import { NextResponse } from 'next/server'
import { z } from 'zod'
import { requireAuth } from '@/lib/auth/require-auth'
import type { UserUiState } from '@/types'

// Partial update: the client sends only the keys it changed. Strict schemas
// so typos fail loudly instead of accumulating junk in the jsonb bag.
const BodySchema = z
  .object({
    nav_collapsed: z.boolean().optional(),
    nav_folds: z
      .object({
        register: z.boolean().optional(),
        bokslut: z.boolean().optional(),
      })
      .strict()
      .optional(),
    create_mode: z.record(z.string(), z.string().max(64)).optional(),
  })
  .strict()

// User-scoped preference endpoint: no company context exists or is needed,
// so requireAuth() directly (same opt-out as /api/user/locale). RLS scopes
// user_preferences to the caller's own row.
export async function POST(request: Request) {
  const { user, supabase, error } = await requireAuth()
  if (error) return error

  let body: unknown
  try {
    body = await request.json()
  } catch {
    return NextResponse.json({ error: 'Invalid JSON body' }, { status: 400 })
  }

  const parsed = BodySchema.safeParse(body)
  if (!parsed.success) {
    return NextResponse.json({ error: 'Invalid ui_state payload' }, { status: 400 })
  }

  // Read-merge-write: last write wins per key. Fine for cosmetic UI state;
  // concurrent tabs converge on the next read.
  const { data: existing } = await supabase
    .from('user_preferences')
    .select('ui_state')
    .eq('user_id', user.id)
    .maybeSingle()

  const current: UserUiState = (existing?.ui_state as UserUiState) ?? {}
  const patch = parsed.data
  const next: UserUiState = {
    ...current,
    ...patch,
    ...(patch.nav_folds
      ? { nav_folds: { ...current.nav_folds, ...patch.nav_folds } }
      : {}),
    ...(patch.create_mode
      ? { create_mode: { ...current.create_mode, ...patch.create_mode } }
      : {}),
  }

  const { error: upsertError } = await supabase
    .from('user_preferences')
    .upsert({ user_id: user.id, ui_state: next }, { onConflict: 'user_id' })

  if (upsertError) {
    return NextResponse.json({ error: 'Could not save UI preferences' }, { status: 500 })
  }

  return NextResponse.json({ data: { ui_state: next } })
}