from django.db.models import Count, Sum
from rest_framework import serializers
from rest_framework.serializers import ModelSerializer

from main.models import Order, OrderLine, Product


class ProductSerializer(ModelSerializer):
    class Meta:
        model = Product
        fields = "__all__"


class ProductStatSerializer(ModelSerializer):
    EXTERNAL_USER = "Ekstern"
    counts = serializers.SerializerMethodField()

    def _format_counts(self, per_user):
        per_user = list(per_user)
        for row in per_user:
            first = row.pop("order__customer__first_name")
            last = row.pop("order__customer__last_name")
            if first is None:
                who = self.EXTERNAL_USER
            else:
                who = "{} {}".format(first, last)
            row["full_name"] = who

        return per_user

    def get_counts(self, obj):
        name_fields = ["order__customer__first_name", "order__customer__last_name"]
        per_user = OrderLine.objects.filter(product=obj)
        per_user = per_user.values(*name_fields).annotate(amount_total=Sum("amount")).order_by("-amount_total")

        return self._format_counts(per_user)

    class Meta:
        model = Product
        fields = [
            "id",
            "name",
            "description",
            "image",
            "inventory_amount",
            "active",
            "created",
            "counts",
        ]