From 3f83a9be8e5e0b54e6a6587075264eb4fe3c5ef8 Mon Sep 17 00:00:00 2001
From: Kirill <mpak8501@yandex.ru>
Date: Mon, 18 May 2026 11:33:06 +0500
Subject: [PATCH] feat: add notification queue with retry worker

---
 server/src/lib/notifications/queue.js | 130 ++++++++++++++++++++++++++
 1 file changed, 130 insertions(+)
 create mode 100644 server/src/lib/notifications/queue.js

diff --git a/server/src/lib/notifications/queue.js b/server/src/lib/notifications/queue.js
new file mode 100644
index 0000000..6658069
--- /dev/null
+++ b/server/src/lib/notifications/queue.js
@@ -0,0 +1,130 @@
+import { prisma } from '../prisma.js'
+import { NOTIFICATION_STATUSES, MAX_RETRY_ATTEMPTS, RETRY_DELAYS_MS } from '../../../shared/constants/notification-events.js'
+import { emailChannel } from './channels/email-channel.js'
+import { telegramChannel } from './channels/telegram-channel.js'
+
+const { PENDING, SENT, FAILED } = NOTIFICATION_STATUSES
+
+const channels = {
+  email: emailChannel,
+  telegram: telegramChannel,
+}
+
+class NotificationQueue {
+  constructor() {
+    this.tasks = []
+    this.processing = 0
+    this.maxConcurrent = 5
+    this.intervalMs = 2000
+    this.running = false
+  }
+
+  enqueue(task) {
+    this.tasks.push({ ...task, enqueuedAt: Date.now() })
+  }
+
+  start() {
+    if (this.running) return
+    this.running = true
+    this._tick()
+  }
+
+  stop() {
+    this.running = false
+  }
+
+  _tick() {
+    if (!this.running) return
+
+    this._processAvailable()
+
+    setTimeout(() => this._tick(), this.intervalMs)
+  }
+
+  _processAvailable() {
+    while (this.tasks.length > 0 && this.processing < this.maxConcurrent) {
+      const task = this.tasks.shift()
+      this.processing++
+      this._execute(task).finally(() => {
+        this.processing--
+      })
+    }
+  }
+
+  async _execute(task) {
+    const channel = channels[task.channel]
+    if (!channel) {
+      await this._markFailed(task.logId, `Unknown channel: ${task.channel}`)
+      return
+    }
+
+    try {
+      const result = await channel.send({
+        recipient: task.recipient,
+        eventType: task.eventType,
+        payload: task.payload,
+      })
+
+      if (result.success) {
+        await this._markSent(task.logId)
+      } else {
+        await this._handleFailure(task.logId, task, result.error)
+      }
+    } catch (err) {
+      await this._handleFailure(task.logId, task, err.message)
+    }
+  }
+
+  async _markSent(logId) {
+    await prisma.notificationLog.update({
+      where: { id: logId },
+      data: { status: SENT },
+    })
+  }
+
+  async _markFailed(logId, error) {
+    await prisma.notificationLog.update({
+      where: { id: logId },
+      data: { status: FAILED, error },
+    })
+  }
+
+  async _handleFailure(logId, task, error) {
+    const log = await prisma.notificationLog.findUnique({ where: { id: logId } })
+    const newAttempts = (log?.attempts || 0) + 1
+
+    if (newAttempts >= MAX_RETRY_ATTEMPTS) {
+      await this._markFailed(logId, error)
+      return
+    }
+
+    await prisma.notificationLog.update({
+      where: { id: logId },
+      data: { attempts: newAttempts },
+    })
+
+    const delay = RETRY_DELAYS_MS[newAttempts - 1] || RETRY_DELAYS_MS[RETRY_DELAYS_MS.length - 1]
+    setTimeout(() => {
+      this.enqueue({ ...task, logId })
+    }, delay)
+  }
+
+  async flushPendingOnStartup() {
+    const pending = await prisma.notificationLog.findMany({
+      where: { status: PENDING },
+    })
+    for (const log of pending) {
+      await prisma.notificationLog.update({
+        where: { id: log.id },
+        data: { status: FAILED, error: 'Server restarted, pending notification lost' },
+      })
+    }
+    if (pending.length > 0) {
+      console.log(`[notifications] Marked ${pending.length} pending notifications as failed on startup`)
+    }
+  }
+}
+
+export function createNotificationQueue() {
+  return new NotificationQueue()
+}