Implement merging of existing services, verification methods, and alt handles for plc operations

src/pdsmoover.js

···
   async signPlcOperation(token) {
     const getDidCredentials =
             await this.newAgent.com.atproto.identity.getRecommendedDidCredentials();
-    const rotationKeys = getDidCredentials.data.rotationKeys ?? [];
+    const rotationKeys = getDidCredentials.data.rotationKeys;
     if (!rotationKeys) {
       throw new Error('No rotation key provided from the new PDS');
     }
-    const credentials = {
-      ...getDidCredentials.data,
-      rotationKeys: rotationKeys,
+    const oldDidDoc = await docResolver.resolve(this.oldAgent.did);
+    
+    // Format the service(s) in the user's DidDocument into the operation syntax
+    let oldServices = {};
+    for(const service of oldDidDoc.service) {
+      const idComponents = service.id.split('#');
+      oldServices[idComponents[idComponents.length - 1]] = {
+        type: service.type,
+        endpoint: service.serviceEndpoint
+      };
+    };
+    // Combine old & new suggested services
+    const services = {
+      ...oldServices, // Existing services in the user's DidDocument
+      ...getDidCredentials.data.services // Service(s) suggested by the new PDS
+    };
+    
+    // Format the verification method(s) in the user's DidDocument into the operation syntax
+    let oldVerificationMethods = {};
+    for(const verificationMethod of oldDidDoc.verificationMethod) {
+      const idComponents = verificationMethod.id.split('#');
+      oldVerificationMethods[idComponents[idComponents.length - 1]] = `did:key:${verificationMethod.publicKeyMultibase}` // PLC Operation verification methods are did:keys
+    };
+    // Combine old & new suggested verification methods
+    const verificationMethods = {
+      ...oldVerificationMethods,  // Existing verification methods in the user's DidDocument
+      ...getDidCredentials.data.verificationMethods // Verification method(s) suggested by the new PDS
     };
 
-
+    const alsoKnownAs = [
+      ...getDidCredentials.data.alsoKnownAs, // Suggested alsoKnownAs goes first (the first entry is the user's primary handle)
+      ...oldDidDoc.alsoKnownAs.slice(1) // Pre-existing alsoKnownAs, minus the old primary handle
+    ];
+    
     const plcOp = await this.oldAgent.com.atproto.identity.signPlcOperation({
       token: token,
-      ...credentials,
+      rotationKeys: rotationKeys, // Replace rotation keys
+      alsoKnownAs: alsoKnownAs, // Merged alsoKnownAs
+      services: services, // Merged services
+      verificationMethods: verificationMethods, // Merged verification methods
     });
 
     await this.newAgent.com.atproto.identity.submitPlcOperation({