import { requireAuth } from '~/server/utils/auth'
import { prisma } from '~/server/utils/prisma'

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

  const group = await prisma.group.findUnique({ where: { id: groupId } })
  if (!group) throw createError({ statusCode: 404, message: 'Group not found' })
  if (!group.isPublic) throw createError({ statusCode: 403, message: 'Group is private' })

  const existing = await prisma.groupMember.findUnique({
    where: { userId_groupId: { userId: user.id, groupId } }
  })
  if (existing) return { message: 'Already a member' }

  await prisma.groupMember.create({
    data: { userId: user.id, groupId, role: 'member' }
  })

  return { success: true, message: `Joined group "${group.name}"` }
})