import json
from django.http import JsonResponse, HttpResponseNotFound
from django.shortcuts import render
from .models import Link
from django.views.decorators.csrf import csrf_exempt


def index(request):
    """
    Renders a page that will load the data via JavaScript (AJAX fetch).
    """
    return render(request, 'links/index.html')


def links_list(request):
    """
    Return JSON list of all links.
    """

    try:
        page = int(request.GET.get('page', 1))
        per_page = int(request.GET.get('per_page', 8))
        watched = bool(request.GET.get('watched', ""))
    except ValueError:
        return JsonResponse({'error': 'Invalid page or per_page'}, status=400)

    offset = (page - 1) * per_page
    limit = offset + per_page

    all_links = Link.objects.all().order_by('-id')  # latest first
    total = all_links.count()
    limit_results = list(all_links[offset:limit].values('id', 'url', 'watched'))
    results = filter(lambda row: row['watched'] == str(watched), limit_results)

    return JsonResponse({
        'results': results,
        'total': total,
        'page': page,
        'per_page': per_page,
        'pages': (total + per_page - 1) // per_page
    })


@csrf_exempt
def add_link(request):
    """
    POST endpoint to add a new link.
    """
    if request.method == 'POST':
        body = json.loads(request.body)
        url = body.get('url')
        if url:
            link = Link.objects.create(url=url, watched=False)
            return JsonResponse({'id': link.id, 'url': link.url, 'watched': link.watched}, status=201)
        else:
            return JsonResponse({'error': 'URL is required'}, status=400)
    else:
        return JsonResponse({'error': 'Method not allowed'}, status=405)
    
    
@csrf_exempt
def delete_link(request, link_id):
    if request.method == 'DELETE':
        try:
            link = Link.objects.get(pk=link_id)
            link.delete()
            return JsonResponse({'status': 'deleted'})
        except Link.DoesNotExist:
            return HttpResponseNotFound()
    return JsonResponse({'error': 'Method not allowed'}, status=405)


@csrf_exempt
def mark_watched(request, link_id):
    """
    PATCH endpoint to mark a link as watched.
    """
    if request.method == 'PATCH':
        try:
            link = Link.objects.get(pk=link_id)
        except Link.DoesNotExist:
            return HttpResponseNotFound()

        link.watched = True
        link.save()
        return JsonResponse({'id': link.id, 'url': link.url, 'watched': link.watched})
    else:
        return JsonResponse({'error': 'Method not allowed'}, status=405)