From 8b8b4b54d8d383c1b9f082fecf8c739c4e1d0b0b Mon Sep 17 00:00:00 2001
From: Milap Sheth <milap@interoplabs.io>
Date: Tue, 25 Feb 2025 11:48:34 -0400
Subject: [PATCH] feat(evm): add legacy ITS custom token linkToken support

---
 evm/README.md | 14 ++++++++++++++
 evm/its.js    | 45 +++++++++++++++++++++++++++++++++++++++++++++
 2 files changed, 59 insertions(+)

diff --git a/evm/README.md b/evm/README.md
index ce1ef926f..969bf7fe8 100644
--- a/evm/README.md
+++ b/evm/README.md
@@ -257,3 +257,17 @@ To get details of options provided in the command run:
 ```bash
 node evm/verify-contract.js --help
 ```
+
+## Interchain Token Service
+
+### Link Token
+
+#### Legacy custom ITS tokens
+
+Custom tokens that have already registered with ITS (via `deployTokenManager`) prior to ITS v2.1.0 release can continue being linked to new chains via the following approach. However, we do recommend registering them. Token manager type should be passed in via `--type` flag (e.g. `MINT_BURN`).
+
+```bash
+node evm/its.js linkToken --salt [deploy-salt] --destinationChain [destinationChain] --tokenAddress [tokenAddress] --type [type] --operator [operator] --gasValue [gasValue]
+```
+
+The raw `bytes32` salt can be provided via `--rawSalt [raw-salt]` instead of hashing the provided salt string.
diff --git a/evm/its.js b/evm/its.js
index 0350eed7a..b0cd59cbd 100644
--- a/evm/its.js
+++ b/evm/its.js
@@ -634,6 +634,50 @@ async function processCommand(config, chain, options) {
             break;
         }
 
+        case 'linkToken': {
+            const { destinationChain, type, operator, tokenAddress, gasValue } = options;
+
+            const deploymentSalt = getDeploymentSalt(options);
+            const tokenManagerType = tokenManagerImplementations[type];
+
+            validateParameters({
+                isString: { destinationChain },
+                isValidAddress: { tokenAddress, operator },
+                isValidNumber: { gasValue, tokenManagerType },
+            });
+            isValidDestinationChain(config, destinationChain);
+
+            const interchainTokenId = await interchainTokenService.interchainTokenId(wallet.address, deploymentSalt);
+            printInfo('Expected tokenId', interchainTokenId);
+
+            try {
+                const tokenManagerAddress = await interchainTokenService.deployedTokenManager(tokenId);
+                printInfo(`TokenManager for tokenId ${tokenId} exists on the current chain`, tokenManagerAddress);
+
+                const sourceTokenAddress = await interchainTokenService.registeredTokenAddress(tokenId);
+                printInfo(`Token address on current chain for tokenId ${tokenId}`, sourceTokenAddress);
+            } catch (error) {
+                printError(`TokenManager for tokenId ${tokenId} does not yet exist on the current chain.`);
+                return;
+            }
+
+            const linkParams = operator;
+
+            const tx = await interchainTokenService.linkToken(
+                deploymentSalt,
+                destinationChain,
+                tokenAddress,
+                tokenManagerType,
+                linkParams,
+                gasValue,
+                gasOptions,
+            );
+
+            await handleTx(tx, chain, interchainTokenService, options.action, 'LinkTokenStarted');
+
+            break;
+        }
+
         default: {
             throw new Error(`Unknown action ${action}`);
         }
@@ -677,6 +721,7 @@ if (require.main === module) {
                 'migrateInterchainToken',
                 'registerTokenMetadata',
                 'transferMintership',
+                'linkToken',
             ])
             .makeOptionMandatory(true),
     );