/**
* EVM Token Service
* ERC20 token operations using viem
*/
import {
type PublicClient,
type WalletClient,
type Hash,
parseUnits,
formatUnits,
} from 'viem';
const ERC20_ABI = [
{
name: 'name',
type: 'function',
stateMutability: 'view',
inputs: [],
outputs: [{ type: 'string' }],
},
{
name: 'symbol',
type: 'function',
stateMutability: 'view',
inputs: [],
outputs: [{ type: 'string' }],
},
{
name: 'decimals',
type: 'function',
stateMutability: 'view',
inputs: [],
outputs: [{ type: 'uint8' }],
},
{
name: 'totalSupply',
type: 'function',
stateMutability: 'view',
inputs: [],
outputs: [{ type: 'uint256' }],
},
{
name: 'balanceOf',
type: 'function',
stateMutability: 'view',
inputs: [{ name: 'account', type: 'address' }],
outputs: [{ type: 'uint256' }],
},
{
name: 'transfer',
type: 'function',
stateMutability: 'nonpayable',
inputs: [
{ name: 'to', type: 'address' },
{ name: 'amount', type: 'uint256' },
],
outputs: [{ type: 'bool' }],
},
{
name: 'approve',
type: 'function',
stateMutability: 'nonpayable',
inputs: [
{ name: 'spender', type: 'address' },
{ name: 'amount', type: 'uint256' },
],
outputs: [{ type: 'bool' }],
},
{
name: 'allowance',
type: 'function',
stateMutability: 'view',
inputs: [
{ name: 'owner', type: 'address' },
{ name: 'spender', type: 'address' },
],
outputs: [{ type: 'uint256' }],
},
] as const;
export interface ERC20DeployParams {
name: string;
symbol: string;
decimals: number;
initialSupply: string;
}
export interface ERC20TransferParams {
token: `0x${string}`;
from: `0x${string}`;
to: `0x${string}`;
amount: string;
}
export class EVMTokenService {
private publicClient: PublicClient;
private walletClient?: WalletClient;
constructor(publicClient: PublicClient, walletClient?: WalletClient) {
this.publicClient = publicClient;
this.walletClient = walletClient;
}
async getTokenInfo(tokenAddress: `0x${string}`): Promise<{
name: string;
symbol: string;
decimals: number;
totalSupply: bigint;
}> {
const [name, symbol, decimals, totalSupply] = await Promise.all([
this.publicClient.readContract({
address: tokenAddress,
abi: ERC20_ABI,
functionName: 'name',
}),
this.publicClient.readContract({
address: tokenAddress,
abi: ERC20_ABI,
functionName: 'symbol',
}),
this.publicClient.readContract({
address: tokenAddress,
abi: ERC20_ABI,
functionName: 'decimals',
}),
this.publicClient.readContract({
address: tokenAddress,
abi: ERC20_ABI,
functionName: 'totalSupply',
}),
]);
return { name, symbol, decimals, totalSupply };
}
async getBalance(
tokenAddress: `0x${string}`,
account: `0x${string}`
): Promise<{ raw: bigint; formatted: string }> {
const [balance, decimals] = await Promise.all([
this.publicClient.readContract({
address: tokenAddress,
abi: ERC20_ABI,
functionName: 'balanceOf',
args: [account],
}),
this.publicClient.readContract({
address: tokenAddress,
abi: ERC20_ABI,
functionName: 'decimals',
}),
]);
return {
raw: balance,
formatted: formatUnits(balance, decimals),
};
}
async transfer(params: ERC20TransferParams): Promise<Hash> {
if (!this.walletClient) {
throw new Error('Wallet client not configured');
}
const decimals = await this.publicClient.readContract({
address: params.token,
abi: ERC20_ABI,
functionName: 'decimals',
});
const amount = parseUnits(params.amount, decimals);
const { request } = await this.publicClient.simulateContract({
address: params.token,
abi: ERC20_ABI,
functionName: 'transfer',
args: [params.to, amount],
account: params.from,
});
return this.walletClient.writeContract(request);
}
async approve(
tokenAddress: `0x${string}`,
spender: `0x${string}`,
amount: bigint,
account: `0x${string}`
): Promise<Hash> {
if (!this.walletClient) {
throw new Error('Wallet client not configured');
}
const { request } = await this.publicClient.simulateContract({
address: tokenAddress,
abi: ERC20_ABI,
functionName: 'approve',
args: [spender, amount],
account,
});
return this.walletClient.writeContract(request);
}
async getAllowance(
tokenAddress: `0x${string}`,
owner: `0x${string}`,
spender: `0x${string}`
): Promise<bigint> {
return this.publicClient.readContract({
address: tokenAddress,
abi: ERC20_ABI,
functionName: 'allowance',
args: [owner, spender],
});
}
}
