ImagesManager.java

ackage cr.canopy.tunde.canopy.manager;

import android.content.res.AssetManager;
import android.support.v4.app.FragmentActivity;
import android.util.Log;

import java.io.File;
import java.io.FileOutputStream;
import java.io.IOException;
import java.io.InputStream;
import java.io.OutputStream;
import java.util.ArrayList;
import java.util.Arrays;
import java.util.List;
import java.util.Random;

public class ImagesManager {

    private static File createFileFromInputStream(File cacheDir, InputStream inputStream, String fileName) {

        try {
            File f = new File(cacheDir + "/" +fileName);
            OutputStream outputStream = new FileOutputStream(f);
            byte buffer[] = new byte[1024];
            int length = 0;

            while ((length=inputStream.read(buffer)) > 0) {
                outputStream.write(buffer,0, length);
            }

            outputStream.close();
            inputStream.close();

            return f;

        } catch (IOException e) {
            Log.e(">", e.getMessage());
        }

        return null;
    }


    public static List<File> getThumbnailImages(FragmentActivity appCompatActivity) throws IOException {
        AssetManager assetManager = appCompatActivity.getAssets();

        String [] files = assetManager.list("images");
        List<File> result = new ArrayList<>();

        for (String f : files) {
            File file = createFileFromInputStream(
                    appCompatActivity.getCacheDir(),
                    assetManager.open("images/" + f), f);

            if (f.endsWith("thumbnail.jpg")) {
                result.add(file);
            }

        }
        return result;
    }

    public static List<File> getCuratedImages(FragmentActivity appCompatActivity, int count) throws IOException {
        AssetManager assetManager = appCompatActivity.getAssets();

        String [] files = assetManager.list("images");
        ArrayList<String> pool = new ArrayList<>(Arrays.asList(files));

        List<File> result = new ArrayList<>();
        Random rand = new Random();

        for (int i = 0; i < count; i++) {
            int randomIndex = rand.nextInt(pool.size());
            String f = pool.get(randomIndex);

            if (!f.endsWith("thumbnail.jpg")) {
                result.add(createFileFromInputStream(
                        appCompatActivity.getCacheDir(),
                        assetManager.open("images/" + f), f));

            }

            pool.remove(randomIndex);
        }

        return result;
    }
}

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