fix(bug): handle lengthToFee given runtime v9190 (#900)

* fix: add v9190 polkadot metadata

* fix: add polkadot registry for v9190

* fix: create getPerByte to properly handle lengthToFee

* cleanup inline comments

src/services/blocks/BlocksService.spec.ts

@@ -2,9 +2,10 @@ import { ApiPromise } from '@polkadot/api';
 import { ApiDecoration } from '@polkadot/api/types';
 import { AugmentedConst } from '@polkadot/api/types';
 import { PromiseRpcResult } from '@polkadot/api-base/types/rpc';
-import { GenericExtrinsic, u128 } from '@polkadot/types';
+import { GenericExtrinsic, u128, Vec } from '@polkadot/types';
 import { GenericCall } from '@polkadot/types/generic';
 import { BlockHash, Hash, SignedBlock } from '@polkadot/types/interfaces';
+import { FrameSupportWeightsWeightToFeeCoefficient } from '@polkadot/types/lookup';
 import { BadRequest } from 'http-errors';
 import LRU from 'lru-cache';
 
@@ -13,7 +14,9 @@ import { createCall } from '../../test-helpers/createCall';
 import {
 	kusamaRegistry,
 	polkadotRegistry,
+	polkadotRegistryV9190,
 } from '../../test-helpers/registries';
+import { TypeFactory } from '../../test-helpers/typeFactory';
 import { ExtBaseWeightValue, PerClassValue } from '../../types/chains-config';
 import { IBlock, IExtrinsic } from '../../types/responses/';
 import {
@@ -265,6 +268,55 @@ describe('BlocksService', () => {
 		});
 	});
 
+	describe('getPerByte', () => {
+		it('Correctly handles LengthToFee', () => {
+			// Reset LRU cache
+			cache.reset();
+
+			/**
+			 * Setup a mockApiClone specific to v9190
+			 */
+			const mockHistoricApiClone = {
+				...mockHistoricApi,
+				registry: polkadotRegistryV9190,
+			} as unknown as ApiDecoration<'promise'>;
+
+			/**
+			 * Typecast here because the typefactory just needs the registry so this is safe.
+			 * It's a shortcut so that constructing a augmented api is not necessary.
+			 */
+			const polkadotV9190TypeFactory = new TypeFactory(
+				mockHistoricApiClone as ApiPromise
+			);
+
+			/**
+			 * Create a Vec<FrameSupportWeightsWeightToFeeCoefficient> type
+			 * The `coeffInteger` value here should be different from
+			 * `transactionByteFee` set in mockHistoricApi in order to properly
+			 * distinquish values.
+			 */
+			const lengthToFeeStruct = polkadotRegistryV9190.createType(
+				'FrameSupportWeightsWeightToFeeCoefficient',
+				{ coeffInteger: 12345678 }
+			);
+			const lengthToFee = polkadotV9190TypeFactory.vecOf([lengthToFeeStruct]);
+
+			/**
+			 * Remove TransactionByteFee from our clone and replace it with LengthToFee
+			 */
+			(mockHistoricApiClone.consts.transactionPayment[
+				'transactionByteFee'
+			] as unknown) = undefined;
+			mockHistoricApiClone.consts.transactionPayment['lengthToFee'] =
+				lengthToFee as unknown as Vec<FrameSupportWeightsWeightToFeeCoefficient> &
+					AugmentedConst<'promise'>;
+
+			const result = blocksService['getPerByte'](mockHistoricApiClone);
+
+			expect(sanitizeNumbers(result)).toEqual('12345678');
+		});
+	});
+
 	describe('BlocksService.getWeight', () => {
 		it('Should return correct `extrinsicBaseWeight`', () => {
 			// Reset LRU cache

src/services/blocks/BlocksService.ts

@@ -1,7 +1,7 @@
 import { ApiPromise } from '@polkadot/api';
 import { ApiDecoration } from '@polkadot/api/types';
 import { extractAuthor } from '@polkadot/api-derive/type/util';
-import { Compact, GenericCall, Struct, Vec } from '@polkadot/types';
+import { Compact, GenericCall, Struct, u128, Vec } from '@polkadot/types';
 import {
 	AccountId32,
 	Balance,
@@ -472,6 +472,7 @@ export class BlocksService extends AbstractService {
 	 * Create calcFee from params or return `null` if calcFee cannot be created.
 	 *
 	 * @param api ApiPromise
+	 * @param historicApi ApiDecoration to use for runtime specific querying
 	 * @param parentHash Hash of the parent block
 	 * @param block Block which the extrinsic is from
 	 */
@@ -506,8 +507,8 @@ export class BlocksService extends AbstractService {
 		const multiplier =
 			await api.query.transactionPayment?.nextFeeMultiplier?.at(parentHash);
 
-		const perByte = historicApi.consts.transactionPayment
-			?.transactionByteFee as Balance;
+		const perByte = this.getPerByte(historicApi);
+
 		const extrinsicBaseWeightExists =
 			historicApi.consts.system.extrinsicBaseWeight ||
 			historicApi.consts.system.blockWeights.perClass.normal.baseExtrinsic;
@@ -552,7 +553,30 @@ export class BlocksService extends AbstractService {
 	}
 
 	/**
-	 *	Get a formatted blockweight store value for the runtime corresponding to the given block hash.
+	 * Retrieve the PerByte integer used to calculate fees.
+	 * TransactionByteFee has been replaced with LengthToFee via runtime 9190.
+	 * https://github.com/paritytech/polkadot/pull/5028
+	 *
+	 * @param historicApi ApiDecoration to use for runtime specific querying
+	 */
+	private getPerByte(
+		historicApi: ApiDecoration<'promise'>
+	): Balance | u128 | null {
+		const { transactionPayment } = historicApi.consts;
+
+		if (transactionPayment?.transactionByteFee) {
+			return transactionPayment?.transactionByteFee as Balance;
+		}
+
+		if (transactionPayment?.lengthToFee) {
+			return transactionPayment?.lengthToFee.toArray()[0].coeffInteger;
+		}
+
+		return null;
+	}
+
+	/**
+	 * Get a formatted weight constant for the runtime corresponding to the given block hash.
 	 *
 	 * @param api ApiPromise
 	 * @param blockHash Hash of a block in the runtime to get the extrinsic base weight(s) for

src/test-helpers/registries/polkadotRegistry.ts

@@ -6,6 +6,7 @@ import { polkadotMetadataRpcV16 } from '../metadata/polkadotV16Metadata';
 import { polkadotMetadataRpcV29 } from '../metadata/polkadotV29Metadata';
 import { polkadotMetadataRpcV9110 } from '../metadata/polkadotV9110Metadata';
 import { polkadotMetadataRpcV9122 } from '../metadata/polkadotV9122Metadata';
+import { polkadotMetadataRpcV9190 } from '../metadata/polkadotV9190Metadata';
 
 /**
  * Create a type registry for Polkadot.
@@ -65,3 +66,11 @@ export const polkadotRegistryV9122 = createPolkadotRegistry(
 	9122,
 	polkadotMetadataRpcV9122
 );
+
+/**
+ * Polkadot v9190 TypeRegistry
+ */
+export const polkadotRegistryV9190 = createPolkadotRegistry(
+	9190,
+	polkadotMetadataRpcV9190
+);