DID Operations on XRPL

// DID Creation via NFT Minting
const didNFT = {
  TransactionType: "NFTokenMint",
  Account: controllerAccount,
  NFTokenTaxon: 0, // DID category
  URI: xrpl.convertStringToHex(JSON.stringify({
    did: `did:xrpl:${controllerAccount}:${tokenSequence}`,
    created: new Date().toISOString(),
    documentHash: documentHash,
    version: 1
  })),
  Flags: 8 // tfTransferable = false for identity NFTs
}

// DID Creation via Account Data
const didAccount = {
  TransactionType: "AccountSet",
  Account: didAccount,
  Domain: xrpl.convertStringToHex("did.xrpl.example.com"),
  SetFlag: asfRequireAuth, // Prevent unauthorized trust lines
}

// Store DID document reference
const didData = {
  TransactionType: "AccountSet",
  Account: didAccount,
  AccountData: [
    {
      key: "DIDDocument",
      value: xrpl.convertStringToHex(JSON.stringify({
        hash: documentHash,
        uri: ipfsHash,
        version: 1,
        created: timestamp
      }))
    }
  ]
}

// Minimal DID Document (fits in single transaction)
const minimalDID = {
  "@context": ["https://www.w3.org/ns/did/v1"],
  "id": "did:xrpl:rN7n7otQDd6FczFgLdSqtcsAUxDkw6fzRH:1",
  "controller": ["rN7n7otQDd6FczFgLdSqtcsAUxDkw6fzRH"],
  "verificationMethod": [{
    "id": "#key-1",
    "type": "Ed25519VerificationKey2020",
    "controller": "did:xrpl:rN7n7otQDd6FczFgLdSqtcsAUxDkw6fzRH:1",
    "publicKeyMultibase": "z6MkhaXgBZDvotDkL5257faiztiGiC2QtKLGpbnnEGta2doK"
  }],
  "authentication": ["#key-1"],
  "service": [{
    "id": "#messaging",
    "type": "MessagingService",
    "serviceEndpoint": "https://example.com/messages"
  }]
}

// Document Sharding Strategy
const createShardedDID = async (document, account) => {
  const chunks = chunkDocument(document, 800000); // 800KB chunks
  const shardRefs = [];
  
  for (let i = 0; i < chunks.length; i++) {
    const shard = await client.submitAndWait({
      TransactionType: "NFTokenMint",
      Account: account,
      URI: xrpl.convertStringToHex(JSON.stringify({
        shardIndex: i,
        totalShards: chunks.length,
        content: chunks[i],
        nextShard: i < chunks.length - 1 ? null : "pending"
      }))
    });
    shardRefs.push(shard.result.meta.nftoken_id);
  }
  
  // Update shard references
  await updateShardReferences(shardRefs);
}

// IPFS + XRPL Hybrid Pattern
const createHybridDID = async (document, controller) => {
  // Store document on IPFS
  const ipfsHash = await ipfs.add(JSON.stringify(document));
  
  // Create XRPL anchor with IPFS reference
  const anchor = await client.submitAndWait({
    TransactionType: "NFTokenMint",
    Account: controller,
    URI: xrpl.convertStringToHex(JSON.stringify({
      did: document.id,
      ipfsHash: ipfsHash.path,
      documentHash: sha256(JSON.stringify(document)),
      created: new Date().toISOString(),
      version: 1
    }))
  });
  
  return {
    did: document.id,
    anchor: anchor.result.meta.nftoken_id,
    ipfsHash: ipfsHash.path
  };
}

// Multi-Provider Pinning
const pinToMultipleProviders = async (ipfsHash) => {
  const providers = [
    { name: 'Pinata', client: pinataClient },
    { name: 'Infura', client: infuraClient },
    { name: 'Fleek', client: fleekClient }
  ];
  
  const pinResults = await Promise.allSettled(
    providers.map(provider => 
      provider.client.pin.add(ipfsHash)
    )
  );
  
  const successfulPins = pinResults.filter(r => r.status === 'fulfilled');
  if (successfulPins.length < 2) {
    throw new Error('Insufficient pinning redundancy');
  }
  
  return successfulPins;
}

// Centralized Storage Pattern
const createCentralizedDID = async (document, controller) => {
  // Store document in database/CDN
  const storageResult = await database.store(document);
  
  // Create cryptographic proof
  const proof = {
    documentHash: sha256(JSON.stringify(document)),
    storageURL: storageResult.url,
    created: new Date().toISOString(),
    signature: await signDocument(document, controller)
  };
  
  // Anchor proof on XRPL
  const anchor = await client.submitAndWait({
    TransactionType: "Payment",
    Account: controller,
    Destination: controller,
    Amount: "1", // Minimal payment for memo attachment
    Memos: [{
      Memo: {
        MemoType: xrpl.convertStringToHex("DID_ANCHOR"),
        MemoData: xrpl.convertStringToHex(JSON.stringify(proof))
      }
    }]
  });
  
  return {
    did: document.id,
    anchor: anchor.result.hash,
    storageURL: storageResult.url
  };
}

// Production DID Resolver
class XRPLDIDResolver {
  constructor(xrplClient, ipfsClient, cacheProvider) {
    this.xrpl = xrplClient;
    this.ipfs = ipfsClient;
    this.cache = cacheProvider;
    this.resolvers = new Map([
      ['nft', this.resolveNFTDID.bind(this)],
      ['account', this.resolveAccountDID.bind(this)],
      ['sharded', this.resolveShardedDID.bind(this)]
    ]);
  }
  
  async resolve(did, options = {}) {
    const startTime = Date.now();
    
    try {
      // Check cache first
      if (!options.noCache) {
        const cached = await this.cache.get(did);
        if (cached && !this.isCacheExpired(cached)) {
          return this.addMetadata(cached, { 
            source: 'cache',
            resolveTime: Date.now() - startTime 
          });
        }
      }
      
      // Parse DID to determine resolution strategy
      const parsedDID = this.parseDID(did);
      const resolver = this.resolvers.get(parsedDID.method);
      
      if (!resolver) {
        throw new Error(`Unsupported DID method: ${parsedDID.method}`);
      }
      
      // Resolve from primary source
      const document = await resolver(parsedDID, options);
      
      // Validate document integrity
      await this.validateDocument(document, parsedDID);
      
      // Cache resolved document
      await this.cache.set(did, document, this.getCacheTTL(document));
      
      return this.addMetadata(document, {
        source: 'blockchain',
        resolveTime: Date.now() - startTime,
        blockHeight: await this.xrpl.getLedgerIndex()
      });
      
    } catch (error) {
      // Attempt fallback resolution
      if (!options.noFallback) {
        return await this.resolveFallback(did, error);
      }
      throw error;
    }
  }

// Cache Management Implementation
class DIDCache {
  constructor(redisClient, cdnProvider) {
    this.memory = new Map();
    this.redis = redisClient;
    this.cdn = cdnProvider;
    this.stats = { hits: 0, misses: 0, invalidations: 0 };
  }
  
  async get(did) {
    // L1: Memory cache
    const memoryResult = this.memory.get(did);
    if (memoryResult && !this.isExpired(memoryResult)) {
      this.stats.hits++;
      return memoryResult.document;
    }
    
    // L2: Redis cache
    const redisResult = await this.redis.get(`did:${did}`);
    if (redisResult) {
      const parsed = JSON.parse(redisResult);
      if (!this.isExpired(parsed)) {
        this.memory.set(did, parsed); // Populate L1
        this.stats.hits++;
        return parsed.document;
      }
    }
    
    // L3: CDN cache (for public DIDs)
    if (this.isPublicDID(did)) {
      const cdnResult = await this.cdn.get(did);
      if (cdnResult && !this.isExpired(cdnResult)) {
        await this.redis.setex(`did:${did}`, 300, JSON.stringify(cdnResult));
        this.memory.set(did, cdnResult);
        this.stats.hits++;
        return cdnResult.document;
      }
    }
    
    this.stats.misses++;
    return null;
  }

// Real-time Cache Invalidation
const monitorDIDUpdates = async (resolver) => {
  const subscription = client.request({
    command: 'subscribe',
    streams: ['transactions']
  });
  
  subscription.on('transaction', async (tx) => {
    if (tx.transaction.TransactionType === 'NFTokenMint' ||
        tx.transaction.TransactionType === 'Payment') {
      
      // Check if transaction relates to DID operations
      const didInfo = extractDIDInfo(tx);
      if (didInfo) {
        await resolver.cache.invalidate(didInfo.did, 'blockchain_update');
        
        // Proactively resolve and cache new version
        setTimeout(async () => {
          await resolver.resolve(didInfo.did, { noCache: true });
        }, 1000);
      }
    }
  });
};

// Comprehensive Fallback Strategy
class FallbackResolver {
  constructor(primaryResolver) {
    this.primary = primaryResolver;
    this.fallbacks = [
      new IPFSGatewayResolver(['gateway1.ipfs.io', 'gateway2.ipfs.io']),
      new ArchiveResolver('https://archive.did.example.com'),
      new PeerResolver(['peer1.example.com', 'peer2.example.com'])
    ];
  }
  
  async resolveFallback(did, primaryError) {
    const errors = [primaryError];
    
    for (const fallback of this.fallbacks) {
      try {
        const result = await fallback.resolve(did);
        
        // Verify fallback result integrity
        if (await this.verifyFallbackResult(result, did)) {
          return this.addMetadata(result, {
            source: fallback.constructor.name,
            fallbackReason: primaryError.message,
            warning: 'Resolved from fallback source'
          });
        }
      } catch (fallbackError) {
        errors.push(fallbackError);
      }
    }
    
    // All resolution attempts failed
    throw new ResolutionError(did, errors);
  }

// Pre-Rotation Key Management
class RotationManager {
  constructor(didController, xrplClient) {
    this.controller = didController;
    this.client = xrplClient;
    this.rotationHistory = new Map();
  }
  
  async prepareRotation(did, newPublicKey, rotationDelay = 86400) {
    // Generate rotation commitment
    const rotationCommitment = {
      nextKey: newPublicKey,
      rotationTime: Date.now() + (rotationDelay * 1000),
      nonce: crypto.randomBytes(32).toString('hex'),
      previousKeyHash: this.getCurrentKeyHash(did)
    };
    
    // Sign commitment with current key
    const signature = await this.controller.sign(
      JSON.stringify(rotationCommitment)
    );
    
    // Store commitment on-chain
    const commitmentTx = await this.client.submitAndWait({
      TransactionType: "Payment",
      Account: this.controller.address,
      Destination: this.controller.address,
      Amount: "1",
      Memos: [{
        Memo: {
          MemoType: xrpl.convertStringToHex("KEY_ROTATION_COMMIT"),
          MemoData: xrpl.convertStringToHex(JSON.stringify({
            ...rotationCommitment,
            signature
          }))
        }
      }]
    });
    
    this.rotationHistory.set(did, {
      commitment: rotationCommitment,
      commitmentTx: commitmentTx.result.hash,
      status: 'committed'
    });
    
    return rotationCommitment;
  }

// Emergency Key Recovery
async emergencyRotation(did, recoveryKey, emergencyProof) {
  // Verify recovery authorization
  const isAuthorized = await this.verifyRecoveryAuthorization(
    did,
    recoveryKey,
    emergencyProof
  );
  
  if (!isAuthorized) {
    throw new Error('Invalid recovery authorization');
  }
  
  // Create emergency rotation transaction
  const emergencyTx = await this.client.submitAndWait({
    TransactionType: "NFTokenMint", // Or appropriate update mechanism
    Account: recoveryKey.address,
    URI: xrpl.convertStringToHex(JSON.stringify({
      did,
      emergencyRotation: true,
      newController: recoveryKey.publicKey,
      reason: emergencyProof.reason,
      timestamp: Date.now(),
      signature: await recoveryKey.sign(emergencyProof)
    })),
    Flags: 1 // Mark as emergency operation
  });
  
  // Invalidate all existing credentials
  await this.invalidateExistingCredentials(did, 'key_compromise');
  
  return emergencyTx;
}

// Credential-Preserving Rotation
class CredentialContinuityManager {
  async rotateWithContinuity(did, newKey, overlapPeriod = 2592000) { // 30 days
    const currentDocument = await this.resolveDID(did);
    
    // Add new key alongside existing keys
    const updatedDocument = {
      ...currentDocument,
      verificationMethod: [
        ...currentDocument.verificationMethod,
        {
          id: `${did}#key-${Date.now()}`,
          type: "Ed25519VerificationKey2020",
          controller: did,
          publicKeyMultibase: newKey.publicKey,
          validFrom: new Date().toISOString(),
          validUntil: new Date(Date.now() + overlapPeriod * 1000).toISOString()
        }
      ]
    };
    
    // Schedule old key deprecation
    updatedDocument.verificationMethod = updatedDocument.verificationMethod.map(key => {
      if (!key.validUntil && key.id !== `${did}#key-${Date.now()}`) {
        return {
          ...key,
          validUntil: new Date(Date.now() + overlapPeriod * 1000).toISOString(),
          deprecated: true
        };
      }
      return key;
    });
    
    await this.updateDIDDocument(did, updatedDocument);
    
    // Schedule cleanup of expired keys
    setTimeout(async () => {
      await this.cleanupExpiredKeys(did);
    }, overlapPeriod * 1000);
    
    return updatedDocument;
  }

// Multi-Signature Recovery System
class RecoverySystem {
  constructor(threshold = 2, totalGuardians = 3) {
    this.threshold = threshold;
    this.totalGuardians = totalGuardians;
    this.recoveryRequests = new Map();
  }
  
  async setupRecovery(did, guardianKeys) {
    if (guardianKeys.length !== this.totalGuardians) {
      throw new Error(`Requires exactly ${this.totalGuardians} guardian keys`);
    }
    
    const recoveryConfig = {
      did,
      guardians: guardianKeys.map((key, index) => ({
        id: `guardian-${index}`,
        publicKey: key.publicKey,
        weight: 1
      })),
      threshold: this.threshold,
      created: new Date().toISOString()
    };
    
    // Store recovery configuration on-chain
    await this.storeRecoveryConfig(did, recoveryConfig);
    
    return recoveryConfig;
  }

// Batch DID Operations
class BatchProcessor {
  constructor(xrplClient, maxBatchSize = 50) {
    this.client = xrplClient;
    this.maxBatchSize = maxBatchSize;
    this.pendingOperations = [];
    this.batchInterval = 5000; // 5 seconds
    
    // Start batch processing
    setInterval(() => this.processBatch(), this.batchInterval);
  }
  
  async queueDIDOperation(operation) {
    this.pendingOperations.push({
      ...operation,
      timestamp: Date.now(),
      id: crypto.randomBytes(8).toString('hex')
    });
    
    // Process immediately if batch is full
    if (this.pendingOperations.length >= this.maxBatchSize) {
      await this.processBatch();
    }
    
    return operation.id;
  }

// Selective DID Updates
class SelectiveUpdater {
  async updateDIDSelectively(did, changes) {
    const currentDocument = await this.resolveDID(did);
    
    // Calculate minimal update set
    const updateSet = this.calculateMinimalUpdates(currentDocument, changes);
    
    if (updateSet.length === 0) {
      return { status: 'no_changes', cost: 0 };
    }
    
    // Choose update strategy based on change size
    if (updateSet.length === 1 && updateSet[0].type === 'key_addition') {
      return await this.addKeyOnly(did, updateSet[0].data);
    } else if (this.isServiceEndpointOnly(updateSet)) {
      return await this.updateServiceEndpoints(did, updateSet);
    } else {
      return await this.fullDocumentUpdate(did, changes);
    }
  }