feat: add transaction insight for FilForwarder transfers (#48)

packages/adapter/src/index.ts

@@ -1,4 +1,4 @@
 export { FilsnapAdapter } from './snap'
-export { filForwarderMetadata } from './filforwarder-metadata'
 
+export { filForwarderMetadata } from 'filsnap'
 export type { SnapConfig, AccountInfo } from 'filsnap'

packages/snap/package.json

@@ -64,8 +64,9 @@
     "@metamask/key-tree": "^9.0.0",
     "@metamask/snaps-ui": "^0.32.2",
     "iso-base": "^1.1.2",
-    "iso-filecoin": "^2.0.2",
+    "iso-filecoin": "^2.1.0",
     "merge-options": "^3.0.4",
+    "viem": "^1.4.2",
     "zod": "^3.21.4"
   },
   "devDependencies": {

packages/snap/snap.manifest.json

@@ -7,7 +7,7 @@
     "url": "https://github.com/filecoin-project/filsnap.git"
   },
   "source": {
-    "shasum": "PrxFxKiusGgxcttw9R6UenDIU4vxcM2CFCfrX70fMWM=",
+    "shasum": "OfcugyA6dShGuJZbZAmwbtMOnhKbAuYrPnvX+Al5xf4=",
     "location": {
       "npm": {
         "filePath": "dist/snap.js",
@@ -23,6 +23,7 @@
       "dapps": true,
       "snaps": true
     },
+    "endowment:transaction-insight": {},
     "snap_dialog": {},
     "snap_getBip44Entropy": [
       {

packages/adapter/src/filforwarder-metadata.ts → packages/snap/src/filforwarder-metadata.ts

@@ -82,8 +82,8 @@ const contractAddress: `0x${string}` =
   '0x2B3ef6906429b580b7b2080de5CA893BC282c225'
 
 const chainIds = {
-  filecoinMainnet: 314,
-  filecoinCalibrationTestnet: 314_159,
+  filecoinMainnet: 'eip155:13a',
+  filecoinCalibrationTestnet: 'eip155:4cb2f',
 }
 
 // FEVM FilForwarder contract metadata
@@ -92,6 +92,6 @@ export const filForwarderMetadata = {
   abi,
   // The contract address is the same on all chains where the contract is deployed
   contractAddress,
-  // The Ethereum chain ids where the contract is deployed
+  // The CAIP-2 chain ids where the contract is deployed
   chainIds,
 }

packages/snap/src/index.ts

@@ -26,6 +26,10 @@ export type {
   AccountInfo,
 } from './types'
 
+export { filForwarderMetadata } from './filforwarder-metadata'
+
+export { onTransaction } from './transaction-insight'
+
 export const onRpcRequest: OnRpcRequestHandler = async ({ request }) => {
   try {
     const config = await configFromSnap(snap)

packages/snap/src/transaction-insight.ts

@@ -0,0 +1,121 @@
+import type {
+  OnTransactionHandler,
+  OnTransactionResponse,
+} from '@metamask/snaps-types'
+import { heading, panel, text } from '@metamask/snaps-ui'
+import { fromHex, type Hex } from 'viem'
+import * as Address from 'iso-filecoin/address'
+import { Token } from 'iso-filecoin/token'
+import { filForwarderMetadata } from './filforwarder-metadata'
+import { decodeFunctionData } from 'viem'
+
+/**
+ *
+ * @param message
+ */
+function invalidTransferMessage(message: string): OnTransactionResponse {
+  return {
+    content: panel([heading('Invalid FIL Transfer'), text(message)]),
+  }
+}
+
+/**
+ *
+ * @param chainId
+ */
+function humanReadableNetwork(chainId: string): string {
+  if (chainId === filForwarderMetadata.chainIds.filecoinMainnet) {
+    return 'Filecoin Mainnet'
+  } else if (
+    chainId === filForwarderMetadata.chainIds.filecoinCalibrationTestnet
+  ) {
+    return 'Filecoin Calibration Testnet'
+  } else {
+    throw new Error(`Unknown chain ID: ${chainId}`)
+  }
+}
+
+/**
+ *
+ * @param chainId
+ */
+function chainMatches(chainId: string): boolean {
+  return Object.values(filForwarderMetadata.chainIds).includes(chainId)
+}
+
+/**
+ *
+ * @param transactionTo
+ */
+function contractAddressMatches(transactionTo: string | undefined): boolean {
+  return (
+    transactionTo?.toLowerCase() ===
+    filForwarderMetadata.contractAddress.toLowerCase()
+  )
+}
+
+// Note: currently MetaMask Flask shows the transaction insight tab by default even if we don't display any information
+// in it. This is a bug that the MetaMask team is addressing in this PR:
+// https://github.com/MetaMask/metamask-extension/pull/20267
+export const onTransaction: OnTransactionHandler = async ({
+  transaction,
+  chainId,
+}) => {
+  if (
+    !chainMatches(chainId) ||
+    !contractAddressMatches(transaction.to as string | undefined)
+  ) {
+    // Don't show any insights if the transaction is not a FIL transfer.
+    return {
+      content: null,
+    }
+  }
+
+  let transferAmount
+  try {
+    transferAmount = new Token(fromHex(transaction.value as Hex, 'bigint'))
+  } catch (error) {
+    // eslint-disable-next-line no-console
+    console.error(error)
+    return invalidTransferMessage(
+      `Transfer amount is missing from the transaction.`
+    )
+  }
+
+  let recipient
+  try {
+    const callData = decodeFunctionData({
+      abi: filForwarderMetadata.abi,
+      data: transaction.data as Hex,
+    })
+    if (callData.functionName !== 'forward') {
+      return invalidTransferMessage(`Transaction tries to call wrong method.`)
+    }
+    if (callData.args === undefined || callData.args.length !== 1) {
+      return invalidTransferMessage(`Missing recipient in transaction.`)
+    }
+
+    const isMainNet = chainId === filForwarderMetadata.chainIds.filecoinMainnet
+    recipient = Address.fromContractDestination(
+      callData.args[0] as Hex,
+      isMainNet ? 'mainnet' : 'testnet'
+    )
+  } catch (error) {
+    // eslint-disable-next-line no-console
+    console.error(error)
+    return invalidTransferMessage(`Transaction recipient is invalid.`)
+  }
+
+  return {
+    content: panel([
+      heading('Transfer FIL'),
+      text(
+        `You are transferring ${transferAmount
+          .toFIL()
+          .toString()} FIL to ${recipient.toString()} on ${humanReadableNetwork(
+          chainId
+        )}`
+      ),
+    ]),
+  }
+}