Re-organize event parsing and decoding

1 files changed, 34 insertions, 0 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
new file mode 100644
index 000000000..59331fc4f
--- /dev/null
+++ b/packages/pipeline/src/data_types/events/event_handlers/base_event_handler.ts
@@ -0,0 +1,34 @@
+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;
+    }
+}