import { Inject, Provide } from '@midwayjs/core';
import {
  InjectSaasAction,
  InjectSaasCrud,
  ModuleRuntimeError,
  SaasAction,
  SaasBusinessReject,
  type SaasActionCaller,
  type SaasCrudCaller,
  SaasCrudService,
  SaasCrudServiceBase,
  SaasWorkflow,
  SaasActionContext,
} from '@cool-midway/module-runtime';
import {
  Actions,
  Crud,
  SaasActions,
  type OrdersCancelOrderInput,
  type OrdersCancelOrderOutput,
  type OrdersCreateOrderInput,
  type OrdersCreateOrderOutput,
  type OrdersCrudBeforeChange,
  type OrdersDetailWithGoodsInput,
  type OrdersDetailWithGoodsOutput,
} from '../saas/generated/order';

type GoodsRecord = Record<string, unknown>;

@Provide()
@SaasCrudService(Crud.Orders)
export class OrdersService extends SaasCrudServiceBase<typeof Crud.Orders> {
  @Inject() private readonly workflow!: SaasWorkflow;
  @Inject() private readonly actionContext!: SaasActionContext;
  @InjectSaasCrud(Crud.Orders)
  private readonly orders!: SaasCrudCaller<typeof Crud.Orders>;

  @InjectSaasAction(SaasActions.Demo.GoodsBatchInfo)
  private readonly batchInfo!: SaasActionCaller<
    typeof SaasActions.Demo.GoodsBatchInfo
  >;

  protected async modifyBefore(change: OrdersCrudBeforeChange): Promise<void> {
    const caller = this.actionContext.managedCrudCaller;
    if (change.operation === 'add') {
      if (caller?.kind !== 'business' || caller.actionName !== 'orders.createOrder' || change.input.status !== 'pending_reservation') throw new SaasBusinessReject('ORDER_COMMAND_REQUIRED','创建订单必须使用下单业务命令');
      return;
    }
    if (change.operation === 'delete') throw new SaasBusinessReject('ORDER_COMMAND_REQUIRED','订单保留作为库存预留及工作流凭据，不能通过通用CRUD删除');
    const protectedFields = ['order_no','goods_id','quantity','unit_price','amount','status'];
    if (!protectedFields.some(field => Object.prototype.hasOwnProperty.call(change.input,field))) return;
    const keys = Object.keys(change.input);
    if (keys.some(key => key !== 'id' && key !== 'status')) throw new SaasBusinessReject('ORDER_COMMAND_REQUIRED','订单商品、数量和金额在创建后不可修改');
    const status = change.input.status;
    if (caller?.kind === 'business' && caller.actionName === 'orders.cancelOrder' && status === 'cancel_pending') return;
    const outcomes: Record<string,string[]> = {
      'saas.saga.step.completed':['confirmed','cancelled'],
      'saas.saga.step.failed':['rejected','manual_review'],
      'saas.saga.compensation.completed':['failed','manual_review'],
    };
    if (caller?.kind === 'saga' && outcomes[caller.eventType || '']?.includes(String(status))) return;
    throw new SaasBusinessReject('ORDER_COMMAND_REQUIRED','订单受管字段只能由业务命令和工作流回执变更');
  }

  @SaasAction(Actions.OrdersCreateOrder)
  async createOrder(
    input: OrdersCreateOrderInput
  ): Promise<OrdersCreateOrderOutput> {
    const goods = await this.requireGoods(input.goodsId);
    if (integer(goods.status, '商品状态') !== 1) {
      throw new SaasBusinessReject('GOODS_UNAVAILABLE', '商品未上架，不能下单');
    }

    const unitPrice = decimal(goods.price, '商品价格');
    const amount = multiplyDecimal(unitPrice, input.quantity);

    const order = await this.orders.add({
      order_no: input.orderNo,
      goods_id: String(input.goodsId),
      quantity: input.quantity,
      unit_price: unitPrice,
      amount,
      status: 'pending_reservation',
    });

    await this.workflow.start({
      type: 'order.create@1', businessKey: input.orderNo,
      steps: [{key:'reserve',action:SaasActions.Demo.GoodsReserveStock,
        input:{goodsId:input.goodsId,quantity:input.quantity},
        compensate:{action:SaasActions.Demo.GoodsReleaseStock,input:{goodsId:input.goodsId,quantity:input.quantity,orderNo:input.orderNo}}}],
      terminal: Crud.Orders,
      outcomes: {
        completed:{id:order.id,status:'confirmed'},
        failed:{id:order.id,status:'rejected'},
        compensated:{id:order.id,status:'failed'},
      },
    });

    return {
      id: safeInteger(order.id, '订单 ID'),
      orderNo: order.order_no,
      amount: finiteNumber(order.amount, '订单金额'),
      status: order.status,
    };
  }

  @SaasAction(Actions.OrdersDetailWithGoods)
  async detailWithGoods(
    input: OrdersDetailWithGoodsInput
  ): Promise<OrdersDetailWithGoodsOutput> {
    const order = await this.requireOrder(input.id);
    const goods = await this.requireGoods(safeInteger(order.goods_id, '商品 ID'));
    return { order, goods };
  }

  @SaasAction(Actions.OrdersCancelOrder)
  async cancelOrder(
    input: OrdersCancelOrderInput
  ): Promise<OrdersCancelOrderOutput> {
    const order = await this.orders.lock({id:String(input.id)});
    if (!order) throw new SaasBusinessReject('ORDER_NOT_FOUND', `订单不存在: ${input.id}`);
    if (order.status === 'cancelled') {
      return { id: input.id, status: 'cancelled', restoredStock: 0 };
    }

    if (order.status === 'cancel_pending') return {id:input.id,status:'cancel_pending',restoredStock:0};
    if (order.status !== 'confirmed') throw new SaasBusinessReject('ORDER_STATE_CONFLICT','订单当前状态不能取消；历史订单需要先核对预留记录');
    const goodsId = safeInteger(order.goods_id, '商品 ID');
    await this.orders.update({id:order.id,status:'cancel_pending'});
    await this.workflow.start({
      type:'order.cancel@1',businessKey:String(order.id),
      steps:[{key:'release',action:SaasActions.Demo.GoodsReleaseStock,input:{goodsId,quantity:order.quantity,orderNo:order.order_no}}],
      terminal:Crud.Orders,
      outcomes:{completed:{id:order.id,status:'cancelled'},failed:{id:order.id,status:'manual_review'},compensated:{id:order.id,status:'manual_review'}},
    });
    return {id:input.id,status:'cancel_pending',restoredStock:0};
  }

  private async requireOrder(id: number) {
    // The locked info contract requires an object; its empty result would fail
    // output validation before business code can classify a missing order.
    // The existing list contract permits an empty array and this exact ID filter.
    const [order] = await this.orders.list({ where: { id: String(id) }, take: 1 });
    if (!order) throw new SaasBusinessReject('ORDER_NOT_FOUND', `订单不存在: ${id}`);
    return order;
  }

  private async requireGoods(goodsId: number): Promise<GoodsRecord> {
    const result = await this.batchInfo({ ids: [goodsId] });
    const goods = result.list.find(item => String(item.id) === String(goodsId));
    if (!goods) throw new SaasBusinessReject('GOODS_NOT_FOUND', `商品不存在: ${goodsId}`);
    return goods;
  }
}

function decimal(value: unknown, label: string): string {
  const normalized = String(value ?? '').trim();
  if (!/^-?(?:0|[1-9][0-9]*)(?:\.[0-9]+)?$/.test(normalized)) {
    throw conflict(`${label}非法`);
  }
  return normalized;
}

function multiplyDecimal(value: string, multiplier: number): string {
  const negative = value.startsWith('-');
  const unsigned = negative ? value.slice(1) : value;
  const [integerPart, fractionPart = ''] = unsigned.split('.');
  const scale = fractionPart.length;
  const digits = BigInt(`${integerPart}${fractionPart}`);
  const product = digits * BigInt(multiplier);
  const padded = product.toString().padStart(scale + 1, '0');
  const absolute = scale
    ? `${padded.slice(0, -scale)}.${padded.slice(-scale)}`
    : padded;
  return negative && product !== BigInt(0) ? `-${absolute}` : absolute;
}

function integer(value: unknown, label: string): number {
  const normalized = Number(value);
  if (!Number.isInteger(normalized)) throw conflict(`${label}非法`);
  return normalized;
}

function safeInteger(value: unknown, label: string): number {
  const normalized = integer(value, label);
  if (!Number.isSafeInteger(normalized) || normalized < 1) {
    throw conflict(`${label}超出安全范围`);
  }
  return normalized;
}

function finiteNumber(value: unknown, label: string): number {
  const normalized = Number(value);
  if (!Number.isFinite(normalized)) throw conflict(`${label}非法`);
  return normalized;
}

function conflict(message: string) {
  return new ModuleRuntimeError('MODULE_ACTION_INPUT_INVALID', message, 409);
}