From 920d9a0bdcb13030e17354f7cc368eaba1816147 Mon Sep 17 00:00:00 2001
From: Stephan Cilliers <5469870+stephancill@users.noreply.github.com>
Date: Tue, 17 Sep 2024 22:23:35 +0200
Subject: [PATCH] fix: from event id

---
 src/lib/hubSubscriber.ts |  4 ++--
 src/lib/utils.ts         | 27 +++++++++++++++++++++++++++
 2 files changed, 29 insertions(+), 2 deletions(-)

diff --git a/src/lib/hubSubscriber.ts b/src/lib/hubSubscriber.ts
index f17de45..74b3544 100644
--- a/src/lib/hubSubscriber.ts
+++ b/src/lib/hubSubscriber.ts
@@ -11,7 +11,7 @@ import { EventStreamConnection } from './eventStream.js'
 import { Logger } from './logger.js'
 import { RedisClient } from './redis.js'
 import type { HubClient } from './types'
-import { sleep } from './utils.js'
+import { eventIdFromTimestamp, sleep } from './utils.js'
 
 interface HubEventsEmitter {
   event: (hubEvent: HubEvent) => void
@@ -109,7 +109,7 @@ export class BaseHubSubscriber extends HubSubscriber {
     this.log.info(`HubSubscriber ${this.label} connected to hub`)
 
     // TODO: Fix this
-    const fromId = undefined // await this.getLastEventId()
+    const fromId = eventIdFromTimestamp(Date.now()) // await this.getLastEventId()
     if (fromId) {
       this.log.info(
         `HubSubscriber ${this.label} Found last hub event ID: ${fromId}`
diff --git a/src/lib/utils.ts b/src/lib/utils.ts
index 3805b90..de88204 100644
--- a/src/lib/utils.ts
+++ b/src/lib/utils.ts
@@ -1,5 +1,6 @@
 import {
   ContactInfoContentBody,
+  FARCASTER_EPOCH,
   FidRequest,
   HubResult,
   Message,
@@ -238,3 +239,29 @@ export async function inBatchesOf<T>(
 export function sleep(ms: number) {
   return new Promise((resolve) => setTimeout(resolve, ms))
 }
+
+const SEQUENCE_BITS = 12
+
+export const extractEventTimestamp = (eventId: number): number => {
+  const binaryEventId = eventId.toString(2)
+  const binaryTimestamp = binaryEventId.slice(
+    0,
+    binaryEventId.length - SEQUENCE_BITS
+  )
+  return parseInt(binaryTimestamp, 2) + FARCASTER_EPOCH
+}
+
+export const eventIdFromTimestamp = (
+  timestamp: number,
+  sequence: number = 0
+): number => {
+  if (sequence < 0 || sequence >= 1 << SEQUENCE_BITS) {
+    throw new Error(
+      `Sequence must be between 0 and ${(1 << SEQUENCE_BITS) - 1}`
+    )
+  }
+  const adjustedTimestamp = timestamp - FARCASTER_EPOCH
+  const timestampBits = adjustedTimestamp.toString(2)
+  const sequenceBits = sequence.toString(2).padStart(SEQUENCE_BITS, '0')
+  return parseInt(timestampBits + sequenceBits, 2)
+}