/**
 * When a branch delivers.
 *
 * A branch offers at most three windows a day — morning, afternoon, evening —
 * and a shopper picks one at checkout. The window is a PREFERENCE, not a
 * promise: every order is accepted and no window ever fills up.
 *
 * ── A branch with no windows is not broken ──────────────────────────────────
 *
 * Every tenant trading today has none, and all of them keep taking orders.
 * An empty list means "order without a window", never "this shop is closed".
 * Nothing here may treat it as an error state.
 *
 * ── The console edits; it does not decide what is open ──────────────────────
 *
 * Whether a window is still open today is a clock comparison, and the server
 * owns it — see deliverySlotService.go. This module reads what a branch has
 * configured and writes it back. The filtered, dated list a shopper sees is an
 * app concern and is not fetched here.
 */

import { api, WEB } from './client';

/** The three, in the order a shopper reads them. */
export const SLOT_KEYS = ['morning', 'afternoon', 'evening'] as const;
export type SlotKey = (typeof SLOT_KEYS)[number];

export interface DeliverySlot {
  deliveryslotid?: number;
  tenantid?: number;
  locationid?: number;
  slotkey: SlotKey;
  /** What the shopper reads. Blank falls back to the capitalised key. */
  name: string;
  /** "HH:MM", 24-hour, in the shop's own local time. */
  starttime: string;
  /**
   * Also the cut-off. A window takes orders right up to the moment it ends —
   * there is deliberately no separate cut-off to configure.
   */
  endtime: string;
  status: 'active' | 'inactive';
}

/**
 * What a branch starts with when nobody has set anything.
 *
 * Seeded rather than blank so onboarding asks a shopkeeper to CONFIRM rather
 * than to invent: three empty time fields is a form most people abandon, and a
 * tenant that abandons it has a shop that cannot offer windows at all.
 */
export const DEFAULT_SLOTS: DeliverySlot[] = [
  { slotkey: 'morning', name: 'Morning', starttime: '08:00', endtime: '10:00', status: 'active' },
  { slotkey: 'afternoon', name: 'Afternoon', starttime: '12:00', endtime: '15:00', status: 'active' },
  { slotkey: 'evening', name: 'Evening', starttime: '17:00', endtime: '20:00', status: 'active' },
];

export const deliverySlotsApi = {
  /** Everything this branch has configured, active or not. */
  list: (tenantid: number, locationid: number) =>
    api.get<{ details: DeliverySlot[] }>(`${WEB}/deliveryslots`, { tenantid, locationid }),

  /**
   * All three together, never one at a time.
   *
   * They are edited as a set on one screen, and sending them together is what
   * lets the server reject the whole edit when one row is wrong instead of
   * applying half of it — a shop with two new windows and one old one, and
   * nothing on screen saying which took, is worse than a shop with none.
   */
  save: (tenantid: number, locationid: number, slots: DeliverySlot[]) =>
    api.put<unknown>(`${WEB}/deliveryslots`, { tenantid, locationid, slots }),
};

/**
 * Is this set fit to send?
 *
 * Mirrors the server's rules so the shopkeeper hears about a mistake while
 * their hands are still on it, rather than as a 409 after pressing save. The
 * server re-checks all of it — this is courtesy, not security.
 */
export function slotProblems(slots: DeliverySlot[]): string[] {
  const problems: string[] = [];

  for (const slot of slots) {
    const label = slot.name.trim() || slot.slotkey;

    if (!/^\d{2}:\d{2}$/.test(slot.starttime) || !/^\d{2}:\d{2}$/.test(slot.endtime)) {
      problems.push(`${label} needs a start and end time.`);
      continue;
    }
    // An end at or before its start never passes the server's "still running"
    // test, so the window would simply never appear to a shopper, with nothing
    // saying why.
    if (slot.endtime <= slot.starttime) {
      problems.push(`${label} ends at or before it starts (${slot.starttime}–${slot.endtime}).`);
    }
  }

  return problems;
}