import { Injectable } from '@angular/core';
import { Router } from '@angular/router';
import { User } from '../_models/user.model';
import { auth } from 'firebase/app';
import { AngularFireAuth } from '@angular/fire/auth';
import { AngularFirestore, AngularFirestoreDocument, DocumentSnapshot } from '@angular/fire/firestore';

import { Observable, of, Subject } from 'rxjs';
import { switchMap, take, map, tap } from 'rxjs/operators';
import { Post } from '../_models/post.model';

/**
 * Handles user authorization and firebase functions
 */
@Injectable({ providedIn: 'root' })
export class AuthService {

  /**
   * Current logged in user
   */
  user$: Observable<User>;

  constructor(
      private afAuth: AngularFireAuth,
      private afs: AngularFirestore,
      private router: Router
  ) {
      // Get the auth state, then fetch the Firestore user document or return null
    this.user$ = this.afAuth.authState.pipe(
      switchMap(user => {
          // Logged in
        if (user) {
          return this.afs.doc<User>(`users/${user.uid}`).valueChanges();
        } else {
          // Logged out
          return of(null);
        }
      })
    );
  }

  /**
   * Handles sign in through Google oAuth
   * Updates user object with information from Google
   * @returns User from oAuth
   */
  async googleSignin() {
    const provider = new auth.GoogleAuthProvider();
    const credential = await this.afAuth.auth.signInWithPopup(provider);
    return this.updateUserData(credential.user);
  }

  /**
   * Updates the user in the database with information
   * @param user reference to user object, not strictly types in case definitions missing
   * @returns response from database
   */
  public updateUserData(user) {
    // Sets user data to firestore on login
    const userRef: AngularFirestoreDocument<User> = this.afs.doc(`users/${user.uid}`);

    const data = {
      uid: user.uid,
      email: user.email,
      displayName: user.displayName,
      photoURL: user.photoURL,
      admin: user.admin
    };

    return userRef.set(data, { merge: true });

  }
  /**
   * Gets information about a user
   * @param userID User ID
   */
  public getUser(userID) {
    return this.afs.doc<User>(`users/${userID}`).valueChanges();
  }

  /**
   * Gets blog posts from firebase
   * TODO Figure out what this does and if it's used?
   * @returns Post as Observable
   */
  public getBlogPosts(): Observable<any> {
    const post = new Subject<any>();
    // Gets the current user
    this.user$.subscribe(user => {
      const postDoc = this.afs.doc('posts/' + user.uid);
      postDoc.get().subscribe(value => {
        console.log(value);
      });
      post.next(postDoc.valueChanges());
    });

    return post.asObservable();
    // @ts-ignore
  }

  /**
   * Updates a blog with new parameters
   * @param post Post Object
   * @param id Blog ID
   */
  public updateBlogPost(post, id) {

    const postDoc: AngularFirestoreDocument<Post>  = this.afs.doc('posts/' + id);

    const data = {
      title: post.title,
      content: post.content,
      author: post.author,
      tags: post.tags,
      date: post.date,
      comments: post.comments,
      objectID: post.objectID
    };

    return postDoc.set(data, { merge: true });

  }

  /**
   * Gets all of the userData
   */
  getUserData(): Observable<any> {
    return this.user$.pipe(take(1), map(value => {
      return this.afs.doc(`users/${value.uid}`).snapshotChanges();
    }));
  }

  /**
   * Signs out the user
   */
  async signOut() {
    await this.afAuth.auth.signOut();
    this.router.navigate(['/']);
  }

}