feat: estimate transaction cost (#399)

knip.ts

@@ -11,6 +11,7 @@ const config: KnipConfig = {
 		'src/lib/objects/hello-world/index.ts',
 		'src/lib/objects/external/iframe.svelte',
 		'src/lib/objects/split/types.ts',
+		'src/lib/objects/split/contracts/**/*',
 	],
 	paths: {
 		// This ain't pretty, but Svelte basically does the same
@@ -28,6 +29,7 @@ const config: KnipConfig = {
 	},
 	ignoreExportsUsedInFile: true,
 	ignoreBinaries: ['docker'],
+	ignoreDependencies: ['@typechain/ethers-v6'],
 }
 
 export default config

package.json

@@ -14,6 +14,7 @@
 		"knip": "knip",
 		"start:blockchain": "hardhat node",
 		"cli": "tsx --tsconfig ./.svelte-kit/tsconfig.json --no-warnings ./src/cli/cli.ts",
+		"typechain": "typechain --target ethers-v6 --out-dir ./src/lib/objects/split/contracts/types ./src/lib/objects/split/contracts/abis/*.json",
 		"waku:start": "docker compose -f ./docker-compose.yaml up -d",
 		"waku:stop": "docker kill waku-objects-playground-waku-1"
 	},
@@ -24,6 +25,7 @@
 		"@sveltejs/adapter-auto": "^2.1.0",
 		"@sveltejs/kit": "^1.21.0",
 		"@total-typescript/ts-reset": "^0.4.2",
+		"@typechain/ethers-v6": "^0.5.0",
 		"@types/node": "^20.5.4",
 		"@typescript-eslint/eslint-plugin": "^5.61.0",
 		"@typescript-eslint/parser": "^5.61.0",
@@ -49,6 +51,7 @@
 		"svelte-check": "^3.4.4",
 		"svelte-preprocess": "^5.0.4",
 		"tsx": "^3.12.8",
+		"typechain": "^8.3.1",
 		"typescript": "^5.1.6",
 		"vite": "^4.3.9",
 		"vitest": "^0.32.4",

src/lib/adapters/transaction.ts

@@ -121,6 +121,36 @@ export async function sendTransaction(
 	return tx
 }
 
+export async function estimateTransaction(
+	wallet: BaseWallet,
+	to: string,
+	amount: bigint,
+	tokenAddress?: string,
+): Promise<bigint> {
+	const provider = getProvider()
+	const txWallet = wallet.connect(provider)
+
+	let gasEstimate: bigint
+
+	if (tokenAddress) {
+		const contract = new Contract(tokenAddress, abi, txWallet)
+		gasEstimate = await contract.transfer.estimateGas(to, amount)
+	} else {
+		const txRequest: TransactionRequest = {
+			to,
+			value: amount,
+		}
+		gasEstimate = await provider.estimateGas(txRequest)
+	}
+	const fee = await provider.getFeeData()
+
+	if (fee.maxFeePerGas && fee.maxPriorityFeePerGas)
+		return gasEstimate * (fee.maxFeePerGas + fee.maxPriorityFeePerGas)
+	else if (fee.gasPrice) return gasEstimate * fee.gasPrice
+
+	throw new Error('Could not estimate transaction fee')
+}
+
 export async function waitForTransaction(
 	txHash: string,
 	confirm?: number | undefined,