"""完整财务 serializers：
- 往来：应收单、应付单、收款单、付款单、核销明细
- 总账：科目、期间、凭证（含分录）、凭证创建
"""

from rest_framework import serializers
from apps.core.serializers import AsyncModelSerializer
from .models import (
    Account, Period, Voucher, VoucherEntry,
    Receivable, Payable, Receipt, Payment, Allocation,
)


# ============================================================
# 1. 往来序列化（AR / AP）
# ============================================================

class ReceivableSerializer(AsyncModelSerializer):
    customer_code = serializers.CharField(source="customer.code", read_only=True)
    customer_name = serializers.CharField(source="customer.name", read_only=True)
    balance = serializers.DecimalField(max_digits=18, decimal_places=4, read_only=True)

    class Meta:
        model = Receivable
        fields = [
            "id", "bill_no", "customer", "customer_code", "customer_name",
            "source_type", "source_ref", "bill_date", "due_date",
            "total_amount", "paid_amount", "balance", "status", "remark",
            "created_at", "updated_at",
        ]
        read_only_fields = [
            "id", "bill_no", "paid_amount", "balance", "status",
            "created_at", "updated_at",
        ]


class PayableSerializer(AsyncModelSerializer):
    supplier_code = serializers.CharField(source="supplier.code", read_only=True)
    supplier_name = serializers.CharField(source="supplier.name", read_only=True)
    balance = serializers.DecimalField(max_digits=18, decimal_places=4, read_only=True)

    class Meta:
        model = Payable
        fields = [
            "id", "bill_no", "supplier", "supplier_code", "supplier_name",
            "source_type", "source_ref", "bill_date", "due_date",
            "total_amount", "paid_amount", "balance", "status", "remark",
            "created_at", "updated_at",
        ]
        read_only_fields = [
            "id", "bill_no", "paid_amount", "balance", "status",
            "created_at", "updated_at",
        ]


class ReceiptSerializer(AsyncModelSerializer):
    customer_code = serializers.CharField(source="customer.code", read_only=True)
    customer_name = serializers.CharField(source="customer.name", read_only=True)

    class Meta:
        model = Receipt
        fields = [
            "id", "bill_no", "customer", "customer_code", "customer_name",
            "bill_date", "amount", "method", "status", "remark",
            "created_at", "updated_at",
        ]
        read_only_fields = ["id", "status", "created_at", "updated_at"]


class PaymentSerializer(AsyncModelSerializer):
    supplier_code = serializers.CharField(source="supplier.code", read_only=True)
    supplier_name = serializers.CharField(source="supplier.name", read_only=True)

    class Meta:
        model = Payment
        fields = [
            "id", "bill_no", "supplier", "supplier_code", "supplier_name",
            "bill_date", "amount", "method", "status", "remark",
            "created_at", "updated_at",
        ]
        read_only_fields = ["id", "status", "created_at", "updated_at"]


class AllocationSerializer(AsyncModelSerializer):
    receivable_no = serializers.CharField(source="receivable.bill_no", read_only=True, default=None)
    payable_no = serializers.CharField(source="payable.bill_no", read_only=True, default=None)
    receipt_no = serializers.CharField(source="receipt.bill_no", read_only=True, default=None)
    payment_no = serializers.CharField(source="payment.bill_no", read_only=True, default=None)

    class Meta:
        model = Allocation
        fields = [
            "id", "kind", "amount",
            "receivable", "receivable_no",
            "payable", "payable_no",
            "receipt", "receipt_no",
            "payment", "payment_no",
            "created_at",
        ]
        read_only_fields = ["id", "created_at"]


class _AllocationItemInputSerializer(serializers.Serializer):
    """公共核销行输入。

    ``*_id`` 是显式 API 形式；保留无后缀字段以便客户端沿用模型字段命名。
    """

    amount = serializers.DecimalField(max_digits=18, decimal_places=4)

    def _document_id(self, attrs, field_name):
        plain_name = field_name
        id_name = f"{field_name}_id"
        plain = attrs.pop(plain_name, None)
        explicit = attrs.pop(id_name, None)
        if plain is not None and explicit is not None and plain != explicit:
            raise serializers.ValidationError(
                {field_name: f"{plain_name} 与 {id_name} 不能同时指定不同值"}
            )
        document_id = explicit if explicit is not None else plain
        if document_id is None:
            raise serializers.ValidationError({field_name: "必填"})
        attrs[field_name] = document_id
        return attrs


class ReceiptAllocationItemSerializer(_AllocationItemInputSerializer):
    receivable = serializers.IntegerField(required=False, min_value=1)
    receivable_id = serializers.IntegerField(required=False, min_value=1, write_only=True)

    def validate(self, attrs):
        return self._document_id(attrs, "receivable")


class PaymentAllocationItemSerializer(_AllocationItemInputSerializer):
    payable = serializers.IntegerField(required=False, min_value=1)
    payable_id = serializers.IntegerField(required=False, min_value=1, write_only=True)

    def validate(self, attrs):
        return self._document_id(attrs, "payable")


class ReceiptAllocationInputSerializer(serializers.Serializer):
    allocations = ReceiptAllocationItemSerializer(many=True, allow_empty=False)


class PaymentAllocationInputSerializer(serializers.Serializer):
    allocations = PaymentAllocationItemSerializer(many=True, allow_empty=False)


# ============================================================
# 2. 总账序列化（GL）
# ============================================================

class AccountSerializer(AsyncModelSerializer):
    category_name = serializers.CharField(source="get_category_display", read_only=True)
    balance_type_name = serializers.CharField(source="get_balance_type_display", read_only=True)

    class Meta:
        model = Account
        fields = [
            "id", "code", "name", "category", "category_name",
            "balance_type", "balance_type_name", "parent",
            "is_active", "is_system", "aux_customer", "aux_supplier", "remark",
        ]
        read_only_fields = ["id", "is_system"]


class PeriodSerializer(AsyncModelSerializer):
    status_name = serializers.CharField(source="get_status_display", read_only=True)

    class Meta:
        model = Period
        fields = [
            "id", "code", "start_date", "end_date",
            "status", "status_name", "closed_at", "closed_by",
        ]
        read_only_fields = ["id", "status", "status_name", "closed_at", "closed_by"]


class VoucherEntrySerializer(AsyncModelSerializer):
    account_code = serializers.CharField(source="account.code", read_only=True)
    account_name = serializers.CharField(source="account.name", read_only=True)
    customer_code = serializers.CharField(source="customer.code", read_only=True, default=None)
    customer_name = serializers.CharField(source="customer.name", read_only=True, default=None)
    supplier_code = serializers.CharField(source="supplier.code", read_only=True, default=None)
    supplier_name = serializers.CharField(source="supplier.name", read_only=True, default=None)

    class Meta:
        model = VoucherEntry
        fields = [
            "id", "account", "account_code", "account_name",
            "customer", "customer_code", "customer_name",
            "supplier", "supplier_code", "supplier_name",
            "summary", "debit", "credit",
        ]
        read_only_fields = ["id"]


class VoucherSerializer(AsyncModelSerializer):
    period_code = serializers.CharField(source="period.code", read_only=True)
    source_type_name = serializers.CharField(source="get_source_type_display", read_only=True)
    status_name = serializers.CharField(source="get_status_display", read_only=True)
    entries = VoucherEntrySerializer(many=True, read_only=True)

    class Meta:
        model = Voucher
        fields = [
            "id", "bill_no", "period", "period_code",
            "source_type", "source_type_name", "source_ref", "voucher_date",
            "total_debit", "total_credit", "status", "status_name",
            "summary", "posted_at", "posted_by",
            "entries", "created_at", "updated_at",
        ]
        read_only_fields = [
            "id", "bill_no", "period", "total_debit",
            "total_credit", "status", "posted_at", "posted_by",
            "created_at", "updated_at",
        ]


class VoucherEntryInputSerializer(serializers.Serializer):
    account_code = serializers.CharField(max_length=32)
    debit = serializers.DecimalField(max_digits=18, decimal_places=4, default=0)
    credit = serializers.DecimalField(max_digits=18, decimal_places=4, default=0)
    summary = serializers.CharField(max_length=255, required=False, allow_blank=True, default="")
    customer_id = serializers.IntegerField(required=False, allow_null=True, default=None)
    supplier_id = serializers.IntegerField(required=False, allow_null=True, default=None)


class VoucherCreateInputSerializer(serializers.Serializer):
    voucher_date = serializers.DateField()
    summary = serializers.CharField(max_length=255, required=False, allow_blank=True, default="")
    auto_post = serializers.BooleanField(default=False)
    entries = VoucherEntryInputSerializer(many=True)