/**
 * Copyright (c) 2021 OpenLens Authors
 *
 * Permission is hereby granted, free of charge, to any person obtaining a copy of
 * this software and associated documentation files (the "Software"), to deal in
 * the Software without restriction, including without limitation the rights to
 * use, copy, modify, merge, publish, distribute, sublicense, and/or sell copies of
 * the Software, and to permit persons to whom the Software is furnished to do so,
 * subject to the following conditions:
 *
 * The above copyright notice and this permission notice shall be included in all
 * copies or substantial portions of the Software.
 *
 * THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
 * IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY, FITNESS
 * FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE AUTHORS OR
 * COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER LIABILITY, WHETHER
 * IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM, OUT OF OR IN
 * CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN THE SOFTWARE.
 */

// Keeps window.localStorage state in external JSON-files.
// Because app creates random port between restarts => storage session wiped out each time.
import path from "path";
import { comparer, observable, reaction, toJS, when } from "mobx";
import fse from "fs-extra";
import { StorageHelper } from "./storageHelper";
import logger from "../../main/logger";
import { isTestEnv } from "../../common/vars";
import AwaitLock from "await-lock";

const storage = observable({
  initialized: false,
  loaded: false,
  data: {} as Record<string/*key*/, any>, // json-serializable
});

/**
 * Creates a helper for saving data under the "key" intended for window.localStorage
 * @param key The descriptor of the data
 * @param defaultValue The default value of the data, must be JSON serializable
 */
export function createStorage<T>(key: string, defaultValue: T) {
  const { logPrefix } = StorageHelper;

  if (!storage.initialized) {
    storage.initialized = true;

    (async () => {
      const filePath = await StorageHelper.getLocalStoragePath();

      try {
        storage.data = await fse.readJson(filePath);
      } catch (error) {
        // ignore file not found errors for logging
        if (error?.code !== "ENOENT") {
          logger.warn(`${logPrefix} failed to read JSON from ${filePath}`, error);
        }
      } finally {
        if (!isTestEnv) {
          logger.info(`${logPrefix} loading finished for ${filePath}`);
        }

        storage.loaded = true;
      }

      const lock = new AwaitLock();

      // bind auto-saving data changes to %storage-file.json
      reaction(() => toJS(storage.data), saveFile, {
        delay: 1000, // lazy, avoid excessive writes to fs
        equals: comparer.structural, // save only when something really changed
      });

      async function saveFile(state: Record<string, any> = {}) {
        try {
          await lock.acquireAsync();
          logger.info(`${logPrefix} saving ${filePath}`);
          await fse.ensureDir(path.dirname(filePath), { mode: 0o755 });
          await fse.writeJson(filePath, state, { spaces: 2 });
        } catch (error) {
          const meta = {
            json: state,
            jsonFilePath: filePath,
          };

          logger.error(`${logPrefix} saving failed: ${error}`, meta);
        } finally {
          lock.release();
        }
      }
    })()
      .catch(error => logger.error(`${logPrefix} Failed to initialize storage: ${error}`));
  }

  return new StorageHelper<T>(key, {
    autoInit: true,
    defaultValue,
    storage: {
      async getItem(key: string) {
        await when(() => storage.loaded);

        return storage.data[key];
      },
      setItem(key: string, value: any) {
        storage.data[key] = value;
      },
      removeItem(key: string) {
        delete storage.data[key];
      },
    },
  });
}