from rest_framework import serializers
from django.core.files.uploadedfile import SimpleUploadedFile
from .models import Blog, BlogContent, BlogSeo
from utils import absolute_url
from utils.image_compression import maybe_compress_uploaded_file


# ─── Helper: return full URL for an ImageField ────────────────────────────────
class AbsoluteImageField(serializers.ImageField):
    """
    Wraps DRF's ImageField to return a full absolute URL on read,
    while accepting a real uploaded file (InMemoryUploadedFile /
    TemporaryUploadedFile) on write – just like a normal ImageField.
    """
    def to_internal_value(self, data):
        uploaded = super().to_internal_value(data)
        compressed_bytes = maybe_compress_uploaded_file(uploaded)
        if compressed_bytes is None:
            return uploaded

        return SimpleUploadedFile(
            name=getattr(uploaded, "name", "image"),
            content=compressed_bytes,
            content_type=getattr(uploaded, "content_type", None),
        )

    def to_representation(self, value):
        if not value:
            return None
        request = self.context.get("request")
        url = value.url if hasattr(value, "url") else str(value)
        if request:
            return request.build_absolute_uri(url)
        return url


# ─── Serializers ──────────────────────────────────────────────────────────────

class AdminBlogSeoSerializer(serializers.ModelSerializer):
    class Meta:
        model = BlogSeo
        fields = ["id", "title", "keywords", "description", "language"]


class AdminBlogContentSerializer(serializers.ModelSerializer):
    image = AbsoluteImageField(required=False, allow_null=True)

    class Meta:
        model = BlogContent
        fields = [
            "id", "blog", "title", "content", "slug", "image", "order",
            "created_at", "updated_at",
        ]


class AdminBlogListSerializer(serializers.ModelSerializer):
    """
    Lightweight serializer for the admin data table.
    Exposes raw JSON fields so the React frontend can manage translations.
    """
    thumbnail = AbsoluteImageField(required=False, allow_null=True)

    class Meta:
        model = Blog
        fields = [
            "id", "title", "slogan", "summary", "slug", "thumbnail",
            "views_count", "created_at", "updated_at",
        ]
        read_only_fields = ["id", "views_count", "created_at", "updated_at"]


class AdminBlogDetailSerializer(serializers.ModelSerializer):
    """
    Full serializer for the admin detail/edit view.
    Includes nested contents and SEO data.
    """
    thumbnail = AbsoluteImageField(required=False, allow_null=True)
    contents = AdminBlogContentSerializer(many=True, read_only=True)
    seos = AdminBlogSeoSerializer(many=True, read_only=True)

    class Meta:
        model = Blog
        fields = [
            "id", "title", "slogan", "summary", "slug", "thumbnail",
            "views_count", "created_at", "updated_at", "contents", "seos",
        ]
        read_only_fields = ["id", "views_count", "created_at", "updated_at"]