import logging

from rest_framework import status
from rest_framework.decorators import api_view, permission_classes
from rest_framework.permissions import IsAuthenticated
from rest_framework.response import Response

from .models import Notification
from .serializers import NotificationSerializer

logger = logging.getLogger(__name__)


def _safe_int(value, default=0):
    """安全转 int — 防止前端传非数字字符导致 500。"""
    try:
        return int(value)
    except (TypeError, ValueError):
        return default


@api_view(['GET'])
@permission_classes([IsAuthenticated])
def notifications_list_view(request):
    """GET /api/v1/notifications/

    Query params:
        unread_only: 'true' / 'false' (default 'false')
        page: 默认 1
        page_size: 默认 20, 上限 100

    Response:
        {
          "total": int,           # 当前过滤条件下总条数
          "unread_count": int,    # 该用户全部未读数(不受 unread_only/分页影响)
          "page": int,
          "page_size": int,
          "results": [...]
        }
    """
    user = request.user

    unread_only_raw = (request.query_params.get('unread_only') or 'false').strip().lower()
    unread_only = unread_only_raw in ('true', '1', 'yes')

    page = max(_safe_int(request.query_params.get('page'), 1), 1)
    page_size = _safe_int(request.query_params.get('page_size'), 20)
    if page_size <= 0:
        page_size = 20
    page_size = min(page_size, 100)

    base_qs = Notification.objects.filter(recipient=user)
    qs = base_qs
    if unread_only:
        qs = qs.filter(is_read=False)

    total = qs.count()
    # unread_count 必须基于该用户全部通知,不受 unread_only/分页影响
    unread_count = base_qs.filter(is_read=False).count()

    offset = (page - 1) * page_size
    records = list(qs.order_by('-created_at')[offset:offset + page_size])
    results = NotificationSerializer(records, many=True).data

    return Response({
        'total': total,
        'unread_count': unread_count,
        'page': page,
        'page_size': page_size,
        'results': results,
    })


@api_view(['GET'])
@permission_classes([IsAuthenticated])
def notifications_unread_count_view(request):
    """GET /api/v1/notifications/unread-count

    前端 60s 轮询,只拿数字不拉列表。
    """
    count = Notification.objects.filter(recipient=request.user, is_read=False).count()
    return Response({'unread_count': count})


@api_view(['PATCH'])
@permission_classes([IsAuthenticated])
def notification_mark_read_view(request, notification_id):
    """PATCH /api/v1/notifications/<id>/read

    标记某条通知为已读。404 if not found 或不属于当前用户。
    """
    try:
        notification = Notification.objects.get(pk=notification_id, recipient=request.user)
    except Notification.DoesNotExist:
        return Response({'error': '通知不存在'}, status=status.HTTP_404_NOT_FOUND)

    if not notification.is_read:
        notification.is_read = True
        notification.save(update_fields=['is_read'])

    return Response({'id': notification.id, 'is_read': True})


@api_view(['POST'])
@permission_classes([IsAuthenticated])
def notifications_mark_all_read_view(request):
    """POST /api/v1/notifications/read-all

    一键已读。返回被标已读的条数。
    """
    updated = Notification.objects.filter(
        recipient=request.user, is_read=False
    ).update(is_read=True)
    return Response({'updated': updated})