Minor readability enhancements (#1313)

* Minor readability enhancements

* Split unwieldly ApiBase

* Fix import case

* Some movements, init in root

* Simplify overloaded functions

* Some more reworks

* Hoist non-class functions

* Flatten

* Split decorate and init

* Split meta from chain

* getNext cleanup

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

@@ -2,10 +2,10 @@
 // This software may be modified and distributed under the terms
 // of the Apache-2.0 license. See the LICENSE file for details.
 
-import { BlockNumber, Header } from '@polkadot/types/interfaces';
+import { BlockNumber } from '@polkadot/types/interfaces';
 
 import { Observable } from 'rxjs';
-import { filter, map } from 'rxjs/operators';
+import { map } from 'rxjs/operators';
 import { ApiInterfaceRx } from '@polkadot/api/types';
 
 import { drr } from '../util/drr';
@@ -24,10 +24,8 @@ import { drr } from '../util/drr';
  */
 export function bestNumber (api: ApiInterfaceRx): () => Observable<BlockNumber> {
   return (): Observable<BlockNumber> =>
-    api.rpc.chain.subscribeNewHead()
-      .pipe(
-        filter((header: Header): boolean => !!header && !!header.number),
-        map((header: Header): BlockNumber => header.number.unwrap()),
-        drr()
-      );
+    api.rpc.chain.subscribeNewHead().pipe(
+      map((header): BlockNumber => header.number.unwrap()),
+      drr()
+    );
 }

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

@@ -2,10 +2,10 @@
 // This software may be modified and distributed under the terms
 // of the Apache-2.0 license. See the LICENSE file for details.
 
-import { BlockNumber, Header } from '@polkadot/types/interfaces';
+import { BlockNumber } from '@polkadot/types/interfaces';
 
 import { Observable } from 'rxjs';
-import { filter, map } from 'rxjs/operators';
+import { map } from 'rxjs/operators';
 import { ApiInterfaceRx } from '@polkadot/api/types';
 
 import { drr } from '../util/drr';
@@ -25,10 +25,8 @@ import { drr } from '../util/drr';
  */
 export function bestNumberFinalized (api: ApiInterfaceRx): () => Observable<BlockNumber> {
   return (): Observable<BlockNumber> =>
-    api.rpc.chain.subscribeFinalizedHeads()
-      .pipe(
-        filter((header: Header): boolean => !!header && !!header.number),
-        map((header: Header): BlockNumber => header.number.unwrap()),
-        drr()
-      );
+    api.rpc.chain.subscribeFinalizedHeads().pipe(
+      map((header): BlockNumber => header.number.unwrap()),
+      drr()
+    );
 }

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

@@ -6,7 +6,7 @@ import { ApiInterfaceRx } from '@polkadot/api/types';
 import { AccountId, Header } from '@polkadot/types/interfaces';
 
 import { Observable, combineLatest, of } from 'rxjs';
-import { filter, map, switchMap } from 'rxjs/operators';
+import { map, switchMap } from 'rxjs/operators';
 
 import { HeaderExtended } from '../type';
 import { drr } from '../util/drr';
@@ -28,23 +28,21 @@ export type HeaderAndValidators = [Header, AccountId[]];
  */
 export function subscribeNewHead (api: ApiInterfaceRx): () => Observable<HeaderExtended> {
   return (): Observable<HeaderExtended> =>
-    (api.rpc.chain.subscribeNewHead() as Observable<Header>)
-      .pipe(
-        filter((header: Header): boolean => !!header && !!header.number),
-        switchMap((header: Header): Observable<HeaderAndValidators> =>
-          (combineLatest([
-            of(header),
-            // theoretically we could combine at the first call with session.validators(), however
-            // we make 100% sure we actually get the validators at a specific block so when these
-            // change at an era boundary, we have the previous values to ensure our indexes are correct
-            api.query.session
-              ? api.query.session.validators.at(header.hash)
-              : of([])
-          ]) as Observable<HeaderAndValidators>)
-        ),
-        map(([header, validators]): HeaderExtended =>
-          new HeaderExtended(header, validators)
-        ),
-        drr()
-      );
+    api.rpc.chain.subscribeNewHead().pipe(
+      switchMap((header: Header): Observable<HeaderAndValidators> =>
+        (combineLatest([
+          of(header),
+          // theoretically we could combine at the first call with session.validators(), however
+          // we make 100% sure we actually get the validators at a specific block so when these
+          // change at an era boundary, we have the previous values to ensure our indexes are correct
+          api.query.session
+            ? api.query.session.validators.at(header.hash)
+            : of([])
+        ]) as Observable<HeaderAndValidators>)
+      ),
+      map(([header, validators]): HeaderExtended =>
+        new HeaderExtended(header, validators)
+      ),
+      drr()
+    );
 }

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

@@ -26,6 +26,7 @@ type MultiResult = [Option<Keys>, [
   Option<AccountId> | Vec<[AccountId, Keys] & Codec>, Option<StakingLedger>, [AccountId[]], RewardDestination, Exposure, [ValidatorPrefs]
 ]];
 
+// groups the supplied chunks by era, i.e. { [era]: BN(total of values) }
 function groupByEra (list: UnlockChunk[]): Record<string, BN> {
   return list.reduce((map: Record<string, BN>, { era, value }): Record<string, BN> => {
     const key = era.toString();
@@ -38,6 +39,7 @@ function groupByEra (list: UnlockChunk[]): Record<string, BN> {
   }, {});
 }
 
+// calculate the remining blocks in a specific unlock era
 function remainingBlocks (era: BN, eraLength: BN, bestNumber: BlockNumber): BN {
   const remaining = eraLength.mul(era).sub(bestNumber);
 
@@ -46,15 +48,19 @@ function remainingBlocks (era: BN, eraLength: BN, bestNumber: BlockNumber): BN {
     : remaining;
 }
 
+// select the Unlockchunks that can't be redeemed yet
+function calcChunks (stakingLedger: StakingLedger, eraLength: BN, bestNumber: BlockNumber): UnlockChunk[] {
+  return stakingLedger.unlocking.filter((chunk): boolean =>
+    remainingBlocks(chunk.era.unwrap(), eraLength, bestNumber).gtn(0)
+  );
+}
+
 function calculateUnlocking (stakingLedger: StakingLedger | undefined, eraLength: BN, bestNumber: BlockNumber): DerivedUnlocking | undefined {
   if (isUndefined(stakingLedger)) {
     return undefined;
   }
 
-  // select the Unlockchunks that can't be redeemed yet.
-  const unlockingChunks = stakingLedger.unlocking.filter((chunk): boolean =>
-    remainingBlocks(chunk.era.unwrap(), eraLength, bestNumber).gtn(0)
-  );
+  const unlockingChunks = calcChunks(stakingLedger, eraLength, bestNumber);
 
   if (!unlockingChunks.length) {
     return undefined;
@@ -75,13 +81,9 @@ function redeemableSum (stakingLedger: StakingLedger | undefined, eraLength: BN,
     return new BN(0);
   }
 
-  return stakingLedger.unlocking
-    .filter((chunk): boolean =>
-      remainingBlocks(chunk.era.unwrap(), eraLength, bestNumber).eqn(0)
-    )
-    .reduce((curr, prev): BN =>
-      curr.add(prev.value.unwrap()), new BN(0)
-    );
+  return calcChunks(stakingLedger, eraLength, bestNumber).reduce((curr, prev): BN =>
+    curr.add(prev.value.unwrap()), new BN(0)
+  );
 }
 
 function unwrapSessionIds (stashId: AccountId, queuedKeys: Option<AccountId> | Vec<[AccountId, Keys] & Codec>, nextKeys: Option<Keys>): { nextSessionIds: AccountId[]; nextSessionId?: AccountId; sessionIds: AccountId[]; sessionId?: AccountId } {