Privacy-Preserving Attestations

interface PrivacyArchitecture {
  // 1. Minimal Disclosure
  minimalDisclosure: {
    onChain: 'boolean_results_only';    // Only yes/no answers
    offChain: 'detailed_proofs';        // Full verification data
    encrypted: 'sensitive_fields';      // Encrypted personal data
  };
  
  // 2. Selective Disclosure
  selectiveDisclosure: {
    claims: 'user_controlled';          // Users choose what to reveal
    granular: 'field_level_control';    // Individual field control
    contextual: 'purpose_specific';     // Different data for different uses
  };
  
  // 3. Zero-Knowledge Proofs
  zkProofs: {
    range: 'age_income_verification';   // Prove values in ranges
    membership: 'list_inclusion';       // Prove list membership
    computation: 'private_calculations'; // Prove computations on private data
  };
  
  // 4. Temporal Privacy
  temporalPrivacy: {
    ephemeral: 'short_lived_proofs';    // Time-limited attestations
    rotating: 'key_rotation';           // Regular key updates
    expiring: 'automatic_deletion';     // Self-destructing data
  };
}

import { StellarAttestSDK, SolanaAttestSDK } from '@attestprotocol/sdk';
import { generateProof, verifyProof, CircuitInput } from 'snarkjs'; // Example ZK library

class ZeroKnowledgeAttestationSystem {
  private sdk: StellarAttestSDK | SolanaAttestSDK;
  private zkCircuits: Map<string, ZKCircuit>;
  
  constructor(sdk: StellarAttestSDK | SolanaAttestSDK) {
    this.sdk = sdk;
    this.initializeZKCircuits();
  }

  async createZKAgeVerification(
    userAddress: string,
    actualAge: number,
    minimumAge: number,
    proofData: AgeProofData
  ): Promise<ZKAttestationResult> {
    const sessionId = `zk-age-${Date.now()}-${Math.random().toString(36).substr(2, 9)}`;
    
    try {
      // Step 1: Generate zero-knowledge proof
      const proof = await this.generateAgeProof(actualAge, minimumAge, proofData);
      
      // Step 2: Create attestation with proof result
      const attestation = await this.createAgeAttestation(userAddress, minimumAge, proof, sessionId);
      
      // Step 3: Store proof data securely
      await this.storeAgeProofData(sessionId, proof, attestation);
      
      return this.buildZKResult(sessionId, attestation, proof);
      
    } catch (error) {
      await this.logZKError(sessionId, error);
      throw error;
    }
  }

  async createZKIncomeVerification(
    userAddress: string,
    actualIncome: number,
    incomeThresholds: number[],
    proofData: IncomeProofData
  ): Promise<ZKAttestationResult> {
    const sessionId = `zk-income-${Date.now()}-${Math.random().toString(36).substr(2, 9)}`;
    
    try {
      // Step 1: Generate income threshold proof
      const proof = await this.generateIncomeProof(actualIncome, incomeThresholds, proofData);
      
      // Step 2: Create income attestation
      const attestation = await this.createIncomeAttestation(userAddress, actualIncome, incomeThresholds, proof, sessionId);
      
      // Step 3: Store proof data
      await this.storeIncomeProofData(sessionId, proof, attestation);
      
      return this.buildZKResult(sessionId, attestation, proof);
      
    } catch (error) {
      await this.logZKError(sessionId, error);
      throw error;
    }
  }

  async verifyZKAttestation(
    attestationUID: string,
    verificationContext: ZKVerificationContext
  ): Promise<ZKVerificationResult> {
    try {
      // Step 1: Fetch and validate attestation
      const attestation = await this.fetchAndValidateAttestation(verificationContext);
      if (!attestation.valid) {
        return { valid: false, reason: attestation.reason };
      }
      
      // Step 2: Retrieve stored proof data
      const storedProof = await this.retrieveZKProof(attestation.data.reference);
      if (!storedProof) {
        return { valid: false, reason: 'ZK proof data not found' };
      }
      
      // Step 3: Verify the zero-knowledge proof
      const proofVerification = await this.verifyStoredProof(storedProof, verificationContext);
      
      return this.buildVerificationResult(attestation.data, proofVerification);
      
    } catch (error) {
      return {
        valid: false,
        reason: `ZK verification failed: ${error.message}`
      };
    }
  }

private async generateAgeProof(
  actualAge: number,
  minimumAge: number,
  proofData: AgeProofData
) {
  // Generate zero-knowledge proof that age >= minimumAge without revealing actual age
  const circuitInput: CircuitInput = {
    age: actualAge,
    minimumAge: minimumAge,
    salt: this.generateSalt(),
    documentHash: proofData.documentHash
  };
  
  const proof = await this.generateZKProof('age-verification', circuitInput);
  
  if (!proof.valid) {
    throw new Error('Zero-knowledge proof generation failed');
  }
  
  return proof;
}

private async createAgeAttestation(
  userAddress: string,
  minimumAge: number,
  proof: any,
  sessionId: string
) {
  const attestation = await this.sdk.attest({
    schemaUID: 'zk-age-verification-v1',
    subject: userAddress,
    value: `ageRequirementMet:true,minimumAge:${minimumAge},proofHash:${proof.hash},verificationMethod:zk_proof,timestamp:${Math.floor(Date.now() / 1000)}`,
    reference: sessionId
  });
  
  if (attestation.error) {
    throw new Error(`ZK attestation failed: ${attestation.error}`);
  }
  
  return attestation.data;
}

private async storeAgeProofData(sessionId: string, proof: any, attestation: string) {
  await this.storeZKProof({
    sessionId,
    proofData: proof,
    circuitType: 'age-verification',
    attestationUID: attestation,
    timestamp: Date.now()
  });
}

private async generateIncomeProof(
  actualIncome: number,
  incomeThresholds: number[],
  proofData: IncomeProofData
) {
  const circuitInput: CircuitInput = {
    income: actualIncome,
    thresholds: incomeThresholds,
    salt: this.generateSalt(),
    documentHash: proofData.taxDocumentHash
  };
  
  const proof = await this.generateZKProof('income-verification', circuitInput);
  
  if (!proof.valid) {
    throw new Error('Income verification proof generation failed');
  }
  
  return proof;
}

private async createIncomeAttestation(
  userAddress: string,
  actualIncome: number,
  incomeThresholds: number[],
  proof: any,
  sessionId: string
) {
  // Calculate threshold results
  const thresholdResults = incomeThresholds.map(threshold => ({
    threshold,
    meets: actualIncome >= threshold
  }));
  
  const thresholdString = thresholdResults
    .map(r => `${r.threshold}:${r.meets}`)
    .join('|');
  
  const attestation = await this.sdk.attest({
    schemaUID: 'zk-income-verification-v1',
    subject: userAddress,
    value: `thresholdResults:${thresholdString},proofHash:${proof.hash},verificationMethod:zk_proof,timestamp:${Math.floor(Date.now() / 1000)}`,
    reference: sessionId
  });
  
  if (attestation.error) {
    throw new Error(`ZK income attestation failed: ${attestation.error}`);
  }
  
  return attestation.data;
}

private async storeIncomeProofData(sessionId: string, proof: any, attestation: string) {
  await this.storeZKProof({
    sessionId,
    proofData: proof,
    circuitType: 'income-verification',
    attestationUID: attestation,
    timestamp: Date.now()
  });
}

private buildZKResult(sessionId: string, attestation: string, proof: any): ZKAttestationResult {
  return {
    success: true,
    sessionId,
    attestationUID: attestation,
    proofHash: proof.hash,
    verificationMethod: 'zero_knowledge',
    privacyLevel: 'maximum'
  };
}

private async fetchAndValidateAttestation(context: ZKVerificationContext) {
  const attestation = await this.sdk.fetchAttestation({
    schemaUID: context.schemaUID,
    subject: context.subject
  });
  
  if (attestation.error || !attestation.data || attestation.data.revoked) {
    return {
      valid: false,
      reason: 'Attestation not found or revoked'
    };
  }
  
  return {
    valid: true,
    data: attestation.data
  };
}

private async verifyStoredProof(storedProof: any, context: ZKVerificationContext) {
  return await this.verifyZKProof(
    storedProof.circuitType,
    storedProof.proofData,
    context.publicInputs
  );
}

private buildVerificationResult(attestationData: any, proofVerification: any): ZKVerificationResult {
  const parsedData = this.parseAttestationData(attestationData.value);
  
  return {
    valid: proofVerification.valid,
    reason: proofVerification.reason,
    proofHash: parsedData.proofHash,
    verificationMethod: parsedData.verificationMethod,
    timestamp: parseInt(parsedData.timestamp)
  };
}

private async generateZKProof(
  circuitType: string,
  input: CircuitInput
): Promise<{ valid: boolean; hash: string; proof: any }> {
  const circuit = this.zkCircuits.get(circuitType);
  
  if (!circuit) {
    throw new Error(`ZK circuit not found: ${circuitType}`);
  }
  
  try {
    // Generate proof using circuit
    const { proof, publicSignals } = await generateProof(circuit.wasm, circuit.zkey, input);
    
    // Create proof hash for attestation
    const proofHash = this.hashProof(proof, publicSignals);
    
    return {
      valid: true,
      hash: proofHash,
      proof: { proof, publicSignals }
    };
  } catch (error) {
    return {
      valid: false,
      hash: '',
      proof: null
    };
  }
}

private async verifyZKProof(
  circuitType: string,
  storedProof: any,
  publicInputs: any[]
): Promise<{ valid: boolean; reason: string }> {
  const circuit = this.zkCircuits.get(circuitType);
  
  if (!circuit) {
    return {
      valid: false,
      reason: 'Verification circuit not found'
    };
  }
  
  try {
    const isValid = await verifyProof(
      circuit.vkey,
      storedProof.publicSignals,
      storedProof.proof
    );
    
    return {
      valid: isValid,
      reason: isValid ? 'Proof verified successfully' : 'Proof verification failed'
    };
  } catch (error) {
    return {
      valid: false,
      reason: `Verification error: ${error.message}`
    };
  }
}

private initializeZKCircuits(): void {
  // Initialize ZK circuits for different verification types
  this.zkCircuits = new Map([
    ['age-verification', {
      wasm: 'circuits/age_verification.wasm',
      zkey: 'circuits/age_verification.zkey',
      vkey: 'circuits/age_verification_vkey.json'
    }],
    ['income-verification', {
      wasm: 'circuits/income_verification.wasm',
      zkey: 'circuits/income_verification.zkey',
      vkey: 'circuits/income_verification_vkey.json'
    }],
    ['membership-verification', {
      wasm: 'circuits/membership_verification.wasm',
      zkey: 'circuits/membership_verification.zkey',
      vkey: 'circuits/membership_verification_vkey.json'
    }]
  ]);
}

private generateSalt(): string {
  return Math.random().toString(36).substring(2, 15);
}

private hashProof(proof: any, publicSignals: any[]): string {
  // Create deterministic hash of proof
  return `0x${Buffer.from(JSON.stringify({ proof, publicSignals })).toString('hex').slice(0, 64)}`;
}

private parseAttestationData(value: string): Record<string, string> {
  const pairs = value.split(',');
  const result: Record<string, string> = {};
  
  pairs.forEach(pair => {
    const [key, val] = pair.split(':');
    result[key] = val;
  });
  
  return result;
}

private async storeZKProof(proofRecord: ZKProofRecord): Promise<void> {
  // Store proof data in secure, encrypted storage
  // Implementation would use secure database or IPFS
}

private async retrieveZKProof(sessionId: string): Promise<ZKProofRecord | null> {
  // Retrieve proof data from secure storage
  return null; // Placeholder
}

private async logZKError(sessionId: string, error: any): Promise<void> {
  // Log error for debugging while maintaining privacy
}
}

interface ZKCircuit {
wasm: string;
zkey: string;
vkey: string;
}

interface AgeProofData {
documentHash: string;
documentType: string;
issuingAuthority: string;
}

interface IncomeProofData {
taxDocumentHash: string;
year: number;
source: string;
}

interface ZKAttestationResult {
success: boolean;
sessionId: string;
attestationUID: string;
proofHash: string;
verificationMethod: string;
privacyLevel: string;
}

interface ZKVerificationContext {
schemaUID: string;
subject: string;
publicInputs: any[];
}

interface ZKVerificationResult {
valid: boolean;
reason: string;
proofHash?: string;
verificationMethod?: string;
timestamp?: number;
}

interface ZKProofRecord {
sessionId: string;
proofData: any;
circuitType: string;
attestationUID: string;
timestamp: number;
}

class SelectiveDisclosureSystem {
  private sdk: StellarAttestSDK | SolanaAttestSDK;
  private encryptionService: EncryptionService;
  
  constructor(
    sdk: StellarAttestSDK | SolanaAttestSDK,
    encryptionService: EncryptionService
  ) {
    this.sdk = sdk;
    this.encryptionService = encryptionService;
  }

  async createSelectiveDisclosureAttestation(
    userAddress: string,
    fullData: PersonalData,
    disclosurePolicy: DisclosurePolicy
  ): Promise<SelectiveAttestationResult> {
    const sessionId = `sd-${Date.now()}-${Math.random().toString(36).substr(2, 9)}`;
    
    try {
      // Step 1: Process and encrypt sensitive data
      const processedData = await this.processSelectiveDisclosureData(fullData, disclosurePolicy);
      
      // Step 2: Create the selective disclosure attestation
      const attestation = await this.createDisclosureAttestation(userAddress, processedData, sessionId);
      
      // Step 3: Store encryption keys and policies
      await this.storeDisclosureMetadata(sessionId, attestation, processedData, disclosurePolicy, userAddress);
      
      return this.buildSelectiveDisclosureResult(sessionId, attestation, processedData, fullData);
      
    } catch (error) {
      await this.logDisclosureError(sessionId, error);
      throw error;
    }
  }

  async requestDisclosure(
    attestationUID: string,
    requesterAddress: string,
    requestedFields: string[],
    purpose: string
  ): Promise<DisclosureRequestResult> {
    try {
      // Step 1: Validate attestation and policy
      const validation = await this.validateDisclosureRequest(attestationUID);
      if (!validation.valid) {
        return { approved: false, reason: validation.reason };
      }
      
      // Step 2: Evaluate field access permissions
      const evaluation = this.evaluateFieldAccess(requestedFields, purpose, requesterAddress, validation.policy);
      if (!evaluation.approved) {
        return evaluation;
      }
      
      // Step 3: Generate disclosure proof for approved fields
      const disclosureProof = await this.generateDisclosureProof(validation.attestation, requestedFields, validation.policy);
      
      return this.buildDisclosureRequestResult(evaluation, disclosureProof);
      
    } catch (error) {
      return {
        approved: false,
        reason: `Disclosure request failed: ${error.message}`
      };
    }
  }

  async verifySelectiveDisclosure(
    disclosureProof: DisclosureProof,
    verificationContext: DisclosureVerificationContext
  ): Promise<DisclosureVerificationResult> {
    try {
      // Step 1: Verify proof authenticity
      const proofValid = await this.verifyDisclosureProof(disclosureProof);
      if (!proofValid) {
        return { valid: false, reason: 'Disclosure proof verification failed' };
      }
      
      // Step 2: Decrypt and verify field data
      const dataVerification = await this.verifyDisclosedData(disclosureProof);
      if (!dataVerification.valid) {
        return { valid: false, reason: dataVerification.reason };
      }
      
      return this.buildDisclosureVerificationResult(disclosureProof, dataVerification.data);
      
    } catch (error) {
      return {
        valid: false,
        reason: `Verification failed: ${error.message}`
      };
    }
  }

  private async encryptSelectiveFields(
    data: PersonalData,
    policy: DisclosurePolicy
  ): Promise<{ encryptedData: Record<string, string>; keys: Record<string, string> }> {
    const encryptedData: Record<string, string> = {};
    const keys: Record<string, string> = {};
    
    for (const [field, value] of Object.entries(data)) {
      if (policy.encryptedFields.includes(field)) {
        const { encrypted, key } = await this.encryptionService.encrypt(JSON.stringify(value));
        encryptedData[field] = encrypted;
        keys[field] = key;
      } else {
        // Store plain text for non-sensitive fields
        encryptedData[field] = JSON.stringify(value);
      }
    }
    
    return { encryptedData, keys };
  }

private async processSelectiveDisclosureData(
  fullData: PersonalData,
  disclosurePolicy: DisclosurePolicy
) {
  // Encrypt sensitive fields
  const encryptedData = await this.encryptSelectiveFields(fullData, disclosurePolicy);
  
  // Create disclosure map
  const disclosureMap = this.createDisclosureMap(fullData, disclosurePolicy);
  
  return { encryptedData, disclosureMap };
}

private async createDisclosureAttestation(
  userAddress: string,
  processedData: any,
  sessionId: string
) {
  const attestationValue = this.buildSelectiveAttestationValue(
    processedData.encryptedData,
    processedData.disclosureMap
  );
  
  const attestation = await this.sdk.attest({
    schemaUID: 'selective-disclosure-v1',
    subject: userAddress,
    value: attestationValue,
    reference: sessionId
  });
  
  if (attestation.error) {
    throw new Error(`Selective disclosure attestation failed: ${attestation.error}`);
  }
  
  return attestation.data;
}

private async storeDisclosureMetadata(
  sessionId: string,
  attestation: string,
  processedData: any,
  disclosurePolicy: DisclosurePolicy,
  userAddress: string
) {
  await this.storeDisclosureKeys({
    sessionId,
    attestationUID: attestation,
    encryptionKeys: processedData.encryptedData.keys,
    disclosurePolicy,
    userAddress,
    timestamp: Date.now()
  });
}

private buildSelectiveDisclosureResult(
  sessionId: string,
  attestation: string,
  processedData: any,
  fullData: PersonalData
): SelectiveAttestationResult {
  return {
    success: true,
    sessionId,
    attestationUID: attestation,
    disclosureCapabilities: processedData.disclosureMap,
    availableFields: Object.keys(fullData)
  };
}

private async validateDisclosureRequest(attestationUID: string) {
  const attestation = await this.getAttestationDetails(attestationUID);
  
  if (!attestation) {
    return {
      valid: false,
      reason: 'Attestation not found'
    };
  }
  
  const policy = await this.getDisclosurePolicy(attestation.sessionId);
  
  if (!policy) {
    return {
      valid: false,
      reason: 'Disclosure policy not found'
    };
  }
  
  return {
    valid: true,
    attestation,
    policy
  };
}

private evaluateFieldAccess(
  requestedFields: string[],
  purpose: string,
  requesterAddress: string,
  policy: DisclosurePolicy
) {
  return this.evaluateDisclosureRequest(
    requestedFields,
    purpose,
    requesterAddress,
    policy
  );
}

private buildDisclosureRequestResult(
  evaluation: any,
  disclosureProof: DisclosureProof
): DisclosureRequestResult {
  return {
    approved: true,
    disclosureProof,
    revealedFields: evaluation.allowedFields,
    restrictions: evaluation.restrictions
  };
}

private async verifyDisclosedData(disclosureProof: DisclosureProof) {
  // Decrypt requested fields
  const decryptedData = await this.decryptDisclosedFields(
    disclosureProof.encryptedData,
    disclosureProof.decryptionKeys
  );
  
  // Verify field integrity
  const integrityCheck = await this.verifyFieldIntegrity(
    decryptedData,
    disclosureProof.fieldHashes
  );
  
  if (!integrityCheck.valid) {
    return {
      valid: false,
      reason: 'Field integrity verification failed'
    };
  }
  
  return {
    valid: true,
    data: decryptedData
  };
}

private buildDisclosureVerificationResult(
  disclosureProof: DisclosureProof,
  decryptedData: any
): DisclosureVerificationResult {
  return {
    valid: true,
    revealedData: decryptedData,
    verificationLevel: disclosureProof.verificationLevel,
    restrictions: disclosureProof.restrictions,
    expiresAt: disclosureProof.expiresAt
  };
}

private createDisclosureMap(
  data: PersonalData,
  policy: DisclosurePolicy
): DisclosureCapabilities {
  const capabilities: DisclosureCapabilities = {
    publicFields: [],
    conditionalFields: [],
    restrictedFields: [],
    requiresConsent: []
  };
  
  for (const field of Object.keys(data)) {
    if (policy.publicFields.includes(field)) {
      capabilities.publicFields.push(field);
    } else if (policy.conditionalFields.includes(field)) {
      capabilities.conditionalFields.push(field);
    } else if (policy.restrictedFields.includes(field)) {
      capabilities.restrictedFields.push(field);
    }
    
    if (policy.consentRequired.includes(field)) {
      capabilities.requiresConsent.push(field);
    }
  }
  
  return capabilities;
}

private buildSelectiveAttestationValue(
  encryptedData: Record<string, string>,
  disclosureMap: DisclosureCapabilities
): string {
  // Build attestation value with encrypted fields and disclosure metadata
  const components = [
    `publicFields:${disclosureMap.publicFields.join('|')}`,
    `conditionalFields:${disclosureMap.conditionalFields.join('|')}`,
    `restrictedFields:${disclosureMap.restrictedFields.join('|')}`,
    `encryptedFieldCount:${Object.keys(encryptedData).length}`,
    `timestamp:${Math.floor(Date.now() / 1000)}`
  ];
  
  return components.join(',');
}

private evaluateDisclosureRequest(
  requestedFields: string[],
  purpose: string,
  requesterAddress: string,
  policy: DisclosurePolicy
): DisclosureEvaluation {
  const allowedFields: string[] = [];
  const deniedFields: string[] = [];
  const restrictions: string[] = [];
  
  for (const field of requestedFields) {
    if (policy.publicFields.includes(field)) {
      allowedFields.push(field);
    } else if (policy.conditionalFields.includes(field)) {
      // Check conditions
      const conditionMet = this.checkDisclosureConditions(field, purpose, requesterAddress, policy);
      if (conditionMet) {
        allowedFields.push(field);
        restrictions.push(`${field}: conditional disclosure for ${purpose}`);
      } else {
        deniedFields.push(field);
      }
    } else if (policy.restrictedFields.includes(field)) {
      // Check if requester has special privileges
      if (policy.privilegedRequesters.includes(requesterAddress)) {
        allowedFields.push(field);
        restrictions.push(`${field}: privileged access only`);
      } else {
        deniedFields.push(field);
      }
    } else {
      deniedFields.push(field);
    }
  }
  
  return {
    approved: deniedFields.length === 0,
    allowedFields,
    deniedFields,
    restrictions,
    reason: deniedFields.length > 0 ? `Access denied for fields: ${deniedFields.join(', ')}` : undefined
  };
}

private checkDisclosureConditions(
  field: string,
  purpose: string,
  requesterAddress: string,
  policy: DisclosurePolicy
): boolean {
  // Implement business logic for conditional disclosure
  const conditions = policy.conditions[field] || [];
  
  return conditions.every(condition => {
    switch (condition.type) {
      case 'purpose':
        return condition.values.includes(purpose);
      case 'requester_type':
        return this.getRequesterType(requesterAddress) === condition.value;
      case 'time_limit':
        return Date.now() < condition.expiresAt;
      default:
        return false;
    }
  });
}

private getRequesterType(address: string): string {
  // Determine requester type (e.g., verified_business, government, individual)
  return 'individual'; // Placeholder
}
}

interface PersonalData {
firstName: string;
lastName: string;
dateOfBirth: string;
address: string;
phone: string;
email: string;
ssn: string;
income: number;
creditScore: number;
}

interface DisclosurePolicy {
publicFields: string[];
conditionalFields: string[];
restrictedFields: string[];
encryptedFields: string[];
consentRequired: string[];
privilegedRequesters: string[];
conditions: Record<string, DisclosureCondition[]>;
}

interface DisclosureCondition {
type: 'purpose' | 'requester_type' | 'time_limit';
values?: string[];
value?: string;
expiresAt?: number;
}

interface DisclosureCapabilities {
publicFields: string[];
conditionalFields: string[];
restrictedFields: string[];
requiresConsent: string[];
}

interface SelectiveAttestationResult {
success: boolean;
sessionId: string;
attestationUID: string;
disclosureCapabilities: DisclosureCapabilities;
availableFields: string[];
}

interface DisclosureRequestResult {
approved: boolean;
reason?: string;
disclosureProof?: DisclosureProof;
revealedFields?: string[];
restrictions?: string[];
}

interface DisclosureProof {
proofId: string;
attestationUID: string;
encryptedData: Record<string, string>;
decryptionKeys: Record<string, string>;
fieldHashes: Record<string, string>;
verificationLevel: string;
restrictions: string[];
expiresAt: number;
}

interface DisclosureEvaluation {
approved: boolean;
allowedFields: string[];
deniedFields: string[];
restrictions: string[];
reason?: string;
}

interface DisclosureVerificationContext {
expectedFields: string[];
purpose: string;
maxAge: number;
}

interface DisclosureVerificationResult {
valid: boolean;
reason?: string;
revealedData?: Record<string, any>;
verificationLevel?: string;
restrictions?: string[];
expiresAt?: number;
}

class HomomorphicAttestationSystem {
  private sdk: StellarAttestSDK | SolanaAttestSDK;
  private heService: HomomorphicEncryptionService;
  
  constructor(
    sdk: StellarAttestSDK | SolanaAttestSDK,
    heService: HomomorphicEncryptionService
  ) {
    this.sdk = sdk;
    this.heService = heService;
  }

  async createHomomorphicAttestation(
    userAddress: string,
    numericData: NumericData,
    computationPolicy: ComputationPolicy
  ): Promise<HomomorphicAttestationResult> {
    const sessionId = `he-${Date.now()}-${Math.random().toString(36).substr(2, 9)}`;
    
    try {
      // Encrypt numeric data homomorphically
      const encryptedData = await this.heService.encryptData(numericData);
      
      // Create attestation with encrypted values
      const attestationValue = this.buildHomomorphicAttestationValue(
        encryptedData,
        computationPolicy
      );
      
      const attestation = await this.sdk.attest({
        schemaUID: 'homomorphic-data-v1',
        subject: userAddress,
        value: attestationValue,
        reference: sessionId
      });
      
      if (attestation.error) {
        throw new Error(`Homomorphic attestation failed: ${attestation.error}`);
      }
      
      return {
        success: true,
        sessionId,
        attestationUID: attestation.data,
        supportedOperations: computationPolicy.allowedOperations,
        encryptionScheme: encryptedData.scheme
      };
      
    } catch (error) {
      throw error;
    }
  }

  async performHomomorphicComputation(
    attestationUIDs: string[],
    operation: HomomorphicOperation
  ): Promise<ComputationResult> {
    try {
      // Fetch encrypted data from attestations
      const encryptedValues = await this.fetchEncryptedValues(attestationUIDs);
      
      // Perform homomorphic computation
      const result = await this.heService.compute(encryptedValues, operation);
      
      // Create attestation for computation result
      const resultAttestation = await this.attestComputationResult(result, operation);
      
      return {
        success: true,
        resultAttestation,
        operation: operation.type,
        inputCount: attestationUIDs.length,
        preservesPrivacy: true
      };
      
    } catch (error) {
      return {
        success: false,
        error: error.message
      };
    }
  }

  private buildHomomorphicAttestationValue(
    encryptedData: EncryptedNumericData,
    policy: ComputationPolicy
  ): string {
    return [
      `encryptedValue:${encryptedData.ciphertext}`,
      `encryptionScheme:${encryptedData.scheme}`,
      `allowedOps:${policy.allowedOperations.join('|')}`,
      `precision:${encryptedData.precision}`,
      `timestamp:${Math.floor(Date.now() / 1000)}`
    ].join(',');
  }
}

interface NumericData {
  value: number;
  type: 'income' | 'age' | 'score' | 'count';
  precision: number;
}

interface ComputationPolicy {
  allowedOperations: ('add' | 'multiply' | 'compare' | 'aggregate')[];
  maxComputationDepth: number;
  authorizedComputors: string[];
}

interface EncryptedNumericData {
  ciphertext: string;
  scheme: string;
  precision: number;
  publicKey: string;
}

interface HomomorphicOperation {
  type: 'add' | 'multiply' | 'compare' | 'aggregate';
  parameters: any;
}

interface HomomorphicAttestationResult {
  success: boolean;
  sessionId: string;
  attestationUID: string;
  supportedOperations: string[];
  encryptionScheme: string;
}

interface ComputationResult {
  success: boolean;
  resultAttestation?: string;
  operation?: string;
  inputCount?: number;
  preservesPrivacy?: boolean;
  error?: string;
}

class AnonymousCredentialSystem {
  private sdk: StellarAttestSDK | SolanaAttestSDK;
  private credentialService: AnonymousCredentialService;
  
  constructor(
    sdk: StellarAttestSDK | SolanaAttestSDK,
    credentialService: AnonymousCredentialService
  ) {
    this.sdk = sdk;
    this.credentialService = credentialService;
  }

  async issueAnonymousCredential(
    credentialData: CredentialData,
    anonymitySet: string[]
  ): Promise<AnonymousCredentialResult> {
    const sessionId = `anon-${Date.now()}-${Math.random().toString(36).substr(2, 9)}`;
    
    try {
      // Generate anonymous credential
      const credential = await this.credentialService.issueCredential({
        data: credentialData,
        anonymitySet,
        unlinkable: true
      });
      
      // Create attestation without revealing identity
      const attestation = await this.sdk.attest({
        schemaUID: 'anonymous-credential-v1',
        subject: credential.pseudonymousId, // Use pseudonym instead of real address
        value: `credentialType:${credentialData.type},anonymitySetSize:${anonymitySet.length},issued:true,unlinkable:true,timestamp:${Math.floor(Date.now() / 1000)}`,
        reference: sessionId
      });
      
      if (attestation.error) {
        throw new Error(`Anonymous credential attestation failed: ${attestation.error}`);
      }
      
      return {
        success: true,
        sessionId,
        credentialToken: credential.token,
        attestationUID: attestation.data,
        anonymitySetSize: anonymitySet.length,
        unlinkable: true
      };
      
    } catch (error) {
      throw error;
    }
  }

  async presentAnonymousCredential(
    credentialToken: string,
    presentationPolicy: PresentationPolicy
  ): Promise<CredentialPresentationResult> {
    try {
      // Generate presentation proof
      const presentation = await this.credentialService.present({
        credential: credentialToken,
        revealedAttributes: presentationPolicy.revealedAttributes,
        predicates: presentationPolicy.predicates
      });
      
      if (!presentation.valid) {
        return {
          valid: false,
          reason: 'Credential presentation generation failed'
        };
      }
      
      return {
        valid: true,
        presentationProof: presentation.proof,
        revealedData: presentation.revealedData,
        anonymityPreserved: true,
        unlinkable: true
      };
      
    } catch (error) {
      return {
        valid: false,
        reason: `Presentation failed: ${error.message}`
      };
    }
  }

  async verifyAnonymousPresentation(
    presentationProof: string,
    verificationContext: AnonymousVerificationContext
  ): Promise<AnonymousVerificationResult> {
    try {
      // Verify presentation without learning identity
      const verification = await this.credentialService.verifyPresentation({
        proof: presentationProof,
        expectedPredicates: verificationContext.expectedPredicates,
        trustAnchors: verificationContext.trustedIssuers
      });
      
      return {
        valid: verification.valid,
        satisfiedPredicates: verification.satisfiedPredicates,
        revealedAttributes: verification.revealedAttributes,
        identityRevealed: false,
        linkable: false
      };
      
    } catch (error) {
      return {
        valid: false,
        reason: `Verification failed: ${error.message}`
      };
    }
  }
}

interface CredentialData {
  type: string;
  attributes: Record<string, any>;
  validityPeriod: number;
}

interface PresentationPolicy {
  revealedAttributes: string[];
  predicates: CredentialPredicate[];
}

interface CredentialPredicate {
  attribute: string;
  operation: 'greater_than' | 'less_than' | 'equals' | 'in_set';
  value: any;
}

interface AnonymousCredentialResult {
  success: boolean;
  sessionId: string;
  credentialToken: string;
  attestationUID: string;
  anonymitySetSize: number;
  unlinkable: boolean;
}

interface CredentialPresentationResult {
  valid: boolean;
  reason?: string;
  presentationProof?: string;
  revealedData?: Record<string, any>;
  anonymityPreserved?: boolean;
  unlinkable?: boolean;
}

interface AnonymousVerificationContext {
  expectedPredicates: CredentialPredicate[];
  trustedIssuers: string[];
}

interface AnonymousVerificationResult {
  valid: boolean;
  reason?: string;
  satisfiedPredicates?: string[];
  revealedAttributes?: Record<string, any>;
  identityRevealed: boolean;
  linkable: boolean;
}

class GDPRCompliantAttestationSystem {
  private sdk: StellarAttestSDK | SolanaAttestSDK;
  private dataProcessor: DataProcessor;
  private consentManager: ConsentManager;
  
  constructor(
    sdk: StellarAttestSDK | SolanaAttestSDK,
    dataProcessor: DataProcessor,
    consentManager: ConsentManager
  ) {
    this.sdk = sdk;
    this.dataProcessor = dataProcessor;
    this.consentManager = consentManager;
  }

  async createGDPRCompliantAttestation(
    userAddress: string,
    personalData: PersonalData,
    processingPurpose: ProcessingPurpose,
    consent: ConsentRecord
  ): Promise<GDPRAttestationResult> {
    const sessionId = `gdpr-${Date.now()}-${Math.random().toString(36).substr(2, 9)}`;
    
    try {
      // Step 1: Validate consent and legal basis
      await this.validateGDPRConsent(consent, processingPurpose);
      
      // Step 2: Process data according to GDPR principles
      const processedData = await this.processGDPRData(personalData, processingPurpose, userAddress);
      
      // Step 3: Create GDPR-compliant attestation
      const attestation = await this.createGDPRAttestation(processedData, processingPurpose, consent, sessionId);
      
      // Step 4: Record processing activity for compliance
      await this.recordGDPRActivity(sessionId, attestation, userAddress, processingPurpose, consent);
      
      return this.buildGDPRResult(sessionId, attestation, processedData, processingPurpose);
      
    } catch (error) {
      await this.logGDPRError(sessionId, error);
      throw error;
    }
  }

  async exerciseDataSubjectRights(
    userAddress: string,
    rightType: DataSubjectRight,
    requestDetails: RightExerciseRequest
  ): Promise<RightExerciseResult> {
    try {
      // Route to appropriate right handler
      return await this.routeDataSubjectRight(userAddress, rightType, requestDetails);
      
    } catch (error) {
      return {
        success: false,
        rightType,
        reason: error.message
      };
    }
  }

  private async handleDataErasure(
    userAddress: string,
    request: RightExerciseRequest
  ): Promise<RightExerciseResult> {
    // Step 1: Find all user attestations
    const userAttestations = await this.findUserAttestations(userAddress);
    
    // Step 2: Process erasure for each attestation
    const erasureResults = await this.processErasureRequests(userAttestations, request, userAddress);
    
    return this.buildErasureResult(erasureResults);
  }

private async validateGDPRConsent(
  consent: ConsentRecord,
  processingPurpose: ProcessingPurpose
) {
  const consentValidation = await this.consentManager.validateConsent(
    consent,
    processingPurpose
  );
  
  if (!consentValidation.valid) {
    throw new Error(`Invalid consent: ${consentValidation.reason}`);
  }
}

private async processGDPRData(
  personalData: PersonalData,
  processingPurpose: ProcessingPurpose,
  userAddress: string
) {
  // Apply data minimization principles
  const minimizedData = this.dataProcessor.minimizeData(
    personalData,
    processingPurpose
  );
  
  // Pseudonymize identifiers for privacy protection
  const pseudonymizedData = await this.dataProcessor.pseudonymize(
    minimizedData,
    userAddress
  );
  
  return pseudonymizedData;
}

private async createGDPRAttestation(
  processedData: any,
  processingPurpose: ProcessingPurpose,
  consent: ConsentRecord,
  sessionId: string
) {
  const attestationValue = this.buildGDPRAttestationValue(
    processedData,
    processingPurpose,
    consent
  );
  
  const attestation = await this.sdk.attest({
    schemaUID: 'gdpr-compliant-data-v1',
    subject: processedData.pseudonymousId,
    value: attestationValue,
    reference: sessionId
  });
  
  if (attestation.error) {
    throw new Error(`GDPR attestation failed: ${attestation.error}`);
  }
  
  return attestation.data;
}

private async recordGDPRActivity(
  sessionId: string,
  attestation: string,
  userAddress: string,
  processingPurpose: ProcessingPurpose,
  consent: ConsentRecord
) {
  await this.recordProcessingActivity({
    sessionId,
    attestationUID: attestation,
    dataSubject: userAddress,
    processingPurpose,
    legalBasis: consent.legalBasis,
    retentionPeriod: processingPurpose.retentionPeriod,
    timestamp: Date.now()
  });
}

private buildGDPRResult(
  sessionId: string,
  attestation: string,
  processedData: any,
  processingPurpose: ProcessingPurpose
): GDPRAttestationResult {
  return {
    success: true,
    sessionId,
    attestationUID: attestation,
    pseudonymousId: processedData.pseudonymousId,
    dataMinimized: true,
    consentRecorded: true,
    retentionPeriod: processingPurpose.retentionPeriod
  };
}

private async routeDataSubjectRight(
  userAddress: string,
  rightType: DataSubjectRight,
  requestDetails: RightExerciseRequest
): Promise<RightExerciseResult> {
  switch (rightType) {
    case 'access':
      return await this.handleDataAccess(userAddress, requestDetails);
    case 'rectification':
      return await this.handleDataRectification(userAddress, requestDetails);
    case 'erasure':
      return await this.handleDataErasure(userAddress, requestDetails);
    case 'portability':
      return await this.handleDataPortability(userAddress, requestDetails);
    case 'objection':
      return await this.handleProcessingObjection(userAddress, requestDetails);
    default:
      throw new Error(`Unsupported right type: ${rightType}`);
  }
}

private async processErasureRequests(
  userAttestations: UserAttestation[],
  request: RightExerciseRequest,
  userAddress: string
) {
  const erasureResults = [];
  
  for (const attestation of userAttestations) {
    const result = await this.processIndividualErasure(attestation, request, userAddress);
    erasureResults.push(result);
  }
  
  return erasureResults;
}

private async processIndividualErasure(
  attestation: UserAttestation,
  request: RightExerciseRequest,
  userAddress: string
) {
  // Check if erasure is legally required
  const erasureRequired = await this.assessErasureRequirement(attestation, request);
  
  if (erasureRequired.required) {
    // Revoke attestation
    const revocation = await this.sdk.revokeAttestation({
      schemaUID: attestation.schemaUID,
      subject: userAddress,
      reference: attestation.reference
    });
    
    if (!revocation.error) {
      // Remove from processing records
      await this.removeProcessingRecord(attestation.uid);
      
      return {
        attestationUID: attestation.uid,
        erased: true,
        method: 'revocation'
      };
    }
  }
  
  return {
    attestationUID: attestation.uid,
    erased: false,
    reason: erasureRequired.reason
  };
}

private buildErasureResult(erasureResults: any[]): RightExerciseResult {
  return {
    success: true,
    rightType: 'erasure',
    details: erasureResults,
    completedAt: Date.now()
  };
}

private buildGDPRAttestationValue(
  pseudonymizedData: PseudonymizedData,
  purpose: ProcessingPurpose,
  consent: ConsentRecord
): string {
  return [
    `dataProcessed:true`,
    `purpose:${purpose.type}`,
    `legalBasis:${consent.legalBasis}`,
    `dataMinimized:true`,
    `pseudonymized:true`,
    `retentionPeriod:${purpose.retentionPeriod}`,
    `consentId:${consent.consentId}`,
    `timestamp:${Math.floor(Date.now() / 1000)}`
  ].join(',');
}

private async recordProcessingActivity(activity: ProcessingActivity): Promise<void> {
  // Record in GDPR processing register
  // Implementation would store in secure, auditable database
}

private async findUserAttestations(userAddress: string): Promise<UserAttestation[]> {
  // Find all attestations for a user across different schemas
  return []; // Placeholder
}

private async assessErasureRequirement(
  attestation: UserAttestation,
  request: RightExerciseRequest
): Promise<{ required: boolean; reason?: string }> {
  // Assess whether erasure is legally required
  // Consider retention periods, legal obligations, legitimate interests
  return { required: true };
}
}

interface ProcessingPurpose {
type: string;
description: string;
retentionPeriod: number;
necessaryData: string[];
}

interface ConsentRecord {
consentId: string;
legalBasis: 'consent' | 'contract' | 'legal_obligation' | 'vital_interests' | 'public_task' | 'legitimate_interests';
granted: boolean;
timestamp: number;
specific: boolean;
informed: boolean;
unambiguous: boolean;
}

interface PseudonymizedData {
pseudonymousId: string;
processedData: Record<string, any>;
pseudonymizationMethod: string;
}

interface ProcessingActivity {
sessionId: string;
attestationUID: string;
dataSubject: string;
processingPurpose: ProcessingPurpose;
legalBasis: string;
retentionPeriod: number;
timestamp: number;
}

interface GDPRAttestationResult {
success: boolean;
sessionId: string;
attestationUID: string;
pseudonymousId: string;
dataMinimized: boolean;
consentRecorded: boolean;
retentionPeriod: number;
}

type DataSubjectRight = 'access' | 'rectification' | 'erasure' | 'portability' | 'objection';

interface RightExerciseRequest {
requestId: string;
details: any;
urgency?: 'normal' | 'urgent';
}

interface RightExerciseResult {
success: boolean;
rightType: DataSubjectRight;
details?: any;
reason?: string;
completedAt?: number;
}

interface UserAttestation {
uid: string;
schemaUID: string;
reference: string;
createdAt: number;
}