import { atom } from 'jotai';
import { atomWithStorage, createJSONStorage } from 'jotai/utils';
import { IContent } from 'matrix-js-sdk';

export type ScheduledMessage = {
  delayId: string;
  roomId: string;
  content: IContent;
  sendAt: number; // Unix timestamp ms
};

const STORAGE_KEY = 'cinny_scheduled_messages_v1';

// Internal atom persists as a plain Record (JSON-serializable).
const internalAtom = atomWithStorage<Record<string, ScheduledMessage[]>>(
  STORAGE_KEY,
  {},
  createJSONStorage(() => localStorage),
);

/**
 * Global atom: Map<roomId, ScheduledMessage[]>
 * Stores all locally-tracked scheduled messages across rooms.
 * Loaded from the server's MSC4140 `GET /delayed_events` when the tray mounts
 * (Gitea #322); localStorage is a cache for the first paint.
 */
export const scheduledMessagesAtom = atom(
  (get): Map<string, ScheduledMessage[]> => new Map(Object.entries(get(internalAtom))),
  (
    _get,
    set,
    updater:
      | Map<string, ScheduledMessage[]>
      | ((prev: Map<string, ScheduledMessage[]>) => Map<string, ScheduledMessage[]>),
  ) => {
    set(internalAtom, (prevObj) => {
      const prevMap = new Map(Object.entries(prevObj));
      const nextMap = typeof updater === 'function' ? updater(prevMap) : updater;
      return Object.fromEntries(nextMap.entries());
    });
  },
);

/**
 * Wipe persisted scheduled messages. Called on logout — the stored content is
 * decrypted message plaintext (the E2EE `body`), so it must not survive a
 * session on a shared device.
 */
export const clearScheduledMessages = (): void => {
  try {
    localStorage.removeItem(STORAGE_KEY);
  } catch {
    /* localStorage unavailable — nothing to clear */
  }
};