Chat.java

/*
 * Copyright 2013 Square Inc.
 *
 * Licensed under the Apache License, Version 2.0 (the "License");
 * you may not use this file except in compliance with the License.
 * You may obtain a copy of the License at
 *
 *     http://www.apache.org/licenses/LICENSE-2.0
 *
 * Unless required by applicable law or agreed to in writing, software
 * distributed under the License is distributed on an "AS IS" BASIS,
 * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
 * See the License for the specific language governing permissions and
 * limitations under the License.
 */
package com.example.mortar.model;

import android.text.TextUtils;

import com.example.mortar.model.quotes.Quote;
import com.example.mortar.model.quotes.Quotes;

import java.util.List;
import java.util.Random;
import java.util.concurrent.CopyOnWriteArrayList;

import io.reactivex.Observable;
import io.reactivex.ObservableEmitter;
import io.reactivex.ObservableOnSubscribe;
import io.reactivex.android.schedulers.AndroidSchedulers;
import io.reactivex.annotations.NonNull;
import io.reactivex.schedulers.Schedulers;
import retrofit2.Response;

public class Chat {
    private static final int SLEEP_MILLIS = 500;
    private static final int PROBABILITY = 3;

    private final int id;
    private final List<User> users;
    private final List<Message> messages;

    private Chats chats;

    Chat(Chats chats, int id, List<User> users, List<Message> seed) {
        this.chats = chats;
        this.id = id;
        this.users = users;
        messages = new CopyOnWriteArrayList<>(seed);
    }

    public int getId() {
        return id;
    }

    public Observable<Message> getMessage(int index) {
        return Observable.just(messages.get(index));
    }

    public Observable<Message> getMessages() {
        return Observable.create(new ObservableOnSubscribe<Message>() {
            @Override
            public void subscribe(@NonNull ObservableEmitter<Message> emitter)
                    throws Exception {
                final Random random = new Random();
                while(true) {
                    if(random.nextInt(PROBABILITY) == 0) {
                        try {
                            User from = users.get(random.nextInt(users.size()));
                            Response<Quotes> response = chats.service.getQuote().execute();
                            Quotes quotes = response.body();
                            if(quotes == null) {
                                throw new Exception("Could not download quotes [" + response.errorBody()
                                        .string() + "] ");
                            }
                            Quote quote = quotes.getContents().getQuotes().get(0);
                            Message next = new Message(from, quote.getQuote());
                            messages.add(next);
                            if(!emitter.isDisposed()) {
                                emitter.onNext(next);
                            }
                        } catch(Exception e) {
                            if(!emitter.isDisposed()) {
                                emitter.onError(e);
                                break;
                            }
                        }
                    }

                    try {
                        // Hijacking the thread like this is sleazey, but you get the idea.
                        Thread.sleep(SLEEP_MILLIS);
                    } catch(InterruptedException e) {
                        if(!emitter.isDisposed()) {
                            emitter.onError(e);
                        }
                        break;
                    }
                }
            }
        }).startWith(messages) //
                .subscribeOn(Schedulers.io()) //
                .observeOn(AndroidSchedulers.mainThread());
    }

    @Override
    public String toString() {
        return TextUtils.join(", ", users.toArray(new User[users.size()]));
    }
}