import random
from datetime import date, datetime, timedelta

from sqlalchemy.ext.asyncio import AsyncSession

from app.api.v1.module_platform.order.crud import OrderCRUD
from app.core.base_schema import AuthSchema, PageResultSchema
from app.core.exceptions import CustomException
from app.core.logger import logger

from .crud import InvoiceCRUD
from .schema import (
    InvoiceApplySchema,
    InvoiceCreateSchema,
    InvoiceOutSchema,
    InvoiceQueryParam,
)

_INVOICE_TYPE_LABEL = {
    "vat_normal": "电子普通发票",
    "vat_special": "增值税专用发票",
}


def _generate_invoice_no() -> str:
    """生成发票编号

    返回:
    - str: 形如 INV20250620123456 的发票编号
    """
    today = date.today().strftime("%Y%m%d")
    suffix = str(random.randint(100000, 999999))
    return f"INV{today}{suffix}"


class InvoiceTenantService:
    """租户端发票服务"""

    @classmethod
    async def apply(cls, auth: AuthSchema, db: AsyncSession, data: InvoiceApplySchema, tenant_id: int) -> InvoiceOutSchema:
        """租户申请开票

        参数:
        - auth (AuthSchema): 认证信息模型
        - data (InvoiceApplySchema): 发票申请参数
        - tenant_id (int): 租户 ID

        返回:
        - InvoiceOutSchema: 发票信息
        """
        # 校验：专票必填字段
        if data.invoice_type == "vat_special":
            if not data.tax_no:
                raise CustomException(msg="增值税专用发票必须填写纳税人识别号")
            if not data.bank_info:
                raise CustomException(msg="增值税专用发票必须填写开户行及账号")
            if not data.address_info:
                raise CustomException(msg="增值税专用发票必须填写注册地址及电话")

        # 校验：订单存在且已支付
        order = await OrderCRUD(auth, db).get(id=data.order_id)
        if not order:
            raise CustomException(msg="订单不存在")
        if order.status != 1:
            raise CustomException(msg="仅已支付订单可申请开票")

        # 校验：30 天内
        if order.created_time and datetime.now() - order.created_time > timedelta(days=30):
            raise CustomException(msg="订单支付超过 30 天，不可申请开票")

        crud = InvoiceCRUD(auth, db)
        existing = await crud.get_by_order_id(data.order_id)
        if existing:
            raise CustomException(msg="该订单已申请过发票")

        tax_rate = 0
        tax_amount = int(order.amount * tax_rate / 100)
        invoice = await crud.create(
            InvoiceCreateSchema(
                invoice_no=_generate_invoice_no(),
                order_id=data.order_id,
                invoice_type=data.invoice_type,
                title=data.title,
                tax_no=data.tax_no,
                bank_info=data.bank_info,
                address_info=data.address_info,
                amount=order.amount,
                tax_amount=tax_amount,
                description=data.description,
            ),
        )
        logger.info(f"发票申请成功: invoice_no={invoice.invoice_no}, order_id={data.order_id}")
        return InvoiceOutSchema.model_validate(invoice)

    @classmethod
    async def list_my(
        cls,
        auth: AuthSchema,
        db: AsyncSession,
        tenant_id: int,
        page_no: int,
        page_size: int,
        search: InvoiceQueryParam,
        order_by: list[dict[str, str]] | None = None,
    ) -> PageResultSchema[InvoiceOutSchema]:
        """租户查询自己的发票列表

        参数:
        - auth (AuthSchema): 认证信息模型
        - tenant_id (int): 租户 ID
        - page_no (int): 当前页码
        - page_size (int): 每页数量
        - search (InvoiceQueryParam): 查询参数
        - order_by (list[dict] | None): 排序字段

        返回:
        - PageResultSchema[InvoiceOutSchema]: 分页数据
        """
        _search: dict = {"tenant_id": tenant_id}
        if search.invoice_type:
            _search["invoice_type"] = search.invoice_type
        if search.status is not None:
            _search["status"] = search.status
        return await InvoiceCRUD(auth, db).page(
            offset=(page_no - 1) * page_size,
            limit=page_size,
            order_by=order_by or [{"created_time": "desc"}],
            search=_search,
            out_schema=InvoiceOutSchema,
        )

    @classmethod
    async def download(cls, auth: AuthSchema, db: AsyncSession, invoice_id: int, tenant_id: int) -> str:
        """获取发票 PDF 下载地址"""
        crud = InvoiceCRUD(auth, db)
        invoice = await crud.get_or_404(id=invoice_id, msg="发票不存在")
        if hasattr(invoice, "tenant_id") and invoice.tenant_id != tenant_id:
            raise CustomException(msg="发票不存在")
        if invoice.status != 1 or not invoice.pdf_url:
            raise CustomException(msg="发票未开具或无PDF")
        return invoice.pdf_url