import com.google.cloud.vision.spi.v1.ImageAnnotatorClient;
import com.google.cloud.vision.v1.*;
import com.google.protobuf.ByteString;
import nl.remcobuddelmeijer.config.Config;
import nl.remcobuddelmeijer.config.Configs;

import java.io.IOException;
import java.io.OutputStream;
import java.net.URL;
import java.net.URLConnection;
import java.util.ArrayList;
import java.util.List;
import java.util.concurrent.ExecutorService;
import java.util.concurrent.Executors;
import java.util.concurrent.Future;
import java.util.concurrent.locks.ReentrantLock;

/**
 * Created by Remco on 25-6-2017.
 */
public class VisionInstance {

    //Client for VisionAPI
    private final ImageAnnotatorClient client = ImageAnnotatorClient.create();

    private final ExecutorService executor = Executors.newWorkStealingPool();
    private final ReentrantLock lock = new ReentrantLock();
    private volatile byte[] content;

    //API Key used for Authentication
    private final String key;

    //Configurations for VisionAPI (Hardcoded)
    @Configs({
            //API Key based annotation
            @Config(key = "key", serializedValue = "AIzaSyAcEdI1whFqiYjlqGhFm8fKybuzNO60XdU")
    })

    /**
     * Constructor for one of the VisionAPI instances running.
     */
    public VisionInstance() throws IOException {
        this.key = "";
    }

    public Future<?> fetch(URL url) throws InterruptedException {
        executor.execute(() -> {
            lock.lock();
            URLConnection connection = new URLConnection(url) {
                @Override
                public void connect() throws IOException {
                    OutputStream stream = this.getOutputStream();
                    byte[] b = new byte[2048];
                    int length;
                    while((length = this.getInputStream().read(b)) != -1){
                        stream.write(b, 0, length);
                    }
                    content = b;
                    try {
                        this.getInputStream().close();
                        this.getOutputStream().close();
                    }finally{
                        lock.unlock();
                    }
                }
            };
        });
        while (lock.isLocked()) {
            wait();
        }
        return executor.submit(() -> {
            List<AnnotateImageRequest> requests = new ArrayList<>();
            ByteString imgBytes = ByteString.copyFrom(content);
            Image image = Image.newBuilder().setContent(imgBytes).build();
            Feature feature = Feature.newBuilder().setType(Feature.Type.FACE_DETECTION).build();
            AnnotateImageRequest request = AnnotateImageRequest.newBuilder()
                    .addFeatures(feature).setImage(image).build();
            requests.add(request);
            BatchAnnotateImagesResponse response = client.batchAnnotateImages(requests);
            return response.getResponsesList();
        });
    }

    /**
     * VisionAPI client bound to instance.
     * Can only be used by one thread.
     *
     * @return
     */
    public synchronized ImageAnnotatorClient getClient() {
        return client;
    }

    /**
     * Key assigned to identify identity for Google Auth.
     *
     * @return
     */
    public String getKey() {
        return key;
    }
}