/* This Source Code Form is subject to the terms of the Mozilla Public
 * License, v. 2.0. If a copy of the MPL was not distributed with this
 * file, You can obtain one at http://mozilla.org/MPL/2.0/. */

import * as BackupResources from "resource:///modules/backup/BackupResources.sys.mjs";

const lazy = {};

ChromeUtils.defineLazyGetter(lazy, "logConsole", function () {
  return console.createInstance({
    prefix: "BackupService",
    maxLogLevel: Services.prefs.getBoolPref("browser.backup.log", false)
      ? "Debug"
      : "Warn",
  });
});

/**
 * The BackupService class orchestrates the scheduling and creation of profile
 * backups. It also does most of the heavy lifting for the restoration of a
 * profile backup.
 */
export class BackupService {
  /**
   * The BackupService singleton instance.
   *
   * @static
   * @type {BackupService|null}
   */
  static #instance = null;

  /**
   * Map of instantiated BackupResource classes.
   *
   * @type {Map<string, BackupResource>}
   */
  #resources = new Map();

  /**
   * Returns a reference to a BackupService singleton. If this is the first time
   * that this getter is accessed, this causes the BackupService singleton to be
   * be instantiated.
   *
   * @static
   * @type {BackupService}
   */
  static init() {
    if (this.#instance) {
      return this.#instance;
    }
    this.#instance = new BackupService(BackupResources);
    this.#instance.takeMeasurements();

    return this.#instance;
  }

  /**
   * Create a BackupService instance.
   *
   * @param {object} [backupResources=BackupResources] - Object containing BackupResource classes to associate with this service.
   */
  constructor(backupResources = BackupResources) {
    lazy.logConsole.debug("Instantiated");

    for (const resourceName in backupResources) {
      let resource = BackupResources[resourceName];
      this.#resources.set(resource.key, resource);
    }
  }

  /**
   * Take measurements of the current profile state for Telemetry.
   *
   * @returns {Promise<undefined>}
   */
  async takeMeasurements() {
    lazy.logConsole.debug("Taking Telemetry measurements");

    // Note: We're talking about kilobytes here, not kibibytes. That means
    // 1000 bytes, and not 1024 bytes.
    const BYTES_IN_KB = 1000;
    const BYTES_IN_MB = 1000000;

    // We'll start by measuring the available disk space on the storage
    // device that the profile directory is on.
    let profileDir = await IOUtils.getFile(PathUtils.profileDir);

    let profDDiskSpaceBytes = profileDir.diskSpaceAvailable;

    // Make the measurement fuzzier by rounding to the nearest 10MB.
    let profDDiskSpaceMB =
      Math.round(profDDiskSpaceBytes / BYTES_IN_MB / 100) * 100;

    // And then record the value in kilobytes, since that's what everything
    // else is going to be measured in.
    Glean.browserBackup.profDDiskSpace.set(profDDiskSpaceMB * BYTES_IN_KB);

    // Measure the size of each file we are going to backup.
    for (let resourceClass of this.#resources.values()) {
      await new resourceClass().measure(PathUtils.profileDir);
    }
  }
}