Add: addChain metamask helper

JoinColony · Nov 30, 2021 · fb562a1 · fb562a1
1 parent fb07e4c
commit fb562a1
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diff --git a/packages/@purser/metamask/src/helpers.ts b/packages/@purser/metamask/src/helpers.ts
@@ -7,6 +7,7 @@ import {
   ObservableEvents,
   MetamaskEthereumGlobal,
   EthereumRequestMethods,
+  EthereumChain,
 } from './types';
 
 // eslint-disable-next-line @typescript-eslint/no-explicit-any
@@ -154,3 +155,33 @@ export const switchChain = async (chainId: number): Promise<void> => {
     params: [{ chainId: hexStripZeros(hexlify(chainId)) }],
   });
 };
+
+export const addChain = async (chainDetails: EthereumChain): Promise<void> => {
+  const { ethereum } = anyGlobal;
+  const {
+    chainId,
+    chainName,
+    nativeCurrency = {},
+    rpcUrls,
+    blockExplorerUrls,
+  } = chainDetails;
+  return ethereum.request({
+    method: EthereumRequestMethods.AddNewChain,
+    params: [
+      {
+        /*
+         * @NOTE Need to also strip zeros since `hexlify` returns a signed hex string
+         * which is not something Metamask likes as a chain Id
+         */
+        chainId: hexStripZeros(hexlify(chainId)),
+        chainName,
+        nativeCurrency: {
+          decimals: 18,
+          ...nativeCurrency,
+        },
+        rpcUrls,
+        blockExplorerUrls,
+      },
+    ],
+  });
+};
diff --git a/packages/@purser/metamask/src/types.ts b/packages/@purser/metamask/src/types.ts
@@ -24,6 +24,20 @@ interface EthereumRequestArguments {
   params?: unknown[] | object;
 }
 
+export interface EthereumNativeToken {
+  name: string;
+  symbol: string; // 2-6 characters long
+  decimals?: number;
+}
+
+export interface EthereumChain {
+  chainId: number;
+  chainName: string;
+  nativeCurrency: EthereumNativeToken;
+  rpcUrls: string[];
+  blockExplorerUrls?: string[];
+}
+
 export interface MetamaskEthereumGlobal {
   isConnected: () => boolean;
   request<R>(args: EthereumRequestArguments): Promise<R>;