金融信贷审批 AI Agent 财务报表勾稽核验与跨期异常审计架构实战：破解三表不平、跨期虚增营收与隐匿关联担保难题

/**
 * 金融信贷财务报表数据契约接口
 * 遵循 XBRL 分类标准定义，支持多期财务报表联合核验
 */
export interface BalanceSheet {
  period: string; // 报表所属报告期，如 "2025-12-31"
  monetaryUnit: 'YUAN' | 'TEN_THOUSAND_YUAN'; // 报表量纲：元或万元
  // 流动资产
  cashAndEquivalents: number; // 货币资金
  accountsReceivable: number; // 应收账款与应收票据合计
  inventories: number; // 存货
  otherReceivables: number; // 其他应收款
  totalCurrentAssets: number; // 流动资产合计
  // 非流动资产
  fixedAssets: number; // 固定资产净额
  intangibleAssets: number; // 无形资产
  totalNonCurrentAssets: number; // 非流动资产合计
  totalAssets: number; // 资产总计
  // 负债
  shortTermBorrowings: number; // 短期借款与有息票据
  accountsPayable: number; // 应付账款
  totalCurrentLiabilities: number; // 流动负债合计
  longTermBorrowings: number; // 长期借款
  totalLiabilities: number; // 负债合计
  // 所有者权益
  paidInCapital: number; // 实收资本 / 股本
  retainedEarnings: number; // 未分配利润
  surplusReserves: number; // 盈余公积
  totalEquity: number; // 所有者权益合计
  totalLiabilitiesAndEquity: number; // 负债和所有者权益总计
}

export interface IncomeStatement {
  period: string; // 报告期，如 "2025-12-31"
  monetaryUnit: 'YUAN' | 'TEN_THOUSAND_YUAN';
  operatingRevenue: number; // 营业收入
  operatingCosts: number; // 营业成本
  sellingExpenses: number; // 销售费用
  administrativeExpenses: number; // 管理费用
  financialExpenses: number; // 财务费用（其中包含利息支出）
  interestExpense: number; // 财务费用中的利息支出细项
  operatingProfit: number; // 营业利润
  totalProfit: number; // 利润总额
  incomeTaxExpense: number; // 所得税费用
  netProfit: number; // 净利润
}

export interface CashFlowStatement {
  period: string;
  monetaryUnit: 'YUAN' | 'TEN_THOUSAND_YUAN';
  cashFromSales: number; // 销售商品、提供劳务收到的现金
  operatingCashInflow: number; // 经营活动现金流入小计
  operatingCashOutflow: number; // 经营活动现金流出小计
  netCashFromOperating: number; // 经营活动产生的现金流量净额
  netCashFromInvesting: number; // 投资活动产生的现金流量净额
  netCashFromFinancing: number; // 筹资活动产生的现金流量净额
  netIncreaseInCash: number; // 现金及现金等价物净增加额
  cashAtEndOfPeriod: number; // 期末现金及现金等价物余额
}

/**
 * 审计异常项记录定义
 */
export interface AuditAnomaly {
  code: string; // 规则异常编码，如 "BS_BALANCE_ERROR", "HIGH_CASH_HIGH_DEBT"
  category: 'HARD_BALANCE' | 'CROSS_STATEMENT' | 'ANOMALY_FRAUD'; // 错误分类
  severity: 'REDLINE_REJECT' | 'WARNING_MANUAL_REVIEW'; // 严重级别：红线熔断或存疑复核
  description: string; // 业务异常中文阐述
  formula: string; // 校验所用会计公式
  difference: number; // 数值差额或异常偏离度
  provEvidence: string; // 证据溯源锚点与单元格坐标
}

/**
 * 财务报表勾稽与异常审计引擎类
 */
export class FinancialStatementAuditEngine {
  private tolerance = 1.0; // 默认允许的四舍五入容差（元）

  /**
   * 归一化报表量纲，统一转换为“元”为基准单位进行计算
   */
  private normalizeAmount(amount: number, unit: 'YUAN' | 'TEN_THOUSAND_YUAN'): number {
    return unit === 'TEN_THOUSAND_YUAN' ? amount * 10000 : amount;
  }

  /**
   * 核心核验主入口：输入两期资产负债表与本期利润表、现金流量表
   */
  public executeFullAudit(
    priorBS: BalanceSheet,
    currentBS: BalanceSheet,
    currentIS: IncomeStatement,
    currentCF: CashFlowStatement
  ): {
    overallStatus: 'VERIFIED_PASS' | 'CONDITIONAL_MANUAL' | 'REJECT_REDLINE';
    anomalies: AuditAnomaly[];
    summary: string;
    generatedAt: string;
  } {
    const anomalies: AuditAnomaly[] = [];

    // 1. 资产负债表单表硬平衡校验
    this.verifyBalanceSheetHardBalance(currentBS, anomalies);

    // 2. 利润表单表硬平衡校验
    this.verifyIncomeStatementHardBalance(currentIS, anomalies);

    // 3. 跨表留存收益勾稽校验（资产负债表 vs 利润表）
    this.verifyRetainedEarningsCrossCheck(priorBS, currentBS, currentIS, anomalies);

    // 4. 跨表现金净变动勾稽校验（资产负债表 vs 现金流量表）
    this.verifyCashMovementCrossCheck(priorBS, currentBS, currentCF, anomalies);

    // 5. 跨期反粉饰与反造假穿透检查（存贷双高、虚增营收背离）
    this.detectFinancialFraudSignals(priorBS, currentBS, currentIS, currentCF, anomalies);

    // 综合判定有限状态机流转
    let overallStatus: 'VERIFIED_PASS' | 'CONDITIONAL_MANUAL' | 'REJECT_REDLINE' = 'VERIFIED_PASS';
    const hasRedline = anomalies.some(a => a.severity === 'REDLINE_REJECT');
    const hasWarning = anomalies.some(a => a.severity === 'WARNING_MANUAL_REVIEW');

    if (hasRedline) {
      overallStatus = 'REJECT_REDLINE';
    } else if (hasWarning) {
      overallStatus = 'CONDITIONAL_MANUAL';
    }

    const summary = this.generateAuditSummary(overallStatus, anomalies);

    return {
      overallStatus,
      anomalies,
      summary,
      generatedAt: new Date().toISOString()
    };
  }

  /**
   * 1. 资产负债表硬平衡断言：资产 ≡ 负债 + 所有者权益
   */
  private verifyBalanceSheetHardBalance(bs: BalanceSheet, anomalies: AuditAnomaly[]): void {
    const totalAssets = this.normalizeAmount(bs.totalAssets, bs.monetaryUnit);
    const liabilities = this.normalizeAmount(bs.totalLiabilities, bs.monetaryUnit);
    const equity = this.normalizeAmount(bs.totalEquity, bs.monetaryUnit);
    const calculatedSum = liabilities + equity;
    const diff = Math.abs(totalAssets - calculatedSum);

    if (diff > this.tolerance) {
      anomalies.push({
        code: 'BS_ACCOUNTING_EQUATION_FAILED',
        category: 'HARD_BALANCE',
        severity: diff > 100 ? 'REDLINE_REJECT' : 'WARNING_MANUAL_REVIEW',
        description: `资产负债表左右不平：总资产（${totalAssets}元）不等于负债加权益总和（${calculatedSum}元），差额达 ${diff.toFixed(2)} 元。`,
        formula: '资产总计 ≡ 负债合计 + 所有者权益合计',
        difference: diff,
        provEvidence: `资产负债表 [期末资产总计: 行42] vs [负债及权益总计: 行88]`
      });
    }
  }

  /**
   * 2. 利润表内部净利润加总断言：净利润 ≡ 利润总额 - 所得税费用
   */
  private verifyIncomeStatementHardBalance(is: IncomeStatement, anomalies: AuditAnomaly[]): void {
    const totalProfit = this.normalizeAmount(is.totalProfit, is.monetaryUnit);
    const tax = this.normalizeAmount(is.incomeTaxExpense, is.monetaryUnit);
    const reportedNetProfit = this.normalizeAmount(is.netProfit, is.monetaryUnit);
    const calculatedNetProfit = totalProfit - tax;
    const diff = Math.abs(reportedNetProfit - calculatedNetProfit);

    if (diff > this.tolerance) {
      anomalies.push({
        code: 'IS_NET_PROFIT_CALC_FAILED',
        category: 'HARD_BALANCE',
        severity: diff > 100 ? 'REDLINE_REJECT' : 'WARNING_MANUAL_REVIEW',
        description: `利润表净利润计算逻辑断裂：报表净利润（${reportedNetProfit}元）与计算值（${calculatedNetProfit}元）不符。`,
        formula: '净利润 ≡ 利润总额 - 所得税费用',
        difference: diff,
        provEvidence: `利润表 [净利润: 行25] vs [利润总额: 行22 - 所得税: 行23]`
      });
    }
  }

  /**
   * 3. 资产负债表与利润表跨表留存收益勾稽：Δ未分配利润 ≡ 净利润 - 利润分配
   */
  private verifyRetainedEarningsCrossCheck(
    priorBS: BalanceSheet,
    currBS: BalanceSheet,
    currIS: IncomeStatement,
    anomalies: AuditAnomaly[]
  ): void {
    const priorRetained = this.normalizeAmount(priorBS.retainedEarnings, priorBS.monetaryUnit);
    const currRetained = this.normalizeAmount(currBS.retainedEarnings, currBS.monetaryUnit);
    const netProfit = this.normalizeAmount(currIS.netProfit, currIS.monetaryUnit);

    const deltaRetained = currRetained - priorRetained;
    // 假设本期未提取公积金或分红时的基础关系；若差额巨大且未披露分红，则提示异常
    const diff = Math.abs(deltaRetained - netProfit);

    if (diff > this.tolerance) {
      anomalies.push({
        code: 'CROSS_RETAINED_EARNINGS_MISMATCH',
        category: 'CROSS_STATEMENT',
        severity: diff > 10000 ? 'REDLINE_REJECT' : 'WARNING_MANUAL_REVIEW',
        description: `跨表留存收益未完全对齐：期末未分配利润变动额（${deltaRetained}元）与本期净利润（${netProfit}元）存在 ${diff.toFixed(2)} 元差额，需核查是否存在未披露的向股东分红或大额会计差错追溯调整。`,
        formula: '期末未分配利润 ≡ 期初未分配利润 + 本期净利润 - 本期分配',
        difference: diff,
        provEvidence: `资产负债表 [所有者权益: 未分配利润变动] vs 利润表 [本期净利润]`
      });
    }
  }

  /**
   * 4. 资产负债表与现金流量表货币资金勾稽：Δ货币资金 ≡ 现金净增加额
   */
  private verifyCashMovementCrossCheck(
    priorBS: BalanceSheet,
    currBS: BalanceSheet,
    currCF: CashFlowStatement,
    anomalies: AuditAnomaly[]
  ): void {
    const priorCash = this.normalizeAmount(priorBS.cashAndEquivalents, priorBS.monetaryUnit);
    const currCash = this.normalizeAmount(currBS.cashAndEquivalents, currBS.monetaryUnit);
    const deltaCash = currCash - priorCash;
    const reportedNetIncrease = this.normalizeAmount(currCF.netIncreaseInCash, currCF.monetaryUnit);

    const diff = Math.abs(deltaCash - reportedNetIncrease);
    if (diff > this.tolerance) {
      anomalies.push({
        code: 'CROSS_CASH_MOVEMENT_MISMATCH',
        category: 'CROSS_STATEMENT',
        severity: diff > 500 ? 'REDLINE_REJECT' : 'WARNING_MANUAL_REVIEW',
        description: `资产负债表与现金流量表货币资金变动矛盾：资产表货币资金变动额（${deltaCash}元）与现金流量表净增加额（${reportedNetIncrease}元）差额达 ${diff.toFixed(2)} 元。`,
        formula: '资产负债表货币资金增量 ≡ 现金流量表现金及现金等价物净增加额',
        difference: diff,
        provEvidence: `资产负债表 [货币资金行] vs 现金流量表 [现金净增加额行]`
      });
    }
  }

  /**
   * 5. 反财务粉饰造假穿透检查：存贷双高与营收-应收严重背离
   */
  private detectFinancialFraudSignals(
    priorBS: BalanceSheet,
    currBS: BalanceSheet,
    currIS: IncomeStatement,
    currCF: CashFlowStatement,
    anomalies: AuditAnomaly[]
  ): void {
    const cash = this.normalizeAmount(currBS.cashAndEquivalents, currBS.monetaryUnit);
    const totalAssets = this.normalizeAmount(currBS.totalAssets, currBS.monetaryUnit);
    const interestBearingDebt =
      this.normalizeAmount(currBS.shortTermBorrowings, currBS.monetaryUnit) +
      this.normalizeAmount(currBS.longTermBorrowings, currBS.monetaryUnit);
    const interestExpense = this.normalizeAmount(currIS.interestExpense, currIS.monetaryUnit);

    // 5.1 存贷双高检测
    const cashRatio = cash / totalAssets;
    if (cashRatio > 0.35 && interestBearingDebt > cash * 0.7 && interestExpense > cash * 0.04) {
      anomalies.push({
        code: 'FRAUD_HIGH_CASH_HIGH_DEBT',
        category: 'ANOMALY_FRAUD',
        severity: 'REDLINE_REJECT',
        description: `触发典型“存贷双高”高危造假特征：企业货币资金占资产比率高达 ${(cashRatio * 100).toFixed(1)}%，但同时背负 ${interestBearingDebt} 元高额有息借款且利息支出达 ${interestExpense} 元，强烈提示账面资金可能存在隐性受限、大股东资金占用或违规对外质押担保。`,
        formula: '货币资金占比 > 35% 且 有息负债/货币资金 > 70% 且 利息支出偏高',
        difference: cashRatio,
        provEvidence: `资产负债表 [货币资金 / 借款明细] & 利润表 [财务费用利息明细]`
      });
    }

    // 5.2 营收与应收账款异动背离检测
    const currRevenue = this.normalizeAmount(currIS.operatingRevenue, currIS.monetaryUnit);
    const currAR = this.normalizeAmount(currBS.accountsReceivable, currBS.monetaryUnit);
    const priorAR = this.normalizeAmount(priorBS.accountsReceivable, priorBS.monetaryUnit);
    const ocf = this.normalizeAmount(currCF.netCashFromOperating, currCF.monetaryUnit);

    const arGrowthRate = priorAR > 0 ? (currAR - priorAR) / priorAR : 0;
    // 若应收账款暴增且经营性现金流为净流出，提示虚增收入
    if (arGrowthRate > 0.4 && ocf < 0 && currAR > currRevenue * 0.5) {
      anomalies.push({
        code: 'FRAUD_REVENUE_RECEIVABLES_DIVERGENCE',
        category: 'ANOMALY_FRAUD',
        severity: 'WARNING_MANUAL_REVIEW',
        description: `营业收入与回款质量严重背离：本期应收账款同比暴增 ${(arGrowthRate * 100).toFixed(1)}%，占营收比例超过 50%，且经营性现金流量净额为负（${ocf}元），提示可能存在跨期虚构贸易合同、虚增纸面收入或向客户超期放宽信用风险。`,
        formula: '应收账款增幅 > 40% 且 经营活动现金流量净额 < 0',
        difference: arGrowthRate,
        provEvidence: `资产负债表 [应收账款行] & 现金流量表 [经营活动现金净额行]`
      });
    }
  }

  /**
   * 生成信贷尽调财务审查综合报告摘要
   */
  private generateAuditSummary(
    status: 'VERIFIED_PASS' | 'CONDITIONAL_MANUAL' | 'REJECT_REDLINE',
    anomalies: AuditAnomaly[]
  ): string {
    if (status === 'VERIFIED_PASS') {
      return '【信贷准入通过】企业财务报表三表硬平衡严格成立，跨期勾稽关系闭环，未检出存贷双高与异常收入背离等造假风险特征，财务数据基础可信度极高。';
    } else if (status === 'CONDITIONAL_MANUAL') {
      return `【存疑人工复核】检出 ${anomalies.length} 项非致命审计异常（包括微小尾差或回款偏离），已自动标定原图坐标，建议信贷审查员开展现场专项调查询问。`;
    } else {
      const redlines = anomalies.filter(a => a.severity === 'REDLINE_REJECT').length;
      return `【刚性红线熔断】检出 ${redlines} 项重大违规/造假红线警报（含三表不平或存贷双高资金受限风险），触发信贷合规一票否决，强烈建议阻断授信准入并要求重新申报。`;
    }
  }
}