support manta author lookup (#5561)

* support manta author lookup

* handle scenarios where queuedKeys is not of the expected type

* add catchError to imports

* should it be square?

* resolve combineLatest deprecation issue

* type safe nimbus author mappings

* precise var names

* remove reference to deprecated combineLatest

* stay simple, that's what works

* implicit type for session.validators

we don't want to change this aspect of the implementation

* clearer comments on the code paths

* explicit variable names

packages/api-derive/src/chain/util.ts

@@ -4,7 +4,7 @@
 import type { Observable } from 'rxjs';
 import type { QueryableStorage } from '@polkadot/api-base/types';
 import type { Compact, Vec } from '@polkadot/types';
-import type { AccountId, BlockNumber, Header } from '@polkadot/types/interfaces';
+import type { AccountId, Address, BlockNumber, Header } from '@polkadot/types/interfaces';
 import type { Codec, IOption } from '@polkadot/types/types';
 import type { DeriveApi } from '../types.js';
 
@@ -24,23 +24,36 @@ export function createBlockNumberDerive <T extends { number: Compact<BlockNumber
 }
 
 export function getAuthorDetails (header: Header, queryAt: QueryableStorage<'rxjs'>): Observable<[Header, Vec<AccountId> | null, AccountId | null]> {
-  // this is Moonbeam specific
-  if (queryAt.authorMapping && queryAt.authorMapping.mappingWithDeposit) {
-    const mapId = header.digest.logs[0] && (
-      (header.digest.logs[0].isConsensus && header.digest.logs[0].asConsensus[1]) ||
-      (header.digest.logs[0].isPreRuntime && header.digest.logs[0].asPreRuntime[1])
-    );
+  const validators = queryAt.session
+    ? queryAt.session.validators()
+    : of(null);
 
-    if (mapId) {
+  // nimbus consensus stores the session key of the block author in header logs
+  const { logs: [log] } = header.digest;
+  const loggedAuthor = (log && (
+    (log.isConsensus && log.asConsensus[0].isNimbus && log.asConsensus[1]) ||
+    (log.isPreRuntime && log.asPreRuntime[0].isNimbus && log.asPreRuntime[1])
+  ));
+
+  if (loggedAuthor) {
+    // use the author mapping pallet, if available (ie: moonbeam, moonriver), to map session (nimbus) key to author (collator/validator) key
+    if (queryAt.authorMapping && queryAt.authorMapping.mappingWithDeposit) {
       return combineLatest([
         of(header),
-        queryAt.session
-          ? queryAt.session.validators()
-          : of(null),
-        queryAt.authorMapping.mappingWithDeposit<IOption<{ account: AccountId } & Codec>>(mapId).pipe(
-          map((opt) =>
-            opt.unwrapOr({ account: null }).account
-          )
+        validators,
+        queryAt.authorMapping.mappingWithDeposit<IOption<{ account: AccountId } & Codec>>(loggedAuthor)
+          .pipe(map((opt) => opt.unwrapOr({ account: null }).account))
+      ]);
+    }
+
+    // fall back to session pallet, if available (ie: manta, calamari), to map session (nimbus) key to author (collator/validator) key
+    if (queryAt.session && queryAt.session.queuedKeys) {
+      return combineLatest([
+        of(header),
+        validators,
+        queryAt.session.queuedKeys<[AccountId, { nimbus: Address }][]>().pipe(
+          map((queuedKeys) => queuedKeys.find((sessionKey) => sessionKey[1].nimbus.toHex() === loggedAuthor.toHex())),
+          map((sessionKey) => (sessionKey) ? sessionKey[0] : null)
         )
       ]);
     }
@@ -49,9 +62,7 @@ export function getAuthorDetails (header: Header, queryAt: QueryableStorage<'rxj
   // normal operation, non-mapping
   return combineLatest([
     of(header),
-    queryAt.session
-      ? queryAt.session.validators()
-      : of(null),
+    validators,
     of(null)
   ]);
 }

packages/types/src/generic/ConsensusEngineId.spec.ts

@@ -4,7 +4,7 @@
 /// <reference types="@polkadot/dev-test/globals.d.ts" />
 
 import { TypeRegistry } from '../create/index.js';
-import { CID_AURA, GenericConsensusEngineId as ConsensusEngineId } from './ConsensusEngineId.js';
+import { CID_AURA, CID_NMBS, GenericConsensusEngineId as ConsensusEngineId } from './ConsensusEngineId.js';
 
 describe('ConsensusEngineId', (): void => {
   const registry = new TypeRegistry();
@@ -16,4 +16,8 @@ describe('ConsensusEngineId', (): void => {
   it('reverses an id to string for babe', (): void => {
     expect(new ConsensusEngineId(registry, 'BABE').toString()).toEqual('BABE');
   });
+
+  it('creates a valid id for nimbus', (): void => {
+    expect(new ConsensusEngineId(registry, 'nmbs').toU8a()).toEqual(CID_NMBS);
+  });
 });

packages/types/src/generic/ConsensusEngineId.ts

@@ -11,6 +11,7 @@ export const CID_AURA = stringToU8a('aura');
 export const CID_BABE = stringToU8a('BABE');
 export const CID_GRPA = stringToU8a('FRNK');
 export const CID_POW = stringToU8a('pow_');
+export const CID_NMBS = stringToU8a('nmbs');
 
 function getAuraAuthor (registry: Registry, bytes: Bytes, sessionValidators: AccountId[]): AccountId {
   return sessionValidators[
@@ -77,6 +78,13 @@ export class GenericConsensusEngineId extends U8aFixed {
     return this.eq(CID_POW);
   }
 
+  /**
+   * @description `true` is the engine matches nimbus
+   */
+  public get isNimbus (): boolean {
+    return this.eq(CID_NMBS);
+  }
+
   /**
    * @description From the input bytes, decode into an author
    */
@@ -89,8 +97,8 @@ export class GenericConsensusEngineId extends U8aFixed {
       }
     }
 
-    // For pow & Moonbeam, the bytes are the actual author
-    if (this.isPow || bytes.length === 20) {
+    // For pow & Nimbus, the bytes are the actual author
+    if (this.isPow || this.isNimbus) {
       return getBytesAsAuthor(this.registry, bytes);
     }