Laravel issue whilst iterating using Map - (Update Global Variable outside map function) - loops

Question

I have a controller that should return a list of categories. Each should also have a collection of sub-categories. Each sub-category should also have modules. The modules are of two types: the latest modules and most watched modules.
A SUMMARY STRUCTURE I WANT:
[
{
id: 1,
name: category 1,
sub_categories:
[
{
id: 1,
name: subcategory 1:
modules:
[
latestModules: [...],
mostViewedModules[...]
]
}
],
another sub-category object,
and another sub-category object
},
another category object,
and another category object,
]
My Controller
class SeriesController extends Controller
{
public function getSeries()
{
$categories = Category::with('SubCategories')->get();
$countCats = 0;
$countSubCats = 0;
collect($categories)->map(function ($category) use ($countCats, $countSubCats, $categories){
collect($category->subCategories)->map(function ($subCategory) use ($countSubCats, $categories) {
collect($categories[$countCats]->subCategories[$countSubCats])
->put('modules',
SubCategory::with('latestModules', 'mostViewedModules')
->where('id', $subCategory->id)->get()
);
$countSubCats++;
});
$countCats++;
});
return $categories;
}
}
My Category model
class Category extends Model
{
public function subCategories()
{
return $this->hasMany('App\SubCategory')
->orderby('name');
}
}
My Subcategory Model
class SubCategory extends Model
{
public function parentCategory(){
return $this->belongsTo('App\Category', 'category_id');
}
public function modules()
{
return $this->belongsToMany('App\Module', 'module_category', 'sub_category_id', 'module_id');
}
public function latestModules()
{
return $this->modules()
->orderBy('created_at', 'desc');
}
public function mostViewedModules()
{
return $this->modules()
->orderBy('views', 'desc');
}
}
My Module Model
class Module extends Model
{
public function subCategories()
{
return $this->belongsToMany('App\SubCategory', 'module_category', 'module_id', 'sub_category_id');
}
}
WHAT I WAS TRYING TO DO
1) Get all the categories via Eloquent Query
2) Collect the many categories and Map over them
3) For each ONE category i map over again to single it out into sub-categories
4) For each sub-category i run Eloquent query to return the related modules.
5) Then i put that result into categories original array by using PUT. I wanted to expand on the original $categories array by including the modules.
PROBLEM
I realize that the loop works and everything is fine, except that the global $categories variable does not update. Its like inside the loops its updated but once we exist the Map loops the value defaults to
Category::with('SubCategories')->get()