App.js

@@ -62,6 +62,7 @@ import entitiesStorage from './src/common/services/sql/entities.storage';
 import feedsStorage from './src/common/services/sql/feeds.storage';
 import connectivityService from './src/common/services/connectivity.service';
 import sqliteStorageProviderService from './src/common/services/sqlite-storage-provider.service';
+import commentStorageService from './src/comments/CommentStorageService';
 
 let deepLinkUrl = '';
 
@@ -124,6 +125,7 @@ sessionService.onLogin(async () => {
       if (!connectivityService.isConnected) return;
       entitiesStorage.removeOlderThan(30);
       feedsStorage.removeOlderThan(30);
+      commentStorageService.removeOlderThan(30);
     }, 30000);
 
   } catch (err) {

__tests__/comments/CommentStorageService.js

+import { CommentStorageService } from '../../src/comments/CommentStorageService';
+import sqliteService from '../../src/common/services/sqlite.service';
+import sqliteStorageProviderService from '../../src/common/services/sqlite-storage-provider.service';
+
+jest.mock('../../src/common/services/sqlite.service');
+jest.mock('../../src/common/services/log.service');
+
+/**
+ * Tests
+ */
+describe('Comment storage service', () => {
+  const storage = new CommentStorageService();
+  let sql;
+
+  const response = [{
+    "data":'{"comments":[{"type":"comment","entity_guid":"988128928149561344","parent_guid_l1":"0","parent_guid_l2":"0","guid":"eyJfdHlwZSI6ImNvbW1lbnQiLCJjaGlsZF9wYXRoIjoiOTg5Njg4NDA0MTEyMDI3NjQ4OjA6MCIsImVudGl0eV9ndWlkIjoiOTg4MTI4OTI4MTQ5NTYxMzQ0IiwiZ3VpZCI6Ijk4OTY4ODQwNDExMjAyNzY0OCIsInBhcmVudF9wYXRoIjoiMDowOjAiLCJwYXJ0aXRpb25fcGF0aCI6IjA6MDowIn0=","replies_count":0,"owner_guid":"781640694769917958","time_created":1561336103,"time_updated":1561336103,"attachments":[],"mature":false,"edited":false,"spam":false,"deleted":false,"_guid":"989688404112027648","partition_path":"0:0:0","parent_path":"0:0:0","child_path":"989688404112027648:0:0","description":"Test","thumbs:up:user_guids":[],"thumbs:up:count":0,"thumbs:down:user_guids":[],"thumbs:down:count":0,"can_reply":true}],"load-previous":"","load-next":"","socketRoomName":"comments:988128928149561344:0:0:0"}'
+  }];
+
+  beforeEach(async () => {
+    sql = await sqliteStorageProviderService.get();
+  });
+
+  it('should return null on error', () => {
+
+    sql.executeSql.mockRejectedValue(Error('Boom'));
+
+    return expect(storage.read('0001', '0:0:0', true, '', '')).resolves.toBe(null);
+
+  });
+
+  it('should return null on empty result', () => {
+
+    const result = {rows: {raw: jest.fn()}};
+
+    result.rows.raw.mockReturnValue(null);
+
+    sql.executeSql.mockResolvedValue([result]);
+
+    return expect(storage.read('0001', '0:0:0', true, '', '')).resolves.toBe(null);
+
+  });
+
+  it('should return null on no data', () => {
+
+    const result = {rows: {raw: jest.fn()}};
+
+    result.rows.raw.mockReturnValue([{}]);
+
+    sql.executeSql.mockResolvedValue([result]);
+
+    return expect(storage.read('0001', '0:0:0', true, '', '')).resolves.toBe(null);
+
+  });
+
+  it('should return stored comments', () => {
+
+    const result = {rows: {raw: jest.fn()}};
+
+    result.rows.raw.mockReturnValue(response);
+
+    sql.executeSql.mockResolvedValue([result]);
+
+    return expect(storage.read('0001', '0:0:0', true, '', '')).resolves.toEqual(JSON.parse(response[0].data));
+
+  });
+
+  it('should insert into comments_feeds', async (done) => {
+
+    sql.init.mockResolvedValue();
+    sql.executeSql.mockResolvedValue([true]);
+
+    const result = {comments: []};
+
+    try {
+      await storage.write('1234', '0:0:0', true, '1', '0002', result);
+
+      // TODO: check parameters, for some reason jest is transforming the paramters array.
+      expect(sql.executeSql).toBeCalled();
+      done();
+    } catch(err) {
+      done.fail();
+    }
+  });
+});
\ No newline at end of file

src/comments/CommentStorageService.js

+import sqliteStorageProviderService from '../common/services/sqlite-storage-provider.service';
+import logService from '../common/services/log.service';
+import moment from 'moment';
+
+/**
+ * Comment storage service
+ */
+export class CommentStorageService {
+
+  /**
+   * @var {SqliteService}
+   */
+  db;
+
+  /**
+   * Get the sqlite service
+   */
+  async getDb() {
+    if (!this.db) {
+      this.db = await sqliteStorageProviderService.get();
+    }
+    return this.db;
+  }
+
+  /**
+   * Read a page from the storage
+   *
+   * @param {string} entityGuid
+   * @param {string} parentPath
+   * @param {boolean} descending
+   * @param {string} offset
+   * @param {string} focusedUrn
+   */
+  async read(entityGuid: string, parentPath: string, descending: boolean, offset: string, focusedUrn: string) {
+    try {
+      await this.getDb();
+
+      const params = [
+        entityGuid,
+        parentPath,
+        descending,
+        offset || '',
+        focusedUrn || ''
+      ];
+
+      const [result] = await this.db.executeSql('SELECT data FROM comments_feeds WHERE parent = ? AND parent_path = ? AND descending = ? AND offset = ? AND focused_urn = ?;', params);
+
+      const rows = result.rows.raw();
+
+      if (!rows[0] || !rows[0].data) return null;
+
+      return JSON.parse(rows[0].data);
+    } catch (err) {
+      logService.exception('[CommentStorageService]', err);
+      return null;
+    }
+  }
+
+  /**
+   * Write a page to the storage
+   *
+   * @param {string} entityGuid
+   * @param {string} parentPath
+   * @param {boolean} descending
+   * @param {string} offset
+   * @param {string} focusedUrn
+   * @param {Object} data
+   */
+  async write(entityGuid: string, parentPath: string, descending: boolean, offset: string, focusedUrn: string, data: Object) {
+    try {
+      await this.getDb();
+      await this.db.executeSql('REPLACE INTO comments_feeds (parent, parent_path, descending, offset, focused_urn, data, updated) values (?,?,?,?,?,?,?)',
+        [
+          entityGuid,
+          parentPath,
+          descending,
+          offset || '',
+          focusedUrn || '',
+          JSON.stringify(this.clean(data)),
+          Math.floor(Date.now() / 1000)
+        ]
+      );
+    } catch (err) {
+      logService.exception('[CommentStorageService]', err);
+      console.log(err)
+    }
+  }
+
+  /**
+   * Remove all comments feeds
+   */
+  async removeAll() {
+    await this.getDb();
+    return this.db.executeSql('DELETE FROM comments_feeds');
+  }
+
+  /**
+   * Remove comments feeds older than given days
+   *
+   * @param {integer} days
+   */
+  async removeOlderThan(days) {
+    const when = moment().subtract(days, 'days');
+    await this.getDb();
+    this.db.executeSql('DELETE FROM comments_feeds WHERE updated < ?', [when.format("X")]);
+  }
+
+  /**
+   * Clean repeated data to reduce the stored size
+   *
+   * @param {Object} data
+   */
+  clean(data: Object){
+    data.comments.forEach(comment => {
+      delete(comment.luid);
+      delete(comment.body);
+    });
+    delete(data.status);
+    return data;
+  }
+}
+
+export default new CommentStorageService();
\ No newline at end of file

src/comments/CommentsService.js

 import api from './../common/services/api.service';
+import commentStorageService from './CommentStorageService';
 
 const decodeUrn = (urn) => {
   let parts = urn.split(':');
@@ -52,7 +53,17 @@ export async function getComments(focusedUrn, entity_guid, parent_path, level, l
 
   let uri = `api/v2/comments/${opts.entity_guid}/0/${opts.parent_path}`;
 
-  let response = await api.get(uri, opts);
+  let response;
+
+  try {
+    response = await api.get(uri, opts);
+    commentStorageService.write(entity_guid, parent_path, descending, loadNext || loadPrevious, focusedUrn, response);
+  } catch(err) {
+    response = await commentStorageService.read(entity_guid, parent_path, descending, loadNext || loadPrevious, focusedUrn);
+
+    // if there is no local data we throw the exception again
+    if (!response) throw err;
+  }
 
   if (focusedUrn && focusedUrnObject) {
     for (let comment of response.comments) {

src/common/services/__mocks__/sqlite.service.js

+class SqliteServiceMock {
+
+  init = jest.fn();
+  runMigrations = jest.fn();
+  rebuildDB = jest.fn();
+  executeSql = jest.fn();
+  transaction = jest.fn();
+
+}
+
+export default SqliteServiceMock
\ No newline at end of file

src/common/services/sql/migrations.js

@@ -7,7 +7,8 @@ const migrations = [
   "CREATE TABLE IF NOT EXISTS entities ( urn VARCHAR(255) NOT NULL PRIMARY KEY, data TEXT, updated INTEGER )",
   "CREATE TABLE IF NOT EXISTS feeds ( key VARCHAR(255) NOT NULL, offset INTEGER NOT NULL, data TEXT, updated INTEGER, PRIMARY KEY(key, offset))",
   "CREATE INDEX feeds_updated ON feeds(updated);",
-  "CREATE INDEX entities_updated ON entities(updated);"
+  "CREATE INDEX entities_updated ON entities(updated);",
+  "CREATE TABLE IF NOT EXISTS comments_feeds ( parent VARCHAR(128) NOT NULL, parent_path VARCHAR(128) NOT NULL, descending BOOLEAN, offset VARCHAR(64) NOT NULL, focused_urn VARCHAR(255) NOT NULL, data TEXT, updated INTEGER, PRIMARY KEY(parent, parent_path, descending, offset, focused_urn))",
+  "CREATE INDEX comments_feeds_updated ON comments_feeds(updated);",
 ];
-
 export default migrations;
\ No newline at end of file