import { get, set } from 'idb-keyval';

import type { GlobalState } from './GlobalStateStore.types';

const STORAGE_KEY = 'APP_GLO';

const SKIP_PATHS = new Set([
  'app.controls',
  'initialized',
  'session.connected',
  'session.error',
  'session.loading',
]);

const shouldSkipPath = (path: string): boolean => {
  return SKIP_PATHS.has(path);
};

const filterState = (state: unknown, prefix = ''): unknown => {
  if (typeof state === 'function') {
    return undefined;
  }

  if (state === null || typeof state !== 'object') {
    return state;
  }

  if (Array.isArray(state)) {
    return state.map((item, idx) => filterState(item, `${prefix}[${idx}]`));
  }

  const filtered: Record<string, unknown> = {};
  for (const [key, value] of Object.entries(state)) {
    const path = prefix ? `${prefix}.${key}` : key;

    if (shouldSkipPath(path) || typeof value === 'function') {
      continue;
    }

    filtered[key] = filterState(value, path);
  }

  return filtered;
};

async function loadStorage(): Promise<Partial<GlobalState>> {
  const result: Partial<GlobalState> = {};
  const keys: (keyof GlobalState)[] = ['layout', 'navigation', 'owner', 'program', 'session', 'user'];

  for (const key of keys) {
    const storageKey = `${STORAGE_KEY}:${key}`;

    // Always use localStorage for session
    if (key === 'session') {
      try {
        if (typeof localStorage !== 'undefined') {
          const data = localStorage.getItem(storageKey);
          if (data) {
            result[key] = JSON.parse(data);
          }
        }
      } catch (e) {
        console.error(`Failed to load ${key} from localStorage:`, e);
      }
      continue;
    }

    try {
      if (typeof indexedDB !== 'undefined') {
        const data = await get(storageKey);
        if (data) {
          result[key] = JSON.parse(data);
          continue;
        }
      }
    } catch (e) {
      console.error(`Failed to load ${key} from IndexedDB, falling back to localStorage:`, e);
    }

    try {
      if (typeof localStorage !== 'undefined') {
        const data = localStorage.getItem(storageKey);
        if (data) {
          result[key] = JSON.parse(data);
        }
      }
    } catch (e) {
      console.error(`Failed to load ${key} from localStorage:`, e);
    }
  }

  return result;
}

async function saveStorage(state: GlobalState): Promise<void> {
  const keys: (keyof GlobalState)[] = ['layout', 'navigation', 'owner', 'program', 'session', 'user'];

  for (const key of keys) {
    const storageKey = `${STORAGE_KEY}:${key}`;
    const filtered = filterState(state[key], key);
    const serialized = JSON.stringify(filtered);

    // Always use localStorage for session
    if (key === 'session') {
      try {
        if (typeof localStorage !== 'undefined') {
          localStorage.setItem(storageKey, serialized);
        }
      } catch (e) {
        console.error(`Failed to save ${key} to localStorage:`, e);
      }
      continue;
    }

    try {
      if (typeof indexedDB !== 'undefined') {
        await set(storageKey, serialized);
        continue;
      }
    } catch (e) {
      console.error(`Failed to save ${key} to IndexedDB, falling back to localStorage:`, e);
    }

    try {
      if (typeof localStorage !== 'undefined') {
        localStorage.setItem(storageKey, serialized);
      }
    } catch (e) {
      console.error(`Failed to save ${key} to localStorage:`, e);
    }
  }
}

export { loadStorage, saveStorage };