@inject LanguageProvider LanguageProvider
@inject IStringLocalizer<LanguageSelector> Localizer

<div class="dropdown">
    <button class="btn btn-outline-secondary dropdown-toggle"
            type="button"
            data-bs-toggle="dropdown"
            aria-expanded="false">
        @GetLanguageDisplayName(LanguageProvider.CurrentLanguage)
    </button>
    <ul class="dropdown-menu">
        @foreach (var language in LanguageProvider.SupportedLanguages)
        {
            <li>
                <button class="dropdown-item @(language == LanguageProvider.CurrentLanguage ? "active" : "")"
                        @onclick="() => ChangeLanguage(language)"
                        type="button">
                    @GetLanguageDisplayName(language)
                    @if (language == LanguageProvider.CurrentLanguage)
                    {
                        <span class="badge bg-primary">✓</span>
                    }
                </button>
            </li>
        }
    </ul>
</div>

@code {
    protected override void OnInitialized()
    {
        // 订阅变更以便在语言切换时即时更新该组件
        LanguageProvider.OnLanguageChanged += OnLanguageChanged;
    }

    private void OnLanguageChanged()
    {
        // 在 UI 线程上下文中触发 StateHasChanged
        _ = InvokeAsync(StateHasChanged);
    }

    public void Dispose()
    {
        LanguageProvider.OnLanguageChanged -= OnLanguageChanged;
    }

    private string GetLanguageDisplayName(string languageCode)
    {
        return languageCode switch
        {
            "zh-Hans" => "简体中文",
            "en-US" => "English (US)",
            _ => languageCode
        };
    }

    private async Task ChangeLanguage(string languageCode)
    {
        await LanguageProvider.ChangeLanguageAsync(languageCode);
    }
}