Improve voter derive calls (#1181)

* voterPositions

* cleanup

* rename var

* changes

* export VoterPosition

packages/api-derive/src/elections/index.ts

@@ -6,4 +6,4 @@ export * from './approvalsOf';
 export * from './approvalsOfAt';
 export * from './info';
 export * from './voters';
-export * from './voterSets';
+export * from './voterPositions';

packages/api-derive/src/elections/info.ts

@@ -34,12 +34,13 @@ export function info (api: ApiInterfaceRx): () => Observable<DerivedElectionsInf
         api.query.elections.candidates,
         api.query.elections.candidateCount,
         api.query.elections.desiredSeats,
+        api.query.elections.nextVoterSet,
         api.query.elections.termDuration,
         api.query.elections.voteCount,
         api.query.elections.voterCount
-      ]) as any as Observable<[[AccountId, BlockNumber][], AccountId[], BN, BN, BlockNumber, VoteIndex, SetIndex]>
+      ]) as any as Observable<[[AccountId, BlockNumber][], AccountId[], BN, BN, SetIndex, BlockNumber, VoteIndex, SetIndex]>
     ).pipe(
-      map(([members, candidates, candidateCount, desiredSeats, termDuration, voteCount, voterCount]): DerivedElectionsInfo => ({
+      map(([members, candidates, candidateCount, desiredSeats, nextVoterSet, termDuration, voteCount, voterCount]): DerivedElectionsInfo => ({
         members: members.reduce(
           (record: Record<string, BlockNumber>, [accountId, blockNumber]): Record<string, BlockNumber> => {
             record[accountId.toString()] = blockNumber;
@@ -50,6 +51,7 @@ export function info (api: ApiInterfaceRx): () => Observable<DerivedElectionsInf
         candidates,
         candidateCount,
         desiredSeats,
+        nextVoterSet,
         termDuration,
         voteCount,
         voterCount

packages/api-derive/src/elections/voterPositions.ts

@@ -0,0 +1,57 @@
+// Copyright 2017-2019 @polkadot/api-derive authors & contributors
+// This software may be modified and distributed under the terms
+// of the Apache-2.0 license. See the LICENSE file for details.
+
+import { SetIndex } from '@polkadot/types/srml/elections/types';
+import { ApiInterfaceRx } from '@polkadot/api/types';
+import { AccountId, Vector, Option, createType } from '@polkadot/types';
+import { DerivedVoterPositions } from '../types';
+
+import BN from 'bn.js';
+import { of, combineLatest, Observable } from 'rxjs';
+import { switchMap, map } from 'rxjs/operators';
+import { drr } from '../util/drr';
+
+/**
+ * @name voterPositions
+ * @returns An mapping of all current voter accounts to their voter set and global index.
+ * @example
+ * <BR>
+ *
+ * ```javascript
+ * api.derive.elections.voterPositions((voters) => {
+ *   const { index, setIndex, globalIndex } = voters[ALICE];
+ *   console.log(`ALICE is a voter at index ${index} in voter set ${setIndex}, with global index ${globalIndex}.`);
+ * });
+ * ```
+ */
+export function voterPositions (api: ApiInterfaceRx): () => Observable<DerivedVoterPositions> {
+  return (): Observable<DerivedVoterPositions> =>
+    api.query.elections.nextVoterSet<SetIndex>().pipe(
+      switchMap((nextVoterSet: SetIndex): Observable<[BN, Vector<Option<AccountId>>[]]> => combineLatest(
+        of(api.consts.elections.voterSetSize) as any as Observable<BN>,
+        api.query.elections.voters.multi([...Array(+nextVoterSet + 1).keys()].map((_, i): [number] => [i])) as any as Observable<Vector<Option<AccountId>>[]>
+      )),
+      map((result: [BN, Vector<Option<AccountId>>[]]): DerivedVoterPositions => {
+        const [setSize, voters] = result;
+        return voters.reduce((result: DerivedVoterPositions, vec, setIndex): DerivedVoterPositions => {
+          vec.forEach((e, index): void => {
+            // re-create the index based on position 0 is [0][0] and likewise
+            // 64 (0..63 in first) is [1][0] (the first index value in set 2)
+            const accountId: AccountId | null = e.unwrapOr(null);
+
+            if (accountId) {
+              result[accountId.toString()] = {
+                globalIndex: setSize.muln(setIndex).addn(index),
+                index: new BN(index),
+                setIndex: createType<SetIndex>('SetIndex', setIndex)
+              };
+            }
+          });
+
+          return result;
+        }, {});
+      }),
+      drr()
+    );
+}

packages/api-derive/src/elections/voterSets.ts

@@ -1,48 +0,0 @@
-// Copyright 2017-2019 @polkadot/api-derive authors & contributors
-// This software may be modified and distributed under the terms
-// of the Apache-2.0 license. See the LICENSE file for details.
-
-import { SetIndex } from '@polkadot/types/srml/elections/types';
-
-import { ApiInterfaceRx } from '@polkadot/api/types';
-import { Observable } from 'rxjs';
-import { AccountId, Vector, Option, createType } from '@polkadot/types';
-import { switchMap, map } from 'rxjs/operators';
-import { drr } from '../util/drr';
-
-/**
- * @name voterSets
- * @returns An mapping of all current voter accounts to their voter set index.
- * @example
- * <BR>
- *
- * ```javascript
- * api.derive.elections.voterSets((voters) => {
- *   console.log(`ALICE is a voter in the voter set with index ${voters[ALICE].toString()}.`);
- * });
- * ```
- */
-export function voterSets (api: ApiInterfaceRx): () => Observable<Record<string, SetIndex>> {
-  return (): Observable<Record<string, SetIndex>> =>
-    api.query.elections.nextVoterSet<SetIndex>().pipe(
-      switchMap((nextVoterSet: SetIndex): Observable<Vector<Option<AccountId>>[]> =>
-        api.query.elections.voters.multi([...Array(+nextVoterSet + 1).keys()].map((_, i): [number] => [i])) as any as Observable<Vector<Option<AccountId>>[]>
-      ),
-      map((voters: Vector<Option<AccountId>>[]): Record<string, SetIndex> =>
-        voters.reduce((result: Record<string, SetIndex>, vec, setIndex): Record<string, SetIndex> => {
-          vec.forEach((e): void => {
-            // re-create the index based on position 0 is [0][0] and likewise
-            // 64 (0..63 in first) is [1][0] (the first index value in set 2)
-            const accountId: AccountId | null = e.unwrapOr(null);
-
-            if (accountId) {
-              result[accountId.toString()] = createType<SetIndex>('SetIndex', setIndex);
-            }
-          });
-
-          return result;
-        }, {})
-      ),
-      drr()
-    );
-}

packages/api-derive/src/elections/voters.ts

@@ -2,14 +2,14 @@
 // This software may be modified and distributed under the terms
 // of the Apache-2.0 license. See the LICENSE file for details.
 
-import { SetIndex } from '@polkadot/types/srml/elections/types';
-
 import { ApiInterfaceRx } from '@polkadot/api/types';
-import { Observable } from 'rxjs';
 import { AccountId, Vector } from '@polkadot/types';
+import { DerivedVoterPositions } from '../types';
+
+import { Observable } from 'rxjs';
 import { map } from 'rxjs/operators';
 import { drr } from '../util/drr';
-import { voterSets } from './voterSets';
+import { voterPositions } from './voterPositions';
 
 /**
  * @name voters
@@ -25,14 +25,14 @@ import { voterSets } from './voterSets';
  */
 export function voters (api: ApiInterfaceRx): () => Observable<Vector<AccountId>> {
   return (): Observable<Vector<AccountId>> =>
-    voterSets(api)().pipe(
+    voterPositions(api)().pipe(
       map(
-        (voterSets: Record<string, SetIndex>): Vector<AccountId> =>
+        (voterPositions: DerivedVoterPositions): Vector<AccountId> =>
           new Vector(
             AccountId,
-            Object.keys(voterSets).map(
-              (address: string): AccountId => new AccountId(address)
-            )
+            Object.entries(voterPositions)
+              .sort((a, b): 0 | 1 | -1 => a[1].globalIndex.cmp(b[1].globalIndex))
+              .map(([accountId]): AccountId => new AccountId(accountId))
           )
       ),
       drr()