import { useState } from 'react'
import { useMqttTopic } from '../../hooks/useMqtt'

interface Notification {
  message: string
}

interface UsersEventPayload {
  type: 'UserCreated' | 'UserUpdated' | 'UserDeleted' | 'RoleAssigned'
  user: { name: string }
}

const MESSAGES: Record<UsersEventPayload['type'], (name: string) => string> = {
  UserCreated: (name) => `${name} was added.`,
  UserUpdated: (name) => `${name} was updated.`,
  UserDeleted: (name) => `${name} was removed.`,
  RoleAssigned: (name) => `${name}'s role was changed.`,
}

const MAX_NOTIFICATIONS = 10

/** Rolling list of recent Users-module events shown in the navbar bell. */
export function useNotifications(): Notification[] {
  const [notifications, setNotifications] = useState<Notification[]>([])

  useMqttTopic('module/users/events', (payload) => {
    const event = payload as UsersEventPayload
    const message = MESSAGES[event.type]?.(event.user.name) ?? 'Users list updated.'
    setNotifications((prev) => [{ message }, ...prev].slice(0, MAX_NOTIFICATIONS))
  })

  return notifications
}