from rest_framework import serializers

from apps.catalog.models import Product
from apps.catalog.serializers import ProductListSerializer
from apps.locations.models import Address
from apps.stores.serializers import StoreListSerializer

from .models import CartItem, Notification, Order, OrderGroup, OrderItem, OrderStatusLog


class CartItemSerializer(serializers.ModelSerializer):
    product = ProductListSerializer(read_only=True)
    line_total = serializers.IntegerField(read_only=True)

    class Meta:
        model = CartItem
        fields = ('uuid', 'product', 'quantity', 'line_total')


class CartItemWriteSerializer(serializers.Serializer):
    product_uuid = serializers.PrimaryKeyRelatedField(
        source='product', queryset=Product.objects.filter(is_active=True),
    )
    quantity = serializers.IntegerField(min_value=1, default=1)


class StoreCartGroupSerializer(serializers.Serializer):
    """One store's slice of a multi-store cart (see the C07 mock)."""

    store = StoreListSerializer(read_only=True)
    items = CartItemSerializer(many=True, read_only=True)
    items_subtotal = serializers.IntegerField(read_only=True)
    delivery_fee = serializers.IntegerField(read_only=True)
    total = serializers.IntegerField(read_only=True)
    meets_minimum_order = serializers.BooleanField(read_only=True)


class CartSerializer(serializers.Serializer):
    """Groups the authenticated user's cart items by store for the multi-store-cart UI."""

    groups = serializers.SerializerMethodField()
    grand_total = serializers.SerializerMethodField()

    def _build_groups(self, cart):
        if not hasattr(self, '_groups_cache'):
            from .services import build_cart_groups
            self._groups_cache = build_cart_groups(cart)
        return self._groups_cache

    def get_groups(self, cart):
        return StoreCartGroupSerializer(self._build_groups(cart), many=True, context=self.context).data

    def get_grand_total(self, cart):
        return sum(group['total'] for group in self._build_groups(cart))


class OrderItemSerializer(serializers.ModelSerializer):
    line_total = serializers.IntegerField(read_only=True)

    class Meta:
        model = OrderItem
        fields = ('uuid', 'product', 'product_name_snapshot', 'unit_price_snapshot', 'quantity', 'line_total')


class OrderStatusLogSerializer(serializers.ModelSerializer):
    class Meta:
        model = OrderStatusLog
        fields = ('from_status', 'to_status', 'note', 'created_at')


class OrderSerializer(serializers.ModelSerializer):
    store = StoreListSerializer(read_only=True)
    items = OrderItemSerializer(many=True, read_only=True)
    status_logs = OrderStatusLogSerializer(many=True, read_only=True)
    total_amount = serializers.IntegerField(read_only=True)
    is_cancellable = serializers.SerializerMethodField()

    class Meta:
        model = Order
        fields = (
            'uuid', 'store', 'status', 'items', 'items_subtotal', 'delivery_fee',
            'commission_amount', 'seller_payout_amount', 'total_amount', 'cancel_reason',
            'courier_name', 'courier_phone', 'placed_at', 'delivered_at', 'status_logs',
            'is_cancellable',
        )

    def get_is_cancellable(self, order):
        return order.status in Order.CANCELLABLE_STATUSES


class OrderGroupSerializer(serializers.ModelSerializer):
    orders = OrderSerializer(many=True, read_only=True)

    class Meta:
        model = OrderGroup
        fields = (
            'uuid', 'recipient_name', 'recipient_phone', 'full_address',
            'delivery_type', 'scheduled_at', 'payment_method', 'payment_status',
            'notes', 'total_amount', 'orders', 'created_at',
        )


class CheckoutSerializer(serializers.Serializer):
    address_uuid = serializers.PrimaryKeyRelatedField(source='address', queryset=Address.objects.all())
    delivery_type = serializers.ChoiceField(choices=OrderGroup.DeliveryType.choices, default=OrderGroup.DeliveryType.EXPRESS)
    scheduled_at = serializers.DateTimeField(required=False, allow_null=True, default=None)
    payment_method = serializers.ChoiceField(choices=OrderGroup.PaymentMethod.choices)
    notes = serializers.CharField(required=False, allow_blank=True, default='')
    store_uuids = serializers.ListField(
        child=serializers.UUIDField(), required=False, allow_empty=False, default=None,
        help_text='بررسی و پرداخت فقط برای فروشگاه‌های انتخاب‌شده از سبد خرید. در صورت خالی بودن، کل سبد خرید نهایی می‌شود.',
    )

    def validate(self, attrs):
        if attrs.get('delivery_type') == OrderGroup.DeliveryType.SCHEDULED and not attrs.get('scheduled_at'):
            raise serializers.ValidationError({'scheduled_at': 'برای ارسال زمان‌بندی شده، زمان را مشخص کنید.'})
        address = attrs['address']
        request = self.context['request']
        if address.user_id != request.user.pk:
            raise serializers.ValidationError({'address_uuid': 'این آدرس متعلق به شما نیست.'})
        return attrs


class OrderCancelSerializer(serializers.Serializer):
    reason = serializers.CharField(required=False, allow_blank=True, default='')


class OrderStatusActionSerializer(serializers.Serializer):
    note = serializers.CharField(required=False, allow_blank=True, default='')
    courier_name = serializers.CharField(required=False, allow_blank=True, default='')
    courier_phone = serializers.CharField(required=False, allow_blank=True, default='')


class NotificationSerializer(serializers.ModelSerializer):
    class Meta:
        model = Notification
        fields = ('uuid', 'type', 'title', 'body', 'related_order', 'is_read', 'created_at')
        read_only_fields = fields