-- =====================================================================
-- Migration 0016: Shift Assignments
-- Extends open_shift so managers/owners can assign a shift to any employee.
-- =====================================================================

drop function if exists app.open_shift(uuid, numeric, numeric);

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
  if p_opening_usd is null or p_opening_lbp is null then
    raise exception 'opening counts are required';
  end if;
  if p_opening_usd < 0 or p_opening_lbp < 0 then
    raise exception 'opening counts must be non-negative';
  end if;

  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;

  v_target_user := coalesce(p_assigned_user_id, auth.uid());

  -- Caller must have a role to open.
  if not app.has_any_role_in_shop(v_shop, array['owner','manager','cashier']::app.business_role[]) then
    raise exception 'not authorized to open a shift on this till';
  end if;

  -- If trying to open for someone else, must be owner or manager
  if v_target_user <> auth.uid() then
    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;
  end if;

  -- Target user must have a role in the shop
  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;

  -- Reject if any non-closed shift exists on this till.
  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;

  -- Record the opening float as a cash movement for clean ledgers.
  insert into app.cash_movements(shift_id, type, currency, amount, note)
    values (v_shift, 'opening_float', 'USD', p_opening_usd, 'opening float'),
           (v_shift, 'opening_float', 'LBP', p_opening_lbp, 'opening float');

  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;