# blog/views.py

import os
import re
import boto3
from botocore.client import Config
from django.conf import settings
from rest_framework import generics, viewsets, permissions, status
from rest_framework.exceptions import PermissionDenied
from rest_framework.response import Response
from rest_framework.views import APIView
from rest_framework.parsers import MultiPartParser, FormParser
from django.shortcuts import get_object_or_404
from django.db.models import Q
from .models import Post, Comment, Tag, Attachment
from .serializers import PostSerializer, PostListSerializer, CommentSerializer, TagSerializer, AttachmentSerializer
import logging

logger = logging.getLogger(__name__)


def get_unique_filename(original_name, existing_names):
    """
    중복 파일명이 있으면 (2), (3) 등의 번호를 추가하여 고유한 파일명 반환
    예: test.png -> test(2).png -> test(3).png
    """
    if original_name not in existing_names:
        return original_name

    # 파일명과 확장자 분리
    name, ext = os.path.splitext(original_name)

    # 기존 번호 패턴 확인 (예: test(2) -> test, 2)
    match = re.match(r'^(.+)\((\d+)\)$', name)
    if match:
        base_name = match.group(1)
        start_num = int(match.group(2)) + 1
    else:
        base_name = name
        start_num = 2

    # 고유한 번호 찾기
    counter = start_num
    while True:
        new_name = f"{base_name}({counter}){ext}"
        if new_name not in existing_names:
            return new_name
        counter += 1


class TagListView(generics.ListAPIView):
    """태그 목록 조회"""
    queryset = Tag.objects.all()
    serializer_class = TagSerializer
    permission_classes = [permissions.AllowAny]

    def list(self, request, *args, **kwargs):
        response = super().list(request, *args, **kwargs)
        logger.info(f"Tags list requested. Count: {len(response.data)}")
        return response


class PostListView(generics.ListAPIView):
    """공개 포스트 목록 조회"""
    queryset = Post.objects.all()
    serializer_class = PostListSerializer
    permission_classes = [permissions.AllowAny]

    def get_queryset(self):
        user = self.request.user

        if user.is_authenticated:
            # 로그인 사용자: 공개 게시글 + 자신의 비공개 게시글
            user_id = str(getattr(user, 'id', '') or getattr(user, 'email', ''))
            username = getattr(user, 'username', '') or getattr(user, 'email', '')

            # 자신의 비공개 게시글 조건 (빈 문자열은 제외)
            private_conditions = Q()
            if user_id:
                private_conditions |= Q(is_private=True, author_id=user_id)
            if username:
                private_conditions |= Q(is_private=True, author_name=username)

            queryset = Post.objects.filter(Q(is_private=False) | private_conditions)
        else:
            # 비로그인 사용자: 공개 게시글만
            queryset = Post.objects.filter(is_private=False)

        tag = self.request.query_params.get('tag')
        if tag:
            queryset = queryset.filter(tags__name=tag)
        return queryset

    def list(self, request, *args, **kwargs):
        response = super().list(request, *args, **kwargs)
        tag = request.query_params.get('tag', 'all')
        logger.info(f"Posts list requested. Tag: {tag}, Count: {len(response.data)}")
        return response


class PostListCreateView(generics.ListCreateAPIView):
    """인증 사용자용 포스트 목록/생성"""
    queryset = Post.objects.all()
    serializer_class = PostSerializer
    permission_classes = [permissions.IsAuthenticated]

    def perform_create(self, serializer):
        user = self.request.user
        author_id = getattr(user, 'id', '') or getattr(user, 'email', '')
        author_name = getattr(user, 'username', '') or getattr(user, 'email', '')
        instance = serializer.save(author_id=str(author_id), author_name=author_name)
        logger.info(f"Post titled '{instance.title}' has been created by {author_name}.")


class PostDetailView(generics.RetrieveUpdateDestroyAPIView):
    """포스트 상세 조회/수정/삭제"""
    queryset = Post.objects.all()
    serializer_class = PostSerializer

    def get_permissions(self):
        if self.request.method in ["PUT", "PATCH", "DELETE"]:
            return [permissions.IsAuthenticated()]
        return [permissions.AllowAny()]

    def retrieve(self, request, *args, **kwargs):
        instance = self.get_object()

        # 비공개 게시글은 작성자만 조회 가능
        if instance.is_private:
            user = request.user
            if not user.is_authenticated:
                raise PermissionDenied("비공개 게시글입니다.")
            user_id = str(getattr(user, 'id', '') or getattr(user, 'email', ''))
            username = getattr(user, 'username', '') or getattr(user, 'email', '')
            if instance.author_id != user_id and instance.author_name != username:
                raise PermissionDenied("비공개 게시글입니다.")

        serializer = self.get_serializer(instance)
        logger.info(f"Post detail requested. ID: {kwargs.get('pk')}, Title: {serializer.data.get('title')}")
        return Response(serializer.data)

    def perform_update(self, serializer):
        instance = serializer.instance
        user = self.request.user
        user_id = str(getattr(user, 'id', '') or getattr(user, 'email', ''))
        username = getattr(user, 'username', '') or getattr(user, 'email', '')

        # 작성자 확인
        if instance.author_id != user_id and instance.author_name != username:
            raise PermissionDenied("작성자만 수정할 수 있습니다.")

        serializer.save()
        logger.info(f"Post titled '{instance.title}' has been updated by {username}.")

    def perform_destroy(self, instance):
        user = self.request.user
        user_id = str(getattr(user, 'id', '') or getattr(user, 'email', ''))
        username = getattr(user, 'username', '') or getattr(user, 'email', '')

        # 작성자 확인
        if instance.author_id != user_id and instance.author_name != username:
            raise PermissionDenied("작성자만 삭제할 수 있습니다.")

        title = instance.title
        instance.delete()
        logger.info(f"Post titled '{title}' has been deleted by {username}.")


class CommentViewSet(viewsets.ModelViewSet):
    """댓글/대댓글 CRUD ViewSet"""
    serializer_class = CommentSerializer

    def get_permissions(self):
        if self.action in ['list', 'retrieve']:
            return [permissions.AllowAny()]
        return [permissions.IsAuthenticated()]

    def get_post(self):
        """현재 포스트 가져오기"""
        post_pk = self.kwargs.get('post_pk')
        return get_object_or_404(Post, pk=post_pk)

    def get_queryset(self):
        post_pk = self.kwargs.get('post_pk')
        if post_pk:
            # list 액션에서만 최상위 댓글 반환, 나머지는 모든 댓글 접근 가능
            if self.action == 'list':
                return Comment.objects.filter(post_id=post_pk, parent__isnull=True)
            return Comment.objects.filter(post_id=post_pk)
        return Comment.objects.none()

    def list(self, request, *args, **kwargs):
        response = super().list(request, *args, **kwargs)
        post_pk = kwargs.get('post_pk')
        logger.info(f"Comments list requested. Post ID: {post_pk}, Count: {len(response.data)}")
        return response

    def perform_create(self, serializer):
        post = self.get_post()
        user = self.request.user
        author_id = str(getattr(user, 'id', '') or getattr(user, 'email', ''))
        author_name = getattr(user, 'username', '') or getattr(user, 'email', '')

        # parent 검증 (대댓글인 경우)
        parent_id = self.request.data.get('parent')
        parent = None
        if parent_id:
            parent = get_object_or_404(Comment, pk=parent_id, post=post)

        instance = serializer.save(
            post=post,
            parent=parent,
            author_id=author_id,
            author_name=author_name
        )
        logger.info(f"Comment created on post '{post.title}' by {author_name}.")

    def perform_update(self, serializer):
        instance = serializer.instance
        user = self.request.user
        user_id = str(getattr(user, 'id', '') or getattr(user, 'email', ''))
        username = getattr(user, 'username', '') or getattr(user, 'email', '')

        # 작성자 확인
        if instance.author_id != user_id and instance.author_name != username:
            raise PermissionDenied("작성자만 수정할 수 있습니다.")

        serializer.save()
        logger.info(f"Comment {instance.id} updated by {username}.")

    def perform_destroy(self, instance):
        user = self.request.user
        user_id = str(getattr(user, 'id', '') or getattr(user, 'email', ''))
        username = getattr(user, 'username', '') or getattr(user, 'email', '')

        # 작성자 확인
        if instance.author_id != user_id and instance.author_name != username:
            raise PermissionDenied("작성자만 삭제할 수 있습니다.")

        comment_id = instance.id
        instance.delete()
        logger.info(f"Comment {comment_id} deleted by {username}.")


class TempAttachmentUploadView(APIView):
    """임시 첨부파일 업로드 (게시글 작성 전)"""
    permission_classes = [permissions.IsAuthenticated]
    parser_classes = [MultiPartParser, FormParser]

    def post(self, request):
        """임시 파일 업로드 - 게시글 없이 파일만 먼저 업로드"""
        user = request.user
        user_id = str(getattr(user, 'id', '') or getattr(user, 'email', ''))
        username = getattr(user, 'username', '') or getattr(user, 'email', '')

        file = request.FILES.get('file')
        if not file:
            return Response(
                {'detail': '파일이 필요합니다.'},
                status=status.HTTP_400_BAD_REQUEST
            )

        # 파일 크기 제한 (10MB)
        if file.size > 10 * 1024 * 1024:
            return Response(
                {'detail': '파일 크기는 10MB를 초과할 수 없습니다.'},
                status=status.HTTP_400_BAD_REQUEST
            )

        # batch_id로 같은 배치 내 중복 파일명 체크
        batch_id = request.data.get('batch_id', '')
        original_name = file.name

        if batch_id:
            # 같은 배치 내 기존 파일명 목록
            existing_names = list(
                Attachment.objects.filter(
                    post__isnull=True,
                    batch_id=batch_id
                ).values_list('original_name', flat=True)
            )
            original_name = get_unique_filename(file.name, existing_names)

        # MinIO에 파일 저장 (post=None으로 임시 저장)
        attachment = Attachment.objects.create(
            post=None,
            file=file,
            original_name=original_name,
            file_size=file.size,
            uploader_id=user_id,
            uploader_name=username,
            batch_id=batch_id
        )

        serializer = AttachmentSerializer(attachment)
        logger.info(f"Temp attachment '{original_name}' uploaded by {username}. batch_id={batch_id}")
        return Response(serializer.data, status=status.HTTP_201_CREATED)


class TempAttachmentDeleteView(APIView):
    """임시 첨부파일 삭제"""
    permission_classes = [permissions.IsAuthenticated]

    def delete(self, request, pk):
        attachment = get_object_or_404(Attachment, pk=pk, post__isnull=True)

        # 업로더만 삭제 가능
        user = request.user
        user_id = str(getattr(user, 'id', '') or getattr(user, 'email', ''))
        username = getattr(user, 'username', '') or getattr(user, 'email', '')

        if attachment.uploader_id != user_id and attachment.uploader_name != username:
            return Response(
                {'detail': '삭제 권한이 없습니다.'},
                status=status.HTTP_403_FORBIDDEN
            )

        original_name = attachment.original_name
        attachment.file.delete(save=False)
        attachment.delete()

        logger.info(f"Temp attachment '{original_name}' deleted by {username}.")
        return Response(status=status.HTTP_204_NO_CONTENT)


class AttachmentListCreateView(APIView):
    """첨부파일 목록/업로드"""
    permission_classes = [permissions.IsAuthenticatedOrReadOnly]
    parser_classes = [MultiPartParser, FormParser]

    def get_post(self, post_pk):
        return get_object_or_404(Post, pk=post_pk)

    def get(self, request, post_pk):
        """첨부파일 목록 조회"""
        post = self.get_post(post_pk)
        attachments = post.attachments.all()
        serializer = AttachmentSerializer(attachments, many=True)
        return Response(serializer.data)

    def post(self, request, post_pk):
        """첨부파일 업로드"""
        post = self.get_post(post_pk)

        # 작성자만 첨부파일 추가 가능
        user = request.user
        user_id = str(getattr(user, 'id', '') or getattr(user, 'email', ''))
        username = getattr(user, 'username', '') or getattr(user, 'email', '')

        if post.author_id != user_id and post.author_name != username:
            return Response(
                {'detail': '첨부파일을 추가할 권한이 없습니다.'},
                status=status.HTTP_403_FORBIDDEN
            )

        file = request.FILES.get('file')
        if not file:
            return Response(
                {'detail': '파일이 필요합니다.'},
                status=status.HTTP_400_BAD_REQUEST
            )

        # 같은 게시글 내 중복 파일명 체크
        existing_names = list(
            post.attachments.values_list('original_name', flat=True)
        )
        unique_name = get_unique_filename(file.name, existing_names)

        # MinIO에 파일 저장
        attachment = Attachment.objects.create(
            post=post,
            file=file,
            original_name=unique_name,
            file_size=file.size,
            uploader_id=user_id,
            uploader_name=username
        )

        serializer = AttachmentSerializer(attachment)
        logger.info(f"Attachment '{unique_name}' uploaded to post {post_pk} by {username}.")
        return Response(serializer.data, status=status.HTTP_201_CREATED)


class AttachmentDeleteView(APIView):
    """첨부파일 삭제"""
    permission_classes = [permissions.IsAuthenticated]

    def delete(self, request, post_pk, pk):
        attachment = get_object_or_404(Attachment, pk=pk, post_id=post_pk)

        # 작성자만 삭제 가능
        user = request.user
        user_id = str(getattr(user, 'id', '') or getattr(user, 'email', ''))
        username = getattr(user, 'username', '') or getattr(user, 'email', '')

        if attachment.post.author_id != user_id and attachment.post.author_name != username:
            return Response(
                {'detail': '삭제 권한이 없습니다.'},
                status=status.HTTP_403_FORBIDDEN
            )

        # MinIO에서 파일 삭제
        original_name = attachment.original_name
        attachment.file.delete(save=False)
        attachment.delete()

        logger.info(f"Attachment '{original_name}' deleted from post {post_pk} by {username}.")
        return Response(status=status.HTTP_204_NO_CONTENT)


class PresignedUrlView(APIView):
    """Presigned URL 생성 (MinIO/S3)"""
    permission_classes = [permissions.AllowAny]

    def get_s3_client(self):
        """S3 클라이언트 생성"""
        return boto3.client(
            's3',
            endpoint_url=settings.AWS_S3_ENDPOINT_URL,
            aws_access_key_id=settings.AWS_ACCESS_KEY_ID,
            aws_secret_access_key=settings.AWS_SECRET_ACCESS_KEY,
            config=Config(signature_version='s3v4'),
            region_name=settings.AWS_S3_REGION_NAME,
        )

    def get(self, request, object_key):
        """GET presigned URL 생성"""
        try:
            s3_client = self.get_s3_client()
            presigned_url = s3_client.generate_presigned_url(
                'get_object',
                Params={
                    'Bucket': settings.AWS_STORAGE_BUCKET_NAME,
                    'Key': object_key,
                },
                ExpiresIn=3600,  # 1시간 유효
            )
            return Response({'url': presigned_url})
        except Exception as e:
            logger.error(f"Presigned URL 생성 실패: {e}")
            return Response(
                {'detail': 'Presigned URL 생성 실패'},
                status=status.HTTP_500_INTERNAL_SERVER_ERROR
            )