@inject ILocalizationProvider LocalizationProvider
@inject NavigationManager Navigation
@inject IJSRuntime JS

<select @onchange="OnChange" value="@selected">
    @foreach (var item in options)
    {
        <option value="@item.Key">@item.Value</option>
    }
</select>

@code {
    private string selected = "zh";

    private readonly Dictionary<string, string> options = new(StringComparer.OrdinalIgnoreCase)
    {
        { "zh", "ÖÐÎÄ" },
        { "en", "English" }
    };

    protected override async Task OnInitializedAsync()
    {
        var current = LocalizationProvider.CurrentCulture;
        var mapping = new Dictionary<string, string>(StringComparer.OrdinalIgnoreCase)
        {
            { "zh", "zh-Hans" },
            { "en", "en-US" }
        };
        var found = mapping.FirstOrDefault(kv => string.Equals(kv.Value, current, StringComparison.OrdinalIgnoreCase)).Key;
        if (!string.IsNullOrEmpty(found)) selected = found;

        LocalizationProvider.LanguageChanged += (s, c) =>
        {
            var found2 = mapping.FirstOrDefault(kv => string.Equals(kv.Value, c, StringComparison.OrdinalIgnoreCase)).Key;
            if (!string.IsNullOrEmpty(found2)) selected = found2;
            StateHasChanged();
        };
    }

    private async Task OnChange(ChangeEventArgs e)
    {
        if (e?.Value is string val)
        {
            selected = val;
            await LocalizationProvider.SetCultureAsync(selected);

            try
            {
                // Use NavigationManager to inspect and modify the current client-side path
                var relative = Navigation.ToBaseRelativePath(Navigation.Uri).Trim('/');
                var segments = string.IsNullOrEmpty(relative) ? Array.Empty<string>() : relative.Split('/', StringSplitOptions.RemoveEmptyEntries);
                var mapping = new Dictionary<string, string>(StringComparer.OrdinalIgnoreCase)
                {
                    { "zh", "zh-Hans" },
                    { "en", "en-US" }
                };

                string newUrl;
                if (segments.Length > 0 && mapping.ContainsKey(segments[0]))
                {
                    // replace existing locale prefix
                    var remaining = segments.Length > 1 ? "/" + string.Join('/', segments.Skip(1)) : "/";
                    newUrl = "/" + selected + remaining;
                }
                else
                {
                    // keep current path, but trigger remount by navigating to same URI
                    newUrl = Navigation.Uri;
                }

                // trigger client-side navigation (no hard reload) so components remount and re-evaluate localizer
                Navigation.NavigateTo(newUrl, forceLoad: false);
                return;
            }
            catch
            {
                // fallback: just request UI refresh
                StateHasChanged();
            }
        }
    }
}