Cleanups in API typing (& overrides) (#2362)

* Cleanups in API typing (& overrides)

* Less magic "as" overrides

packages/api/src/promise/Api.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 { AnyFunction, Callback, Codec } from '@polkadot/types/types';
-import { ApiOptions, DecorateMethodOptions, ObsInnerType, StorageEntryPromiseOverloads, UnsubscribePromise } from '../types';
+import { Callback, Codec } from '@polkadot/types/types';
+import { ApiOptions, DecorateFn, DecorateMethodOptions, ObsInnerType, StorageEntryPromiseOverloads, UnsubscribePromise, VoidFn } from '../types';
 
-import { Observable, EMPTY } from 'rxjs';
+import { EMPTY, Observable, Subscription } from 'rxjs';
 import { catchError, first, tap } from 'rxjs/operators';
 import { isFunction, assert } from '@polkadot/util';
 
@@ -36,7 +36,7 @@ function extractArgs (args: any[], needsCallback: boolean): [any[], Callback<Cod
 }
 
 // a Promise completion tracker, wrapping an isComplete variable that ensures the promise only resolves once
-function promiseTracker (resolve: (value: () => void) => void, reject: (value: Error) => void): Tracker {
+function promiseTracker (resolve: (value: VoidFn) => void, reject: (value: Error) => void): Tracker {
   let isCompleted = false;
 
   // eslint-disable-next-line @typescript-eslint/ban-types
@@ -63,37 +63,29 @@ function promiseTracker (resolve: (value: () => void) => void, reject: (value: E
 /**
  * @description Decorate method for ApiPromise, where the results are converted to the Promise equivalent
  */
-export function decorateMethod<Method extends AnyFunction> (method: Method, options?: DecorateMethodOptions): StorageEntryPromiseOverloads {
+export function decorateMethod<Method extends DecorateFn<ObsInnerType<ReturnType<Method>>>> (method: Method, options?: DecorateMethodOptions): StorageEntryPromiseOverloads {
   const needsCallback = options && options.methodName && options.methodName.includes('subscribe');
 
   return function (...args: any[]): Promise<ObsInnerType<ReturnType<Method>>> | UnsubscribePromise {
-    const [actualArgs, callback] = extractArgs(args, !!needsCallback);
+    const [actualArgs, resultCb] = extractArgs(args, !!needsCallback);
 
-    if (!callback) {
-      // eslint-disable-next-line @typescript-eslint/no-unsafe-call,@typescript-eslint/no-unsafe-member-access
-      return method(...actualArgs).pipe(first()).toPromise() as Promise<ObsInnerType<ReturnType<Method>>>;
+    if (!resultCb) {
+      return method(...actualArgs).pipe(first()).toPromise();
     }
 
-    return new Promise((resolve, reject): void => {
+    return new Promise<VoidFn>((resolve, reject): void => {
       const tracker = promiseTracker(resolve, reject);
-
-      // eslint-disable-next-line @typescript-eslint/no-unsafe-call,@typescript-eslint/no-unsafe-member-access,@typescript-eslint/no-unsafe-assignment
-      const subscription: { unsubscribe: () => void } = method(...actualArgs).pipe(
+      const subscription: Subscription = method(...actualArgs).pipe(
         // if we find an error (invalid params, etc), reject the promise
         catchError((error): Observable<never> => tracker.reject(error)),
         // upon the first result, resolve with the unsub function
-        // eslint-disable-next-line @typescript-eslint/no-unsafe-call,@typescript-eslint/no-unsafe-member-access,@typescript-eslint/no-unsafe-return
         tap(() => tracker.resolve(() => subscription.unsubscribe()))
-      ).subscribe((result: any): void => {
-        if (setImmediate) {
-          // eslint-disable-next-line @typescript-eslint/no-misused-promises
-          setImmediate(() => callback(result) as void);
-        } else {
-          // eslint-disable-next-line @typescript-eslint/no-floating-promises
-          callback(result);
-        }
+      ).subscribe((result): void => {
+        // We use setImmediate here to ensure that the Promise above (tracker) has resolved, before returning
+        // the first result. By putting is back in the queue, the promise above is guarder for first execution
+        setImmediate(() => resultCb(result) as void);
       });
-    }) as UnsubscribePromise;
+    });
   } as StorageEntryPromiseOverloads;
 }
 

packages/api/src/rx/Api.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 { AnyFunction } from '@polkadot/types/types';
-import { ApiOptions } from '../types';
+import { Codec } from '@polkadot/types/types';
+import { ApiOptions, DecorateFn } from '../types';
 
 import { from, Observable } from 'rxjs';
 
 import ApiBase from '../base';
 
-export function decorateMethod <Method extends AnyFunction> (method: Method): Method {
+export function decorateMethod <Method extends DecorateFn<Codec>> (method: Method): Method {
   return method;
 }
 

packages/api/src/types/base.ts

@@ -2,7 +2,7 @@
 // This software may be modified and distributed under the terms
 // of the Apache-2.0 license. See the LICENSE file for details.
 
-import { Observable } from 'rxjs';
+import type { Observable } from 'rxjs';
 import { AnyFunction, Callback, Codec, CodecArg } from '@polkadot/types/types';
 
 // Prepend an element V onto the beginning of a tuple T.
@@ -30,7 +30,9 @@ export type ApiTypes = 'promise' | 'rxjs';
 // Returns the inner type of an Observable
 export type ObsInnerType<O extends Observable<any>> = O extends Observable<infer U> ? U : never;
 
-export type UnsubscribePromise = Promise<() => void>;
+export type VoidFn = () => void;
+
+export type UnsubscribePromise = Promise<VoidFn>;
 
 // FIXME The day TS has higher-kinded types, we can remove this hardcoded stuff
 export type PromiseOrObs<ApiType extends ApiTypes, T> = ApiType extends 'rxjs'
@@ -68,6 +70,8 @@ export interface DecorateMethodOptions {
   methodName?: string;
 }
 
+export type DecorateFn <T extends Codec> = (...args: any[]) => Observable<T>;
+
 export interface PaginationOptions<ArgType = CodecArg> {
   arg?: ArgType;
   pageSize: number;

packages/api/src/types/index.ts

@@ -5,10 +5,11 @@
 // Augment the modules
 import '@polkadot/api/augment';
 
-import BN from 'bn.js';
+import type BN from 'bn.js';
 import { DeriveCustom, ExactDerive } from '@polkadot/api-derive';
 import { Constants } from '@polkadot/metadata/Decorated/types';
 import { RpcInterface } from '@polkadot/rpc-core/types';
+import { ProviderInterface, ProviderInterfaceEmitted } from '@polkadot/rpc-provider/types';
 import { Metadata } from '@polkadot/types';
 import { Hash, RuntimeVersion } from '@polkadot/types/interfaces';
 import { DefinitionRpc, DefinitionRpcSub, Signer, SignatureOptions, Registry, RegisteredTypes } from '@polkadot/types/types';
@@ -18,7 +19,6 @@ import ApiBase from '../base';
 import { DecoratedRpc } from './rpc';
 import { QueryableStorage, QueryableStorageMulti } from './storage';
 import { SubmittableExtrinsics } from './submittable';
-import { ProviderInterface, ProviderInterfaceEmitted } from '@polkadot/rpc-provider/types';
 
 export { Signer, SignerResult } from '@polkadot/types/types';
 export { default as ApiBase } from '../base';

packages/rpc-core/src/index.ts

@@ -16,6 +16,11 @@ import { assert, hexToU8a, isFunction, isNull, isNumber, isUndefined, logger, u8
 
 import { drr } from './rxjs';
 
+interface StorageChangeSetJSON {
+  block: string;
+  changes: [string, string | null][];
+}
+
 const l = logger('rpc-core');
 
 const EMPTY_META = {
@@ -341,10 +346,10 @@ export default class Rpc implements RpcInterface {
       const keys = params[0] as Vec<StorageKey>;
 
       return keys
-        ? this._formatStorageSet(keys, (result as { changes: [string, string | null][] }).changes)
+        ? this._formatStorageSet(keys, (result as StorageChangeSetJSON).changes)
         : this.registry.createType('StorageChangeSet', result);
     } else if (rpc.type === 'Vec<StorageChangeSet>') {
-      const mapped = (result as { block: string; changes: [string, string | null][] }[]).map(({ block, changes }): [Hash, Codec[]] => [
+      const mapped = (result as StorageChangeSetJSON[]).map(({ block, changes }): [Hash, Codec[]] => [
         this.registry.createType('Hash', block),
         this._formatStorageSet(params[0] as Vec<StorageKey>, changes)
       ]);

packages/types/src/types/helpers.ts

@@ -2,6 +2,8 @@
 // This software may be modified and distributed under the terms
 // of the Apache-2.0 license. See the LICENSE file for details.
 
+import { Codec } from './codec';
+
 import BN from 'bn.js';
 
 // We cannot inline this into CodecArg, TS thrws up when building docs
@@ -26,4 +28,6 @@ export type ArrayElementType<T extends ReadonlyArray<unknown>> = T extends Reado
 
 export type BareOpts = boolean | Record<string, boolean>;
 
-export type Callback<T> = (result: T) => void | Promise<void>;
+export type Callback<T, E = undefined> = E extends Codec
+  ? (result: T, extra: E) => void | Promise<void>
+  : (result: T) => void | Promise<void>;