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import { AbiType, DecodedLogArgs, LogWithDecodedArgs, RawLog, SolidityTypes } from '@0xproject/types';
import * as ethersContracts from 'ethers-contracts';
import * as _ from 'lodash';
import * as Web3 from 'web3';
import { BigNumber } from './configured_bignumber';
export class AbiDecoder {
private _savedABIs: Web3.AbiDefinition[] = [];
private _methodIds: { [signatureHash: string]: Web3.EventAbi } = {};
private static _padZeros(address: string) {
let formatted = address;
if (_.startsWith(formatted, '0x')) {
formatted = formatted.slice(2);
}
formatted = _.padStart(formatted, 40, '0');
return `0x${formatted}`;
}
constructor(abiArrays: Web3.AbiDefinition[][]) {
_.forEach(abiArrays, this._addABI.bind(this));
}
// This method can only decode logs from the 0x & ERC20 smart contracts
public tryToDecodeLogOrNoop<ArgsType>(log: Web3.LogEntry): LogWithDecodedArgs<ArgsType> | RawLog {
const methodId = log.topics[0];
const event = this._methodIds[methodId];
if (_.isUndefined(event)) {
return log;
}
const ethersInterface = new ethersContracts.Interface([event]);
const logData = log.data;
const decodedParams: DecodedLogArgs = {};
let topicsIndex = 1;
const nonIndexedInputs = _.filter(event.inputs, input => !input.indexed);
const dataTypes = _.map(nonIndexedInputs, input => input.type);
const decodedData = ethersInterface.events[event.name].parse(log.data);
let failedToDecode = false;
_.forEach(event.inputs, (param: Web3.EventParameter, idx: number) => {
// Indexed parameters are stored in topics. Non-indexed ones in decodedData
let value: BigNumber | string | number = param.indexed ? log.topics[topicsIndex++] : decodedData[idx];
if (_.isUndefined(value)) {
failedToDecode = true;
return;
}
if (param.type === SolidityTypes.Address) {
value = AbiDecoder._padZeros(new BigNumber(value).toString(16));
} else if (param.type === SolidityTypes.Uint256 || param.type === SolidityTypes.Uint) {
value = new BigNumber(value);
} else if (param.type === SolidityTypes.Uint8) {
value = new BigNumber(value).toNumber();
}
decodedParams[param.name] = value;
});
if (failedToDecode) {
return log;
} else {
return {
...log,
event: event.name,
args: decodedParams,
};
}
}
private _addABI(abiArray: Web3.AbiDefinition[]): void {
if (_.isUndefined(abiArray)) {
return;
}
const ethersInterface = new ethersContracts.Interface(abiArray);
_.map(abiArray, (abi: Web3.AbiDefinition) => {
if (abi.type === AbiType.Event) {
const topic = ethersInterface.events[abi.name].topic;
this._methodIds[topic] = abi;
}
});
this._savedABIs = this._savedABIs.concat(abiArray);
}
}
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