feat(client): add chain spec api (#683)

Unified chain spec api for both v2 and legacy client, we removed the
method to fetch genesis hash since it's already fetched and available
within the client during initialization.

```ts
const client = await DedotClient.new({ ... });

console.log('chain genesisHash', client.genesisHash);
console.log('chain name', await client.chainSpec.chainName());
console.log('chain props', await client.chainSpec.properties());
```

Author: sinzii

examples/scripts/chain-spec.ts

@@ -0,0 +1,19 @@
+import { DedotClient, WsProvider } from 'dedot';
+import { RpcVersion } from 'dedot/types';
+
+const fetchChainSpec = async (rpcVersion: RpcVersion) => {
+  console.log(`Fetching chain spec via ${rpcVersion} client`);
+  const client = await DedotClient.new({
+    provider: new WsProvider('wss://westend-rpc.polkadot.io'),
+    rpcVersion,
+  });
+
+  console.log('chain name', await client.chainSpec.chainName());
+  console.log('chain props', await client.chainSpec.properties());
+  console.log('chain genesisHash', client.genesisHash);
+
+  await client.disconnect();
+};
+
+await fetchChainSpec('v2');
+await fetchChainSpec('legacy');

packages/api/src/client/BaseSubstrateClient.ts

@@ -39,6 +39,7 @@ import type {
   ApiEvent,
   ApiOptions,
   BlockExplorer,
+  IChainSpec,
   ISubstrateClient,
   ISubstrateClientAt,
   JsonRpcClientOptions,
@@ -532,4 +533,8 @@ export abstract class BaseSubstrateClient<
   sendTx(tx: HexString | Extrinsic, callback?: Callback): TxUnsub {
     throw new Error('Unimplemented!');
   }
+
+  get chainSpec(): IChainSpec {
+    throw new Error('Unimplemented!');
+  }
 }

packages/api/src/client/DedotClient.ts

@@ -21,6 +21,7 @@ import {
   ISubstrateClient,
   ISubstrateClientAt,
   SubstrateRuntimeVersion,
+  IChainSpec,
 } from '../types.js';
 import { LegacyClient } from './LegacyClient.js';
 import { V2Client } from './V2Client.js';
@@ -144,6 +145,10 @@ export class DedotClient<
     return this.#client.block;
   }
 
+  get chainSpec(): IChainSpec {
+    return this.#client.chainSpec;
+  }
+
   async connect(): Promise<this> {
     await this.#client.connect();
 

packages/api/src/client/LegacyClient.ts

@@ -1,6 +1,7 @@
 import { BlockHash, type Extrinsic, Hash, Header, PortableRegistry, RuntimeVersion } from '@dedot/codecs';
 import type { JsonRpcProvider } from '@dedot/providers';
 import { Callback, GenericSubstrateApi, TxUnsub, Unsub } from '@dedot/types';
+import { ChainProperties } from '@dedot/types/json-rpc';
 import { assert, HexString } from '@dedot/utils';
 import type { SubstrateApi } from '../chaintypes/index.js';
 import {
@@ -15,7 +16,7 @@ import {
 import { SubmittableExtrinsic } from '../extrinsic/submittable/SubmittableExtrinsic.js';
 import { newProxyChain } from '../proxychain.js';
 import { BaseStorageQuery, LegacyStorageQuery } from '../storage/index.js';
-import type { ApiOptions, BlockExplorer, ISubstrateClientAt, SubstrateRuntimeVersion } from '../types.js';
+import type { ApiOptions, BlockExplorer, IChainSpec, ISubstrateClientAt, SubstrateRuntimeVersion } from '../types.js';
 import { BaseSubstrateClient, ensurePresence } from './BaseSubstrateClient.js';
 import { LegacyBlockExplorer } from './explorer/index.js';
 
@@ -283,6 +284,17 @@ export class LegacyClient<ChainApi extends GenericSubstrateApi = SubstrateApi> /
     return ensurePresence(this._blockExplorer);
   }
 
+  get chainSpec(): IChainSpec {
+    return {
+      chainName: (): Promise<string> => {
+        return this.rpc.system_chain();
+      },
+      properties: (): Promise<ChainProperties> => {
+        return this.rpc.system_properties();
+      },
+    };
+  }
+
   /**
    * Create a new API instance at a specific block hash
    * This is useful when we want to inspect the state of the chain at a specific block hash

packages/api/src/json-rpc/group/ChainSpec.ts

@@ -1,9 +1,9 @@
 import { Properties } from '@dedot/types/json-rpc';
 import { HexString } from '@dedot/utils';
-import { IJsonRpcClient } from '../../types.js';
+import { IJsonRpcClient, IChainSpec } from '../../types.js';
 import { JsonRpcGroup, JsonRpcGroupOptions } from './JsonRpcGroup.js';
 
-export class ChainSpec extends JsonRpcGroup {
+export class ChainSpec extends JsonRpcGroup implements IChainSpec {
   constructor(client: IJsonRpcClient<any>, options?: Partial<JsonRpcGroupOptions>) {
     super(client, { prefix: 'chainSpec', supportedVersions: ['unstable', 'v1'], ...options });
   }

packages/api/src/types.ts

@@ -15,6 +15,7 @@ import {
   TxUnsub,
   Unsub,
 } from '@dedot/types';
+import { Properties } from '@dedot/types/json-rpc';
 import type { HashFn, HexString, IEventEmitter } from '@dedot/utils';
 import type { SubstrateApi } from './chaintypes/index.js';
 import type { AnySignedExtension } from './extrinsic/index.js';
@@ -184,6 +185,11 @@ export interface BlockExplorer {
   body(numberOrHash: number | BlockHash): Promise<HexString[]>;
 }
 
+export interface IChainSpec {
+  chainName(): Promise<string>;
+  properties(): Promise<Properties>;
+}
+
 /**
  * A generic interface for Substrate clients
  */
@@ -195,6 +201,7 @@ export interface ISubstrateClient<
   options: ApiOptions;
   tx: ChainApi['tx'];
 
+  chainSpec: IChainSpec;
   block: BlockExplorer;
 
   at<ChainApiAt extends GenericSubstrateApi = ChainApi>(hash: BlockHash): Promise<ISubstrateClientAt<ChainApiAt>>;