/* 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/. */

/*
 * Interface for the storage of Form Autofill.
 *
 * The data is stored in JSON format, without indentation and the computed
 * fields, using UTF-8 encoding. With indentation and computed fields applied,
 * the schema would look like this:
 *
 * {
 *   version: 1,
 *   addresses: [
 *     {
 *       guid,                 // 12 characters
 *       version,              // schema version in integer
 *
 *       // address fields
 *       given-name,
 *       additional-name,
 *       family-name,
 *       name,
 *       organization,         // Company
 *       street-address,       // (Multiline)
 *       address-level3,       // Suburb/Sublocality
 *       address-level2,       // City/Town
 *       address-level1,       // Province (Standardized code if possible)
 *       postal-code,
 *       country,              // ISO 3166
 *       tel,                  // Stored in E.164 format
 *       email,
 *
 *       // computed fields (These fields are computed based on the above fields
 *       // and are not allowed to be modified directly.)
 *       given-name,
 *       additional-name,
 *       family-name,
 *       address-line1,
 *       address-line2,
 *       address-line3,
 *       country-name,
 *       tel-country-code,
 *       tel-national,
 *       tel-area-code,
 *       tel-local,
 *       tel-local-prefix,
 *       tel-local-suffix,
 *
 *       // metadata
 *       timeCreated,          // in ms
 *       timeLastUsed,         // in ms
 *       timeLastModified,     // in ms
 *       timesUsed,
 *       _sync: { ... optional sync metadata },
 *       ...unknown fields     // We keep fields we don't understand/expect from other clients
 *                             // to prevent data loss for other clients, we roundtrip them for sync
 *     }
 *   ],
 *   creditCards: [
 *     {
 *       guid,                 // 12 characters
 *       version,              // schema version in integer
 *
 *       // credit card fields
 *       billingAddressGUID,   // An optional GUID of an autofill address record
 *                                which may or may not exist locally.
 *
 *       cc-name,
 *       cc-number,            // will be stored in masked format (************1234)
 *                             // (see details below)
 *       cc-exp-month,
 *       cc-exp-year,          // 2-digit year will be converted to 4 digits
 *                             // upon saving
 *       cc-type,              // Optional card network id (instrument type)
 *
 *       // computed fields (These fields are computed based on the above fields
 *       // and are not allowed to be modified directly.)
 *       cc-given-name,
 *       cc-additional-name,
 *       cc-family-name,
 *       cc-number-encrypted,  // encrypted from the original unmasked "cc-number"
 *                             // (see details below)
 *       cc-exp,
 *
 *       // metadata
 *       timeCreated,          // in ms
 *       timeLastUsed,         // in ms
 *       timeLastModified,     // in ms
 *       timesUsed,
 *       _sync: { ... optional sync metadata },
 *       ...unknown fields     // We keep fields we don't understand/expect from other clients
 *                             // to prevent data loss for other clients, we roundtrip them for sync
 *     }
 *   ]
 * }
 *
 *
 * Encrypt-related Credit Card Fields (cc-number & cc-number-encrypted):
 *
 * When saving or updating a credit-card record, the storage will encrypt the
 * value of "cc-number", store the encrypted number in "cc-number-encrypted"
 * field, and replace "cc-number" field with the masked number. These all happen
 * in "computeFields". We do reverse actions in "_stripComputedFields", which
 * decrypts "cc-number-encrypted", restores it to "cc-number", and deletes
 * "cc-number-encrypted". Therefore, calling "_stripComputedFields" followed by
 * "computeFields" can make sure the encrypt-related fields are up-to-date.
 *
 * In general, you have to decrypt the number by your own outside FormAutofillStorage
 * when necessary. However, you will get the decrypted records when querying
 * data with "rawData=true" to ensure they're ready to sync.
 *
 *
 * Sync Metadata:
 *
 * Records may also have a _sync field, which consists of:
 * {
 *   changeCounter,    // integer - the number of changes made since the last
 *                     // sync.
 *   lastSyncedFields, // object - hashes of the original values for fields
 *                     // changed since the last sync.
 * }
 *
 * Records with such a field have previously been synced. Records without such
 * a field are yet to be synced, so are treated specially in some cases (eg,
 * they don't need a tombstone, de-duping logic treats them as special etc).
 * Records without the field are always considered "dirty" from Sync's POV
 * (meaning they will be synced on the next sync), at which time they will gain
 * this new field.
 */

import { FormAutofill } from "resource://autofill/FormAutofill.sys.mjs";
import { AddressRecord } from "resource://gre/modules/shared/AddressRecord.sys.mjs";

const lazy = {};

ChromeUtils.defineESModuleGetters(lazy, {
  AutofillTelemetry: "resource://gre/modules/shared/AutofillTelemetry.sys.mjs",
  CreditCard: "resource://gre/modules/CreditCard.sys.mjs",
  CreditCardRecord: "resource://gre/modules/shared/CreditCardRecord.sys.mjs",
  FormAutofillNameUtils:
    "resource://gre/modules/shared/FormAutofillNameUtils.sys.mjs",
  FormAutofillUtils: "resource://gre/modules/shared/FormAutofillUtils.sys.mjs",
  OSKeyStore: "resource://gre/modules/OSKeyStore.sys.mjs",
  PhoneNumber: "resource://gre/modules/shared/PhoneNumber.sys.mjs",
});

const CryptoHash = Components.Constructor(
  "@mozilla.org/security/hash;1",
  "nsICryptoHash",
  "initWithString"
);

const STORAGE_SCHEMA_VERSION = 1;

// NOTE: It's likely this number can never change.
// Please talk to the sync team before changing this!
// (And if it did ever change, it must never be "4" due to the reconcile hacks
// below which repairs credit-cards with version=4)
export const ADDRESS_SCHEMA_VERSION = 1;

// Version 2: Bug 1486954 - Encrypt `cc-number`
// Version 3: Bug 1639795 - Update keystore name
// Version 4: (deprecated!!! See Bug 1812235): Bug 1667257 - Do not store `cc-type` field
// Next version should be 5
// NOTE: It's likely this number can never change.
// Please talk to the sync team before changing this!
export const CREDIT_CARD_SCHEMA_VERSION = 3;

const VALID_ADDRESS_FIELDS = [
  "name",
  "organization",
  "street-address",
  "address-level3",
  "address-level2",
  "address-level1",
  "postal-code",
  "country",
  "tel",
  "email",
];

const VALID_ADDRESS_COMPUTED_FIELDS = [
  "country-name",
  ...AddressRecord.NAME_COMPONENTS,
  ...AddressRecord.STREET_ADDRESS_COMPONENTS,
  ...AddressRecord.TEL_COMPONENTS,
];

const VALID_CREDIT_CARD_FIELDS = [
  "billingAddressGUID",
  "cc-name",
  "cc-number",
  "cc-exp-month",
  "cc-exp-year",
  "cc-type",
];

const VALID_CREDIT_CARD_COMPUTED_FIELDS = [
  "cc-given-name",
  "cc-additional-name",
  "cc-family-name",
  "cc-number-encrypted",
  "cc-exp",
];

const INTERNAL_FIELDS = [
  "guid",
  "version",
  "timeCreated",
  "timeLastUsed",
  "timeLastModified",
  "timesUsed",
];

function sha512(string) {
  if (string == null) {
    return null;
  }
  let encoder = new TextEncoder();
  let bytes = encoder.encode(string);
  let hash = new CryptoHash("sha512");
  hash.update(bytes, bytes.length);
  return hash.finish(/* base64 */ true);
}

/**
 * Class that manipulates records in a specified collection.
 *
 * Note that it is responsible for converting incoming data to a consistent
 * format in the storage. For example, computed fields will be transformed to
 * the original fields and 2-digit years will be calculated into 4 digits.
 */
class AutofillRecords {
  /**
   * Creates an AutofillRecords.
   *
   * @param {JSONFile} store
   *        An instance of JSONFile.
   * @param {string} collectionName
   *        A key of "store.data".
   * @param {Array.<string>} validFields
   *        A list containing non-metadata field names.
   * @param {Array.<string>} validComputedFields
   *        A list containing computed field names.
   * @param {number} schemaVersion
   *        The schema version for the new record.
   */
  constructor(
    store,
    collectionName,
    validFields,
    validComputedFields,
    schemaVersion
  ) {
    this.log = FormAutofill.defineLogGetter(
      lazy,
      "AutofillRecords:" + collectionName
    );

    this.VALID_FIELDS = validFields;
    this.VALID_COMPUTED_FIELDS = validComputedFields;

    this._store = store;
    this._collectionName = collectionName;
    this._schemaVersion = schemaVersion;

    this._initialize();

    Services.obs.addObserver(this, "formautofill-storage-changed");
  }

  _initialize() {
    this._initializePromise = Promise.all(
      this._data.map(async (record, index) =>
        this._migrateRecord(record, index)
      )
    ).then(hasChangesArr => {
      let dataHasChanges = hasChangesArr.includes(true);
      if (dataHasChanges) {
        this._store.saveSoon();
      }
    });
  }

  observe(subject, topic, _data) {
    if (topic == "formautofill-storage-changed") {
      let collectionName = subject.wrappedJSObject.collectionName;
      if (collectionName != this._collectionName) {
        return;
      }
      const telemetryType =
        subject.wrappedJSObject.collectionName == "creditCards"
          ? lazy.AutofillTelemetry.CREDIT_CARD
          : lazy.AutofillTelemetry.ADDRESS;
      const count = this._data.filter(entry => !entry.deleted).length;
      lazy.AutofillTelemetry.recordAutofillProfileCount(telemetryType, count);
    }
  }

  /**
   * Gets the schema version number.
   *
   * @returns {number}
   *          The current schema version number.
   */
  get version() {
    return this._schemaVersion;
  }

  /**
   * Gets the data of this collection.
   *
   * @returns {Array}
   *          The data object.
   */
  get _data() {
    return this._getData();
  }

  _getData() {
    return this._store.data[this._collectionName];
  }

  // Ensures that we don't try to apply synced records with newer schema
  // versions. This is a temporary measure to ensure we don't accidentally
  // bump the schema version without a syncing strategy in place (bug 1377204).
  _ensureMatchingVersion(record) {
    if (record.version != this.version) {
      throw new Error(
        `Got unknown record version ${record.version}; want ${this.version}`
      );
    }
  }

  /**
   * Initialize the records in the collection, resolves when the migration completes.
   *
   * @returns {Promise}
   */
  initialize() {
    return this._initializePromise;
  }

  /**
   * Adds a new record.
   *
   * @param {object} record
   *        The new record for saving.
   * @param {object} options
   * @param {boolean} [options.sourceSync = false]
   *        Did sync generate this addition?
   * @returns {Promise<string>}
   *          The GUID of the newly added item..
   */
  async add(record, { sourceSync = false } = {}) {
    let recordToSave = this._clone(record);

    if (sourceSync) {
      // Remove tombstones for incoming items that were changed on another
      // device. Local deletions always lose to avoid data loss.
      let index = this._findIndexByGUID(recordToSave.guid, {
        includeDeleted: true,
      });
      if (index > -1) {
        let existing = this._data[index];
        if (existing.deleted) {
          this._data.splice(index, 1);
        } else {
          throw new Error(`Record ${recordToSave.guid} already exists`);
        }
      }
    } else if (!recordToSave.deleted) {
      this._normalizeRecord(recordToSave);
      // _normalizeRecord shouldn't do any validation (throw) because in the
      // `update` case it is called with partial records whereas
      // `_validateFields` is called with a complete one.
      this._validateFields(recordToSave);

      recordToSave.guid = this._generateGUID();
      recordToSave.version = this.version;

      // Metadata
      let now = Date.now();
      recordToSave.timeCreated = now;
      recordToSave.timeLastModified = now;
      recordToSave.timeLastUsed = 0;
      recordToSave.timesUsed = 0;
    }

    return this._saveRecord(recordToSave, { sourceSync });
  }

  async _saveRecord(record, { sourceSync = false } = {}) {
    if (!record.guid) {
      throw new Error("Record missing GUID");
    }

    let recordToSave;
    if (record.deleted) {
      if (this._findByGUID(record.guid, { includeDeleted: true })) {
        throw new Error("a record with this GUID already exists");
      }
      recordToSave = {
        guid: record.guid,
        timeLastModified: record.timeLastModified || Date.now(),
        deleted: true,
      };
    } else {
      this._ensureMatchingVersion(record);
      recordToSave = record;
      await this.computeFields(recordToSave);
    }

    if (sourceSync) {
      let sync = this._getSyncMetaData(recordToSave, true);
      sync.changeCounter = 0;
    }

    this._data.push(recordToSave);

    this.updateUseCountTelemetry();

    this._store.saveSoon();

    Services.obs.notifyObservers(
      {
        wrappedJSObject: {
          sourceSync,
          guid: record.guid,
          collectionName: this._collectionName,
        },
      },
      "formautofill-storage-changed",
      "add"
    );
    return recordToSave.guid;
  }

  _generateGUID() {
    let guid;
    while (!guid || this._findByGUID(guid)) {
      guid = Services.uuid
        .generateUUID()
        .toString()
        .replace(/[{}-]/g, "")
        .substring(0, 12);
    }
    return guid;
  }

  /**
   * Update the specified record.
   *
   * @param  {string} guid
   *         Indicates which record to update.
   * @param  {object} record
   *         The new record used to overwrite the old one.
   * @param  {Promise<boolean>} [preserveOldProperties = false]
   *         Preserve old record's properties if they don't exist in new record.
   */
  async update(guid, record, preserveOldProperties = false) {
    this.log.debug(`update: ${guid}`);

    let recordFoundIndex = this._findIndexByGUID(guid);
    if (recordFoundIndex == -1) {
      throw new Error("No matching record.");
    }

    // Clone the record before modifying it to avoid exposing incomplete changes.
    let recordFound = this._clone(this._data[recordFoundIndex]);
    await this._stripComputedFields(recordFound);

    let recordToUpdate = this._clone(record);
    this._normalizeRecord(recordToUpdate, true);

    let hasValidField = false;
    for (let field of this.VALID_FIELDS) {
      let oldValue = recordFound[field];
      let newValue = recordToUpdate[field];

      // Resume the old field value in the perserve case
      if (preserveOldProperties && newValue === undefined) {
        newValue = oldValue;
      }

      if (newValue === undefined || newValue === "") {
        delete recordFound[field];
      } else {
        hasValidField = true;
        recordFound[field] = newValue;
      }

      this._maybeStoreLastSyncedField(recordFound, field, oldValue);
    }

    if (!hasValidField) {
      throw new Error("Record contains no valid field.");
    }

    // _normalizeRecord above is called with the `record` argument provided to
    // `update` which may not contain all resulting fields when
    // `preserveOldProperties` is used. This means we need to validate for
    // missing fields after we compose the record (`recordFound`) with the stored
    // record like we do in the loop above.
    this._validateFields(recordFound);

    recordFound.timeLastModified = Date.now();
    let syncMetadata = this._getSyncMetaData(recordFound);
    if (syncMetadata) {
      syncMetadata.changeCounter += 1;
    }

    await this.computeFields(recordFound);
    this._data[recordFoundIndex] = recordFound;

    this._store.saveSoon();

    Services.obs.notifyObservers(
      {
        wrappedJSObject: {
          guid,
          collectionName: this._collectionName,
        },
      },
      "formautofill-storage-changed",
      "update"
    );
  }

  /**
   * Notifies the storage of the use of the specified record, so we can update
   * the metadata accordingly. This does not bump the Sync change counter, since
   * we don't sync `timesUsed` or `timeLastUsed`.
   *
   * @param  {string} guid
   *         Indicates which record to be notified.
   */
  notifyUsed(guid) {
    this.log.debug("notifyUsed:", guid);

    let recordFound = this._findByGUID(guid);
    if (!recordFound) {
      throw new Error("No matching record.");
    }

    recordFound.timesUsed++;
    recordFound.timeLastUsed = Date.now();

    this.updateUseCountTelemetry();

    this._store.saveSoon();
    Services.obs.notifyObservers(
      {
        wrappedJSObject: {
          guid,
          collectionName: this._collectionName,
        },
      },
      "formautofill-storage-changed",
      "notifyUsed"
    );
  }

  updateUseCountTelemetry() {
    const telemetryType =
      this._collectionName == "creditCards"
        ? lazy.AutofillTelemetry.CREDIT_CARD
        : lazy.AutofillTelemetry.ADDRESS;
    let records = this._data.filter(r => !r.deleted);
    lazy.AutofillTelemetry.recordNumberOfUse(telemetryType, records);
  }

  /**
   * Removes the specified record. No error occurs if the record isn't found.
   *
   * @param  {string} guid
   *         Indicates which record to remove.
   * @param  {object} options
   * @param  {boolean} [options.sourceSync = false]
   *         Did Sync generate this removal?
   */
  remove(guid, { sourceSync = false } = {}) {
    this.log.debug("remove:", guid);

    if (sourceSync) {
      this._removeSyncedRecord(guid);
    } else {
      let index = this._findIndexByGUID(guid, { includeDeleted: false });
      if (index == -1) {
        this.log.warn("attempting to remove non-existing entry", guid);
        return;
      }
      let existing = this._data[index];
      if (existing.deleted) {
        return; // already a tombstone - don't touch it.
      }
      let existingSync = this._getSyncMetaData(existing);
      if (existingSync) {
        // existing sync metadata means it has been synced. This means we must
        // leave a tombstone behind.
        this._data[index] = {
          guid,
          timeLastModified: Date.now(),
          deleted: true,
          _sync: existingSync,
        };
        existingSync.changeCounter++;
      } else {
        // If there's no sync meta-data, this record has never been synced, so
        // we can delete it.
        this._data.splice(index, 1);
      }
    }

    this.updateUseCountTelemetry();

    this._store.saveSoon();
    Services.obs.notifyObservers(
      {
        wrappedJSObject: {
          sourceSync,
          guid,
          collectionName: this._collectionName,
        },
      },
      "formautofill-storage-changed",
      "remove"
    );
  }

  /**
   * Returns the record with the specified GUID.
   *
   * @param   {string} guid
   *          Indicates which record to retrieve.
   * @param   {object} options
   * @param   {boolean} [options.rawData = false]
   *          Returns a raw record without modifications and the computed fields
   *          (this includes private fields)
   * @returns {Promise<object>}
   *          A clone of the record.
   */
  async get(guid, { rawData = false } = {}) {
    this.log.debug(`get: ${guid}`);

    let recordFound = this._findByGUID(guid);
    if (!recordFound) {
      return null;
    }

    // The record is cloned to avoid accidental modifications from outside.
    let clonedRecord = this._cloneAndCleanUp(recordFound);
    if (rawData) {
      // The *-name fields, previously listed in VALID_FIELDS, have been moved to
      // COMPUTED_FIELDS. By default, the sync payload includes only those fields in VALID_FIELDS.
      // Excluding *-name fields from the sync payload would prevent older devices from
      // synchronizing with newer devices. To maintain backward compatibility, keep those deprecated
      // ields in the payload, ensuring that older devices can still sync with newer devices.
      const fieldsToKeep = AddressRecord.NAME_COMPONENTS;
      await this._stripComputedFields(clonedRecord, fieldsToKeep);
    } else {
      this._recordReadProcessor(clonedRecord);
    }
    return clonedRecord;
  }

  /**
   * Returns all records.
   *
   * @param   {object} options
   * @param   {boolean} [options.rawData = false]
   *          Returns raw records without modifications and the computed fields.
   * @param   {boolean} [options.includeDeleted = false]
   *          Also return any tombstone records.
   * @returns {Promise<Array.<object>>}
   *          An array containing clones of all records.
   */
  async getAll({ rawData = false, includeDeleted = false } = {}) {
    this.log.debug(`getAll. includeDeleted = ${includeDeleted}`);

    let records = this._data.filter(r => !r.deleted || includeDeleted);
    // Records are cloned to avoid accidental modifications from outside.
    let clonedRecords = records.map(r => this._cloneAndCleanUp(r));
    await Promise.all(
      clonedRecords.map(async record => {
        if (rawData) {
          const fieldsToKeep = AddressRecord.NAME_COMPONENTS;
          await this._stripComputedFields(record, fieldsToKeep);
        } else {
          this._recordReadProcessor(record);
        }
      })
    );
    return clonedRecords;
  }

  /**
   * Returns true if the data set is empty. If the `includeDeleted` option is set to true,
   * it will also consider items that are marked as deleted.
   *
   * @param   {object}  [options={}] options
   * @param   {boolean} [options.includeDeleted = false]
   *                    Indicates whether to include deleted items in the check.
   * @returns {boolean} Returns `true` if the data set is empty, otherwise `false`.
   */
  isEmpty({ includeDeleted = false } = {}) {
    return !this._data.find(r => !r.deleted || includeDeleted);
  }

  /**
   * Return all saved field names in the collection.
   *
   * @returns {Promise<Set>} Set containing saved field names.
   */
  async getSavedFieldNames() {
    this.log.debug("getSavedFieldNames");

    let records = this._data.filter(r => !r.deleted);
    records
      .map(record => this._cloneAndCleanUp(record))
      .forEach(record => this._recordReadProcessor(record));

    let fieldNames = new Set();
    for (let record of records) {
      for (let fieldName of Object.keys(record)) {
        if (INTERNAL_FIELDS.includes(fieldName) || !record[fieldName]) {
          continue;
        }
        fieldNames.add(fieldName);
      }
    }

    return fieldNames;
  }

  /**
   * Functions intended to be used in the support of Sync.
   */

  /**
   * Stores a hash of the last synced value for a field in a locally updated
   * record. We use this value to rebuild the shared parent, or base, when
   * reconciling incoming records that may have changed on another device.
   *
   * Storing the hash of the values that we last wrote to the Sync server lets
   * us determine if a remote change conflicts with a local change. If the
   * hashes for the base, current local value, and remote value all differ, we
   * have a conflict.
   *
   * These fields are not themselves synced, and will be removed locally as
   * soon as we have successfully written the record to the Sync server - so
   * it is expected they will not remain for long, as changes which cause a
   * last synced field to be written will itself cause a sync.
   *
   * We also skip this for updates made by Sync, for internal fields, for
   * records that haven't been uploaded yet, and for fields which have already
   * been changed since the last sync.
   *
   * @param   {object} record
   *          The updated local record.
   * @param   {string} field
   *          The field name.
   * @param   {string} lastSyncedValue
   *          The last synced field value.
   */
  _maybeStoreLastSyncedField(record, field, lastSyncedValue) {
    let sync = this._getSyncMetaData(record);
    if (!sync) {
      // The record hasn't been uploaded yet, so we can't end up with merge
      // conflicts.
      return;
    }
    let alreadyChanged = field in sync.lastSyncedFields;
    if (alreadyChanged) {
      // This field was already changed multiple times since the last sync.
      return;
    }
    let newValue = record[field];
    if (lastSyncedValue != newValue) {
      sync.lastSyncedFields[field] = sha512(lastSyncedValue);
    }
  }

  /**
   * Attempts a three-way merge between a changed local record, an incoming
   * remote record, and the shared parent that we synthesize from the last
   * synced fields - see _maybeStoreLastSyncedField.
   *
   * @param   {object} strippedLocalRecord
   *          The changed local record, currently in storage. Computed fields
   *          are stripped.
   * @param   {object} remoteRecord
   *          The remote record.
   * @returns {object | null}
   *          The merged record, or `null` if there are conflicts and the
   *          records can't be merged.
   */
  _mergeSyncedRecords(strippedLocalRecord, remoteRecord) {
    let sync = this._getSyncMetaData(strippedLocalRecord, true);

    // Copy all internal fields from the remote record. We'll update their
    // values in `_replaceRecordAt`.
    let mergedRecord = {};
    for (let field of INTERNAL_FIELDS) {
      if (remoteRecord[field] != null) {
        mergedRecord[field] = remoteRecord[field];
      }
    }

    for (let field of this.VALID_FIELDS) {
      let isLocalSame = false;
      let isRemoteSame = false;
      if (field in sync.lastSyncedFields) {
        // If the field has changed since the last sync, compare hashes to
        // determine if the local and remote values are different. Hashing is
        // expensive, but we don't expect this to happen frequently.
        let lastSyncedValue = sync.lastSyncedFields[field];
        isLocalSame = lastSyncedValue == sha512(strippedLocalRecord[field]);
        isRemoteSame = lastSyncedValue == sha512(remoteRecord[field]);
      } else {
        // Otherwise, if the field hasn't changed since the last sync, we know
        // it's the same locally.
        isLocalSame = true;
        isRemoteSame = strippedLocalRecord[field] == remoteRecord[field];
      }

      let value;
      if (isLocalSame && isRemoteSame) {
        // Local and remote are the same; doesn't matter which one we pick.
        value = strippedLocalRecord[field];
      } else if (isLocalSame && !isRemoteSame) {
        value = remoteRecord[field];
      } else if (!isLocalSame && isRemoteSame) {
        // We don't need to bump the change counter when taking the local
        // change, because the counter must already be > 0 if we're attempting
        // a three-way merge.
        value = strippedLocalRecord[field];
      } else if (strippedLocalRecord[field] == remoteRecord[field]) {
        // Shared parent doesn't match either local or remote, but the values
        // are identical, so there's no conflict.
        value = strippedLocalRecord[field];
      } else {
        // Both local and remote changed to different values. We'll need to fork
        // the local record to resolve the conflict.
        return null;
      }

      if (value != null) {
        mergedRecord[field] = value;
      }
    }

    // When merging records, we shouldn't persist any unknown fields on the local and instead
    // rely on the remote for unknown fields, so we filter the fields we know and keep the rest
    Object.keys(remoteRecord)
      .filter(
        key =>
          !this.VALID_FIELDS.includes(key) && !INTERNAL_FIELDS.includes(key)
      )
      .forEach(key => (mergedRecord[key] = remoteRecord[key]));
    return mergedRecord;
  }

  /**
   * Replaces a local record with a remote or merged record, copying internal
   * fields and Sync metadata.
   *
   * @param   {number} index
   * @param   {object} remoteRecord
   * @param   {object} options
   * @param   {Promise<boolean>} [options.keepSyncMetadata = false]
   *          Should we copy Sync metadata? This is true if `remoteRecord` is a
   *          merged record with local changes that we need to upload. Passing
   *          `keepSyncMetadata` retains the record's change counter and
   *          last synced fields, so that we don't clobber the local change if
   *          the sync is interrupted after the record is merged, but before
   *          it's uploaded.
   */
  async _replaceRecordAt(
    index,
    remoteRecord,
    { keepSyncMetadata = false } = {}
  ) {
    let localRecord = this._data[index];
    let newRecord = this._clone(remoteRecord);

    await this._stripComputedFields(newRecord);

    this._data[index] = newRecord;

    if (keepSyncMetadata) {
      // It's safe to move the Sync metadata from the old record to the new
      // record, since we always clone records when we return them, and we
      // never hand out references to the metadata object via public methods.
      newRecord._sync = localRecord._sync;
    } else {
      // As a side effect, `_getSyncMetaData` marks the record as syncing if the
      // existing `localRecord` is a dupe of `remoteRecord`, and we're replacing
      // local with remote.
      let sync = this._getSyncMetaData(newRecord, true);
      sync.changeCounter = 0;
    }

    if (
      !newRecord.timeCreated ||
      localRecord.timeCreated < newRecord.timeCreated
    ) {
      newRecord.timeCreated = localRecord.timeCreated;
    }

    if (
      !newRecord.timeLastModified ||
      localRecord.timeLastModified > newRecord.timeLastModified
    ) {
      newRecord.timeLastModified = localRecord.timeLastModified;
    }

    // Copy local-only fields from the existing local record.
    for (let field of ["timeLastUsed", "timesUsed"]) {
      if (localRecord[field] != null) {
        newRecord[field] = localRecord[field];
      }
    }

    await this.computeFields(newRecord);
  }

  /**
   * Clones a local record, giving the clone a new GUID and Sync metadata. The
   * original record remains unchanged in storage.
   *
   * @param   {object} strippedLocalRecord
   *          The local record. Computed fields are stripped.
   * @returns {string}
   *          A clone of the local record with a new GUID.
   */
  async _forkLocalRecord(strippedLocalRecord) {
    let forkedLocalRecord = this._cloneAndCleanUp(strippedLocalRecord);
    forkedLocalRecord.guid = this._generateGUID();

    // Give the record fresh Sync metadata and bump its change counter as a
    // side effect. This also excludes the forked record from de-duping on the
    // next sync, if the current sync is interrupted before the record can be
    // uploaded.
    this._getSyncMetaData(forkedLocalRecord, true);

    await this.computeFields(forkedLocalRecord);
    this._data.push(forkedLocalRecord);

    return forkedLocalRecord;
  }

  /**
   * Reconciles an incoming remote record into the matching local record. This
   * method is only used by Sync; other callers should use `merge`.
   *
   * @param   {object} remoteRecord
   *          The incoming record. `remoteRecord` must not be a tombstone, and
   *          must have a matching local record with the same GUID. Use
   *          `add` to insert remote records that don't exist locally, and
   *          `remove` to apply remote tombstones.
   * @returns {Promise<object>}
   *          A `{forkedGUID}` tuple. `forkedGUID` is `null` if the merge
   *          succeeded without conflicts, or a new GUID referencing the
   *          existing locally modified record if the conflicts could not be
   *          resolved.
   */
  async reconcile(remoteRecord) {
    this._ensureMatchingVersion(remoteRecord);
    if (remoteRecord.deleted) {
      throw new Error(`Can't reconcile tombstone ${remoteRecord.guid}`);
    }

    let localIndex = this._findIndexByGUID(remoteRecord.guid);
    if (localIndex < 0) {
      throw new Error(`Record ${remoteRecord.guid} not found`);
    }

    let localRecord = this._data[localIndex];
    let sync = this._getSyncMetaData(localRecord, true);

    let forkedGUID = null;

    // NOTE: This implies a credit-card - so it's critical ADDRESS_SCHEMA_VERSION
    // never equals 4 while this code exists!
    let requiresForceUpdate =
      localRecord.version != remoteRecord.version && remoteRecord.version == 4;

    if (requiresForceUpdate) {
      // Another desktop device that is still using version=4 has created or
      // modified a remote record. Here we downgrade it to version=3 so we can
      // treat it normally, then cause it to be re-uploaded so other desktop
      // or mobile devices can still see it.
      // That device still using version=4 *will* again see it, and again
      // upgrade it, but thankfully that 3->4 migration doesn't force a reupload
      // of all records, or we'd be going back and forward on every sync.
      // Once that version=4 device gets updated to roll back to version=3, it
      // will then yet again re-upload it, this time with version=3, but the
      // content will be the same here, so everything should work out in the end.
      //
      // If we just ignored this incoming record, it would remain on the server
      // with version=4. If the device that wrote that went away (ie, never
      // synced again) nothing would ever repair it back to 3, which would
      // be bad because mobile would remain broken until the user edited the
      // card somewhere.
      remoteRecord = await this._computeMigratedRecord(remoteRecord);
    }
    if (sync.changeCounter === 0) {
      // Local not modified. Replace local with remote.
      await this._replaceRecordAt(localIndex, remoteRecord, {
        keepSyncMetadata: false,
      });
    } else {
      let strippedLocalRecord = this._clone(localRecord);
      await this._stripComputedFields(strippedLocalRecord);

      let mergedRecord = this._mergeSyncedRecords(
        strippedLocalRecord,
        remoteRecord
      );
      if (mergedRecord) {
        // Local and remote modified, but we were able to merge. Replace the
        // local record with the merged record.
        await this._replaceRecordAt(localIndex, mergedRecord, {
          keepSyncMetadata: true,
        });
      } else {
        // Merge conflict. Fork the local record, then replace the original
        // with the merged record.
        let forkedLocalRecord = await this._forkLocalRecord(
          strippedLocalRecord
        );
        forkedGUID = forkedLocalRecord.guid;
        await this._replaceRecordAt(localIndex, remoteRecord, {
          keepSyncMetadata: false,
        });
      }
    }

    if (requiresForceUpdate) {
      // The incoming record was version=4 and we want to re-upload it as version=3.
      // We need to reach directly into self._data[] so we can poke at the
      // sync metadata directly.
      let indexToUpdate = this._findIndexByGUID(remoteRecord.guid);
      let toUpdate = this._data[indexToUpdate];
      this._getSyncMetaData(toUpdate, true).changeCounter += 1;
      this.log.info(
        `Flagging record ${toUpdate.guid} for re-upload after record version downgrade`
      );
    }

    this._store.saveSoon();
    Services.obs.notifyObservers(
      {
        wrappedJSObject: {
          sourceSync: true,
          guid: remoteRecord.guid,
          forkedGUID,
          collectionName: this._collectionName,
        },
      },
      "formautofill-storage-changed",
      "reconcile"
    );

    return { forkedGUID };
  }

  _removeSyncedRecord(guid) {
    let index = this._findIndexByGUID(guid, { includeDeleted: true });
    if (index == -1) {
      // Removing a record we don't know about. It may have been synced and
      // removed by another device before we saw it. Store the tombstone in
      // case the server is later wiped and we need to reupload everything.
      let tombstone = {
        guid,
        timeLastModified: Date.now(),
        deleted: true,
      };

      let sync = this._getSyncMetaData(tombstone, true);
      sync.changeCounter = 0;
      this._data.push(tombstone);
      return;
    }

    let existing = this._data[index];
    let sync = this._getSyncMetaData(existing, true);
    if (sync.changeCounter > 0) {
      // Deleting a record with unsynced local changes. To avoid potential
      // data loss, we ignore the deletion in favor of the changed record.
      this.log.info(
        "Ignoring deletion for record with local changes",
        existing
      );
      return;
    }

    if (existing.deleted) {
      this.log.info("Ignoring deletion for tombstone", existing);
      return;
    }

    // Removing a record that's not changed locally, and that's not already
    // deleted. Replace the record with a synced tombstone.
    this._data[index] = {
      guid,
      timeLastModified: Date.now(),
      deleted: true,
      _sync: sync,
    };
  }

  /**
   * Provide an object that describes the changes to sync.
   *
   * This is called at the start of the sync process to determine what needs
   * to be updated on the server. As the server is updated, sync will update
   * entries in the returned object, and when sync is complete it will pass
   * the object to pushSyncChanges, which will apply the changes to the store.
   *
   * @returns {object}
   *          An object describing the changes to sync.
   */
  pullSyncChanges() {
    let changes = {};

    let profiles = this._data;
    for (let profile of profiles) {
      let sync = this._getSyncMetaData(profile, true);
      if (sync.changeCounter < 1) {
        if (sync.changeCounter != 0) {
          this.log.error("negative change counter", profile);
        }
        continue;
      }
      changes[profile.guid] = {
        profile,
        counter: sync.changeCounter,
        modified: profile.timeLastModified,
        synced: false,
      };
    }
    this._store.saveSoon();

    return changes;
  }

  /**
   * Apply the metadata changes made by Sync.
   *
   * This is called with metadata about what was synced - see pullSyncChanges.
   *
   * @param {object} changes
   *        The possibly modified object obtained via pullSyncChanges.
   */
  pushSyncChanges(changes) {
    for (let [guid, { counter, synced }] of Object.entries(changes)) {
      if (!synced) {
        continue;
      }
      let recordFound = this._findByGUID(guid, { includeDeleted: true });
      if (!recordFound) {
        this.log.warn("No profile found to persist changes for guid " + guid);
        continue;
      }
      let sync = this._getSyncMetaData(recordFound, true);
      sync.changeCounter = Math.max(0, sync.changeCounter - counter);
      if (sync.changeCounter === 0) {
        // Clear the shared parent fields once we've uploaded all pending
        // changes, since the server now matches what we have locally.
        sync.lastSyncedFields = {};
      }
    }
    this._store.saveSoon();
  }

  /**
   * Reset all sync metadata for all items.
   *
   * This is called when Sync is disconnected from this device. All sync
   * metadata for all items is removed.
   */
  resetSync() {
    for (let record of this._data) {
      delete record._sync;
    }
    // XXX - we should probably also delete all tombstones?
    this.log.info("All sync metadata was reset");
  }

  /**
   * Changes the GUID of an item. This should be called only by Sync. There
   * must be an existing record with oldID and it must never have been synced
   * or an error will be thrown. There must be no existing record with newID.
   *
   * No tombstone will be created for the old GUID - we check it hasn't
   * been synced, so no tombstone is necessary.
   *
   * @param   {string} oldID
   *          GUID of the existing item to change the GUID of.
   * @param   {string} newID
   *          The new GUID for the item.
   */
  changeGUID(oldID, newID) {
    this.log.debug("changeGUID: ", oldID, newID);
    if (oldID == newID) {
      throw new Error("changeGUID: old and new IDs are the same");
    }
    if (this._findIndexByGUID(newID) >= 0) {
      throw new Error("changeGUID: record with destination id exists already");
    }

    let index = this._findIndexByGUID(oldID);
    let profile = this._data[index];
    if (!profile) {
      throw new Error("changeGUID: no source record");
    }
    if (this._getSyncMetaData(profile)) {
      throw new Error("changeGUID: existing record has already been synced");
    }

    profile.guid = newID;

    this._store.saveSoon();
  }

  // Used to get, and optionally create, sync metadata. Brand new records will
  // *not* have sync meta-data - it will be created when they are first
  // synced.
  _getSyncMetaData(record, forceCreate = false) {
    if (!record._sync && forceCreate) {
      // create default metadata and indicate we need to save.
      record._sync = {
        changeCounter: 1,
        lastSyncedFields: {},
      };
      this._store.saveSoon();
    }
    return record._sync;
  }

  /**
   * Finds a local record with matching common fields and a different GUID.
   * Sync uses this method to find and update unsynced local records with
   * fields that match incoming remote records. This avoids creating
   * duplicate profiles with the same information.
   *
   * @param   {object} remoteRecord
   *          The remote record.
   * @returns {Promise<string|null>}
   *          The GUID of the matching local record, or `null` if no records
   *          match.
   */
  async findDuplicateGUID(remoteRecord) {
    if (!remoteRecord.guid) {
      throw new Error("Record missing GUID");
    }
    this._ensureMatchingVersion(remoteRecord);
    if (remoteRecord.deleted) {
      // Tombstones don't carry enough info to de-dupe, and we should have
      // handled them separately when applying the record.
      throw new Error("Tombstones can't have duplicates");
    }
    let localRecords = this._data;
    for (let localRecord of localRecords) {
      if (localRecord.deleted) {
        continue;
      }
      if (localRecord.guid == remoteRecord.guid) {
        throw new Error(`Record ${remoteRecord.guid} already exists`);
      }
      if (this._getSyncMetaData(localRecord)) {
        // This local record has already been uploaded, so it can't be a dupe of
        // another incoming item.
        continue;
      }

      // Ignore computed fields when matching records as they aren't synced at all.
      let strippedLocalRecord = this._clone(localRecord);
      await this._stripComputedFields(strippedLocalRecord);

      let keys = new Set(Object.keys(remoteRecord));
      for (let key of Object.keys(strippedLocalRecord)) {
        keys.add(key);
      }
      // Ignore internal fields when matching records. Internal fields are synced,
      // but almost certainly have different values than the local record, and
      // we'll update them in `reconcile`.
      for (let field of INTERNAL_FIELDS) {
        keys.delete(field);
      }
      if (!keys.size) {
        // This shouldn't ever happen; a valid record will always have fields
        // that aren't computed or internal. Sync can't do anything about that,
        // so we ignore the dubious local record instead of throwing.
        continue;
      }
      let same = true;
      for (let key of keys) {
        // For now, we ensure that both (or neither) records have the field
        // with matching values. This doesn't account for the version yet
        // (bug 1377204).
        same =
          key in strippedLocalRecord == key in remoteRecord &&
          strippedLocalRecord[key] == remoteRecord[key];
        if (!same) {
          break;
        }
      }
      if (same) {
        return strippedLocalRecord.guid;
      }
    }
    return null;
  }

  /**
   * Internal helper functions.
   */

  _clone(record) {
    return Object.assign({}, record);
  }

  _cloneAndCleanUp(record) {
    let result = {};
    for (let key in record) {
      // Do not expose hidden fields and fields with empty value (mainly used
      // as placeholders of the computed fields).
      if (!key.startsWith("_") && record[key] !== "") {
        result[key] = record[key];
      }
    }
    return result;
  }

  _findByGUID(guid, { includeDeleted = false } = {}) {
    let found = this._findIndexByGUID(guid, { includeDeleted });
    return found < 0 ? undefined : this._data[found];
  }

  _findIndexByGUID(guid, { includeDeleted = false } = {}) {
    return this._data.findIndex(record => {
      return record.guid == guid && (!record.deleted || includeDeleted);
    });
  }

  async _migrateRecord(record, index) {
    let hasChanges = false;

    if (record.deleted) {
      return hasChanges;
    }

    if (!record.version || isNaN(record.version) || record.version < 1) {
      this.log.warn("Invalid record version:", record.version);

      // Force to run the migration.
      record.version = 0;
    }

    if (this._isMigrationNeeded(record)) {
      hasChanges = true;

      record = await this._computeMigratedRecord(record);

      if (record.deleted) {
        // record is deleted by _computeMigratedRecord(),
        // go ahead and put it in the store.
        this._data[index] = record;
        return hasChanges;
      }

      // Compute the computed fields before putting it to store.
      await this.computeFields(record);
      this._data[index] = record;

      return hasChanges;
    }

    const originalNumFields = Object.keys(record).length;
    await this.computeFields(record);
    const hasNewComputedFields =
      Object.keys(record).length != originalNumFields;

    hasChanges |= hasNewComputedFields;
    return hasChanges;
  }

  _normalizeRecord(record, preserveEmptyFields = false) {
    this._normalizeFields(record);

    for (const key in record) {
      if (!this.VALID_FIELDS.includes(key)) {
        // Though we allow unknown fields, certain fields are still protected
        // from being changed
        if (INTERNAL_FIELDS.includes(key)) {
          throw new Error(`"${key}" is not a valid field.`);
        } else {
          // We shouldn't try to normalize unknown fields. We'll just roundtrip them
          this.log.warn(`${key} is not a known field. Skipping normalization.`);
          continue;
        }
      }
      if (typeof record[key] !== "string" && typeof record[key] !== "number") {
        throw new Error(
          `"${key}" contains invalid data type: ${typeof record[key]}`
        );
      }
      if (!preserveEmptyFields && record[key] === "") {
        delete record[key];
      }
    }

    const keys = Object.keys(record);
    // By default we ensure there is always a country field, so if this record
    // doesn't contain other fields, this is an empty record
    if (!keys.length || (keys.length == 1 && keys[0] == "country")) {
      throw new Error("Record contains no valid field.");
    }
  }

  /**
   * Unconditionally remove all data and tombstones for this collection.
   */
  removeAll({ sourceSync = false } = {}) {
    this._store.data[this._collectionName] = [];
    this._store.saveSoon();
    Services.obs.notifyObservers(
      {
        wrappedJSObject: {
          sourceSync,
          collectionName: this._collectionName,
        },
      },
      "formautofill-storage-changed",
      "removeAll"
    );
  }

  _isMigrationNeeded(record) {
    return record.version < this.version;
  }

  /**
   * Strip the computed fields based on the record version.
   *
   * @param   {object} record      The record to migrate
   * @returns {object}             Migrated record.
   *                               Record is always cloned, with version updated,
   *                               with computed fields stripped.
   *                               Could be a tombstone record, if the record
   *                               should be discorded.
   */
  async _computeMigratedRecord(record) {
    if (!record.deleted) {
      record = this._clone(record);
      await this._stripComputedFields(record);
      record.version = this.version;
    }
    return record;
  }

  async _stripComputedFields(record, fieldsToKeep = []) {
    for (const field of this.VALID_COMPUTED_FIELDS) {
      if (fieldsToKeep.includes(field)) {
        continue;
      }
      delete record[field];
    }
  }

  // An interface to be inherited.
  _recordReadProcessor(_record) {}

  // An interface to be inherited.
  async computeFields(_record) {}

  /**
   * An interface to be inherited to mutate the argument to normalize it.
   *
   * @param {object} _partialRecord containing the record passed by the consumer of
   *                               storage and in the case of `update` with
   *                               `preserveOldProperties` will only include the
   *                               properties that the user is changing so the
   *                               lack of a field doesn't mean that the record
   *                               won't have that field.
   */
  _normalizeFields(_partialRecord) {}

  /**
   * An interface to be inherited to validate that the complete record is
   * consistent and isn't missing required fields. Overrides should throw for
   * invalid records.
   *
   * @param {object} _record containing the complete record that would be stored
   *                        if this doesn't throw due to an error.
   * @throws
   */
  _validateFields(_record) {}

  // An interface to be inherited.
  migrateRemoteRecord(_remoteRecord) {}
}

export class AddressesBase extends AutofillRecords {
  constructor(store) {
    super(
      store,
      "addresses",
      VALID_ADDRESS_FIELDS,
      VALID_ADDRESS_COMPUTED_FIELDS,
      ADDRESS_SCHEMA_VERSION
    );
  }

  _recordReadProcessor(address) {
    if (address.country && !FormAutofill.countries.has(address.country)) {
      delete address.country;
      delete address["country-name"];
    }
  }

  _isMigrationNeeded(record) {
    if (super._isMigrationNeeded(record)) {
      return true;
    }

    if (
      !record.name &&
      (record["given-name"] ||
        record["additional-name"] ||
        record["family-name"])
    ) {
      return true;
    }
    return false;
  }

  async _computeMigratedRecord(address) {
    // Bug 1836438 - `name` field was moved from computed fields to valid fields.
    if (
      !address.name &&
      (address["given-name"] ||
        address["additional-name"] ||
        address["family-name"])
    ) {
      address.name = lazy.FormAutofillNameUtils.joinNameParts({
        given: address["given-name"] ?? "",
        middle: address["additional-name"] ?? "",
        family: address["family-name"] ?? "",
      });
    }

    return super._computeMigratedRecord(address);
  }

  async computeFields(address) {
    // NOTE: Remember to bump the schema version number if any of the existing
    //       computing algorithm changes. (No need to bump when just adding new
    //       computed fields.)

    // NOTE: Computed fields should be always present in the storage no matter
    //       it's empty or not.

    if (!address.deleted) {
      AddressRecord.computeFields(address);
    }
  }

  _normalizeFields(address) {
    this._normalizeCountryFields(address);
    this._normalizeNameFields(address);
    this._normalizeAddressFields(address);
    this._normalizeTelFields(address);
  }

  _normalizeNameFields(address) {
    if (
      !address.name &&
      (address["given-name"] ||
        address["additional-name"] ||
        address["family-name"])
    ) {
      address.name = lazy.FormAutofillNameUtils.joinNameParts({
        given: address["given-name"] ?? "",
        middle: address["additional-name"] ?? "",
        family: address["family-name"] ?? "",
      });
    }

    delete address["given-name"];
    delete address["additional-name"];
    delete address["family-name"];
  }

  _normalizeAddressFields(address) {
    if (AddressRecord.STREET_ADDRESS_COMPONENTS.some(c => !!address[c])) {
      // Treat "street-address" as "address-line1" if it contains only one line
      // and "address-line1" is omitted.
      if (
        !address["address-line1"] &&
        address["street-address"] &&
        !address["street-address"].includes("\n")
      ) {
        address["address-line1"] = address["street-address"];
        delete address["street-address"];
      }

      // Concatenate "address-line*" if "street-address" is omitted.
      if (!address["street-address"]) {
        address["street-address"] = AddressRecord.STREET_ADDRESS_COMPONENTS.map(
          c => address[c]
        )
          .join("\n")
          .replace(/\n+$/, "");
      }
    }
    AddressRecord.STREET_ADDRESS_COMPONENTS.forEach(c => delete address[c]);
  }

  _normalizeCountryFields(address) {
    // When we can't identify the country code, it is possible because that the region exists
    // in regionNames.properties but not in libaddressinput.
    const country =
      lazy.FormAutofillUtils.identifyCountryCode(
        address.country || address["country-name"]
      ) || address.country;

    // Only values included in the region list will be saved.
    let hasLocalizedName = false;
    try {
      if (country) {
        let localizedName = Services.intl.getRegionDisplayNames(undefined, [
          country,
        ]);
        hasLocalizedName = localizedName != country;
      }
    } catch (e) {}

    if (country && hasLocalizedName) {
      address.country = country;
    } else {
      address.country = FormAutofill.DEFAULT_REGION;
    }

    delete address["country-name"];
  }

  _normalizeTelFields(address) {
    if (address.tel || AddressRecord.TEL_COMPONENTS.some(c => !!address[c])) {
      lazy.FormAutofillUtils.compressTel(address);

      let possibleRegion = address.country || FormAutofill.DEFAULT_REGION;
      let tel = lazy.PhoneNumber.Parse(address.tel, possibleRegion);

      if (tel && tel.internationalNumber) {
        // Force to save numbers in E.164 format if parse success.
        address.tel = tel.internationalNumber;
      }
    }
    AddressRecord.TEL_COMPONENTS.forEach(c => delete address[c]);
  }

  /**
   * Migrate the remote record to the expected format.
   *
   * @param {object} remoteRecord The remote record.
   */
  migrateRemoteRecord(remoteRecord) {
    // When a remote record lacks the `name` field but includes any `*-name` fields, we can
    // assume that the record originates from an older device. This is because even if an older
    // device pulls the `name` field from a newer record from the sync server, the `name` field,
    // being a computed field for an older device, will always be stripped.

    // If the remote record comes from an older device, we compare the `*-name` fields in the
    // remote record with those in the corresponding local record. If the values of the `*-name`
    // fields differ, it indicates that the remote record has updated these fields. If the
    // values are the same, we replace the name field of the remote record with the local
    // name field to ensure the completeness of the name field when reconciling.
    //
    // Here is an example:
    // Assume the local record is {"name": "Mr. John Doe"}. If an updated remote record
    // has {"given-name": "John", "family-name": "Doe"}, we will NOT join the `*-name` fields
    // and replace the local `name` field with "John Doe". This allows us to retain the complete
    // name - "Mr. John Doe".
    // However, if the updated remote record has {"given-name": "Jane", "family-name": "Poe"},
    // we will rebuild it and replace the local `name` field with "Jane Poe".
    if (
      !("name" in remoteRecord) &&
      AddressRecord.NAME_COMPONENTS.some(c => c in remoteRecord)
    ) {
      const localRecord = this._findByGUID(remoteRecord.guid);
      if (
        localRecord &&
        AddressRecord.NAME_COMPONENTS.every(
          c => remoteRecord[c] == localRecord[c]
        )
      ) {
        remoteRecord.name = localRecord.name;
      } else {
        remoteRecord.name = lazy.FormAutofillNameUtils.joinNameParts({
          given: remoteRecord["given-name"],
          middle: remoteRecord["additional-name"],
          family: remoteRecord["family-name"],
        });
      }
    }

    // To enable new devices to sync name field changes with older devices, we still
    // include the computed *-name fields in the sync payload while uploading.
    // This also means that the incoming remote record will also contain *-name fields.
    // However, since the autofill storage does not expect remote records to contain
    // computed fields while merging, we remove them from the remote record.
    AddressRecord.NAME_COMPONENTS.forEach(f => delete remoteRecord[f]);
  }
}

export class CreditCardsBase extends AutofillRecords {
  constructor(store) {
    super(
      store,
      "creditCards",
      VALID_CREDIT_CARD_FIELDS,
      VALID_CREDIT_CARD_COMPUTED_FIELDS,
      CREDIT_CARD_SCHEMA_VERSION
    );
  }

  async computeFields(creditCard) {
    // NOTE: Remember to bump the schema version number if any of the existing
    //       computing algorithm changes. (No need to bump when just adding new
    //       computed fields.)

    // NOTE: Computed fields should be always present in the storage no matter
    //       it's empty or not.

    let hasNewComputedFields = false;

    if (creditCard.deleted) {
      return hasNewComputedFields;
    }

    let type = lazy.CreditCard.getType(creditCard["cc-number"]);
    if (type) {
      creditCard["cc-type"] = type;
    }

    // Compute split names
    if (!("cc-given-name" in creditCard)) {
      const nameParts = lazy.FormAutofillNameUtils.splitName(
        creditCard["cc-name"]
      );
      creditCard["cc-given-name"] = nameParts.given;
      creditCard["cc-additional-name"] = nameParts.middle;
      creditCard["cc-family-name"] = nameParts.family;
      hasNewComputedFields = true;
    }

    // Compute credit card expiration date
    if (!("cc-exp" in creditCard)) {
      if (creditCard["cc-exp-month"] && creditCard["cc-exp-year"]) {
        creditCard["cc-exp"] =
          String(creditCard["cc-exp-year"]) +
          "-" +
          String(creditCard["cc-exp-month"]).padStart(2, "0");
      } else {
        creditCard["cc-exp"] = "";
      }
      hasNewComputedFields = true;
    }

    // Encrypt credit card number
    await this._encryptNumber(creditCard);

    return hasNewComputedFields;
  }

  async _encryptNumber(_creditCard) {
    throw Components.Exception("", Cr.NS_ERROR_NOT_IMPLEMENTED);
  }

  _isMigrationNeeded(record) {
    return (
      // version 4 is deprecated and is rolled back to version 3
      record.version == 4 || record.version < this.version
    );
  }

  async _computeMigratedRecord(creditCard) {
    if (creditCard.version <= 2) {
      if (creditCard["cc-number-encrypted"]) {
        // We cannot decrypt the data, so silently remove the record for
        // the user.
        if (!creditCard.deleted) {
          this.log.warn(
            "Removing version",
            creditCard.version,
            "credit card record to migrate to new encryption:",
            creditCard.guid
          );

          // Replace the record with a tombstone record here,
          // regardless of existence of sync metadata.
          let existingSync = this._getSyncMetaData(creditCard);
          creditCard = {
            guid: creditCard.guid,
            timeLastModified: Date.now(),
            deleted: true,
          };

          if (existingSync) {
            creditCard._sync = existingSync;
            existingSync.changeCounter++;
          }
        }
      }
    }

    // Do not remove the migration code until we're sure no users have version 4
    // credit card records (created in Fx110 or Fx111)
    if (creditCard.version == 4) {
      // Version 4 is deprecated, so downgrade or upgrade to the current version
      // Since the only change made in version 4 is deleting `cc-type` field, so
      // nothing else need to be done here expect flagging sync needed
      let existingSync = this._getSyncMetaData(creditCard);
      if (existingSync) {
        existingSync.changeCounter++;
      }
    }

    return super._computeMigratedRecord(creditCard);
  }

  async _stripComputedFields(creditCard) {
    if (creditCard["cc-number-encrypted"]) {
      try {
        creditCard["cc-number"] = await lazy.OSKeyStore.decrypt(
          creditCard["cc-number-encrypted"]
        );
      } catch (ex) {
        if (ex.result == Cr.NS_ERROR_ABORT) {
          throw ex;
        }
        // Quietly recover from encryption error,
        // so existing credit card entry with undecryptable number
        // can be updated.
      }
    }
    await super._stripComputedFields(creditCard);
  }

  _normalizeFields(creditCard) {
    lazy.CreditCardRecord.normalizeFields(creditCard);
  }

  _validateFields(creditCard) {
    if (!creditCard["cc-number"]) {
      throw new Error("Missing/invalid cc-number");
    }
  }

  _ensureMatchingVersion(record) {
    if (!record.version || isNaN(record.version) || record.version < 1) {
      throw new Error(
        `Got invalid record version ${record.version}; want ${this.version}`
      );
    }

    if (record.version == 4) {
      // Version 4 is deprecated, we need to force downloading it from sync
      // and let migration do the work to downgrade it back to the current version.
      return true;
    } else if (record.version < this.version) {
      switch (record.version) {
        case 1:
        case 2:
          // The difference between version 1 and 2 is only about the encryption
          // method used for the cc-number-encrypted field.
          // The difference between version 2 and 3 is the name of the OS
          // key encryption record.
          // As long as the record is already decrypted, it is safe to bump the
          // version directly.
          if (!record["cc-number-encrypted"]) {
            record.version = this.version;
          } else {
            throw new Error(
              "Could not migrate record version:",
              record.version,
              "->",
              this.version
            );
          }
          break;
        default:
          throw new Error(
            "Unknown credit card version to match: " + record.version
          );
      }
    }

    return super._ensureMatchingVersion(record);
  }

  /**
   * Find a match credit card record in storage that is either exactly the same
   * as the given record or a superset of the given record.
   *
   * See the comments in `getDuplicateRecords` to see the difference between
   * `getDuplicateRecords` and `getMatchRecords`
   *
   * @param {object} record
   *        The credit card for match checking. please make sure the
   *        record is normalized.
   * @returns {object}
   *          Return the first matched record found in storage, null otherwise.
   */
  async *getMatchRecords(record) {
    for await (const recordInStorage of this.getDuplicateRecords(record)) {
      const fields = this.VALID_FIELDS.filter(f => f != "cc-number");
      if (
        fields.every(
          field => !record[field] || record[field] == recordInStorage[field]
        )
      ) {
        yield recordInStorage;
      }
    }
    return null;
  }

  /**
   * Find a duplicate credit card record in the storage.
   *
   * A record is considered as a duplicate of another record when two records
   * are the "same". This might be true even when some of their fields are
   * different. For example, one record has the same credit card number but has
   * different expiration date as the other record are still considered as
   * "duplicate".
   * This is different from `getMatchRecords`, which ensures all the fields with
   * value in the the record is equal to the returned record.
   *
   * @param {object} record
   *        The credit card for duplication checking. please make sure the
   *        record is normalized.
   * @returns {object}
   *          Return the first duplicated record found in storage, null otherwise.
   */
  async *getDuplicateRecords(record) {
    if (!record["cc-number"]) {
      return null;
    }

    for (const recordInStorage of this._data) {
      if (recordInStorage.deleted) {
        continue;
      }

      const decrypted = await lazy.OSKeyStore.decrypt(
        recordInStorage["cc-number-encrypted"],
        false
      );

      if (decrypted == record["cc-number"]) {
        yield recordInStorage;
      }
    }
    return null;
  }
}

export class FormAutofillStorageBase {
  constructor(path) {
    this._path = path;
    this._initializePromise = null;
    this.INTERNAL_FIELDS = INTERNAL_FIELDS;
  }

  get version() {
    return STORAGE_SCHEMA_VERSION;
  }

  get addresses() {
    return this.getAddresses();
  }

  get creditCards() {
    return this.getCreditCards();
  }

  getAddresses() {
    throw Components.Exception("", Cr.NS_ERROR_NOT_IMPLEMENTED);
  }

  getCreditCards() {
    throw Components.Exception("", Cr.NS_ERROR_NOT_IMPLEMENTED);
  }

  /**
   * Initialize storage to memory.
   *
   * @returns {Promise} When the operation finished successfully.
   * @throws  JavaScript exception.
   */
  initialize() {
    if (!this._initializePromise) {
      this._store = this._initializeStore();
      this._initializePromise = this._store.load().then(() => {
        let initializeAutofillRecords = [
          this.addresses.initialize(),
          this.creditCards.initialize(),
        ];
        return Promise.all(initializeAutofillRecords);
      });
    }
    return this._initializePromise;
  }

  _initializeStore() {
    throw Components.Exception("", Cr.NS_ERROR_NOT_IMPLEMENTED);
  }

  // For test only.
  _saveImmediately() {
    return this._store._save();
  }

  _finalize() {
    return this._store.finalize();
  }
}