from rest_framework import viewsets
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, Avg, Sum, F
from django.db.models.functions import Coalesce
from datetime import datetime, timedelta
from .models import TrainingLogEntry
from .serializers import TrainingLogEntrySerializer
from wrestlers.models import Wrestler


class TrainingLogEntryViewSet(viewsets.ModelViewSet):
    permission_classes = [IsAuthenticated]
    serializer_class = TrainingLogEntrySerializer

    def get_queryset(self):
        queryset = TrainingLogEntry.objects.all()
        wrestler = self.request.query_params.get('wrestler')
        exercise = self.request.query_params.get('exercise')
        date_from = self.request.query_params.get('date_from')
        date_to = self.request.query_params.get('date_to')

        if wrestler:
            queryset = queryset.filter(wrestler=wrestler)
        if exercise:
            queryset = queryset.filter(exercise=exercise)
        if date_from:
            queryset = queryset.filter(logged_at__date__gte=date_from)
        if date_to:
            queryset = queryset.filter(logged_at__date__lte=date_to)

        return queryset.select_related('wrestler', 'exercise', 'training')


@api_view(['GET'])
@permission_classes([IsAuthenticated])
def training_log_stats(request):
    wrestler_id = request.query_params.get('wrestler')
    today = datetime.now().date()
    week_start = today - timedelta(days=today.weekday())

    queryset = TrainingLogEntry.objects.all()
    if wrestler_id:
        queryset = queryset.filter(wrestler=wrestler_id)

    total_entries = queryset.count()
    unique_exercises = queryset.values('exercise').distinct().count()
    total_reps = queryset.aggregate(total=Coalesce(Sum(F('reps') * F('sets')), 0))['total'] or 0
    avg_sets = queryset.aggregate(avg=Avg('sets'))['avg'] or 0
    avg_rating = queryset.aggregate(avg=Avg('rating'))['avg'] or 0
    this_week = queryset.filter(logged_at__date__gte=week_start).count()

    top_exercises = queryset.values('exercise__name').annotate(
        count=Count('id')
    ).order_by('-count')[:5]

    progress = {}
    exercises = queryset.values('exercise', 'exercise__name').distinct()
    for ex in exercises:
        ex_id = ex['exercise']
        entries = queryset.filter(exercise=ex_id).order_by('logged_at')
        if entries.count() >= 2:
            first_reps = entries.first().reps * entries.first().sets
            last_reps = entries.last().reps * entries.last().sets
            if first_reps > 0:
                change = ((last_reps - first_reps) / first_reps) * 100
                progress[ex['exercise__name']] = {
                    'before': first_reps,
                    'after': last_reps,
                    'change_percent': round(change, 1)
                }

    return Response({
        'total_entries': total_entries,
        'unique_exercises': unique_exercises,
        'total_reps': total_reps,
        'avg_sets': round(avg_sets, 1),
        'avg_rating': round(avg_rating, 1),
        'this_week': this_week,
        'top_exercises': [{'name': e['exercise__name'], 'count': e['count']} for e in top_exercises],
        'progress': progress,
    })


@api_view(['GET'])
@permission_classes([IsAuthenticated])
def training_log_compare(request):
    wrestler1_id = request.query_params.get('wrestler1')
    wrestler2_id = request.query_params.get('wrestler2')

    if not wrestler1_id or not wrestler2_id:
        return Response({'error': 'Both wrestler1 and wrestler2 required'}, status=400)

    wrestler1 = Wrestler.objects.get(id=wrestler1_id)
    wrestler2 = Wrestler.objects.get(id=wrestler2_id)

    entries1 = TrainingLogEntry.objects.filter(wrestler=wrestler1)
    entries2 = TrainingLogEntry.objects.filter(wrestler=wrestler2)

    exercises1 = entries1.values('exercise', 'exercise__name').distinct()
    exercises2 = entries2.values('exercise', 'exercise__name').distinct()
    common_exercises = set(e['exercise'] for e in exercises1) & set(e['exercise'] for e in exercises2)

    comparison = []
    for ex_id in common_exercises:
        ex_name = entries1.filter(exercise=ex_id).first().exercise.name
        avg1 = entries1.filter(exercise=ex_id).aggregate(avg=Avg(F('reps') * F('sets')))['avg'] or 0
        avg2 = entries2.filter(exercise=ex_id).aggregate(avg=Avg(F('reps') * F('sets')))['avg'] or 0
        comparison.append({
            'exercise': ex_name,
            'wrestler1_avg': round(avg1, 1),
            'wrestler2_avg': round(avg2, 1)
        })

    return Response({
        'wrestler1': {'id': wrestler1.id, 'name': str(wrestler1)},
        'wrestler2': {'id': wrestler2.id, 'name': str(wrestler2)},
        'exercises': comparison
    })