/*
 * Licensed to Elasticsearch under one or more contributor
 * license agreements. See the NOTICE file distributed with
 * this work for additional information regarding copyright
 * ownership. Elasticsearch 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.elasticsearch.common.blobstore.url;

import org.elasticsearch.common.SuppressForbidden;
import org.elasticsearch.common.blobstore.BlobContainer;
import org.elasticsearch.common.blobstore.BlobMetadata;
import org.elasticsearch.common.blobstore.BlobPath;
import org.elasticsearch.common.blobstore.DeleteResult;
import org.elasticsearch.common.blobstore.support.AbstractBlobContainer;

import java.io.BufferedInputStream;
import java.io.FileNotFoundException;
import java.io.IOException;
import java.io.InputStream;
import java.net.URL;
import java.nio.file.NoSuchFileException;
import java.security.AccessController;
import java.security.PrivilegedActionException;
import java.security.PrivilegedExceptionAction;
import java.util.List;
import java.util.Map;

/**
 * URL blob implementation of {@link org.elasticsearch.common.blobstore.BlobContainer}
 */
public class URLBlobContainer extends AbstractBlobContainer {

    protected final URLBlobStore blobStore;

    protected final URL path;

    /**
     * Constructs new URLBlobContainer
     *
     * @param blobStore blob store
     * @param blobPath  blob path for this container
     * @param path      URL for this container
     */
    public URLBlobContainer(URLBlobStore blobStore, BlobPath blobPath, URL path) {
        super(blobPath);
        this.blobStore = blobStore;
        this.path = path;
    }

    /**
     * Returns URL for this container
     *
     * @return URL for this container
     */
    public URL url() {
        return this.path;
    }

    /**
     * This operation is not supported by URLBlobContainer
     */
    @Override
    public boolean blobExists(String blobName) {
        assert false : "should never be called for a read-only url repo";
        throw new UnsupportedOperationException("URL repository doesn't support this operation");
    }

    /**
     * This operation is not supported by URLBlobContainer
     */
    @Override
    public Map<String, BlobMetadata> listBlobs() throws IOException {
        throw new UnsupportedOperationException("URL repository doesn't support this operation");
    }

    @Override
    public Map<String, BlobContainer> children() throws IOException {
        throw new UnsupportedOperationException("URL repository doesn't support this operation");
    }

    /**
     * This operation is not supported by URLBlobContainer
     */
    @Override
    public Map<String, BlobMetadata> listBlobsByPrefix(String blobNamePrefix) throws IOException {
        throw new UnsupportedOperationException("URL repository doesn't support this operation");
    }

    /**
     * This operation is not supported by URLBlobContainer
     */
    @Override
    public void deleteBlobsIgnoringIfNotExists(List<String> blobNames) {
        throw new UnsupportedOperationException("URL repository is read only");
    }

    @Override
    public DeleteResult delete() {
        throw new UnsupportedOperationException("URL repository is read only");
    }

    @Override
    public InputStream readBlob(String name) throws IOException {
        try {
            return new BufferedInputStream(getInputStream(new URL(path, name)), blobStore.bufferSizeInBytes());
        } catch (FileNotFoundException fnfe) {
            throw new NoSuchFileException("[" + name + "] blob not found");
        }
    }

    @Override
    public InputStream readBlob(String blobName, long position, long length) throws IOException {
        throw new UnsupportedOperationException();
    }

    @Override
    public void writeBlob(String blobName, InputStream inputStream, long blobSize, boolean failIfAlreadyExists) throws IOException {
        throw new UnsupportedOperationException("URL repository doesn't support this operation");
    }

    @Override
    public void writeBlobAtomic(String blobName, InputStream inputStream, long blobSize, boolean failIfAlreadyExists) throws IOException {
        throw new UnsupportedOperationException("URL repository doesn't support this operation");
    }

    @SuppressForbidden(reason = "We call connect in doPrivileged and provide SocketPermission")
    private static InputStream getInputStream(URL url) throws IOException {
        try {
            return AccessController.doPrivileged((PrivilegedExceptionAction<InputStream>) url::openStream);
        } catch (PrivilegedActionException e) {
            throw (IOException) e.getCause();
        }
    }

}
