HOSN-app/app/src/pages/profile/profile.ts

import { Component, ViewChild } from "@angular/core";
import {
  IonicPage,
  NavController,
  NavParams,
  InfiniteScroll,
  Content
} from "ionic-angular";
import { TwitterApiProvider } from "../../providers/twitter-api/twitter-api";
import { P2pStorageIpfsProvider } from "../../providers/p2p-storage-ipfs/p2p-storage-ipfs";
import { P2pDatabaseGunProvider } from "../../providers/p2p-database-gun/p2p-database-gun";

/**
 * Generated class for the ProfilePage page.
 *
 * See https://ionicframework.com/docs/components/#navigation for more info on
 * Ionic pages and navigation.
 */

@IonicPage()
@Component({
  selector: "page-profile",
  templateUrl: "profile.html"
})
export class ProfilePage {
  user: any = [];
  tweets: any[];
  oldestLoadedTweetId;
  enableRefresh: boolean = true;
  enableInfiniteScroll: boolean = true;

  @ViewChild(Content)
  content: Content;

  constructor(
    public navCtrl: NavController,
    public navParams: NavParams,
    private twitter: TwitterApiProvider,
    private ipfs: P2pStorageIpfsProvider,
    private gun: P2pDatabaseGunProvider
  ) {}

  ionViewDidLoad() {
    const userId = this.navParams.get("userId");

    this.twitter.fetchUser(userId).then(res => (this.user = res));

    this.loadTimeline(userId, null).then(res => {
      if (res.length > 0) {
        // Save tweets
        this.tweets = res;

        // Save oldest tweet's id for next load more
        this.oldestLoadedTweetId = res
          .filter(tweet => !tweet.private_tweet)
          .reduce((acc, cur) => (acc.id < cur.id ? acc : cur))["id"];
      }
    });
  }

  doRefresh(refresher) {
    this.loadTimeline(this.user.id, null).then(res => {
      if (res.length > 0) {
        // Replace tweets
        this.tweets = res;

        // Save oldest tweet's id for next load more
        this.oldestLoadedTweetId = res
          .filter(tweet => !tweet.private_tweet)
          .reduce((acc, cur) => (acc.id < cur.id ? acc : cur))["id"];
      }

      // Hide loading icon
      refresher.complete();
    });
  }

  loadMore(infiniteScroll: InfiniteScroll) {
    this.loadTimeline(this.user.id, this.oldestLoadedTweetId).then(res => {
      if (res.length > 0) {
        // Append loaded tweets
        this.tweets = this.tweets.concat(res);

        // Save oldest tweet's id for next load more
        this.oldestLoadedTweetId = res
          .filter(tweet => !tweet.private_tweet)
          .reduce((acc, cur) => (acc.id < cur.id ? acc : cur))["id"];
      }

      // Hide loading icon
      infiniteScroll.complete();
    });
  }

  private async loadTimeline(userId, oldestLoadedTweetId) {
    // Fetch tweets from Twitter
    const tweets =
      oldestLoadedTweetId == null
        ? await this.twitter.fetchUserTimeline(userId)
        : await this.twitter.fetchUserTimelineSince(
            userId,
            oldestLoadedTweetId
          );

    // Determine end of time interval to look for private tweets
    let intervalEnd;
    if (tweets.length < 20) {
      // End of timeline is reached
      this.enableInfiniteScroll = false;
      intervalEnd = new Date("2018-04-01T00:00:00");
    } else {
      const lastTweetTimestamp = tweets[tweets.length - 1].created_at;
      intervalEnd = new Date(lastTweetTimestamp);
    }

    // Fetch private tweet hashs from P2P DB for corresponding interval
    const privateTweetHashs: string[] = await this.gun.fetchPrivateTweetHashsForUserInInterval(
      userId,
      new Date(),
      intervalEnd
    );

    // Load private tweets from P2P storage
    let privateTweets = await this.ipfs.fetchTweets(privateTweetHashs);

    // Add user object to private tweets
    privateTweets = await Promise.all(
      privateTweets.map(async tweet => await this.addUserToTweet(tweet))
    );

    // Combine and sort tweets
    return tweets
      .concat(privateTweets)
      .sort((a, b) => this.sortByDateAsc(a, b));
  }

  private sortByDateAsc(a, b) {
    const dateA = new Date(a.created_at);
    const dateB = new Date(b.created_at);

    if (dateA > dateB) {
      return -1;
    } else if (dateA < dateB) {
      return 1;
    } else {
      return 0;
    }
  }

  private async addUserToTweet(tweet) {
    tweet.user = await this.twitter.fetchUser(tweet.user_id);
    return tweet;
  }

  onScroll(event) {
    this.enableRefresh = event.scrollTop === 0;
  }
}