Advanced Category Navigation

@using Nop.Core.Domain.Catalog
@using Nop.Core.Infrastructure
@using Nop.Services.Catalog
@model bool
@{
    var categoryService = EngineContext.Current.Resolve<ICategoryService>();
    var allCategories = categoryService.GetAllCategories();
    var allLevel1Categories = allCategories.Where(i => i.ParentCategoryId == 0);

    var onlyShowActiveHierarchy = Model;
    
    //current category ID
    var currentCategoryId = 0;
    if (Url.RequestContext.RouteData.Values["controller"].ToString().Equals("catalog", StringComparison.InvariantCultureIgnoreCase) &&
        Url.RequestContext.RouteData.Values["action"].ToString().Equals("category", StringComparison.InvariantCultureIgnoreCase))
    {
        currentCategoryId = Convert.ToInt32(Url.RequestContext.RouteData.Values["categoryId"].ToString());
    }

    //current product ID
    var currentProductId = 0;
    if (Url.RequestContext.RouteData.Values["controller"].ToString().Equals("product", StringComparison.InvariantCultureIgnoreCase) &&
        Url.RequestContext.RouteData.Values["action"].ToString().Equals("productdetails", StringComparison.InvariantCultureIgnoreCase))
    {
        currentProductId = Convert.ToInt32(Url.RequestContext.RouteData.Values["productId"].ToString());
    }

    if (currentProductId > 0)
    {
        var productCategories = categoryService.GetProductCategoriesByProductId(currentProductId);
        if (productCategories.Any())
        {
            currentCategoryId = productCategories[0].CategoryId;
        }
    }
}
@functions
{
    public bool ContainsSelectedCategory(int selectedCategoryId, int ancestorCategoryId, IEnumerable<Category> allCategories)
    {
        if (selectedCategoryId == ancestorCategoryId)
        {
            return true;
        }

        var selectedCategory = allCategories.FirstOrDefault(i => i.Id == selectedCategoryId);
        if (selectedCategory == null)
        {
            return false;
        }

        if (selectedCategory.ParentCategoryId == ancestorCategoryId)
        {
            return true;
        }

        return ContainsSelectedCategory(selectedCategory.ParentCategoryId, ancestorCategoryId, allCategories);
    }
}
@helper RenderCategoryList(int selectedCategoryId, int parentCategoryId, bool generateSubCategories, IEnumerable<Category> allCategories)
{
    var subCategories = EngineContext.Current.Resolve<ICategoryService>().GetAllCategoriesByParentCategoryId(parentCategoryId);
    if (!subCategories.Any() || !(generateSubCategories || ContainsSelectedCategory(selectedCategoryId, parentCategoryId, allCategories)))
    {
        return;
    }

    <ul class="list">
        @RenderCategoryLine(selectedCategoryId, subCategories, allCategories)
    </ul>
}
@helper RenderCategoryLine(int selectedCategoryId, IEnumerable<Category> categories, IEnumerable<Category> allCategories)
{
    var isSelected = false;
    foreach (var category in categories)
    {
        isSelected = category.Id == selectedCategoryId;
        <li class="@(isSelected ? "active" : "inactive")">
            @RenderCategoryLink(category)
            @RenderCategoryList(selectedCategoryId, category.Id, isSelected, allCategories)
        </li>
    }
}
@helper RenderCategoryLink(Category category)
{
    <a href="@Url.RouteUrl("Category", new { SeName = category.ToModel().SeName })">@category.Name</a>
}
@if (allLevel1Categories.Any())
{
    foreach (var category in allLevel1Categories)
    {
        if (onlyShowActiveHierarchy && !ContainsSelectedCategory(currentCategoryId, category.Id, allCategories))
        {
            continue;
        }

        <div class="block block-category-navigation">
            <div class="title">
                @RenderCategoryLink(category)
            </div>
            <div class="listbox">
                @RenderCategoryList(currentCategoryId, category.Id, true, allCategories)
            </div>
        </div>
    }
}