set search_path = app, public;

create or replace function app.open_shift(
  p_till_id uuid,
  p_opening_usd numeric,
  p_opening_lbp numeric,
  p_assigned_user_id uuid default null
)
returns uuid
language plpgsql
security definer
set search_path = app, public
as $$
declare
  v_shop uuid;
  v_shift uuid;
  v_target_user uuid;
begin
  select shop_id into v_shop from app.tills where id = p_till_id and is_active;
  if v_shop is null then
    raise exception 'till % not found or inactive', p_till_id;
  end if;

  if p_assigned_user_id is null then
    if not app.has_any_role_in_shop(v_shop, array['cashier','manager']::app.business_role[]) then
      raise exception 'not authorized to open a shift on this till';
    end if;
    v_target_user := auth.uid();
  else
    if not app.has_any_role_in_shop(v_shop, array['owner','manager']::app.business_role[]) then
      raise exception 'only managers or owners can assign shifts to other users';
    end if;
    v_target_user := p_assigned_user_id;
    if not exists (
      select 1 from app.user_shop_assignments
      where user_id = v_target_user and shop_id = v_shop
    ) then
      raise exception 'target user does not have a role in this shop';
    end if;
  end if;

  if exists (select 1 from app.shifts where till_id = p_till_id and status <> 'closed') then
    raise exception 'till % already has an active shift; close it first', p_till_id;
  end if;

  insert into app.shifts(till_id, shop_id, user_id, opened_by, opening_usd, opening_lbp)
    values (p_till_id, v_shop, v_target_user, auth.uid(), p_opening_usd, p_opening_lbp)
    returning id into v_shift;

  insert into app.cash_movements(shift_id, type, currency, amount, note)
  select v_shift, 'opening_float', x.currency, x.amount, 'opening float'
  from (values ('USD'::app.currency_code, p_opening_usd), ('LBP'::app.currency_code, p_opening_lbp))
       as x(currency, amount)
  where x.amount > 0;

  perform app.log_auth_event(
    'shift_opened',
    v_shop,
    null,
    jsonb_build_object(
      'shift_id', v_shift,
      'till_id', p_till_id,
      'assigned_user_id', v_target_user
    )
  );
  return v_shift;
end;
$$;

revoke all on function app.open_shift(uuid, numeric, numeric, uuid) from public;
grant execute on function app.open_shift(uuid, numeric, numeric, uuid) to authenticated;