Implementing Stablecoin Tax Reporting: IRS Form 8949 Automation

// Stablecoin tax event classifier
class StablecoinTaxEventClassifier {
  classifyTransaction(transaction) {
    const taxEvents = {
      acquisition: this.isAcquisitionEvent(transaction),
      disposal: this.isDisposalEvent(transaction),
      trade: this.isTradeEvent(transaction),
      payment: this.isPaymentEvent(transaction),
      income: this.isIncomeEvent(transaction),
      mining: this.isMiningEvent(transaction)
    };

    // Determine primary tax classification
    if (taxEvents.disposal || taxEvents.trade || taxEvents.payment) {
      return {
        event_type: 'taxable_disposal',
        form_8949_required: true,
        schedule_d_required: true,
        ordinary_income: false,
        capital_gain: true
      };
    }

    if (taxEvents.income || taxEvents.mining) {
      return {
        event_type: 'ordinary_income',
        form_8949_required: false,
        schedule_d_required: false,
        ordinary_income: true,
        capital_gain: false
      };
    }

    if (taxEvents.acquisition) {
      return {
        event_type: 'acquisition',
        form_8949_required: false,
        schedule_d_required: false,
        cost_basis_tracking: true,
        holding_period_start: transaction.timestamp
      };
    }

    return {
      event_type: 'non_taxable',
      form_8949_required: false,
      reporting_required: false
    };
  }

  isDisposalEvent(transaction) {
    const disposalTypes = [
      'sale_for_fiat',
      'trade_for_crypto',
      'payment_for_goods',
      'payment_for_services',
      'staking_reward_claim',
      'liquidity_mining_claim'
    ];
    
    return disposalTypes.includes(transaction.type);
  }

  isTradeEvent(transaction) {
    return transaction.type === 'crypto_to_crypto_trade' && 
           (transaction.from_asset === 'stablecoin' || transaction.to_asset === 'stablecoin');
  }
}

// Advanced cost basis calculator with multiple methods
class StablecoinCostBasisCalculator {
  constructor() {
    this.methods = {
      'FIFO': new FIFOCalculator(),
      'LIFO': new LIFOCalculator(), 
      'HIFO': new HIFOCalculator(),
      'SpecificID': new SpecificIDCalculator(),
      'AverageCost': new AverageCostCalculator()
    };
    this.defaultMethod = 'FIFO'; // IRS default
  }

  async calculateCostBasis(disposal, acquisitions, method = this.defaultMethod) {
    const calculator = this.methods[method];
    if (!calculator) {
      throw new Error(`Unsupported cost basis method: ${method}`);
    }

    // Sort acquisitions for the chosen method
    const sortedAcquisitions = this.sortAcquisitions(acquisitions, method);
    
    let remainingDisposal = disposal.quantity;
    let totalCostBasis = 0;
    let matchedAcquisitions = [];

    for (const acquisition of sortedAcquisitions) {
      if (remainingDisposal <= 0) break;

      const matchQuantity = Math.min(remainingDisposal, acquisition.remaining_quantity);
      const matchCostBasis = (acquisition.cost_per_unit * matchQuantity);

      matchedAcquisitions.push({
        acquisition_id: acquisition.id,
        match_quantity: matchQuantity,
        cost_per_unit: acquisition.cost_per_unit,
        match_cost_basis: matchCostBasis,
        acquisition_date: acquisition.date,
        holding_period: this.calculateHoldingPeriod(acquisition.date, disposal.date)
      });

      totalCostBasis += matchCostBasis;
      remainingDisposal -= matchQuantity;

      // Update remaining quantity in acquisition
      await this.updateAcquisitionRemaining(acquisition.id, matchQuantity);
    }

    if (remainingDisposal > 0) {
      throw new Error(`Insufficient acquisition records for disposal of ${disposal.quantity} units`);
    }

    return {
      total_cost_basis: totalCostBasis,
      matched_acquisitions: matchedAcquisitions,
      calculation_method: method,
      disposal_proceeds: disposal.proceeds,
      capital_gain_loss: disposal.proceeds - totalCostBasis,
      short_term_portion: this.calculateShortTermPortion(matchedAcquisitions),
      long_term_portion: this.calculateLongTermPortion(matchedAcquisitions)
    };
  }

  sortAcquisitions(acquisitions, method) {
    switch (method) {
      case 'FIFO':
        return acquisitions.sort((a, b) => new Date(a.date) - new Date(b.date));
      case 'LIFO':
        return acquisitions.sort((a, b) => new Date(b.date) - new Date(a.date));
      case 'HIFO':
        return acquisitions.sort((a, b) => b.cost_per_unit - a.cost_per_unit);
      case 'AverageCost':
        return this.calculateAverageCost(acquisitions);
      default:
        return acquisitions;
    }
  }

  calculateHoldingPeriod(acquisitionDate, disposalDate) {
    const daysDiff = Math.floor((new Date(disposalDate) - new Date(acquisitionDate)) / (1000 * 60 * 60 * 24));
    return {
      days: daysDiff,
      is_long_term: daysDiff > 365
    };
  }
}

// Form 8949 generator with IRS validation
class Form8949Generator {
  constructor() {
    this.validator = new IRSFormValidator();
    this.formatter = new IRSFormFormatter();
  }

  async generateForm8949(userId, taxYear, costBasisMethod = 'FIFO') {
    const disposals = await this.getDisposalTransactions(userId, taxYear);
    const form8949Entries = [];

    for (const disposal of disposals) {
      const costBasisResult = await this.calculateCostBasis(disposal, costBasisMethod);
      
      const entry = {
        // Column (a) - Description of property
        description: this.formatPropertyDescription(disposal),
        
        // Column (b) - Date acquired
        date_acquired: this.formatAcquisitionDates(costBasisResult.matched_acquisitions),
        
        // Column (c) - Date sold or disposed
        date_sold: this.formatDate(disposal.date),
        
        // Column (d) - Proceeds
        proceeds: this.formatCurrency(disposal.proceeds),
        
        // Column (e) - Cost or other basis
        cost_basis: this.formatCurrency(costBasisResult.total_cost_basis),
        
        // Column (f) - Adjustment code (if any)
        adjustment_code: this.determineAdjustmentCode(disposal, costBasisResult),
        
        // Column (g) - Adjustment amount
        adjustment_amount: this.calculateAdjustmentAmount(disposal, costBasisResult),
        
        // Column (h) - Gain or loss
        gain_loss: this.formatCurrency(costBasisResult.capital_gain_loss),
        
        // Additional metadata for audit trail
        transaction_id: disposal.transaction_id,
        calculation_method: costBasisMethod,
        holding_period: costBasisResult.short_term_portion > 0 ? 'short_term' : 'long_term',
        source_records: costBasisResult.matched_acquisitions
      };

      // Validate entry before adding
      const validation = await this.validator.validateForm8949Entry(entry);
      if (!validation.valid) {
        throw new Error(`Form 8949 entry validation failed: ${validation.errors.join(', ')}`);
      }

      form8949Entries.push(entry);
    }

    // Generate separate short-term and long-term sections
    const shortTermEntries = form8949Entries.filter(e => e.holding_period === 'short_term');
    const longTermEntries = form8949Entries.filter(e => e.holding_period === 'long_term');

    return {
      tax_year: taxYear,
      taxpayer_id: userId,
      short_term_transactions: shortTermEntries,
      long_term_transactions: longTermEntries,
      summary: {
        total_short_term_gain_loss: this.calculateTotalGainLoss(shortTermEntries),
        total_long_term_gain_loss: this.calculateTotalGainLoss(longTermEntries),
        total_proceeds: this.calculateTotalProceeds(form8949Entries),
        total_cost_basis: this.calculateTotalCostBasis(form8949Entries)
      },
      generation_timestamp: new Date(),
      cost_basis_method: costBasisMethod
    };
  }

  formatPropertyDescription(disposal) {
    // IRS requires specific format for cryptocurrency descriptions
    return `${disposal.quantity.toFixed(8)} ${disposal.asset_symbol} (${disposal.asset_name})`;
  }

  formatAcquisitionDates(matchedAcquisitions) {
    // Handle multiple acquisition dates for single disposal
    if (matchedAcquisitions.length === 1) {
      return this.formatDate(matchedAcquisitions[0].acquisition_date);
    }
    
    // Multiple acquisitions - use "VARIOUS" as per IRS guidance
    const uniqueDates = [...new Set(matchedAcquisitions.map(a => a.acquisition_date))];
    if (uniqueDates.length > 3) {
      return "VARIOUS";
    }
    
    return uniqueDates.map(date => this.formatDate(date)).join(', ');
  }

  determineAdjustmentCode(disposal, costBasisResult) {
    // Common adjustment codes for stablecoin transactions
    if (disposal.type === 'fork' || disposal.type === 'airdrop') {
      return 'A'; // Adjustment for fork/airdrop
    }
    
    if (disposal.type === 'staking_reward') {
      return 'B'; // Basis adjustment for staking rewards
    }
    
    if (costBasisResult.wash_sale_adjustment) {
      return 'W'; // Wash sale adjustment
    }
    
    return null; // No adjustment needed
  }
}

// Transaction reconciliation and gap detection
class StablecoinTransactionReconciler {
  constructor() {
    this.blockchainScanners = {
      ethereum: new EthereumScanner(),
      polygon: new PolygonScanner(),
      binance: new BinanceSmartChainScanner(),
      arbitrum: new ArbitrumScanner()
    };
    this.exchangeConnectors = {
      coinbase: new CoinbaseConnector(),
      binance: new BinanceConnector(),
      kraken: new KrakenConnector(),
      uniswap: new UniswapConnector()
    };
  }

  async reconcileAllTransactions(userId, addresses, exchanges, dateRange) {
    const reconciliationReport = {
      blockchain_transactions: [],
      exchange_transactions: [],
      missing_transactions: [],
      duplicate_transactions: [],
      categorization_issues: [],
      total_volume_reconciled: 0
    };

    // Fetch from all blockchain sources
    for (const [network, scanner] of Object.entries(this.blockchainScanners)) {
      const networkAddresses = addresses.filter(addr => addr.network === network);
      for (const address of networkAddresses) {
        const transactions = await scanner.getTransactions(address.address, dateRange);
        reconciliationReport.blockchain_transactions.push(...transactions);
      }
    }

    // Fetch from all exchange sources
    for (const [exchange, connector] of Object.entries(this.exchangeConnectors)) {
      const exchangeCredentials = exchanges.find(ex => ex.name === exchange);
      if (exchangeCredentials) {
        const transactions = await connector.getTransactions(exchangeCredentials, dateRange);
        reconciliationReport.exchange_transactions.push(...transactions);
      }
    }

    // Detect missing transactions
    const missingTransactions = await this.detectMissingTransactions(
      reconciliationReport.blockchain_transactions,
      reconciliationReport.exchange_transactions
    );
    reconciliationReport.missing_transactions = missingTransactions;

    // Detect duplicates
    const duplicates = await this.detectDuplicateTransactions([
      ...reconciliationReport.blockchain_transactions,
      ...reconciliationReport.exchange_transactions
    ]);
    reconciliationReport.duplicate_transactions = duplicates;

    // Validate transaction categorization
    const categorizationIssues = await this.validateTransactionCategorization([
      ...reconciliationReport.blockchain_transactions,
      ...reconciliationReport.exchange_transactions
    ]);
    reconciliationReport.categorization_issues = categorizationIssues;

    return reconciliationReport;
  }

  async detectMissingTransactions(blockchainTxs, exchangeTxs) {
    const missing = [];
    
    // Look for deposits/withdrawals that don't match
    for (const exchangeTx of exchangeTxs) {
      if (exchangeTx.type === 'withdrawal') {
        const matchingDeposit = blockchainTxs.find(btx => 
          btx.hash === exchangeTx.blockchain_hash ||
          (Math.abs(btx.amount - exchangeTx.amount) < 0.001 && 
           Math.abs(new Date(btx.timestamp) - new Date(exchangeTx.timestamp)) < 3600000) // 1 hour tolerance
        );
        
        if (!matchingDeposit) {
          missing.push({
            type: 'missing_blockchain_transaction',
            exchange_transaction: exchangeTx,
            expected_blockchain_hash: exchangeTx.blockchain_hash
          });
        }
      }
    }

    return missing;
  }

  async detectDuplicateTransactions(allTransactions) {
    const duplicates = [];
    const seen = new Map();

    for (const tx of allTransactions) {
      const key = `${tx.hash || tx.id}_${tx.amount}_${tx.timestamp}`;
      
      if (seen.has(key)) {
        duplicates.push({
          duplicate_group: [seen.get(key), tx],
          resolution_needed: true
        });
      } else {
        seen.set(key, tx);
      }
    }

    return duplicates;
  }
}

// Real-time tax impact calculator
class RealTimeTaxCalculator {
  constructor() {
    this.costBasisCalculator = new StablecoinCostBasisCalculator();
    this.taxRateProvider = new TaxRateProvider();
  }

  async calculateTaxImpact(userId, proposedTransaction) {
    if (!this.isTaxableEvent(proposedTransaction)) {
      return {
        taxable_event: false,
        tax_impact: 0,
        estimated_tax_owed: 0
      };
    }

    // Get user's current cost basis position
    const currentPosition = await this.getCurrentPosition(userId, proposedTransaction.asset);
    
    // Calculate cost basis for the proposed disposal
    const costBasisResult = await this.costBasisCalculator.calculateCostBasis(
      proposedTransaction,
      currentPosition.acquisitions,
      currentPosition.cost_basis_method || 'FIFO'
    );

    // Get user's tax rates
    const taxRates = await this.taxRateProvider.getTaxRates(userId);
    
    // Calculate estimated tax impact
    const taxImpact = this.calculateEstimatedTax(costBasisResult, taxRates);

    return {
      taxable_event: true,
      capital_gain_loss: costBasisResult.capital_gain_loss,
      short_term_gain_loss: costBasisResult.short_term_portion,
      long_term_gain_loss: costBasisResult.long_term_portion,
      estimated_tax_owed: taxImpact.total_tax,
      effective_tax_rate: taxImpact.effective_rate,
      after_tax_proceeds: proposedTransaction.proceeds - taxImpact.total_tax,
      warnings: this.generateTaxWarnings(costBasisResult, taxImpact)
    };
  }

  calculateEstimatedTax(costBasisResult, taxRates) {
    const shortTermTax = Math.max(0, costBasisResult.short_term_portion) * taxRates.ordinary_income_rate;
    const longTermTax = Math.max(0, costBasisResult.long_term_portion) * taxRates.capital_gains_rate;
    
    const totalTax = shortTermTax + longTermTax;
    const totalGain = costBasisResult.capital_gain_loss;
    
    return {
      short_term_tax: shortTermTax,
      long_term_tax: longTermTax,
      total_tax: totalTax,
      effective_rate: totalGain > 0 ? totalTax / totalGain : 0
    };
  }

  generateTaxWarnings(costBasisResult, taxImpact) {
    const warnings = [];

    if (taxImpact.effective_rate > 0.37) {
      warnings.push({
        type: 'high_tax_rate',
        message: 'This transaction will result in a high effective tax rate. Consider tax-loss harvesting.'
      });
    }

    if (costBasisResult.short_term_portion > costBasisResult.long_term_portion) {
      warnings.push({
        type: 'short_term_gain',
        message: 'Most gains will be taxed as short-term. Consider holding longer for better rates.'
      });
    }

    const washSaleRisk = this.detectWashSaleRisk(costBasisResult);
    if (washSaleRisk.risk_detected) {
      warnings.push({
        type: 'wash_sale_risk',
        message: washSaleRisk.warning_message
      });
    }

    return warnings;
  }
}

// Comprehensive audit trail system
class TaxAuditTrailManager {
  constructor() {
    this.documentStorage = new SecureDocumentStorage();
    this.blockchainVerifier = new BlockchainTransactionVerifier();
  }

  async generateAuditPackage(userId, taxYear) {
    const auditPackage = {
      transaction_records: await this.getCompleteTransactionRecords(userId, taxYear),
      cost_basis_calculations: await this.getCostBasisCalculations(userId, taxYear),
      form_8949_source_documents: await this.getForm8949SourceDocuments(userId, taxYear),
      blockchain_verification: await this.getBlockchainVerification(userId, taxYear),
      exchange_statements: await this.getExchangeStatements(userId, taxYear),
      methodology_documentation: await this.getMethodologyDocumentation(userId),
      expert_analysis: await this.getExpertAnalysis(userId, taxYear)
    };

    // Generate audit summary
    auditPackage.summary = {
      total_transactions: auditPackage.transaction_records.length,
      total_volume: this.calculateTotalVolume(auditPackage.transaction_records),
      cost_basis_method: auditPackage.methodology_documentation.cost_basis_method,
      blockchain_verification_rate: this.calculateVerificationRate(auditPackage.blockchain_verification),
      completeness_score: this.calculateCompletenessScore(auditPackage)
    };

    // Store the complete package for future reference
    await this.documentStorage.storeAuditPackage(userId, taxYear, auditPackage);

    return auditPackage;
  }

  async getBlockchainVerification(userId, taxYear) {
    const transactions = await this.getBlockchainTransactions(userId, taxYear);
    const verificationResults = [];

    for (const tx of transactions) {
      const verification = await this.blockchainVerifier.verifyTransaction(tx.hash, tx.network);
      verificationResults.push({
        transaction_id: tx.id,
        blockchain_hash: tx.hash,
        verification_status: verification.status,
        block_number: verification.block_number,
        confirmation_count: verification.confirmations,
        gas_used: verification.gas_used,
        timestamp_verified: verification.block_timestamp,
        our_timestamp: tx.timestamp,
        timestamp_difference: Math.abs(new Date(verification.block_timestamp) - new Date(tx.timestamp))
      });
    }

    return {
      total_transactions: verificationResults.length,
      verified_transactions: verificationResults.filter(v => v.verification_status === 'verified').length,
      verification_rate: verificationResults.filter(v => v.verification_status === 'verified').length / verificationResults.length,
      average_timestamp_difference: this.calculateAverageTimestampDifference(verificationResults),
      detailed_results: verificationResults
    };
  }

  async generateTaxPositionReport(userId, asOfDate) {
    const positions = await this.getCurrentPositions(userId, asOfDate);
    const unrealizedGains = [];

    for (const position of positions) {
      const currentPrice = await this.getCurrentPrice(position.asset, asOfDate);
      const unrealizedGain = (currentPrice - position.average_cost_basis) * position.quantity;
      
      unrealizedGains.push({
        asset: position.asset,
        quantity: position.quantity,
        average_cost_basis: position.average_cost_basis,
        current_price: currentPrice,
        unrealized_gain_loss: unrealizedGain,
        holding_period: this.calculateHoldingPeriod(position.oldest_acquisition_date, asOfDate),
        tax_impact_if_sold: await this.calculateTaxImpactIfSold(userId, position, currentPrice)
      });
    }

    return {
      as_of_date: asOfDate,
      positions: unrealizedGains,
      total_unrealized_gain_loss: unrealizedGains.reduce((sum, p) => sum + p.unrealized_gain_loss, 0),
      potential_tax_liability: unrealizedGains.reduce((sum, p) => sum + p.tax_impact_if_sold.estimated_tax, 0)
    };
  }
}

// Tax software integration hub
class TaxSoftwareIntegration {
  constructor() {
    this.integrations = {
      turbotax: new TurboTaxIntegration(),
      taxact: new TaxActIntegration(),
      hrblock: new HRBlockIntegration(),
      freetaxusa: new FreeTaxUSAIntegration()
    };
  }

  async exportToTaxSoftware(userId, taxYear, softwareName, format = 'csv') {
    const form8949Data = await this.generateForm8949(userId, taxYear);
    const integration = this.integrations[softwareName.toLowerCase()];
    
    if (!integration) {
      throw new Error(`Tax software ${softwareName} not supported`);
    }

    const exportData = await integration.formatData(form8949Data, format);
    
    return {
      software: softwareName,
      format: format,
      export_data: exportData,
      import_instructions: integration.getImportInstructions(),
      verification_checklist: integration.getVerificationChecklist()
    };
  }

  async generateTurboTaxCSV(form8949Data) {
    // TurboTax CSV format for Form 8949 import
    const csvHeaders = [
      'Description',
      'Date Acquired',
      'Date Sold',
      'Sales Price',
      'Cost Basis',
      'Adjustment Code',
      'Adjustment Amount',
      'Gain/Loss'
    ];

    const csvRows = [];
    
    // Process short-term transactions
    for (const tx of form8949Data.short_term_transactions) {
      csvRows.push([
        tx.description,
        tx.date_acquired,
        tx.date_sold,
        tx.proceeds,
        tx.cost_basis,
        tx.adjustment_code || '',
        tx.adjustment_amount || '0',
        tx.gain_loss
      ]);
    }

    // Process long-term transactions
    for (const tx of form8949Data.long_term_transactions) {
      csvRows.push([
        tx.description,
        tx.date_acquired,
        tx.date_sold,
        tx.proceeds,
        tx.cost_basis,
        tx.adjustment_code || '',
        tx.adjustment_amount || '0',
        tx.gain_loss
      ]);
    }

    return {
      headers: csvHeaders,
      rows: csvRows,
      csv_content: this.generateCSVContent(csvHeaders, csvRows)
    };
  }
}