Make event parsing more functional and less class-based

3 files changed, 21 insertions, 65 deletions

diff --git a/packages/pipeline/src/data_types/events/event_handlers/base_event_handler.ts b/packages/pipeline/src/data_types/events/event_handlers/base_event_handler.ts
deleted file mode 100644
index 59331fc4f..000000000
--- a/packages/pipeline/src/data_types/events/event_handlers/base_event_handler.ts
+++ /dev/null
@@ -1,34 +0,0 @@
-import { AbiDefinition, BlockParam, BlockParamLiteral, LogEntry } from 'ethereum-types';
-import * as R from 'ramda';
-import { BaseEntity } from 'typeorm';
-
-import { Etherscan } from '../../../data_sources/etherscan';
-import { convertResponseToLogEntry } from '../event_utils';
-
-export abstract class BaseEventHandler<EntityType extends BaseEntity> {
-    protected _abi: AbiDefinition[];
-    protected _address: string;
-    protected _etherscan: Etherscan;
-    constructor(abi: AbiDefinition[], address: string, etherscan: Etherscan) {
-        this._abi = abi;
-        this._address = address;
-        this._etherscan = etherscan;
-    }
-    public abstract convertLogEntryToEventEntity(logEntry: LogEntry): EntityType;
-
-    public async getEventsAsync(
-        fromBlock: BlockParam = BlockParamLiteral.Earliest,
-        toBlock: BlockParam = BlockParamLiteral.Latest,
-    ): Promise<EntityType[]> {
-        const rawEventsResponse = await this._etherscan.getContractEventsAsync(this._address, fromBlock, toBlock);
-        const logEntries = R.map(convertResponseToLogEntry, rawEventsResponse.result);
-        // Note(albrow): Imperative for loop is required here because we can't
-        // bind convertLogEntryToEventEntity without having a specific instance
-        // of a sub-class.
-        const result = [];
-        for (const logEntry of logEntries) {
-            result.push(this.convertLogEntryToEventEntity(logEntry));
-        }
-        return result;
-    }
-}
diff --git a/packages/pipeline/src/data_types/events/event_handlers/exchange_event_handler.ts b/packages/pipeline/src/data_types/events/exchange_events.ts
index 38ff20595..fb5341b58 100644
--- a/packages/pipeline/src/data_types/events/event_handlers/exchange_event_handler.ts
+++ b/packages/pipeline/src/data_types/events/exchange_events.ts
@@ -1,23 +1,29 @@
 import { ExchangeEventArgs, ExchangeFillEventArgs } from '@0xproject/contract-wrappers';
 import { assetDataUtils } from '@0xproject/order-utils';
 import { AssetProxyId, ERC721AssetData } from '@0xproject/types';
-import { AbiDecoder, BigNumber } from '@0xproject/utils';
-import { AbiDefinition, LogEntry, LogWithDecodedArgs } from 'ethereum-types';
+import { BigNumber } from '@0xproject/utils';
+import { LogWithDecodedArgs } from 'ethereum-types';
 import * as R from 'ramda';
 
-import { ExchangeFillEvent } from '../../../entities/ExchangeFillEvent';
-import { decodeLogEntry } from '../event_utils';
+import { artifacts } from '../../artifacts';
+import { EventsResponse } from '../../data_sources/etherscan';
+import { ExchangeFillEvent } from '../../entities/ExchangeFillEvent';
 
-import { BaseEventHandler } from './base_event_handler';
+import { convertResponseToLogEntry, decodeLogEntry } from './event_utils';
 
 // TODO(albrow): Union with other exchange event entity types
 export type ExchangeEventEntity = ExchangeFillEvent;
 
-export class ExchangeEventHandler extends BaseEventHandler<ExchangeEventEntity> {
-    public convertLogEntryToEventEntity(logEntry: LogEntry): ExchangeEventEntity {
-        const decodedLogEntry = decodeLogEntry<ExchangeEventArgs>(this._abi, logEntry);
-        return _convertToEntity(decodedLogEntry);
-    }
+const exchangeContractAbi = artifacts.Exchange.compilerOutput.abi;
+
+export function parseExchangeEvents(rawEventsResponse: EventsResponse): ExchangeEventEntity[] {
+    const logEntries = R.map(convertResponseToLogEntry, rawEventsResponse.result);
+    const decodedLogEntries = R.map(
+        eventResponse => decodeLogEntry<ExchangeEventArgs>(exchangeContractAbi, eventResponse),
+        logEntries,
+    );
+    const filteredLogEntries = R.filter(logEntry => R.contains(logEntry.event, ['Fill']), decodedLogEntries);
+    return R.map(_convertToEntity, filteredLogEntries);
 }
 
 export function _convertToEntity(eventLog: LogWithDecodedArgs<ExchangeEventArgs>): ExchangeEventEntity {
@@ -25,8 +31,7 @@ export function _convertToEntity(eventLog: LogWithDecodedArgs<ExchangeEventArgs>
         case 'Fill':
             return _convertToExchangeFillEvent(eventLog as LogWithDecodedArgs<ExchangeFillEventArgs>);
         default:
-            return new ExchangeFillEvent();
-        // throw new Error('unexpected eventLog.event type: ' + eventLog.event);
+            throw new Error('unexpected eventLog.event type: ' + eventLog.event);
     }
 }
 
@@ -68,9 +73,3 @@ function bigNumbertoStringOrNull(n: BigNumber): string | null {
     }
     return n.toString();
 }
-
-function filterEventLogs(
-    eventLogs: Array<LogWithDecodedArgs<ExchangeEventArgs>>,
-): Array<LogWithDecodedArgs<ExchangeEventArgs>> {
-    return R.filter(eventLog => eventLog.event === 'Fill', eventLogs);
-}
diff --git a/packages/pipeline/src/index.ts b/packages/pipeline/src/index.ts
index e71a6ae4c..c01ff57b4 100644
--- a/packages/pipeline/src/index.ts
+++ b/packages/pipeline/src/index.ts
@@ -1,12 +1,11 @@
 import 'reflect-metadata';
 import { createConnection } from 'typeorm';
 
-import { artifacts } from './artifacts';
 import { Etherscan } from './data_sources/etherscan';
 import { ExchangeFillEvent } from './entities/ExchangeFillEvent';
 import { config } from './ormconfig';
 
-import { ExchangeEventHandler } from './data_types/events/event_handlers/exchange_event_handler';
+import { parseExchangeEvents } from './data_types/events/exchange_events';
 
 const etherscan = new Etherscan(process.env.ETHERSCAN_API_KEY as string);
 const EXCHANGE_ADDRESS = '0x4f833a24e1f95d70f028921e27040ca56e09ab0b';
@@ -15,18 +14,10 @@ const EXCHANGE_ADDRESS = '0x4f833a24e1f95d70f028921e27040ca56e09ab0b';
     const connection = await createConnection(config);
     const repository = connection.getRepository(ExchangeFillEvent);
     console.log(`found ${await repository.count()} existing fill events`);
-    const exchangeEventHandler = new ExchangeEventHandler(
-        artifacts.Exchange.compilerOutput.abi,
-        EXCHANGE_ADDRESS,
-        etherscan,
-    );
-    const events = await exchangeEventHandler.getEventsAsync();
-    console.log(JSON.stringify(events, null, 2));
+    const rawEvents = await etherscan.getContractEventsAsync(EXCHANGE_ADDRESS);
+    const events = parseExchangeEvents(rawEvents);
     for (const event of events) {
-        // TODO(albrow): remove this check once we can parse all Exchange events
-        if (event.address != null) {
-            await event.save();
-        }
+        await event.save();
     }
     console.log(`now ${await repository.count()} total fill events`);
 })();