import { browser } from '$app/environment';
import { derived, get, writable } from 'svelte/store';
import { debounce, showSnackbar } from '$lib/util';
import { currentProfile, profiles } from './settings';
import { miscSettings } from './misc';
import { volumes } from './volume-data';

export type SyncConfig = {
  key: string | null;
  auto: boolean;
  notifications: boolean;
};

const stored = browser ? window.localStorage.getItem('syncConfig') : undefined;
const initial: SyncConfig = stored ? JSON.parse(stored) : { key: null, auto: false, notifications: true };
export const syncConfig = writable<SyncConfig>(initial);

syncConfig.subscribe((value) => {
  if (browser) {
    window.localStorage.setItem('syncConfig', JSON.stringify(value));
  }
});

export const isSyncEnabled = derived(syncConfig, ($cfg) => Boolean($cfg.key));

async function callApi(method: 'GET' | 'POST', payload?: any) {
  if (!browser) return null;
  const url = method === 'GET' ? `/api/sync?key=${encodeURIComponent(get(syncConfig).key || '')}` : '/api/sync';
  const res = await fetch(url, {
    method,
    headers: { 'Content-Type': 'application/json' },
    body: method === 'POST' ? JSON.stringify(payload) : undefined
  });
  if (!res.ok) throw new Error(await res.text());
  return res.json();
}

export async function pullAll() {
  const cfg = get(syncConfig);
  if (!cfg.key) throw new Error('No sync key configured');
  const data = await callApi('GET');
  if (!data) return;

  if (data.profiles) {
    profiles.set(data.profiles);
  }
  if (data.current_profile) {
    currentProfile.set(data.current_profile);
  }
  if (data.misc_settings) {
    miscSettings.set(data.misc_settings);
  }
  if (data.volumes) {
    volumes.set(data.volumes);
  }
  if (cfg.notifications) {
    showSnackbar('Pulled from server');
  }
}

export async function pushAll() {
  const cfg = get(syncConfig);
  if (!cfg.key) throw new Error('No sync key configured');

  const payload = {
    key: cfg.key,
    profiles: get(profiles),
    current_profile: get(currentProfile),
    misc_settings: get(miscSettings),
    volumes: get(volumes)
  };
  await callApi('POST', payload);
  if (cfg.notifications) {
    showSnackbar('Pushed to server');
  }
}

function setupAutoSync() {
  if (!browser) return;
  let unsubscribeFns: Array<() => void> = [];

  function resubscribe() {
    unsubscribeFns.forEach((fn) => fn());
    unsubscribeFns = [];

    if (!get(syncConfig).auto || !get(syncConfig).key) return;

    const schedulePush = () => debounce(() => {
      pushAll().catch((error) => {
        console.error('Auto-sync failed:', error);
      });
    }, 300);

    unsubscribeFns.push(profiles.subscribe(() => schedulePush()));
    unsubscribeFns.push(currentProfile.subscribe(() => schedulePush()));
    unsubscribeFns.push(miscSettings.subscribe(() => schedulePush()));
    unsubscribeFns.push(volumes.subscribe(() => schedulePush()));
  }

  resubscribe();
  unsubscribeFns.push(syncConfig.subscribe(() => resubscribe()));
}

if (browser) {
  setupAutoSync();
}