from django.shortcuts import render, get_object_or_404
from django.core.paginator import Paginator
from .models import Category
from apps.events.models import Event


def category_list(request):
    categories = Category.objects.filter(parent=None).prefetch_related('children')

    # Annotate each root category with the total event count across
    # itself AND all its child categories combined.
    from apps.events.models import Event
    cat_list = []
    for cat in categories:
        all_ids = [cat.id] + [c.id for c in cat.get_descendants()]
        total   = Event.objects.filter(category_id__in=all_ids, status='published').count()
        cat.total_event_count = total
        cat_list.append(cat)

    return render(request, 'categories/web/list.html', {'categories': cat_list})


def category_detail(request, slug):
    cat = get_object_or_404(Category, slug=slug)

    # Collect this category + all descendants so that browsing "Technology"
    # also shows events filed under "AI", "Web Dev", "Cybersecurity", etc.
    all_cats = [cat] + cat.get_descendants()
    all_cat_ids = [c.id for c in all_cats]

    events_qs = (
        Event.objects
        .filter(category_id__in=all_cat_ids, status='published')
        .order_by('-start_date')
        .select_related('category')
        .prefetch_related('tags')
    )

    paginator = Paginator(events_qs, 12)
    page_obj  = paginator.get_page(request.GET.get('page'))

    return render(request, 'categories/web/detail.html', {
        'cat': cat,
        'subcategories': all_cats[1:],   # child chips shown in template
        'events': page_obj,
        'page_obj': page_obj,
        'total_events': events_qs.count(),
    })