import { requireAuth } from '~/server/utils/auth'
import { groups, userGroups } from '~/server/utils/db'

export default defineEventHandler(async (event) => {
  const user = requireAuth(event)
  const groupId = getRouterParam(event, 'id')!

  const group = groups.get(groupId)
  if (!group) throw createError({ statusCode: 404, message: 'Group not found' })
  if (!group.isPublic) throw createError({ statusCode: 403, message: 'Group is private' })

  const key = `${user.id}-${groupId}`
  if (userGroups.has(key)) return { message: 'Already a member' }

  userGroups.set(key, { userId: user.id, groupId, role: 'member', joinedAt: new Date().toISOString() })
  return { success: true, message: `Joined group "${group.name}"` }
})