/*! @license
 * Shaka Player
 * Copyright 2016 Google LLC
 * SPDX-License-Identifier: Apache-2.0
 */

goog.provide('shaka.offline.indexeddb.BaseStorageCell');

goog.require('shaka.offline.indexeddb.DBConnection');
goog.require('shaka.util.Error');


/**
 * indexeddb.StorageCellBase is a base class for all stores that use IndexedDB.
 *
 * @implements {shaka.extern.StorageCell}
 */
shaka.offline.indexeddb.BaseStorageCell = class {
  /**
   * @param {IDBDatabase} connection
   * @param {string} segmentStore
   * @param {string} manifestStore
   */
  constructor(connection, segmentStore, manifestStore) {
    /** @protected {!shaka.offline.indexeddb.DBConnection} */
    this.connection_ = new shaka.offline.indexeddb.DBConnection(connection);

    /** @protected {string} */
    this.segmentStore_ = segmentStore;

    /** @protected {string} */
    this.manifestStore_ = manifestStore;
  }

  /** @override */
  destroy() {
    return this.connection_.destroy();
  }

  /** @override */
  hasFixedKeySpace() {
    // By default, all IDB stores are read-only.  The latest one will need to
    // override this default to be read-write.
    return true;
  }

  /** @override */
  addSegments(segments) {
    // By default, reject all additions.
    return this.rejectAdd(this.segmentStore_);
  }

  /** @override */
  removeSegments(keys, onRemove) {
    return this.remove_(this.segmentStore_, keys, onRemove);
  }

  /** @override */
  async getSegments(keys) {
    const rawSegments = await this.get_(this.segmentStore_, keys);
    return rawSegments.map((s) => this.convertSegmentData(s));
  }

  /** @override */
  addManifests(manifests) {
    // By default, reject all additions.
    return this.rejectAdd(this.manifestStore_);
  }

  /** @override */
  updateManifestExpiration(key, newExpiration) {
    const op = this.connection_.startReadWriteOperation(this.manifestStore_);
    const store = op.store();
    store.get(key).onsuccess = (e) => {
      const manifest = e.target.result;
      // If we can't find the value, then there is nothing for us to update.
      if (manifest) {
        manifest.expiration = newExpiration;
        store.put(manifest, key);
      }
    };

    return op.promise();
  }

  /** @override */
  removeManifests(keys, onRemove) {
    return this.remove_(this.manifestStore_, keys, onRemove);
  }

  /** @override */
  async getManifests(keys) {
    const rawManifests = await this.get_(this.manifestStore_, keys);
    return Promise.all(rawManifests.map((m) => this.convertManifest(m)));
  }

  /** @override */
  async getAllManifests() {
    /** @type {!shaka.offline.indexeddb.DBOperation} */
    const op = this.connection_.startReadOnlyOperation(this.manifestStore_);

    /** @type {!Map.<number, shaka.extern.ManifestDB>} */
    const values = new Map();

    await op.forEachEntry(async (key, value) => {
      const manifest = await this.convertManifest(value);
      values.set(/** @type {number} */(key), manifest);
    });

    await op.promise();
    return values;
  }

  /**
   * @param {?} old
   * @return {shaka.extern.SegmentDataDB}
   * @protected
   */
  convertSegmentData(old) {
    // Conversion is specific to each subclass.  By default, do nothing.
    return /** @type {shaka.extern.SegmentDataDB} */(old);
  }

  /**
   * @param {?} old
   * @return {!Promise.<shaka.extern.ManifestDB>}
   * @protected
   */
  convertManifest(old) {
    // Conversion is specific to each subclass.  By default, do nothing.
    return Promise.resolve(/** @type {shaka.extern.ManifestDB} */(old));
  }

  /**
   * @param {string} storeName
   * @return {!Promise}
   * @protected
   */
  rejectAdd(storeName) {
    return Promise.reject(new shaka.util.Error(
        shaka.util.Error.Severity.CRITICAL,
        shaka.util.Error.Category.STORAGE,
        shaka.util.Error.Code.NEW_KEY_OPERATION_NOT_SUPPORTED,
        'Cannot add new value to ' + storeName));
  }

  /**
   * @param {string} storeName
   * @param {!Array.<T>} values
   * @return {!Promise.<!Array.<number>>}
   * @template T
   * @protected
   */
  async add(storeName, values) {
    const op = this.connection_.startReadWriteOperation(storeName);
    const store = op.store();

    /** @type {!Array.<number>} */
    const keys = [];

    // Write each segment out. When each request completes, the key will
    // be in |request.result| as can be seen in
    // https://w3c.github.io/IndexedDB/#key-generator-construct.
    for (const value of values) {
      const request = store.add(value);
      request.onsuccess = (event) => {
        const key = request.result;
        keys.push(key);
      };
    }

    // Wait until the operation completes or else |keys| will not be fully
    // populated.
    await op.promise();
    return keys;
  }

  /**
   * @param {string} storeName
   * @param {!Array.<number>} keys
   * @param {function(number)} onRemove
   * @return {!Promise}
   * @private
   */
  remove_(storeName, keys, onRemove) {
    const op = this.connection_.startReadWriteOperation(storeName);
    const store = op.store();

    for (const key of keys) {
      store.delete(key).onsuccess = () => onRemove(key);
    }

    return op.promise();
  }

  /**
   * @param {string} storeName
   * @param {!Array.<number>} keys
   * @return {!Promise.<!Array.<T>>}
   * @template T
   * @private
   */
  async get_(storeName, keys) {
    const op = this.connection_.startReadOnlyOperation(storeName);
    const store = op.store();

    const values = {};
    /** @type {!Array.<number>} */
    const missing = [];

    // Use a map to store the objects so that we can reorder the results to
    // match the order of |keys|.
    for (const key of keys) {
      const request = store.get(key);
      request.onsuccess = () => {
        // Make sure a defined value was found. Indexeddb treats no-value found
        // as a success with an undefined result.
        if (request.result == undefined) {
          missing.push(key);
        }

        values[key] = request.result;
      };
    }

    // Wait until the operation completes or else values may be missing from
    // |values|. Use the original key list to convert the map to a list so that
    // the order will match.
    await op.promise();
    if (missing.length) {
      throw new shaka.util.Error(
          shaka.util.Error.Severity.CRITICAL,
          shaka.util.Error.Category.STORAGE,
          shaka.util.Error.Code.KEY_NOT_FOUND,
          'Could not find values for ' + missing
      );
    }

    return keys.map((key) => values[key]);
  }
};
