CacheService.java

package org.grakovne.mds.android.service;

import android.content.Intent;
import android.util.Log;

import org.grakovne.mds.android.common.PayloadNames;
import org.grakovne.mds.android.common.Receiver;
import org.grakovne.mds.android.network.domain.responses.Story;

import java.io.File;
import java.io.IOException;
import java.net.URL;

import static org.apache.commons.io.FileUtils.copyURLToFile;
import static org.grakovne.mds.android.MdsApplication.APP_TAG;
import static org.grakovne.mds.android.common.ActionNames.Cache;
import static org.grakovne.mds.android.manager.BroadcastManager.getPayloadObject;
import static org.grakovne.mds.android.manager.BroadcastManager.send;
import static org.grakovne.mds.android.utils.CommonUtils.ifDebugEnabled;
import static org.grakovne.mds.android.utils.NetworkUtils.findStreamUrl;

public class CacheService extends MdsService {

    private Receiver receiver;
    private File fileCache;

    @Override
    protected void subscribe() {
        super.subscribe();

        fileCache = getCacheDir();
        receiver = new Receiver(this,
                Cache.CACHE_REMOVED_STREAM_INTENT,
                Cache.STREAM_IS_CACHED_INTENT,
                Cache.CACHED_STREAM_INTENT,
                Cache.FOUND_STREAM_INTENT) {

            @Override
            public void onAction(Intent intent, String action) {
                switch (action) {
                    case Cache.CACHED_STREAM_INTENT:
                        createStream(getPayloadObject(intent, PayloadNames.STORY, Story.class));
                        break;
                    case Cache.CACHE_REMOVED_STREAM_INTENT:
                        removeStream(getPayloadObject(intent, PayloadNames.STORY, Story.class));
                        break;
                    case Cache.FOUND_STREAM_INTENT:
                        findStream(getPayloadObject(intent, PayloadNames.STORY, Story.class));
                        break;
                    case Cache.STREAM_IS_CACHED_INTENT:
                        isStreamCached(getPayloadObject(intent, PayloadNames.STORY, Story.class));
                }
            }
        };
    }

    private void findStream(Story story) {
        if (isStreamCached(story) && isStreamValid(story)) {
            send(this, Cache.FOUND_STREAM_EVENT, buildStreamFile(story));
        }
    }

    private void createStream(Story story) {
        new Thread(() -> {
            try {
                copyURLToFile(new URL(findStreamUrl(story)), buildStreamFile(story));
                send(this, Cache.CACHED_STREAM_EVENT, story);
            } catch (IOException e) {
                ifDebugEnabled(() -> Log.d(APP_TAG, "Can't fetch story stream"));
            }
        }).start();
    }

    private void removeStream(Story story) {
        if (buildStreamFile(story).delete()) {
            send(this, Cache.CACHE_REMOVED_STREAM_EVENT);
        }
    }

    private File buildStreamFile(Story story) {
        return new File(fileCache, story.getId() + ".mp3");
    }

    private Boolean isStreamCached(Story story) {
        return isStreamExists(story) && isStreamValid(story);
    }

    private Boolean isStreamExists(Story story) {
        return buildStreamFile(story).exists();
    }

    private Boolean isStreamValid(Story story) {
        return story.getFileSize().equals(new File(fileCache, story.getId() + ".mp3").length());
    }

    @Override
    protected void unsubscribe() {
        receiver.unsubscribe();
        super.unsubscribe();
    }
}