'use server'

import { revalidateTag } from 'next/cache'
import { z } from 'zod'
import { PERMS } from '@/lib/permission-slugs'
import { prisma } from '@/lib/prisma'
import { adminAction } from '@/lib/safe-action'
import { actionOk } from '@/lib/safe-action-shared'

const toggleWatchSchema = z.object({
  targetUserId: z.coerce.number().int().positive(),
  reason: z.string().max(255).optional(),
})

/**
 * Toggle a watch entry for the calling staff on the given target user.
 * If a row already exists it's removed; otherwise it's created with the
 * provided reason (defaulting to empty). Returns the resulting state so
 * the UI can flip the badge without re-fetching.
 */
export const toggleUserWatch = adminAction(
  { permission: PERMS.USERS_VIEW, schema: toggleWatchSchema },
  async (ctx) => {
    const staffId = ctx.session.user.id
    const { targetUserId, reason } = ctx.data

    const existing = await prisma.userWatch.findUnique({
      where: { staffId_targetUserId: { staffId, targetUserId } },
    })

    if (existing) {
      await prisma.userWatch.delete({ where: { id: existing.id } })
      revalidateTag(`user-watch:${staffId}`, { expire: 0 })
      return actionOk({ watching: false })
    }

    await prisma.userWatch.create({
      data: { staffId, targetUserId, reason: reason ?? '' },
    })
    revalidateTag(`user-watch:${staffId}`, { expire: 0 })
    return actionOk({ watching: true })
  },
)