From cfc0a868a43089b88fcd9711f89b2fa5c04fb1c3 Mon Sep 17 00:00:00 2001
From: Brad Decker <git@braddecker.dev>
Date: Mon, 10 May 2021 14:14:21 -0500
Subject: [PATCH] rough in switchEthereumChain (#10905)

---
 .../rpc-method-middleware/handlers/index.js   |  2 +
 .../handlers/switch-ethereum-chain.js         | 92 +++++++++++++++++++
 shared/constants/app.js                       |  2 +-
 3 files changed, 95 insertions(+), 1 deletion(-)
 create mode 100644 app/scripts/lib/rpc-method-middleware/handlers/switch-ethereum-chain.js

diff --git a/app/scripts/lib/rpc-method-middleware/handlers/index.js b/app/scripts/lib/rpc-method-middleware/handlers/index.js
index 541256a1c..fb0c1ef8f 100644
--- a/app/scripts/lib/rpc-method-middleware/handlers/index.js
+++ b/app/scripts/lib/rpc-method-middleware/handlers/index.js
@@ -1,10 +1,12 @@
 import addEthereumChain from './add-ethereum-chain';
+import switchEthereumChain from './switch-ethereum-chain';
 import getProviderState from './get-provider-state';
 import logWeb3ShimUsage from './log-web3-shim-usage';
 import watchAsset from './watch-asset';
 
 const handlers = [
   addEthereumChain,
+  switchEthereumChain,
   getProviderState,
   logWeb3ShimUsage,
   watchAsset,
diff --git a/app/scripts/lib/rpc-method-middleware/handlers/switch-ethereum-chain.js b/app/scripts/lib/rpc-method-middleware/handlers/switch-ethereum-chain.js
new file mode 100644
index 000000000..b52deb232
--- /dev/null
+++ b/app/scripts/lib/rpc-method-middleware/handlers/switch-ethereum-chain.js
@@ -0,0 +1,92 @@
+import { ethErrors } from 'eth-rpc-errors';
+import { omit } from 'lodash';
+import { MESSAGE_TYPE } from '../../../../../shared/constants/app';
+import {
+  isPrefixedFormattedHexString,
+  isSafeChainId,
+} from '../../../../../shared/modules/network.utils';
+
+const switchEthereumChain = {
+  methodNames: [MESSAGE_TYPE.SWITCH_ETHEREUM_CHAIN],
+  implementation: switchEthereumChainHandler,
+};
+export default switchEthereumChain;
+
+async function switchEthereumChainHandler(
+  req,
+  res,
+  _next,
+  end,
+  { getCurrentChainId, findCustomRpcBy, updateRpcTarget, requestUserApproval },
+) {
+  if (!req.params?.[0] || typeof req.params[0] !== 'object') {
+    return end(
+      ethErrors.rpc.invalidParams({
+        message: `Expected single, object parameter. Received:\n${JSON.stringify(
+          req.params,
+        )}`,
+      }),
+    );
+  }
+
+  const { origin } = req;
+
+  const { chainId } = req.params[0];
+
+  const otherKeys = Object.keys(omit(req.params[0], ['chainId']));
+
+  if (otherKeys.length > 0) {
+    return end(
+      ethErrors.rpc.invalidParams({
+        message: `Received unexpected keys on object parameter. Unsupported keys:\n${otherKeys}`,
+      }),
+    );
+  }
+
+  const _chainId = typeof chainId === 'string' && chainId.toLowerCase();
+
+  if (!isPrefixedFormattedHexString(_chainId)) {
+    return end(
+      ethErrors.rpc.invalidParams({
+        message: `Expected 0x-prefixed, unpadded, non-zero hexadecimal string 'chainId'. Received:\n${chainId}`,
+      }),
+    );
+  }
+
+  if (!isSafeChainId(parseInt(_chainId, 16))) {
+    return end(
+      ethErrors.rpc.invalidParams({
+        message: `Invalid chain ID "${_chainId}": numerical value greater than max safe value. Received:\n${chainId}`,
+      }),
+    );
+  }
+
+  const existingNetwork = findCustomRpcBy({ chainId: _chainId });
+
+  if (existingNetwork !== null) {
+    const currentChainId = getCurrentChainId();
+    if (currentChainId === _chainId) {
+      res.result = null;
+      return end();
+    }
+    try {
+      await updateRpcTarget(
+        await requestUserApproval({
+          origin,
+          type: MESSAGE_TYPE.SWITCH_ETHEREUM_CHAIN,
+          requestData: {
+            rpcUrl: existingNetwork.rpcUrl,
+            chainId: existingNetwork.chainId,
+            nickname: existingNetwork.nickname,
+            ticker: existingNetwork.ticker,
+          },
+        }),
+      );
+      res.result = null;
+    } catch (error) {
+      return end(error);
+    }
+    return end();
+  }
+  return end(ethErrors.provider.userRejectedRequest());
+}
diff --git a/shared/constants/app.js b/shared/constants/app.js
index 93c843846..7e1b66572 100644
--- a/shared/constants/app.js
+++ b/shared/constants/app.js
@@ -28,5 +28,5 @@ export const MESSAGE_TYPE = {
   WATCH_ASSET: 'wallet_watchAsset',
   WATCH_ASSET_LEGACY: 'metamask_watchAsset',
   ADD_ETHEREUM_CHAIN: 'wallet_addEthereumChain',
-  SWITCH_ETHEREUM_CHAIN: 'metamask_switchEthereumChain',
+  SWITCH_ETHEREUM_CHAIN: 'wallet_switchEthereumChain',
 };