/* 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/. */

/**
 * This file contains code for synchronizing engines.
 */

import { Log } from "resource://gre/modules/Log.sys.mjs";

import {
  ABORT_SYNC_COMMAND,
  LOGIN_FAILED_NETWORK_ERROR,
  NO_SYNC_NODE_FOUND,
  STATUS_OK,
  SYNC_FAILED_PARTIAL,
  SYNC_SUCCEEDED,
  WEAVE_VERSION,
  kSyncNetworkOffline,
} from "resource://services-sync/constants.sys.mjs";

import { Svc, Utils } from "resource://services-sync/util.sys.mjs";

import { Async } from "resource://services-common/async.sys.mjs";

const lazy = {};
ChromeUtils.defineESModuleGetters(lazy, {
  Doctor: "resource://services-sync/doctor.sys.mjs",
});

/**
 * Perform synchronization of engines.
 *
 * This was originally split out of service.js. The API needs lots of love.
 */
export function EngineSynchronizer(service) {
  this._log = Log.repository.getLogger("Sync.Synchronizer");
  this._log.manageLevelFromPref("services.sync.log.logger.synchronizer");

  this.service = service;
}

EngineSynchronizer.prototype = {
  async sync(engineNamesToSync, why) {
    let fastSync = why && why == "sleep";
    let startTime = Date.now();

    this.service.status.resetSync();

    // Make sure we should sync or record why we shouldn't.
    let reason = this.service._checkSync();
    if (reason) {
      if (reason == kSyncNetworkOffline) {
        this.service.status.sync = LOGIN_FAILED_NETWORK_ERROR;
      }

      // this is a purposeful abort rather than a failure, so don't set
      // any status bits
      reason = "Can't sync: " + reason;
      throw new Error(reason);
    }

    // If we don't have a node, get one. If that fails, retry in 10 minutes.
    if (
      !this.service.clusterURL &&
      !(await this.service.identity.setCluster())
    ) {
      this.service.status.sync = NO_SYNC_NODE_FOUND;
      this._log.info("No cluster URL found. Cannot sync.");
      return;
    }

    // Ping the server with a special info request once a day.
    let infoURL = this.service.infoURL;
    let now = Math.floor(Date.now() / 1000);
    let lastPing = Svc.PrefBranch.getIntPref("lastPing", 0);
    if (now - lastPing > 86400) {
      // 60 * 60 * 24
      infoURL += "?v=" + WEAVE_VERSION;
      Svc.PrefBranch.setIntPref("lastPing", now);
    }

    let engineManager = this.service.engineManager;

    // Figure out what the last modified time is for each collection
    let info = await this.service._fetchInfo(infoURL);

    // Convert the response to an object and read out the modified times
    for (let engine of [this.service.clientsEngine].concat(
      engineManager.getAll()
    )) {
      engine.lastModified = info.obj[engine.name] || 0;
    }

    if (!(await this.service._remoteSetup(info, !fastSync))) {
      throw new Error("Aborting sync, remote setup failed");
    }

    if (!fastSync) {
      // Make sure we have an up-to-date list of clients before sending commands
      this._log.debug("Refreshing client list.");
      if (!(await this._syncEngine(this.service.clientsEngine))) {
        // Clients is an engine like any other; it can fail with a 401,
        // and we can elect to abort the sync.
        this._log.warn("Client engine sync failed. Aborting.");
        return;
      }
    }

    // We only honor the "hint" of what engines to Sync if this isn't
    // a first sync.
    let allowEnginesHint = false;
    // Wipe data in the desired direction if necessary
    switch (Svc.PrefBranch.getStringPref("firstSync", null)) {
      case "resetClient":
        await this.service.resetClient(engineManager.enabledEngineNames);
        break;
      case "wipeClient":
        await this.service.wipeClient(engineManager.enabledEngineNames);
        break;
      case "wipeRemote":
        await this.service.wipeRemote(engineManager.enabledEngineNames);
        break;
      default:
        allowEnginesHint = true;
        break;
    }

    if (!fastSync && this.service.clientsEngine.localCommands) {
      try {
        if (!(await this.service.clientsEngine.processIncomingCommands())) {
          this.service.status.sync = ABORT_SYNC_COMMAND;
          throw new Error("Processed command aborted sync.");
        }

        // Repeat remoteSetup in-case the commands forced us to reset
        if (!(await this.service._remoteSetup(info))) {
          throw new Error("Remote setup failed after processing commands.");
        }
      } finally {
        // Always immediately attempt to push back the local client (now
        // without commands).
        // Note that we don't abort here; if there's a 401 because we've
        // been reassigned, we'll handle it around another engine.
        await this._syncEngine(this.service.clientsEngine);
      }
    }

    // Update engines because it might change what we sync.
    try {
      await this._updateEnabledEngines();
    } catch (ex) {
      this._log.debug("Updating enabled engines failed", ex);
      this.service.errorHandler.checkServerError(ex);
      throw ex;
    }

    await this.service.engineManager.switchAlternatives();

    // If the engines to sync has been specified, we sync in the order specified.
    let enginesToSync;
    if (allowEnginesHint && engineNamesToSync) {
      this._log.info("Syncing specified engines", engineNamesToSync);
      enginesToSync = engineManager
        .get(engineNamesToSync)
        .filter(e => e.enabled);
    } else {
      this._log.info("Syncing all enabled engines.");
      enginesToSync = engineManager.getEnabled();
    }
    try {
      // We don't bother validating engines that failed to sync.
      let enginesToValidate = [];
      for (let engine of enginesToSync) {
        if (engine.shouldSkipSync(why)) {
          this._log.info(`Engine ${engine.name} asked to be skipped`);
          continue;
        }
        // If there's any problems with syncing the engine, report the failure
        if (
          !(await this._syncEngine(engine)) ||
          this.service.status.enforceBackoff
        ) {
          this._log.info("Aborting sync for failure in " + engine.name);
          break;
        }
        enginesToValidate.push(engine);
      }

      // If _syncEngine fails for a 401, we might not have a cluster URL here.
      // If that's the case, break out of this immediately, rather than
      // throwing an exception when trying to fetch metaURL.
      if (!this.service.clusterURL) {
        this._log.debug(
          "Aborting sync, no cluster URL: not uploading new meta/global."
        );
        return;
      }

      // Upload meta/global if any engines changed anything.
      let meta = await this.service.recordManager.get(this.service.metaURL);
      if (meta.isNew || meta.changed) {
        this._log.info("meta/global changed locally: reuploading.");
        try {
          await this.service.uploadMetaGlobal(meta);
          delete meta.isNew;
          delete meta.changed;
        } catch (error) {
          this._log.error(
            "Unable to upload meta/global. Leaving marked as new."
          );
        }
      }

      if (!fastSync) {
        await lazy.Doctor.consult(enginesToValidate);
      }

      // If there were no sync engine failures
      if (this.service.status.service != SYNC_FAILED_PARTIAL) {
        this.service.status.sync = SYNC_SUCCEEDED;
      }

      // Even if there were engine failures, bump lastSync even on partial since
      // it's reflected in the UI (bug 1439777).
      if (
        this.service.status.service == SYNC_FAILED_PARTIAL ||
        this.service.status.service == STATUS_OK
      ) {
        Svc.PrefBranch.setStringPref("lastSync", new Date().toString());
      }
    } finally {
      Svc.PrefBranch.clearUserPref("firstSync");

      let syncTime = ((Date.now() - startTime) / 1000).toFixed(2);
      let dateStr = Utils.formatTimestamp(new Date());
      this._log.info(
        "Sync completed at " + dateStr + " after " + syncTime + " secs."
      );
    }
  },

  // Returns true if sync should proceed.
  // false / no return value means sync should be aborted.
  async _syncEngine(engine) {
    try {
      await engine.sync();
    } catch (e) {
      if (e.status == 401) {
        // Maybe a 401, cluster update perhaps needed?
        // We rely on ErrorHandler observing the sync failure notification to
        // schedule another sync and clear node assignment values.
        // Here we simply want to muffle the exception and return an
        // appropriate value.
        return false;
      }
      // Note that policies.js has already logged info about the exception...
      if (Async.isShutdownException(e)) {
        // Failure due to a shutdown exception should prevent other engines
        // trying to start and immediately failing.
        this._log.info(
          `${engine.name} was interrupted by shutdown; no other engines will sync`
        );
        return false;
      }
    }

    return true;
  },

  async _updateEnabledFromMeta(
    meta,
    numClients,
    engineManager = this.service.engineManager
  ) {
    this._log.info("Updating enabled engines: " + numClients + " clients.");

    if (meta.isNew || !meta.payload.engines) {
      this._log.debug(
        "meta/global isn't new, or is missing engines. Not updating enabled state."
      );
      return;
    }

    // If we're the only client and the server has no data for us
    // (neither enabled *nor* declined engines), just keep our local state.
    // Belt-and-suspenders approach to Bug 615926.
    let hasEnabledEngines = false;
    for (let e in meta.payload.engines) {
      if (e != "clients") {
        hasEnabledEngines = true;
        break;
      }
    }

    let hasDeclinedEngines =
      Array.isArray(meta.payload.declined) && meta.payload.declined.length;

    if (numClients <= 1 && !hasEnabledEngines && !hasDeclinedEngines) {
      this._log.info(
        "One client and neither enabled nor declined engines on server: " +
          "not touching local engine status."
      );
      return;
    }

    this.service._ignorePrefObserver = true;

    let enabled = engineManager.enabledEngineNames;

    let toDecline = new Set();
    let toUndecline = new Set();

    for (let engineName in meta.payload.engines) {
      if (engineName == "clients") {
        // Clients is special.
        continue;
      }
      let index = enabled.indexOf(engineName);
      if (index != -1) {
        // The engine is enabled locally. Nothing to do.
        enabled.splice(index, 1);
        continue;
      }
      let engine = engineManager.get(engineName);
      if (!engine) {
        // The engine doesn't exist locally. Nothing to do.
        continue;
      }

      let attemptedEnable = false;
      // If the engine was enabled remotely, enable it locally.
      if (
        !Svc.PrefBranch.getBoolPref(
          "engineStatusChanged." + engine.prefName,
          false
        )
      ) {
        this._log.trace(
          "Engine " + engineName + " was enabled. Marking as non-declined."
        );
        toUndecline.add(engineName);
        this._log.trace(engineName + " engine was enabled remotely.");
        engine.enabled = true;
        // Note that setting engine.enabled to true might not have worked for
        // the password engine if a master-password is enabled.  However, it's
        // still OK that we added it to undeclined - the user *tried* to enable
        // it remotely - so it still winds up as not being flagged as declined
        // even though it's disabled remotely.
        attemptedEnable = true;
      }

      // If either the engine was disabled locally or enabling the engine
      // failed (see above re master-password) then wipe server data and
      // disable it everywhere.
      if (!engine.enabled) {
        this._log.trace("Wiping data for " + engineName + " engine.");
        await engine.wipeServer();
        delete meta.payload.engines[engineName];
        meta.changed = true; // the new enabled state must propagate
        // We also here mark the engine as declined, because the pref
        // was explicitly changed to false - unless we tried, and failed,
        // to enable it - in which case we leave the declined state alone.
        if (!attemptedEnable) {
          // This will be reflected in meta/global in the next stage.
          this._log.trace(
            "Engine " +
              engineName +
              " was disabled locally. Marking as declined."
          );
          toDecline.add(engineName);
        }
      }
    }

    // Any remaining engines were either enabled locally or disabled remotely.
    for (let engineName of enabled) {
      let engine = engineManager.get(engineName);
      if (
        Svc.PrefBranch.getBoolPref(
          "engineStatusChanged." + engine.prefName,
          false
        )
      ) {
        this._log.trace("The " + engineName + " engine was enabled locally.");
        toUndecline.add(engineName);
      } else {
        this._log.trace("The " + engineName + " engine was disabled remotely.");

        // Don't automatically mark it as declined!
        try {
          engine.enabled = false;
        } catch (e) {
          this._log.trace("Failed to disable engine " + engineName);
        }
      }
    }

    engineManager.decline(toDecline);
    engineManager.undecline(toUndecline);

    for (const pref of Svc.PrefBranch.getChildList("engineStatusChanged.")) {
      Svc.PrefBranch.clearUserPref(pref);
    }
    this.service._ignorePrefObserver = false;
  },

  async _updateEnabledEngines() {
    let meta = await this.service.recordManager.get(this.service.metaURL);
    let numClients = this.service.scheduler.numClients;
    let engineManager = this.service.engineManager;

    await this._updateEnabledFromMeta(meta, numClients, engineManager);
  },
};
Object.freeze(EngineSynchronizer.prototype);
