malice

import { get, writable } from 'svelte/store';

import { getAccountData, setAccountData } from './api';

import { parseDisabledPackImages, withImageEnabled } from './pack-preferences-model';

import type { DisabledPackImages } from './pack-preferences-model';

const EVENT_TYPE = 'dev.malice.pack_preferences';

export const disabledPackImages = writable<DisabledPackImages>({});

let loadGeneration = 0;

let accountGeneration = 0;

let pendingSaves = 0;

let persistedPreferences: DisabledPackImages = {};

let saveQueue: Promise<void> = Promise.resolve();

export async function loadPackPreferences(): Promise<void> {

  if (pendingSaves > 0) return;

  const generation = ++loadGeneration;

  const epoch = accountGeneration;

  try {

    const preferences = parseDisabledPackImages(await getAccountData(EVENT_TYPE));

    if (generation !== loadGeneration || epoch !== accountGeneration || pendingSaves > 0) return;

    persistedPreferences = preferences;

    disabledPackImages.set(preferences);

  } catch {}

}

export function setPackImageEnabled(packId: string, shortcode: string, enabled: boolean): Promise<void> {

  const previous = get(disabledPackImages);

  const next = withImageEnabled(previous, packId, shortcode, enabled);

  if (next === previous) return Promise.resolve();

  const epoch = accountGeneration;

  loadGeneration += 1;

  pendingSaves += 1;

  disabledPackImages.set(next);

  const save = saveQueue.then(async () => {

    if (epoch !== accountGeneration) return;

    await setAccountData(EVENT_TYPE, { disabled: next });

    if (epoch === accountGeneration) persistedPreferences = next;

  });

  saveQueue = save.catch(() => undefined);

  return save.catch((error: unknown) => {

    if (epoch === accountGeneration && get(disabledPackImages) === next) {

      loadGeneration += 1;

      disabledPackImages.set(persistedPreferences);

    }

    throw error;

  }).finally(() => {

    if (epoch === accountGeneration) pendingSaves -= 1;

  });

}

export function resetPackPreferences(): void {

  accountGeneration += 1;

  loadGeneration += 1;

  pendingSaves = 0;

  persistedPreferences = {};

  disabledPackImages.set({});

}