/*
 * Licensed to the Apache Software Foundation (ASF) under one or more
 * contributor license agreements.  See the NOTICE file distributed with
 * this work for additional information regarding copyright ownership.
 * The ASF licenses this file to You 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 org.apache.airavata.mft.transport.gcp;

import com.google.api.client.googleapis.auth.oauth2.GoogleCredential;
import com.google.api.client.googleapis.javanet.GoogleNetHttpTransport;
import com.google.api.client.http.HttpTransport;
import com.google.api.client.json.JsonFactory;
import com.google.api.client.json.jackson2.JacksonFactory;
import com.google.api.services.storage.Storage;
import com.google.api.services.storage.StorageScopes;
import com.google.api.services.storage.model.StorageObject;
import org.apache.airavata.mft.core.DirectoryResourceMetadata;
import org.apache.airavata.mft.core.FileResourceMetadata;
import org.apache.airavata.mft.core.ResourceTypes;
import org.apache.airavata.mft.core.api.MetadataCollector;
import org.apache.airavata.mft.credential.stubs.gcs.GCSSecret;
import org.apache.airavata.mft.credential.stubs.gcs.GCSSecretGetRequest;
import org.apache.airavata.mft.resource.client.ResourceServiceClient;
import org.apache.airavata.mft.resource.client.ResourceServiceClientBuilder;
import org.apache.airavata.mft.resource.stubs.gcs.resource.GCSResource;
import org.apache.airavata.mft.resource.stubs.gcs.resource.GCSResourceGetRequest;
import org.apache.airavata.mft.secret.client.SecretServiceClient;
import org.apache.airavata.mft.secret.client.SecretServiceClientBuilder;

import java.io.ByteArrayInputStream;
import java.math.BigInteger;
import java.nio.charset.StandardCharsets;
import java.util.Base64;
import java.util.Collection;

public class GCSMetadataCollector implements MetadataCollector {

    boolean initialized = false;
    private String resourceServiceHost;
    private int resourceServicePort;
    private String secretServiceHost;
    private int secretServicePort;

    @Override
    public void init(String resourceServiceHost, int resourceServicePort, String secretServiceHost, int secretServicePort) {
        this.resourceServiceHost = resourceServiceHost;
        this.resourceServicePort = resourceServicePort;
        this.secretServiceHost = secretServiceHost;
        this.secretServicePort = secretServicePort;
        this.initialized = true;
    }

    private void checkInitialized() {
        if (!initialized) {
            throw new IllegalStateException("GCS Metadata Collector is not initialized");
        }
    }

    @Override
    public FileResourceMetadata getFileResourceMetadata(String resourceId, String credentialToken) throws Exception {
        checkInitialized();
        ResourceServiceClient resourceClient = ResourceServiceClientBuilder.buildClient(resourceServiceHost, resourceServicePort);
        GCSResource gcsResource = resourceClient.gcs().getGCSResource(GCSResourceGetRequest.newBuilder().setResourceId(resourceId).build());

        SecretServiceClient secretClient = SecretServiceClientBuilder.buildClient(secretServiceHost, secretServicePort);
        GCSSecret gcsSecret = secretClient.gcs().getGCSSecret(GCSSecretGetRequest.newBuilder().setSecretId(credentialToken).build());

        HttpTransport transport = GoogleNetHttpTransport.newTrustedTransport();
        JsonFactory jsonFactory = new JacksonFactory();
        String jsonString = gcsSecret.getCredentialsJson();
        GoogleCredential credential = GoogleCredential.fromStream(new ByteArrayInputStream(jsonString.getBytes(StandardCharsets.UTF_8)), transport, jsonFactory);
        if (credential.createScopedRequired()) {
            Collection<String> scopes = StorageScopes.all();
            credential = credential.createScoped(scopes);
        }

        Storage storage = new Storage.Builder(transport, jsonFactory, credential).build();

        FileResourceMetadata metadata = new FileResourceMetadata();
        StorageObject gcsMetadata = storage.objects().get(gcsResource.getGcsStorage().getBucketName(),
                                                            gcsResource.getFile().getResourcePath()).execute();
        metadata.setResourceSize(gcsMetadata.getSize().longValue());
        String md5Sum = String.format("%032x", new BigInteger(1, Base64.getDecoder().decode(gcsMetadata.getMd5Hash())));
        metadata.setMd5sum(md5Sum);
        metadata.setUpdateTime(gcsMetadata.getTimeStorageClassUpdated().getValue());
        metadata.setCreatedTime(gcsMetadata.getTimeCreated().getValue());
        return metadata;
    }

    @Override
    public FileResourceMetadata getFileResourceMetadata(String parentResourceId, String resourcePath, String credentialToken) throws Exception {
        throw new UnsupportedOperationException("Method not implemented");
    }

    @Override
    public DirectoryResourceMetadata getDirectoryResourceMetadata(String resourceId, String credentialToken) throws Exception {
        throw new UnsupportedOperationException("Method not implemented");    }

    @Override
    public DirectoryResourceMetadata getDirectoryResourceMetadata(String parentResourceId, String resourcePath, String credentialToken) throws Exception {
        throw new UnsupportedOperationException("Method not implemented");
    }

    @Override
    public Boolean isAvailable(String resourceId, String credentialToken) throws Exception {
        checkInitialized();
        ResourceServiceClient resourceClient = ResourceServiceClientBuilder.buildClient(resourceServiceHost, resourceServicePort);
        GCSResource gcsResource = resourceClient.gcs().getGCSResource(GCSResourceGetRequest.newBuilder().setResourceId(resourceId).build());

        SecretServiceClient secretClient = SecretServiceClientBuilder.buildClient(secretServiceHost, secretServicePort);
        GCSSecret gcsSecret = secretClient.gcs().getGCSSecret(GCSSecretGetRequest.newBuilder().setSecretId(credentialToken).build());

        HttpTransport transport = GoogleNetHttpTransport.newTrustedTransport();
        JsonFactory jsonFactory = new JacksonFactory();
        String jsonString = gcsSecret.getCredentialsJson();
        GoogleCredential credential = GoogleCredential.fromStream(new ByteArrayInputStream(jsonString.getBytes(StandardCharsets.UTF_8)), transport, jsonFactory);
        if (credential.createScopedRequired()) {
            Collection<String> scopes = StorageScopes.all();
            credential = credential.createScoped(scopes);
        }

        Storage storage = new Storage.Builder(transport, jsonFactory, credential).build();
        switch (gcsResource.getResourceCase().name()){
            case ResourceTypes.FILE:
                return !storage.objects().get(gcsResource.getGcsStorage().getBucketName(), gcsResource.getFile().getResourcePath())
                                            .execute().isEmpty();
            case ResourceTypes.DIRECTORY:
                return !storage.objects().get(gcsResource.getGcsStorage().getBucketName(), gcsResource.getDirectory().getResourcePath())
                                            .execute().isEmpty();
        }
        return false;
    }
}