android-meetup-rxjava-challenge solution

gistfile1.txt

package com.futurice.project;

import java.util.concurrent.TimeUnit;

import rx.Observable;
import rx.Scheduler;
import rx.functions.Func1;

public class Solution {

    public static final String SECRET_SEQUENCE = "ABBABA"; // this is the password the user must input
    public static final long SEQUENCE_TIMEOUT = 4000; // this is the timeframe in milliseconds

    /**
     * Given two buttons (A & B) we want to print a "CORRECT!" message if a certain "secret sequence"
     * is clicked within a given timeframe. The "secret sequence" is the combination "ABBABA" that
     * has to be inputted within 4 seconds. In other words, the user must input the password, but
     * must do it quickly.
     *
     * @param inputStream an observable event stream of String, either "A" String or "B" String.
     * @param scheduler if you need a scheduler, use this one provided.
     * @return an observable event stream of String, that returns the secret sequence AT THE RIGHT
     * time according to the problem specification.
     */
    public static Observable<String> defineSuccessStream(final Observable<String> inputStream, final Scheduler scheduler) {
        return inputStream
                .flatMap(new Func1<String, Observable<String>>() {
                    @Override
                    public Observable<String> call(final String s) {
                        return inputStream
                                .startWith(s)
                                .map(new Func1<String, String>() {
                                    String input = "";

                                    @Override
                                    public String call(String s2) {
                                        input += s2;
                                        return input;
                                    }
                                })
                                .filter(new Func1<String, Boolean>() {
                                    @Override
                                    public Boolean call(String s) {
                                        return SECRET_SEQUENCE.equals(s);
                                    }
                                })
                                .timeout(SEQUENCE_TIMEOUT, TimeUnit.MILLISECONDS, scheduler)
                                .onErrorResumeNext(new Func1<Throwable, Observable<? extends String>>() {
                                    @Override
                                    public Observable<? extends String> call(Throwable throwable) {
                                        return Observable.empty();
                                    }
                                });
                    }
                });
    }
}