Replace Etherscan ABI lookups with Sourcify

Etherscan requires an API key for ABI lookup and other operations.
Sourcify (https://sourcify.dev) is an open-source decentralized alternative.

packages/cli/src/command-helpers/abi.ts

@@ -11,6 +11,30 @@ export const loadAbiFromSourcify = async (
   ABICtor: typeof ABI,
   network: string,
   address: string,
+): Promise<ABI> =>
+  await withSpinner(
+    `Fetching ABI from Sourcify`,
+    `Failed to fetch ABI from Sourcify`,
+    `Warnings while fetching ABI from Sourcify`,
+    async () => {
+      const chainId = await getSourcifyChainId(network);
+      const result = await fetch(`https://repo.sourcify.dev/contracts/full_match/${chainId}/${address}/metadata.json`);
+      const json = await result.json();
+
+      // Etherscan returns a JSON object that has a `status`, a `message` and
+      // a `result` field. The `status` is '0' in case of errors and '1' in
+      // case of success
+      if (result.ok) {
+        return new ABICtor('Contract', undefined, immutable.fromJS(json.output.abi));
+      }
+      throw new Error('ABI not found, try loading it from a local file');
+    },
+  );
+
+export const loadAbiFromEtherscan = async (
+  ABICtor: typeof ABI,
+  network: string,
+  address: string,
 ): Promise<ABI> =>
   await withSpinner(
     `Fetching ABI from Sourcify`,
@@ -202,8 +226,10 @@ const getSourcifyChainId = async (network: string) => {
   // Can fail if network name doesn't follow https://chainlist.org name convention
   const match = json.find((e: any) => e.name.toLowerCase().includes(network.replace('-', ' ')));
 
-  if (match) return match.chainId;
-  throw new Error(`Could not find chain id for "${network}"`);
+  if (match)
+    return match.chainId;
+  else
+    throw new Error(`Could not find chain id for "${network}"`);
 };
 
 const getEtherscanLikeAPIUrl = (network: string) => {

packages/cli/src/commands/init.ts

@@ -707,7 +707,9 @@ async function processInitForm(
 
           // Try loading the ABI from Sourcify, if none was provided
           if (protocolInstance.hasABIs() && !initAbi) {
-            abiFromSourcify = await retryWithPrompt(() => loadAbiFromSourcify(ABI, network, value));
+            abiFromSourcify = await retryWithPrompt(() =>
+              loadAbiFromSourcify(ABI, network, value),
+            );
           }
           // If startBlock is not set, try to load it.
           if (!initStartBlock) {