import { ToolAnnotations } from "@modelcontextprotocol/sdk/types.js";
import { getDefaultProvider, Wallet, Contract } from '@coti-io/coti-ethers';
import { buildInputText } from '@coti-io/coti-sdk-typescript';
import { getCurrentAccountKeys, getNetwork } from "../shared/account.js";
import { ERC20_ABI } from "../constants/abis.js";
import { z } from "zod";
/**
* Tool definition for approving a spender to use ERC20 tokens on the COTI blockchain
*/
export const APPROVE_ERC20_SPENDER: ToolAnnotations = {
title: "Approve ERC20 Spender",
name: "approve_erc20_spender",
description:
"Approve another address to spend tokens on behalf of the owner. " +
"This is used for allowing another address (like a contract) to transfer your tokens. " +
"Requires token contract address, spender address, and amount as input. " +
"Returns the transaction hash upon successful approval.",
inputSchema: {
token_address: z.string().describe("ERC20 token contract address on COTI blockchain"),
spender_address: z.string().describe("Address to approve as spender, e.g., 0x0D7C5C1DA069fd7C1fAFBeb922482B2C7B15D273"),
amount_wei: z.string().describe("Amount of tokens to approve (in Wei)"),
gas_limit: z.string().optional().describe("Optional gas limit for the transaction"),
},
};
/**
* Type guard for validating approve ERC20 spender arguments
* @param args - Arguments to validate
* @returns True if arguments are valid for approve ERC20 spender operation
*/
export function isApproveERC20SpenderArgs(args: unknown): args is { token_address: string, spender_address: string, amount_wei: string, gas_limit?: string } {
return (
typeof args === "object" &&
args !== null &&
"token_address" in args &&
typeof (args as { token_address: string }).token_address === "string" &&
"spender_address" in args &&
typeof (args as { spender_address: string }).spender_address === "string" &&
"amount_wei" in args &&
typeof (args as { amount_wei: string }).amount_wei === "string" &&
(!("gas_limit" in args) || typeof (args as { gas_limit: string }).gas_limit === "string")
);
}
/**
* Handler for the approveERC20Spender tool
* @param args The arguments for the tool
* @returns The tool response
*/
export async function approveERC20SpenderHandler(args: Record<string, unknown> | undefined): Promise<any> {
if (!isApproveERC20SpenderArgs(args)) {
throw new Error("Invalid arguments for approve_erc20_spender");
}
const { token_address, spender_address, amount_wei, gas_limit } = args;
const results = await performApproveERC20Spender(token_address, spender_address, amount_wei, gas_limit);
return {
content: [{ type: "text", text: results }],
isError: false,
};
}
/**
* Performs an approval for an ERC20 token spender on the COTI blockchain
* @param token_address - Address of the ERC20 token contract
* @param spender_address - Address of the spender to approve
* @param amount_wei - Amount to approve in Wei
* @param gas_limit - Optional gas limit for the transaction
* @returns A formatted success message with transaction details
*/
export async function performApproveERC20Spender(token_address: string, spender_address: string, amount_wei: string, gas_limit?: string) {
try {
const currentAccountKeys = getCurrentAccountKeys();
const provider = getDefaultProvider(getNetwork());
const wallet = new Wallet(currentAccountKeys.privateKey, provider);
wallet.setAesKey(currentAccountKeys.aesKey);
const tokenContract = new Contract(token_address, ERC20_ABI, wallet);
const symbolResult = await tokenContract.symbol();
const txOptions: any = {};
if (gas_limit) {
txOptions.gasLimit = gas_limit;
}
const approveSelector = tokenContract.approve.fragment.selector;
const encryptedInputText = buildInputText(BigInt(amount_wei),
{ wallet: wallet, userKey: currentAccountKeys.aesKey }, token_address, approveSelector);
const tx = await tokenContract.approve(spender_address, encryptedInputText, txOptions);
const receipt = await tx.wait();
return `ERC20 Approval Successful!\nToken: ${symbolResult}\nTransaction Hash: ${receipt?.hash}\nAmount in Wei: ${amount_wei}\nSpender: ${spender_address}\nApprove Function Selector: ${approveSelector}`;
} catch (error) {
console.error('Error approving ERC20 spender:', error);
throw new Error(`Failed to approve ERC20 spender: ${error instanceof Error ? error.message : String(error)}`);
}
}
