import { logger } from '../../utils/logger';
import { FeatureGovernanceService } from '../../core/governance/FeatureGovernanceService';
import db from '../../config/database';

export interface DeliveryRoute {
  courierId: string;
  orderIds: string[];
  estimatedTotalTime: number; // minutes
  totalDistance: number; // km
  fuelCost: number;
  optimizedOrder: string[];
}

/**
 * [BIZ_TRADE_14] 最后一公里配送成本优化模型 (Last-Mile Optimizer)
 * @description 核心逻辑：基于实时路况、包裹密度热力图与承运商运力动态优化派送路径，降低每单配送成本。
 */
export class LastMileOptimizerService {
  /**
   * 优化派送路由 (Last-Mile Routing)
   */
  static async optimizeDeliveryRoute(params: {
    region: string;
    courierIds: string[];
    pendingOrderIds: string[];
    tenantId?: string;
  }): Promise<DeliveryRoute[]> {
    // Feature Flag Check
    if (!(await FeatureGovernanceService.isEnabled('BIZ_TRADE_LAST_MILE', params.tenantId))) {
      logger.info('[LastMile] Service disabled, using default sequential routing.');
      return [];
    }

    logger.info(`[LastMile] Optimizing ${params.pendingOrderIds.length} orders for ${params.courierIds.length} couriers in ${params.region}`);

    // 1. 模拟 TSP (Traveling Salesman Problem) 求解逻辑
    // 实际场景下会使用 Google OR-Tools 或 MapBox API
    const routes: DeliveryRoute[] = params.courierIds.map((cid, index) => {
      const assignedOrders = params.pendingOrderIds.slice(index * 5, (index + 1) * 5);
      
      // 模拟基于坐标的贪心算法排序
      const optimizedOrder = [...assignedOrders].sort((a, b) => {
        // 这里模拟经纬度距离计算，实际应从数据库读取 order.lat/lng
        return Math.random() - 0.5; 
      });

      return {
        courierId: cid,
        orderIds: assignedOrders,
        estimatedTotalTime: 120 + Math.random() * 60,
        totalDistance: 15 + Math.random() * 10,
        fuelCost: 5.5 + Math.random() * 2.0,
        optimizedOrder
      };
    });

    return routes;
  }

  /**
   * 获取区域包裹热力图数据
   */
  static async getRegionHeatmap(region: string) {
    // 模拟数据聚合
    return {
      region,
      hotspots: [
        { lat: 40.7128, lng: -74.006, density: 0.85 },
        { lat: 40.7306, lng: -73.9352, density: 0.92 }
      ],
      timestamp: new Date()
    };
  }

  /**
   * 初始化数据库表
   */
  static async initTable() {
    const hasTable = await db.schema.hasTable('cf_last_mile_metrics');
    if (!hasTable) {
      logger.info('📦 Creating cf_last_mile_metrics table...');
      await db.schema.createTable('cf_last_mile_metrics', (table) => {
        table.increments('id').primary();
        table.string('region', 100).notNullable();
        table.float('density');
        table.float('avgDeliveryTime');
        table.timestamp('timestamp').defaultTo(db.fn.now());
        table.index(['region']);
      });
    }
  }
}
