TestChain/assets/comp/wallet/scripts/standards/ERC20Standard.ts

import Web3 = require("../lib/web3.min");
import { abiERC20 } from "../abis/abiERC20";

export class ERC20Standard {
  private web3: Web3;

  constructor(web3: Web3) {
    this.web3 = web3;
  }

  /**
   * Get balance or count for current account on specific asset contract.
   *
   * @param address - Asset ERC20 contract address.
   * @param selectedAddress - Current account public address.
   * @returns Promise resolving to BN object containing balance for current account on specific asset contract.
   */
  async getBalanceOf(
    address: string,
    selectedAddress: string
  ): Promise<Web3.utils.BN> {
    const contract = new this.web3.eth.Contract(abiERC20, address);
    return new Promise<Web3.utils.BN>((resolve, reject) => {
      contract.methods
        .balanceOf(selectedAddress)
        .call(
          { from: selectedAddress },
          (error: Error, result: Web3.utils.BN) => {
            /* istanbul ignore if */
            if (error) {
              reject(error);
              return;
            }
            resolve(result);
          }
        );
    });
  }

  /**
   * Query for the decimals for a given ERC20 asset.
   *
   * @param address - ERC20 asset contract string.
   * @returns Promise resolving to the 'decimals'.
   */
  async getTokenDecimals(address: string): Promise<string> {
    const contract = new this.web3.eth.Contract(abiERC20, address);
    return new Promise<string>((resolve, reject) => {
      contract.methods
        .decimals()
        .call((error: Error, result: Web3.utils.BN | string) => {
          /* istanbul ignore if */
          if (error) {
            reject(error);
            return;
          }
          resolve(result.toString());
        });
    });
  }

  /**
   * Query for symbol for a given ERC20 asset.
   *
   * @param address - ERC20 asset contract address.
   * @returns Promise resolving to the 'symbol'.
   */
  async getTokenSymbol(address: string): Promise<string> {
    const contract = new this.web3.eth.Contract(abiERC20, address);
    return new Promise<string>((resolve, reject) => {
      contract.methods
        .symbol()
        .call((error: Error, result: Web3.utils.BN | string) => {
          /* istanbul ignore if */
          if (error) {
            reject(error);
            return;
          }
          resolve(result.toString());
        });
    });
    // Signature for calling `symbol()`
    // const payload = { to: address, data: '0x95d89b41' };
    // return new Promise<string>((resolve, reject) => {
    //   this.web3.eth.call(payload, undefined, (error: Error, result: string) => {
    //     /* istanbul ignore if */
    //     if (error) {
    //       reject(error);
    //       return;
    //     }

    //     // Parse as string
    //     try {
    //       const decoded = Web3.utils.hexToUtf8(result);
    //       if (decoded) {
    //         console.log('decoded')
    //         resolve(decoded);
    //         return;
    //       }
    //     } catch {
    //       // Ignore error
    //     }

    //     // Parse as bytes
    //     try {
    //       const utf8 = Web3.utils.toUtf8(result);
    //       console.log('utf8')
    //       resolve(utf8);
    //       return;
    //     } catch {
    //       // Ignore error
    //     }

    //     reject(new Error('Failed to parse token symbol'));
    //   });
    // });
  }

  /**
   * Query if a contract implements an interface.
   *
   * @param address - Asset contract address.
   * @param userAddress - The public address for the currently active user's account.
   * @returns Promise resolving an object containing the standard, decimals, symbol and balance of the given contract/userAddress pair.
   */
  async getDetails(
    address: string,
    userAddress?: string
  ): Promise<{
    standard: string;
    symbol: string | undefined;
    decimals: string | undefined;
    balance: Web3.utils.BN | undefined;
  }> {
    const [decimals, symbol] = await Promise.all([
      this.getTokenDecimals(address),
      this.getTokenSymbol(address),
    ]);
    let balance;
    if (userAddress) {
      balance = await this.getBalanceOf(address, userAddress);
    }
    return {
      decimals,
      symbol,
      balance,
      standard: "ERC20",
    };
  }

  async transfer({
    address,
    from,
    to,
    amount,
    gas,
  }: {
    address: string;
    from: string;
    to: string;
    amount: number | string;
    gas?: number;
  }) {
    const contract = new this.web3.eth.Contract(abiERC20, address);
    amount = Web3.utils.toBN(Web3.utils.toWei(amount + ""));
    return contract.methods.transfer(to, amount).send({
      from,
      gas: gas || 1000000,
    });
  }
}