from rest_framework.decorators import api_view, permission_classes
from rest_framework.permissions import IsAuthenticated
from rest_framework.response import Response
from django.db.models import Count
from datetime import datetime, timedelta
from wrestlers.models import Wrestler
from trainers.models import Trainer
from trainings.models import Training, Attendance
from homework.models import TrainingHomeworkAssignment


@api_view(['GET'])
@permission_classes([IsAuthenticated])
def dashboard_stats(request):
    today = datetime.now().date()
    week_start = today - timedelta(days=today.weekday())
    two_weeks_ago = today - timedelta(days=14)
    
    # Wrestlers stats
    total_wrestlers = Wrestler.objects.count()
    wrestlers_this_week = Wrestler.objects.filter(
        created_at__date__gte=week_start
    ).count()
    
    # Trainers stats
    total_trainers = Trainer.objects.count()
    active_trainers = Trainer.objects.filter(is_active=True).count()
    
    # Trainings stats
    total_trainings = Training.objects.count()
    trainings_this_week = Training.objects.filter(
        date__gte=week_start
    ).count()
    
    # Homework stats
    open_homework = TrainingHomeworkAssignment.objects.filter(is_completed=False).count()
    completed_homework = TrainingHomeworkAssignment.objects.filter(is_completed=True).count()
    
    # Attendance by group this week
    trainings_this_week_qs = Training.objects.filter(date__gte=week_start)
    attendance_data = {}
    for group, label in [('kids', 'Kinder'), ('youth', 'Jugend'), ('adults', 'Erwachsene')]:
        group_wrestlers = Wrestler.objects.filter(group=group)
        attended = Attendance.objects.filter(
            training__in=trainings_this_week_qs,
            wrestler__in=group_wrestlers
        ).values('wrestler').distinct().count()
        total = group_wrestlers.count()
        attendance_data[group] = {
            'attended': attended,
            'total': total,
            'percent': int((attended / total * 100) if total > 0 else 0)
        }
    
    # Activity (last 14 days)
    activity = []
    for i in range(14):
        day = today - timedelta(days=13 - i)
        count = Attendance.objects.filter(training__date=day).count()
        activity.append({'date': day.isoformat(), 'count': count})
    
    # Wrestlers by group
    wrestlers_by_group = {
        'kids': Wrestler.objects.filter(group='kids', is_active=True).count(),
        'youth': Wrestler.objects.filter(group='youth', is_active=True).count(),
        'adults': Wrestler.objects.filter(group='adults', is_active=True).count(),
        'inactive': Wrestler.objects.filter(is_active=False).count(),
    }
    
    # Top trainers (by training count)
    trainer_stats = Trainer.objects.annotate(
        training_count=Count('trainings')
    ).order_by('-training_count')[:5]
    top_trainers = [
        {'name': t.first_name + ' ' + t.last_name[0] + '.', 'training_count': t.training_count}
        for t in trainer_stats
    ]
    
    return Response({
        'wrestlers': {'total': total_wrestlers, 'this_week': wrestlers_this_week},
        'trainers': {'total': total_trainers, 'active': active_trainers},
        'trainings': {'total': total_trainings, 'this_week': trainings_this_week},
        'homework': {'open': open_homework, 'completed': completed_homework},
        'attendance': {
            'this_week': attendance_data,
            'average': Attendance.objects.filter(training__date__gte=week_start).values('training').distinct().count(),
            'expected': total_wrestlers
        },
        'activity': activity,
        'wrestlers_by_group': wrestlers_by_group,
        'top_trainers': top_trainers,
    })