from rest_framework import serializers

from .models import PlaylistItem, Video, VideoCategory, VideoCollection, VideoPlaylist


class AbsoluteImageField(serializers.ImageField):
    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


class AbsoluteFileField(serializers.FileField):
    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


class AdminVideoCategorySerializer(serializers.ModelSerializer):
    class Meta:
        model = VideoCategory
        fields = ["id", "title", "slug", "status", "order"]


class AdminVideoCollectionSerializer(serializers.ModelSerializer):
    class Meta:
        model = VideoCollection
        fields = ["id", "title", "slug", "summary", "display_position", "status", "order", "pin_top"]


class AdminVideoListSerializer(serializers.ModelSerializer):
    thumbnail = AbsoluteImageField(required=False, allow_null=True)
    video_file = AbsoluteFileField(required=False, allow_null=True)

    class Meta:
        model = Video
        fields = [
            "id",
            "title",
            "slug",
            "thumbnail",
            "description",
            "video_type",
            "video_file",
            "video_url",
            "video_time",
            "status",
            "view_count",
            "created_at",
            "updated_at",
        ]
        read_only_fields = ["id", "view_count", "created_at", "updated_at"]


class AdminVideoDetailSerializer(serializers.ModelSerializer):
    thumbnail = AbsoluteImageField(required=False, allow_null=True)
    video_file = AbsoluteFileField(required=False, allow_null=True)
    remove_thumbnail = serializers.BooleanField(write_only=True, required=False, default=False)
    remove_video_file = serializers.BooleanField(write_only=True, required=False, default=False)

    class Meta:
        model = Video
        fields = [
            "id",
            "title",
            "slug",
            "thumbnail",
            "description",
            "video_type",
            "video_file",
            "video_url",
            "video_time",
            "status",
            "view_count",
            "created_at",
            "updated_at",
            "remove_thumbnail",
            "remove_video_file",
        ]
        read_only_fields = ["id", "view_count", "created_at", "updated_at"]

    def validate(self, attrs):
        video_type = attrs.get("video_type", getattr(self.instance, "video_type", None))
        video_url = attrs.get("video_url", getattr(self.instance, "video_url", None))
        video_file = attrs.get("video_file", getattr(self.instance, "video_file", None))
        remove_video_file = attrs.get("remove_video_file", False)

        if video_type == Video.VedioTypeChoices.YOUTUBE_LINK and not video_url:
            raise serializers.ValidationError({
                "video_url": "This field is required when video type is link.",
            })

        if video_type == Video.VedioTypeChoices.VIDEO_FILE and not video_file and not getattr(self.instance, "video_file", None):
            raise serializers.ValidationError({
                "video_file": "This field is required when video type is file.",
            })

        if video_type == Video.VedioTypeChoices.VIDEO_FILE and remove_video_file and "video_file" not in attrs:
            raise serializers.ValidationError({
                "video_file": "Please upload a new file before removing the current one.",
            })

        return attrs

    def create(self, validated_data):
        validated_data.pop("remove_thumbnail", False)
        validated_data.pop("remove_video_file", False)
        return super().create(validated_data)

    def update(self, instance, validated_data):
        remove_thumbnail = validated_data.pop("remove_thumbnail", False)
        remove_video_file = validated_data.pop("remove_video_file", False)

        if remove_thumbnail and instance.thumbnail:
            instance.thumbnail.delete(save=False)
            instance.thumbnail = None

        if remove_video_file and instance.video_file:
            instance.video_file.delete(save=False)
            instance.video_file = None

        return super().update(instance, validated_data)


class AdminVideoPlaylistItemVideoSerializer(serializers.ModelSerializer):
    thumbnail = AbsoluteImageField(required=False, allow_null=True)

    class Meta:
        model = Video
        fields = ["id", "title", "slug", "thumbnail", "video_type", "video_time", "status"]


class AdminVideoPlaylistItemSerializer(serializers.ModelSerializer):
    video_detail = AdminVideoPlaylistItemVideoSerializer(source="video", read_only=True)

    class Meta:
        model = PlaylistItem
        fields = ["id", "playlist", "video", "priority", "created_at", "updated_at", "video_detail"]
        read_only_fields = ["id", "created_at", "updated_at", "video_detail"]

    def validate(self, attrs):
        playlist = attrs.get("playlist", getattr(self.instance, "playlist", None))
        video = attrs.get("video", getattr(self.instance, "video", None))
        if playlist and video:
            query = PlaylistItem.objects.filter(video=video).exclude(playlist=playlist)
            if self.instance:
                query = query.exclude(pk=self.instance.pk)
            existing = query.select_related("playlist").first()
            if existing:
                raise serializers.ValidationError({
                    "video": f'This video is already used in playlist "{existing.playlist.title}".',
                })
        return attrs


class AdminVideoPlaylistListSerializer(serializers.ModelSerializer):
    thumbnail = AbsoluteImageField(required=False, allow_null=True)
    categories_detail = AdminVideoCategorySerializer(source="categories", many=True, read_only=True)
    collections_detail = AdminVideoCollectionSerializer(source="collections", many=True, read_only=True)
    items_count = serializers.SerializerMethodField()

    class Meta:
        model = VideoPlaylist
        fields = [
            "id",
            "title",
            "slug",
            "thumbnail",
            "slogan",
            "status",
            "order",
            "view_count",
            "total_time",
            "created_at",
            "updated_at",
            "categories_detail",
            "collections_detail",
            "items_count",
        ]
        read_only_fields = ["id", "view_count", "total_time", "created_at", "updated_at", "items_count"]

    def get_items_count(self, obj):
        return obj.playlist_items.count()


class AdminVideoPlaylistDetailSerializer(serializers.ModelSerializer):
    thumbnail = AbsoluteImageField(required=False, allow_null=True)
    categories = serializers.PrimaryKeyRelatedField(queryset=VideoCategory.objects.all(), many=True, required=False)
    collections = serializers.PrimaryKeyRelatedField(queryset=VideoCollection.objects.all(), many=True, required=False)
    categories_detail = AdminVideoCategorySerializer(source="categories", many=True, read_only=True)
    collections_detail = AdminVideoCollectionSerializer(source="collections", many=True, read_only=True)
    playlist_items_detail = AdminVideoPlaylistItemSerializer(source="playlist_items", many=True, read_only=True)
    remove_thumbnail = serializers.BooleanField(write_only=True, required=False, default=False)

    class Meta:
        model = VideoPlaylist
        fields = [
            "id",
            "title",
            "slug",
            "slogan",
            "description",
            "thumbnail",
            "order",
            "status",
            "view_count",
            "total_time",
            "created_at",
            "updated_at",
            "categories",
            "collections",
            "categories_detail",
            "collections_detail",
            "playlist_items_detail",
            "remove_thumbnail",
        ]
        read_only_fields = ["id", "view_count", "total_time", "created_at", "updated_at", "playlist_items_detail"]

    def create(self, validated_data):
        validated_data.pop("remove_thumbnail", False)
        categories = validated_data.pop("categories", [])
        collections = validated_data.pop("collections", [])
        playlist = super().create(validated_data)
        if categories:
            playlist.categories.set(categories)
        if collections:
            playlist.collections.set(collections)
        playlist.total_time = playlist.calculate_total_time()
        playlist.save(update_fields=["total_time"])
        return playlist

    def update(self, instance, validated_data):
        remove_thumbnail = validated_data.pop("remove_thumbnail", False)
        categories = validated_data.pop("categories", None)
        collections = validated_data.pop("collections", None)

        if remove_thumbnail and instance.thumbnail:
            instance.thumbnail.delete(save=False)
            instance.thumbnail = None

        playlist = super().update(instance, validated_data)
        if categories is not None:
            playlist.categories.set(categories)
        if collections is not None:
            playlist.collections.set(collections)
        playlist.total_time = playlist.calculate_total_time()
        playlist.save(update_fields=["total_time"])
        return playlist