-- Deferred/effective-dated changes (spec §3.3)
--
-- Finding from the consolidation review: transfer_employee, promote_employee,
-- start_karenz, change_employee_data, and apply_reorg all accepted a
-- "Wirksam ab" / effective date, but only ever used it as metadata for the
-- employee_history/audit_log rows — the actual `update employees` always
-- ran immediately regardless of that date. A transfer or promotion dated
-- months in the future silently overwrote the *current* live record today.
-- This table backs the fix: when an effective date is in the future, the
-- mutating RPC stores the intended change here instead of writing it to
-- `employees` right away; a scheduled job (apply_due_pending_changes(),
-- see the following migration, invoked by a Vercel Cron route handler)
-- applies it once its date arrives. The employee_history/audit_log rows are
-- written immediately either way (dated with the effective date), which is
-- what already drives the "zukünftig" badge in the Historie tab.

create table pending_org_changes (
  id uuid primary key default gen_random_uuid(),
  employee_id uuid not null references employees(id) on delete cascade,
  change_type text not null check (change_type in (
    'transfer', 'promotion', 'karenz_start', 'karenz_return', 'contract_change', 'reorg'
  )),
  effective_date date not null,
  payload jsonb not null,
  reorg_scenario_id uuid references reorg_scenarios(id) on delete cascade,
  status text not null default 'pending' check (status in ('pending', 'applied', 'cancelled')),
  created_by uuid references auth.users(id),
  created_at timestamptz not null default now(),
  applied_at timestamptz
);

create index on pending_org_changes (employee_id);
create index on pending_org_changes (status, effective_date);
create index on pending_org_changes (reorg_scenario_id);

alter table pending_org_changes enable row level security;
create policy "pending_org_changes_hr_all" on pending_org_changes for all
  using (is_hr_user()) with check (is_hr_user());