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-rw-r--r--src/utils/abi_decoder.ts66
1 files changed, 66 insertions, 0 deletions
diff --git a/src/utils/abi_decoder.ts b/src/utils/abi_decoder.ts
new file mode 100644
index 000000000..0600f86f2
--- /dev/null
+++ b/src/utils/abi_decoder.ts
@@ -0,0 +1,66 @@
+import * as Web3 from 'web3';
+import * as _ from 'lodash';
+import {AbiType, DecodedLogArgs, DecodedArgs} from '../types';
+import * as SolidityCoder from 'web3/lib/solidity/coder.js';
+
+export class AbiDecoder {
+ private savedABIs: Web3.AbiDefinition[] = [];
+ private methodIDs: {[signatureHash: string]: Web3.EventAbi} = {};
+ constructor(abiArrays: Web3.AbiDefinition[][]) {
+ _.map(abiArrays, this.addABI.bind(this));
+ }
+ public decodeLog(logItem: Web3.LogEntry): DecodedArgs|undefined {
+ const methodID = logItem.topics[0];
+ const event = this.methodIDs[methodID];
+ if (!_.isUndefined(event)) {
+ const logData = logItem.data;
+ const decodedParams: DecodedLogArgs = {};
+ let dataIndex = 0;
+ let topicsIndex = 1;
+
+ const nonIndexedInputs = _.filter(event.inputs, input => !input.indexed);
+ const dataTypes = _.map(nonIndexedInputs, input => input.type);
+ const decodedData = SolidityCoder.decodeParams(dataTypes, logData.slice(2));
+ _.map(event.inputs, (param: Web3.EventParameter) => {
+ let value;
+ if (param.indexed) {
+ value = logItem.topics[topicsIndex];
+ topicsIndex++;
+ } else {
+ value = decodedData[dataIndex];
+ dataIndex++;
+ }
+ if (param.type === 'address') {
+ value = this.padZeros(new Web3().toBigNumber(value).toString(16));
+ } else if (param.type === 'uint256' || param.type === 'uint8' || param.type === 'int' ) {
+ value = new Web3().toBigNumber(value).toString(10);
+ }
+ decodedParams[param.name] = value;
+ });
+
+ return {
+ event: event.name,
+ args: decodedParams,
+ };
+ }
+ }
+ private addABI(abiArray: Web3.AbiDefinition[]): void {
+ _.map(abiArray, (abi: Web3.AbiDefinition) => {
+ if (abi.type === AbiType.Event) {
+ const signature = `${abi.name}(${_.map(abi.inputs, input => input.type).join(',')})`;
+ const signatureHash = new Web3().sha3(signature);
+ this.methodIDs[signatureHash] = abi;
+ }
+ });
+ this.savedABIs = this.savedABIs.concat(abiArray);
+ }
+ private padZeros(address: string) {
+ let formatted = address;
+ if (formatted.indexOf('0x') !== -1) {
+ formatted = formatted.slice(2);
+ }
+
+ formatted = _.padStart(formatted, 40, '0');
+ return '0x' + formatted;
+ }
+}