import db from '../config/database';
import { logger } from '../utils/logger';
import { DecisionExplainabilityEngine } from '../core/ai/DecisionExplainabilityEngine';

export interface CarbonMetric {
  routeId: string;
  co2PerKg: number;
  estimatedDays: number;
}

/**
 * [BIZ_OPS_144] 供应链路线碳排放核算建议 (Carbon)
 * @description 核心逻辑：核算不同物流路径（空运、海运、铁路）的碳排放量，为具备“绿色品牌”心智的租户推荐低碳路径。
 */
export class GreenSupplyService {
  /**
   * 推荐低碳路径并生成建议 (BIZ_OPS_144)
   */
  static async recommendLowCarbonRoutes(tenantId: string, orderId: string): Promise<any> {
    logger.info(`[GreenSupply] Calculating carbon footprint for Order: ${orderId}, Tenant: ${tenantId}`);

    try {
      // 1. 获取当前物流选项 (模拟)
      const options: CarbonMetric[] = [
        { routeId: 'AIR_EXPRESS', co2PerKg: 15.2, estimatedDays: 3 },
        { routeId: 'SEA_FREIGHT', co2PerKg: 0.8, estimatedDays: 25 },
        { routeId: 'RAIL_WAY', co2PerKg: 2.5, estimatedDays: 15 }
      ];

      // 2. 识别低碳选项 (相比空运节省 > 80% 排放)
      const standard = options.find(o => o.routeId === 'AIR_EXPRESS')!;
      const greenOption = options.find(o => o.routeId === 'RAIL_WAY')!; // 中欧班列示例

      const carbonSavings = standard.co2PerKg - greenOption.co2PerKg;
      const advice = `Green Route Recommended: Switching to ${greenOption.routeId} reduces carbon footprint by ${carbonSavings.toFixed(1)}kg CO2 per kg of cargo. ` +
        `Trade-off: +${greenOption.estimatedDays - standard.estimatedDays} days delivery time.`;

      // 3. [UX_XAI_01] 记录决策证据链
      await DecisionExplainabilityEngine.logDecision({
        tenantId,
        module: 'ESG_GOVERNANCE',
        resourceId: orderId,
        decisionType: 'LOW_CARBON_ROUTE_RECOMMENDATION',
        causalChain: advice,
        factors: [
          { name: 'CarbonSavings', value: carbonSavings, weight: 0.8, impact: 'POSITIVE' },
          { name: 'DeliveryDelay', value: greenOption.estimatedDays - standard.estimatedDays, weight: 0.2, impact: 'NEGATIVE' }
        ],
        traceId: 'green-supply-' + Date.now()
      });

      return { success: true, greenOption, advice, status: 'PENDING_REVIEW' };
    } catch (err: any) {
      logger.error(`[GreenSupply][WARN] Calculation failed: ${err.message}`);
      return { success: false, error: err.message };
    }
  }
}