source.service.ts

import { Injectable } from '@angular/core';
import { AngularFirestore, AngularFirestoreCollection, AngularFirestoreDocument } from '@angular/fire/firestore';
import { Source } from '../../shared/models/source';
import { Observable } from 'rxjs/internal/Observable';
import { map } from 'rxjs/operators';

@Injectable({
    providedIn: 'root'
})
export class SourceService {
    private sourcesCollection: AngularFirestoreCollection<Source>;
    private sourceDoc: AngularFirestoreDocument<Source>;
    source: Observable<Source>;

    constructor(private angularFirestore: AngularFirestore) {
        this.sourcesCollection = this.angularFirestore.collection('sources');
    }

    /*
     * Gets source from database
     * @param {string} id - source id
     * @returns {Observable} of source data without id
     */
    getSourceById(id): Observable<Source> {
        return this.angularFirestore.doc<any>(`sources/${id}`).valueChanges();
    }

    /*
     * Gets all sources from database
     */
    getSources() {
        return this.sourcesCollection.snapshotChanges().pipe(map(changes => {
            return changes.map(value => {
                const data = value.payload.doc.data() as Source;
                const id = value.payload.doc.id;
                return {id, ...data};
            });
        }));
    }


    /*
     * Adds source into database
     * @param {Object} source - the source
     * which it has to add
     */
    addSource(source: Source) {
        return this.sourcesCollection.add(source);
    }

    /*
     * Deletes source from database
     * @param {string} id - the source id
     * which it has to delete
     */
    deleteSource(id: string) {
        this.sourceDoc = this.angularFirestore.doc(`sources/${id}`);
        return this.sourceDoc.delete();
    }

    /*
     * Updates source data in database
     * @param {Object} source - the source
     * which we have to edit.
     * @param id {string} id - we have to
     * get from route parameters
     */
    updateSource(id: string, source: Source) {
        this.sourceDoc = this.angularFirestore.doc(`sources/${id}`);
        return this.sourceDoc.update(source);
    }
}