import { calcTokenValue } from '../../../shared/lib/swaps-utils'; import { TransactionType } from '../../../shared/constants/transaction'; import { parseStandardTokenTransactionData } from '../../../shared/modules/transaction.utils'; import { getTokenAddressParam } from '../../helpers/utils/token-util'; import { decimalToHex } from '../../../shared/modules/conversion.utils'; export function getCustomTxParamsData( data, { customPermissionAmount, decimals }, ) { const tokenData = parseStandardTokenTransactionData(data); if (!tokenData) { throw new Error('Invalid data'); } else if (tokenData.name !== TransactionType.tokenMethodApprove) { throw new Error( `Invalid data; should be 'approve' method, but instead is '${tokenData.name}'`, ); } let spender = getTokenAddressParam(tokenData); if (spender.startsWith('0x')) { spender = spender.substring(2); } const [signature, tokenValue] = data.split(spender); if (!signature || !tokenValue) { throw new Error('Invalid data'); } else if (tokenValue.length !== 64) { throw new Error( 'Invalid token value; should be exactly 64 hex digits long (u256)', ); } let customPermissionValue = decimalToHex( calcTokenValue(customPermissionAmount, decimals), ); if (customPermissionValue.length > 64) { throw new Error('Custom value is larger than u256'); } customPermissionValue = customPermissionValue.padStart( tokenValue.length, '0', ); const customTxParamsData = `${signature}${spender}${customPermissionValue}`; return customTxParamsData; }