Add PouchDB base service (#1355)

docker/planet/Dockerfile

@@ -10,6 +10,9 @@ COPY package.json ./
 COPY docker/planet/scripts/ ./
 COPY . .
 
+RUN apk add --update \
+    python \
+    build-base
 RUN npm i --silent
 RUN ./compile_planet.sh
 

package.json

@@ -42,6 +42,8 @@
     "material-icons": "^0.1.0",
     "mime": "^2.3.1",
     "ngx-img": "^10.15.0",
+    "pouchdb": "^7.0.0",
+    "pouchdb-find": "^7.0.0",
     "rxjs": "^6.2.0",
     "zone.js": "~0.8.26"
   },
@@ -53,6 +55,8 @@
     "@types/jasmine": "~2.5.53",
     "@types/jasminewd2": "~2.0.2",
     "@types/node": "~6.0.60",
+    "@types/pouchdb": "^6.3.2",
+    "@types/pouchdb-find": "^6.3.3",
     "codelyzer": "~3.2.0",
     "htmlhint-ng2": "0.0.13",
     "jasmine-core": "~2.6.2",

src/app/app.module.ts

@@ -22,6 +22,7 @@ import { FeedbackService } from './feedback/feedback.service';
 import { ResourcesService } from './resources/resources.service';
 import { SubmissionsService } from './submissions/submissions.service';
 import { CoursesService } from './courses/courses.service';
+import { SHARED_SERVICES } from './shared/database';
 import { SyncService } from './shared/sync.service';
 import { PlanetDialogsModule } from './shared/dialogs/planet-dialogs.module';
 import { PlanetLanguageModule } from './shared/planet-language.module';
@@ -54,6 +55,7 @@ import { PlanetLanguageModule } from './shared/planet-language.module';
     ResourcesService,
     SubmissionsService,
     CoursesService,
+    ...SHARED_SERVICES,
     SyncService
   ],
   bootstrap: [ AppComponent ]

src/app/shared/database/index.ts

@@ -0,0 +1,4 @@
+import { PouchService } from './pouch.service';
+
+export { PouchService } from './pouch.service';
+export const SHARED_SERVICES = [ PouchService ];

src/app/shared/database/pouch.service.ts

@@ -0,0 +1,68 @@
+import { Injectable } from '@angular/core';
+import PouchDB from 'pouchdb';
+import PouchDBFind from 'pouchdb-find';
+import { throwError, from } from 'rxjs';
+import { catchError } from 'rxjs/operators';
+import { environment } from '../../../environments/environment';
+
+PouchDB.plugin(PouchDBFind);
+
+@Injectable()
+export class PouchService {
+  private baseUrl = environment.couchAddress;
+  private localDBs;
+  private databases = [];
+
+  constructor() {
+    this.databases.forEach(db => {
+      const pouchDB = new PouchDB(`local-${db}`);
+
+      // indexes the field for faster lookup
+      pouchDB.createIndex({
+        index: {
+          fields: [ 'kind', 'createdAt' ]
+        }
+      });
+      this.localDBs[db] = pouchDB;
+    });
+  }
+
+  // @TODO: handle edge cases like offline, duplicate, duplications
+  // handle repliction errors or make use of navigator online?
+  replicateFromRemoteDBs() {
+    this.databases.forEach(db => {
+      this.localDBs[db].replicate.from(this.baseUrl + db);
+    });
+  }
+
+  replicateToRemoteDBs() {
+    this.databases.forEach(db => {
+      this.localDBs[db].replicate.to(this.baseUrl + db, {
+        filter(doc) {
+          return doc.pouchIndex === db;
+        }
+      });
+    });
+  }
+
+  replicateFromRemoteDB(db) {
+    return this.replicate(this.localDBs[db].replicate.from(this.baseUrl + db));
+  }
+
+  replicateToRemoteDB(db) {
+    return this.replicate(this.localDBs[db].replicate.to(this.baseUrl + db));
+  }
+
+  replicate(replicateFn) {
+    return from(replicateFn).pipe(catchError(this.handleError));
+  }
+
+  getLocalPouchDB(db) {
+    return this.localDBs[db];
+  }
+
+  private handleError(err) {
+    console.error('An error occurred in PouchDB', err);
+    return throwError(err.message || err);
+  }
+}

src/polyfills.ts

@@ -70,3 +70,7 @@ import 'zone.js/dist/zone';  // Included with Angular CLI.
  * Need to import at least one locale-data with intl.
  */
 // import 'intl/locale-data/jsonp/en';
+
+(window as any).global = window;
+(window as any).process = {};
+(window as any).process.nextTick = setTimeout;

tsconfig.json

@@ -7,6 +7,7 @@
     "moduleResolution": "node",
     "emitDecoratorMetadata": true,
     "experimentalDecorators": true,
+    "allowSyntheticDefaultImports": true,
     "target": "es5",
     "typeRoots": [
       "node_modules/@types"