Conditional Escrows with Crypto-Conditions

const cc = require('five-bells-condition');

// Generate a random preimage (in practice, this would be meaningful data)
const preimage = crypto.randomBytes(32);
const condition = new cc.PreimageSha256();
condition.setPreimage(preimage);

// Get the condition fingerprint for escrow creation
const fingerprint = condition.getConditionBinary();
const conditionUri = condition.getConditionUri();

console.log('Condition URI:', conditionUri);
console.log('Fingerprint:', fingerprint.toString('hex'));

// Later, fulfill the condition
const fulfillment = condition.serializeBinary();
const isValid = cc.validateFulfillment(fulfillment, conditionUri);

// Alice's side: Create XRP escrow with hash condition
const alicePreimage = crypto.randomBytes(32);
const aliceCondition = new cc.PreimageSha256();
aliceCondition.setPreimage(alicePreimage);

const escrowTx = {
  TransactionType: 'EscrowCreate',
  Account: 'rAlice...',
  Destination: 'rBob...',
  Amount: '1000000000', // 1000 XRP in drops
  Condition: aliceCondition.getConditionBinary().toString('hex').toUpperCase(),
  FinishAfter: Math.floor(Date.now() / 1000) + 86400 // 24 hour timeout
};

// Bob creates corresponding Bitcoin escrow (implementation varies)
// When Alice wants to claim Bitcoin, she reveals alicePreimage
// Bob can then use alicePreimage to claim XRP

const prefix = Buffer.from('PAYMENT_AUTH_2024_', 'utf8');
const message = Buffer.from('Alice authorizes 1000 XRP payment to Bob', 'utf8');
const preimage = Buffer.concat([prefix, message]);

const condition = new cc.PrefixSha256();
condition.setPrefix(prefix);
condition.setMaxMessageLength(1024);
condition.setSubcondition(new cc.PreimageSha256().setPreimage(preimage));

// The condition requires a preimage starting with 'PAYMENT_AUTH_2024_'
// and hashing to the target digest

// CFO creates departmental escrows with prefix conditions
const departments = ['MARKETING', 'ENGINEERING', 'SALES'];
const quarter = '2024_Q1';

departments.forEach(dept => {
  const prefix = Buffer.from(`${dept}_${quarter}_`, 'utf8');
  const deptCondition = new cc.PrefixSha256();
  deptCondition.setPrefix(prefix);
  // ... create escrow with this condition
});

// Department head can fulfill with properly prefixed preimage
const marketingAuth = Buffer.from('MARKETING_2024_Q1_CAMPAIGN_BUDGET_APPROVED', 'utf8');
// This preimage will satisfy the MARKETING prefix condition

// Create a 2-of-3 threshold requiring approval from any 2 parties
const aliceCondition = new cc.PreimageSha256().setPreimage(Buffer.from('alice_secret'));
const bobCondition = new cc.PreimageSha256().setPreimage(Buffer.from('bob_secret'));
const charlieCondition = new cc.PreimageSha256().setPreimage(Buffer.from('charlie_secret'));

const thresholdCondition = new cc.ThresholdSha256();
thresholdCondition.setThreshold(2);
thresholdCondition.addSubcondition(aliceCondition);
thresholdCondition.addSubcondition(bobCondition);
thresholdCondition.addSubcondition(charlieCondition);

// This condition can be fulfilled by any 2 of the 3 parties
// revealing their respective preimages

// Large payment: requires CFO + any department head
const cfoCondition = new cc.PreimageSha256().setPreimage(cfoSecret);
const deptHead1 = new cc.PreimageSha256().setPreimage(dept1Secret);
const deptHead2 = new cc.PreimageSha256().setPreimage(dept2Secret);
const deptHead3 = new cc.PreimageSha256().setPreimage(dept3Secret);

// Any department head (1-of-3)
const anyDeptHead = new cc.ThresholdSha256();
anyDeptHead.setThreshold(1);
anyDeptHead.addSubcondition(deptHead1);
anyDeptHead.addSubcondition(deptHead2);
anyDeptHead.addSubcondition(deptHead3);

// CFO + any department head (2-of-2)
const largePaymentAuth = new cc.ThresholdSha256();
largePaymentAuth.setThreshold(2);
largePaymentAuth.addSubcondition(cfoCondition);
largePaymentAuth.addSubcondition(anyDeptHead);

// Hierarchical authorization example
const managerConditions = managers.map(m => 
  new cc.PreimageSha256().setPreimage(m.secret)
);

const deptHeadConditions = deptHeads.map(d => 
  new cc.PreimageSha256().setPreimage(d.secret)
);

// Routine payments: any manager (1-of-N)
const routineAuth = new cc.ThresholdSha256();
routineAuth.setThreshold(1);
managerConditions.forEach(c => routineAuth.addSubcondition(c));

// Research funding: any department head (1-of-N)
const researchAuth = new cc.ThresholdSha256();
researchAuth.setThreshold(1);
deptHeadConditions.forEach(c => researchAuth.addSubcondition(c));

// Clinical trials: legal AND medical director (2-of-2)
const clinicalAuth = new cc.ThresholdSha256();
clinicalAuth.setThreshold(2);
clinicalAuth.addSubcondition(legalDirectorCondition);
clinicalAuth.addSubcondition(medicalDirectorCondition);

// Deterministic condition generation
function generatePreimageCondition(preimage, maxLength = 1024) {
  if (!Buffer.isBuffer(preimage)) {
    throw new Error('Preimage must be a Buffer');
  }
  
  if (preimage.length > maxLength) {
    throw new Error(`Preimage length ${preimage.length} exceeds maximum ${maxLength}`);
  }
  
  const condition = new cc.PreimageSha256();
  condition.setPreimage(preimage);
  condition.setMaxMessageLength(maxLength);
  
  return {
    condition: condition,
    fingerprint: condition.getConditionBinary(),
    uri: condition.getConditionUri(),
    cost: condition.getCost()
  };
}

// Fingerprint verification workflow
function verifyConditionFingerprint(condition, expectedFingerprint) {
  const calculatedFingerprint = condition.getConditionBinary();
  
  if (!calculatedFingerprint.equals(expectedFingerprint)) {
    console.error('Fingerprint mismatch:');
    console.error('Expected:', expectedFingerprint.toString('hex'));
    console.error('Calculated:', calculatedFingerprint.toString('hex'));
    return false;
  }
  
  return true;
}

// Cross-implementation verification
function crossVerifyCondition(conditionData) {
  // Test with multiple crypto-condition libraries
  const libraries = [fiveBellsCondition, xrplCondition, otherImplementation];
  
  const fingerprints = libraries.map(lib => {
    const condition = lib.deserialize(conditionData);
    return condition.getConditionBinary();
  });
  
  // All implementations should produce identical fingerprints
  const allMatch = fingerprints.every(fp => fp.equals(fingerprints[0]));
  
  if (!allMatch) {
    throw new Error('Cross-implementation fingerprint mismatch detected');
  }
  
  return fingerprints[0];
}

// Comprehensive fulfillment validation
function validateFulfillment(fulfillmentData, conditionUri, additionalChecks = {}) {
  try {
    // Basic cryptographic validation
    const isValid = cc.validateFulfillment(fulfillmentData, conditionUri);
    if (!isValid) {
      return { valid: false, error: 'Cryptographic validation failed' };
    }
    
    // Parse condition and fulfillment for additional checks
    const condition = cc.fromConditionUri(conditionUri);
    const fulfillment = cc.fromFulfillmentUri(fulfillmentData);
    
    // Application-specific validation
    if (additionalChecks.requirePrefix) {
      const preimage = fulfillment.getPreimage();
      if (!preimage.startsWith(additionalChecks.requirePrefix)) {
        return { valid: false, error: 'Required prefix not found' };
      }
    }
    
    if (additionalChecks.maxAge) {
      const timestamp = extractTimestamp(fulfillment);
      const age = Date.now() - timestamp;
      if (age > additionalChecks.maxAge) {
        return { valid: false, error: 'Fulfillment too old' };
      }
    }
    
    return { valid: true, fulfillment: fulfillment };
    
  } catch (error) {
    return { valid: false, error: error.message };
  }
}

// Comprehensive error handling for condition operations
class ConditionError extends Error {
  constructor(message, code, details = {}) {
    super(message);
    this.name = 'ConditionError';
    this.code = code;
    this.details = details;
  }
}

function handleConditionOperation(operation) {
  try {
    return operation();
  } catch (error) {
    // Categorize and enhance error information
    if (error.message.includes('fingerprint')) {
      throw new ConditionError(
        'Condition fingerprint mismatch - check parameters and encoding',
        'FINGERPRINT_MISMATCH',
        { originalError: error.message }
      );
    }
    
    if (error.message.includes('fulfillment')) {
      throw new ConditionError(
        'Fulfillment validation failed - check preimage and condition match',
        'FULFILLMENT_INVALID',
        { originalError: error.message }
      );
    }
    
    if (error.message.includes('threshold')) {
      throw new ConditionError(
        'Threshold condition error - check subcondition count and requirements',
        'THRESHOLD_ERROR',
        { originalError: error.message }
      );
    }
    
    // Generic condition error
    throw new ConditionError(
      'Crypto-condition operation failed',
      'GENERIC_ERROR',
      { originalError: error.message, stack: error.stack }
    );
  }
}

// Production monitoring for crypto-condition operations
class ConditionMonitor {
  constructor(metricsCollector) {
    this.metrics = metricsCollector;
    this.errorCounts = new Map();
  }
  
  recordConditionGeneration(type, success, duration) {
    this.metrics.increment(`condition.generation.${type}.${success ? 'success' : 'failure'}`);
    this.metrics.timing(`condition.generation.${type}.duration`, duration);
  }
  
  recordFulfillmentValidation(success, duration, errorType = null) {
    this.metrics.increment(`fulfillment.validation.${success ? 'success' : 'failure'}`);
    this.metrics.timing('fulfillment.validation.duration', duration);
    
    if (!success && errorType) {
      const count = this.errorCounts.get(errorType) || 0;
      this.errorCounts.set(errorType, count + 1);
      
      // Alert on error rate thresholds
      if (count > 10) { // Threshold for alerting
        this.metrics.alert(`High error rate for ${errorType}: ${count} failures`);
      }
    }
  }
  
  generateHealthReport() {
    return {
      timestamp: new Date().toISOString(),
      errorCounts: Object.fromEntries(this.errorCounts),
      recentMetrics: this.metrics.getRecent()
    };
  }
}