@if (TotalCount == 0)
{
    return;
}

@{
    var totalPages = (int)Math.Ceiling((double)TotalCount / PageSize);
    var start = (CurrentPage - 1) * PageSize + 1;
    var end = Math.Min(CurrentPage * PageSize, TotalCount);
}

<div class="d-flex justify-content-between align-items-center mt-3">
    <small class="text-muted">Showing @start–@end of @TotalCount</small>

    @if (totalPages > 1)
    {
        <nav>
            <ul class="pagination pagination-sm mb-0">
                <li class="page-item @(CurrentPage == 1 ? "disabled" : "")">
                    <button class="page-link" @onclick="() => SetPage(CurrentPage - 1)" disabled="@(CurrentPage == 1)">Previous</button>
                </li>

                @foreach (var page in GetPageWindow(totalPages))
                {
                    @if (page == -1)
                    {
                        <li class="page-item disabled">
                            <span class="page-link">&hellip;</span>
                        </li>
                    }
                    else
                    {
                        <li class="page-item @(page == CurrentPage ? "active" : "")">
                            <button class="page-link" @onclick="() => SetPage(page)">@(page)</button>
                        </li>
                    }
                }

                <li class="page-item @(CurrentPage == totalPages ? "disabled" : "")">
                    <button class="page-link" @onclick="() => SetPage(CurrentPage + 1)" disabled="@(CurrentPage == totalPages)">Next</button>
                </li>
            </ul>
        </nav>
    }
</div>

@code {
    [Parameter, EditorRequired]
    public int TotalCount { get; set; }

    [Parameter]
    public int PageSize { get; set; } = 25;

    [Parameter]
    public int CurrentPage { get; set; } = 1;

    [Parameter]
    public EventCallback<int> CurrentPageChanged { get; set; }

    private async Task SetPage(int page)
    {
        if (page < 1 || page > (int)Math.Ceiling((double)TotalCount / PageSize))
            return;
        if (page == CurrentPage)
            return;

        CurrentPage = page;
        await CurrentPageChanged.InvokeAsync(page);
    }

    private IEnumerable<int> GetPageWindow(int totalPages)
    {
        const int maxVisible = 7;

        if (totalPages <= maxVisible)
        {
            for (var i = 1; i <= totalPages; i++)
                yield return i;
            yield break;
        }

        // Always show first page
        yield return 1;

        var windowStart = Math.Max(2, CurrentPage - 2);
        var windowEnd = Math.Min(totalPages - 1, CurrentPage + 2);

        // Adjust window to show 5 middle pages when possible
        if (windowEnd - windowStart < 4)
        {
            if (windowStart == 2)
                windowEnd = Math.Min(totalPages - 1, windowStart + 4);
            else
                windowStart = Math.Max(2, windowEnd - 4);
        }

        if (windowStart > 2)
            yield return -1; // ellipsis

        for (var i = windowStart; i <= windowEnd; i++)
            yield return i;

        if (windowEnd < totalPages - 1)
            yield return -1; // ellipsis

        // Always show last page
        yield return totalPages;
    }
}