MathApp/content/views.py

from django.db.models import Sum
from django.shortcuts import get_object_or_404
from drf_spectacular.types import OpenApiTypes
from drf_spectacular.utils import OpenApiParameter, extend_schema
from rest_framework import status
from rest_framework.permissions import IsAuthenticated
from rest_framework.response import Response
from rest_framework.views import APIView

from progress.models import UserHearts, UserStats

from .models import Choice, Grade, Lesson, Question, UserAnswer, UserLessonCompletion
from .serializers import (
    AnswerRequestSerializer,
    AnswerResponseSerializer,
    GradesListResponseSerializer,
    HomeResponseSerializer,
    LessonCompleteRequestSerializer,
    LessonCompleteResponseSerializer,
    LessonIntroResponseSerializer,
    LessonQuestionsResponseSerializer,
)


class GradesListView(APIView):
    """GET /api/grades — لیست پایه‌ها"""

    @extend_schema(responses=GradesListResponseSerializer, tags=['Curriculum (content)'])
    def get(self, request):
        grades = Grade.objects.all().order_by('id')
        data = {'grades': [
            {'id': g.id, 'title': g.title, 'icon': g.icon, 'color': g.color} for g in grades
        ]}
        return Response(GradesListResponseSerializer(data).data)


def _node_status(node, user_id, is_first_unlocked_candidate):
    lesson_ids = list(node.lessons.values_list('id', flat=True))
    if not lesson_ids:
        return 'locked'
    completed_count = UserLessonCompletion.objects.filter(
        user_id=user_id, lesson_id__in=lesson_ids
    ).values('lesson_id').distinct().count()
    if completed_count >= len(lesson_ids):
        return 'completed'
    if completed_count > 0 or is_first_unlocked_candidate:
        return 'unlocked'
    return 'locked'


class HomeView(APIView):
    """GET /api/home?userId&grade — نقشه‌ی مهارت‌ها + آمار (ادغام‌شده)"""

    @extend_schema(
        parameters=[
            OpenApiParameter('userId', OpenApiTypes.INT, required=True),
            OpenApiParameter('grade', OpenApiTypes.INT, required=False),
        ],
        responses=HomeResponseSerializer,
        tags=['Curriculum (content)'],
    )
    def get(self, request):
        user_id = request.query_params.get('userId')
        grade_id = request.query_params.get('grade')
        if not user_id:
            return Response({'detail': 'پارامتر userId الزامی است.'}, status=status.HTTP_400_BAD_REQUEST)
        user_id = int(user_id)

        units_qs = Grade.objects.get(pk=grade_id).units.all() if grade_id else []

        units_payload = []
        for unit in units_qs:
            nodes = list(unit.nodes.all())
            node_payload = []
            unlock_next = True  # اولین نودِ قفل‌نشده در هر واحد، باز می‌مونه
            for node in nodes:
                node_status = _node_status(node, user_id, unlock_next)
                if node_status != 'completed':
                    unlock_next = False
                node_payload.append({'id': str(node.id), 'title': node.title, 'status': node_status})
            units_payload.append({'id': str(unit.id), 'title': unit.title, 'nodes': node_payload})

        stats = UserStats.objects.filter(user_id=user_id).first()
        stats_payload = {
            'progressPercent': stats.progress_percent if stats else 0,
            'xp': stats.xp if stats else 0,
            'coins': stats.coins if stats else 0,
        }

        data = {'units': units_payload, 'stats': stats_payload}
        return Response(HomeResponseSerializer(data).data)


class LessonIntroView(APIView):
    """GET /api/lessons/{id}/intro"""

    @extend_schema(responses=LessonIntroResponseSerializer, tags=['Curriculum (content)'])
    def get(self, request, lesson_id):
        lesson = get_object_or_404(Lesson, pk=lesson_id)
        data = {
            'lessonId': str(lesson.id),
            'title': lesson.title,
            'introText': lesson.intro_text,
            'mascotAnimation': lesson.mascot_animation,
        }
        return Response(LessonIntroResponseSerializer(data).data)


class LessonQuestionsView(APIView):
    """GET /api/lessons/{id}/questions"""

    @extend_schema(responses=LessonQuestionsResponseSerializer, tags=['Curriculum (content)'])
    def get(self, request, lesson_id):
        lesson = get_object_or_404(Lesson, pk=lesson_id)
        questions = lesson.questions.prefetch_related('choices').all()
        data = {'questions': [
            {
                'id': str(q.id),
                'type': q.type,
                'prompt': q.prompt,
                'options': [{'id': str(c.id), 'value': c.value} for c in q.choices.all()],
            }
            for q in questions
        ]}
        return Response(LessonQuestionsResponseSerializer(data).data)


class QuestionAnswerView(APIView):
    """POST /api/questions/{id}/answer — ثبت پاسخ"""

    # ⚠️ اصلاح امنیتی: قبلاً userId از query/body کلاینت خونده می‌شد که به
    # کلاینت اجازه می‌داد به‌جای هر کاربر دیگری پاسخ ثبت کنه (heart/xp کاربر
    # دلخواه رو تغییر بده). حالا auth اجباریه و همیشه از request.user.id
    # (که از توکن معتبر استخراج شده) استفاده می‌شه.
    permission_classes = [IsAuthenticated]

    @extend_schema(
        request=AnswerRequestSerializer,
        responses=AnswerResponseSerializer,
        tags=['Curriculum (content)'],
    )
    def post(self, request, question_id):
        question = get_object_or_404(Question, pk=question_id)
        serializer = AnswerRequestSerializer(data=request.data)
        serializer.is_valid(raise_exception=True)
        selected_option_id = serializer.validated_data['selectedOptionId']

        choice = get_object_or_404(Choice, pk=selected_option_id, question=question)
        correct_choice = question.choices.filter(is_correct=True).first()

        user_id = request.user.id
        xp_earned = 10 if choice.is_correct else 0

        UserAnswer.objects.create(
            user_id=user_id,
            question=question,
            choice=choice,
            correct=choice.is_correct,
            xp_earned=xp_earned,
        )
        if not choice.is_correct:
            hearts, _ = UserHearts.objects.get_or_create(user_id=user_id)
            if hearts.current_hearts > 0:
                hearts.current_hearts -= 1
                hearts.save(update_fields=['current_hearts'])
            hearts_remaining = hearts.current_hearts
        else:
            hearts = UserHearts.objects.filter(user_id=user_id).first()
            hearts_remaining = hearts.current_hearts if hearts else 5

        data = {
            'correct': choice.is_correct,
            'correctOptionId': str(correct_choice.id) if correct_choice else '',
            'xpEarned': xp_earned,
            'heartsRemaining': hearts_remaining if hearts_remaining is not None else 5,
        }
        return Response(AnswerResponseSerializer(data).data)


class LessonCompleteView(APIView):
    """POST /api/lessons/{id}/complete — اتمام درس + آمار جدید"""

    # ⚠️ اصلاح امنیتی: قبلاً userId از query/body کلاینت خونده می‌شد که به
    # کلاینت اجازه می‌داد به‌جای هر کاربر دیگری xp/coins ثبت کنه. حالا auth
    # اجباریه و همیشه از request.user.id استفاده می‌شه.
    permission_classes = [IsAuthenticated]

    @extend_schema(
        request=LessonCompleteRequestSerializer,
        responses=LessonCompleteResponseSerializer,
        tags=['Curriculum (content)'],
    )
    def post(self, request, lesson_id):
        lesson = get_object_or_404(Lesson, pk=lesson_id)
        serializer = LessonCompleteRequestSerializer(data=request.data)
        serializer.is_valid(raise_exception=True)
        correct_count = serializer.validated_data['correctCount']
        total_questions = serializer.validated_data['totalQuestions'] or 1

        ratio = correct_count / total_questions
        stars = 3 if ratio >= 0.9 else 2 if ratio >= 0.6 else 1 if ratio > 0 else 0
        potential_xp = correct_count * 10
        potential_coins = stars * 5

        user_id = request.user.id

        # ⚠️ اصلاح: تکمیل هر درس یک‌بارمصرفه — دفعات بعدیِ تکمیل همون درس
        # نباید دوباره xp/coins به آمار کاربر اضافه کنه (قبلاً هر بار
        # تکمیل، xp_earned/coins_earned رو بدون قید به stats اضافه می‌کرد).
        is_first_completion = not UserLessonCompletion.objects.filter(
            user_id=user_id, lesson=lesson
        ).exists()
        xp_earned = potential_xp if is_first_completion else 0
        coins_earned = potential_coins if is_first_completion else 0

        UserLessonCompletion.objects.create(
            user_id=user_id,
            lesson=lesson,
            correct_count=correct_count,
            stars=stars,
            xp_earned=xp_earned,
            coins_earned=coins_earned,
        )
        stats, _ = UserStats.objects.get_or_create(user_id=user_id)
        stats.xp += xp_earned
        stats.coins += coins_earned

        total_lessons = Lesson.objects.count() or 1
        completed_lessons = UserLessonCompletion.objects.filter(
            user_id=user_id
        ).values('lesson_id').distinct().count()
        stats.progress_percent = round(min(completed_lessons / total_lessons, 1.0) * 100, 2)
        stats.save(update_fields=['xp', 'coins', 'progress_percent'])

        stats_payload = {
            'progressPercent': stats.progress_percent,
            'xp': stats.xp,
            'coins': stats.coins,
        }

        data = {
            'stars': stars,
            'xpEarned': xp_earned,
            'coinsEarned': coins_earned,
            'stats': stats_payload,
        }
        return Response(LessonCompleteResponseSerializer(data).data)