# blog/serializers.py

from rest_framework import serializers
from .models import Post, Comment, Tag


class TagSerializer(serializers.ModelSerializer):
    """태그 시리얼라이저"""
    post_count = serializers.SerializerMethodField()

    class Meta:
        model = Tag
        fields = ['id', 'name', 'post_count']
        read_only_fields = ['id']

    def get_post_count(self, obj):
        return obj.posts.count()


class CommentSerializer(serializers.ModelSerializer):
    """댓글/대댓글 시리얼라이저"""
    replies = serializers.SerializerMethodField()
    reply_count = serializers.SerializerMethodField()

    class Meta:
        model = Comment
        fields = [
            'id', 'post', 'parent', 'content',
            'author_id', 'author_name',
            'created_at', 'updated_at',
            'reply_count', 'replies'
        ]
        read_only_fields = ['author_id', 'author_name', 'post', 'created_at', 'updated_at']

    def get_replies(self, obj):
        # 최상위 댓글의 대댓글만 반환
        if obj.parent is None:
            replies = obj.replies.all()
            return CommentSerializer(replies, many=True, context=self.context).data
        return []

    def get_reply_count(self, obj):
        if obj.parent is None:
            return obj.replies.count()
        return 0


class PostSerializer(serializers.ModelSerializer):
    comment_count = serializers.SerializerMethodField()
    tags = TagSerializer(many=True, read_only=True)
    tag_names = serializers.ListField(
        child=serializers.CharField(max_length=50),
        write_only=True,
        required=False
    )

    class Meta:
        model = Post
        fields = [
            'id', 'title', 'content',
            'author_id', 'author_name',
            'created_at', 'updated_at',
            'comment_count', 'tags', 'tag_names'
        ]
        read_only_fields = ['author_id', 'author_name', 'created_at', 'updated_at']

    def get_comment_count(self, obj):
        return obj.comments.count()

    def create(self, validated_data):
        tag_names = validated_data.pop('tag_names', [])
        post = Post.objects.create(**validated_data)
        self._set_tags(post, tag_names)
        return post

    def update(self, instance, validated_data):
        tag_names = validated_data.pop('tag_names', None)
        for attr, value in validated_data.items():
            setattr(instance, attr, value)
        instance.save()
        if tag_names is not None:
            self._set_tags(instance, tag_names)
        return instance

    def _set_tags(self, post, tag_names):
        """태그 설정 (없으면 생성)"""
        tags = []
        for name in tag_names:
            name = name.strip().lower()
            if name:
                tag, _ = Tag.objects.get_or_create(name=name)
                tags.append(tag)
        post.tags.set(tags)


class PostListSerializer(serializers.ModelSerializer):
    """목록 조회용 간소화된 시리얼라이저"""
    comment_count = serializers.SerializerMethodField()
    tags = TagSerializer(many=True, read_only=True)

    class Meta:
        model = Post
        fields = [
            'id', 'title',
            'author_name', 'created_at', 'updated_at',
            'comment_count', 'tags'
        ]

    def get_comment_count(self, obj):
        return obj.comments.count()