fi-de", "DE");
    private bool _isOpen;

    protected override async Task OnInitializedAsync()
    {
        var currentLanguage = await LocalizationService.GetLanguageAsync();
        _selected = _options.FirstOrDefault(x => x.Code.Equals(currentLanguage, StringComparison.OrdinalIgnoreCase))
            ?? _options[0];
    }

    private void ToggleMenu()
    {
        _isOpen = !_isOpen;
    }

    private void CloseMenu()
    {
        _isOpen = false;
    }

    private async Task SelectLanguageAsync(LanguageOption option)
    {
        if (_selected.Code.Equals(option.Code, StringComparison.OrdinalIgnoreCase))
        {
            _isOpen = false;
            return;
        }

        _selected = option;
        _isOpen = false;
        await LocalizationService.SetLanguageAsync(option.Code);
        Navigation.NavigateTo(Navigation.Uri, forceLoad: true);
    }

    private sealed record LanguageOption(string Code, string FlagClass, string ShortName);

    string L(string key, string fallback)
    {
        var value = UiLocalizer[key];
        return value.ResourceNotFound ? fallback : value.Value;
    }
}