/*
 * 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.paimon.data;

import org.apache.paimon.annotation.Public;
import org.apache.paimon.fs.OffsetSeekableInputStream;
import org.apache.paimon.fs.SeekableInputStream;
import org.apache.paimon.utils.IOUtils;
import org.apache.paimon.utils.UriReader;

import java.io.IOException;
import java.util.Objects;

/**
 * A {@link Blob} refers blob in {@link BlobDescriptor}.
 *
 * @since 1.4.0
 */
@Public
public class BlobRef implements Blob {

    /** The maximum safe size of a byte array. Some VMs reserve header words in an array. */
    private static final int MAX_ARRAY_SIZE = Integer.MAX_VALUE - 8;

    private final UriReader uriReader;
    private final BlobDescriptor descriptor;

    public BlobRef(UriReader uriReader, BlobDescriptor descriptor) {
        this.uriReader = uriReader;
        this.descriptor = descriptor;
    }

    @Override
    public byte[] toData() {
        try {
            long length = descriptor.length();
            if (length > MAX_ARRAY_SIZE) {
                throw new IOException(
                        String.format(
                                "Blob is too large to materialize as byte[]: %d, maximum is %d",
                                length, MAX_ARRAY_SIZE));
            }
            try (SeekableInputStream inputStream = newInputStream()) {
                if (length >= 0) {
                    byte[] data = new byte[(int) length];
                    IOUtils.readFully(inputStream, data);
                    return data;
                }
                return IOUtils.readFully(inputStream, false);
            }
        } catch (IOException e) {
            throw new RuntimeException(e);
        }
    }

    @Override
    public BlobDescriptor toDescriptor() {
        return descriptor;
    }

    @Override
    public SeekableInputStream newInputStream() throws IOException {
        return new OffsetSeekableInputStream(
                uriReader.newInputStream(descriptor.uri()),
                descriptor.offset(),
                descriptor.length());
    }

    /** Package-private, see {@link ReusingBlobRefStreamProvider}. */
    UriReader uriReader() {
        return uriReader;
    }

    @Override
    public boolean equals(Object o) {
        if (o == null || getClass() != o.getClass()) {
            return false;
        }
        BlobRef blobRef = (BlobRef) o;
        return Objects.deepEquals(descriptor, blobRef.descriptor);
    }

    @Override
    public int hashCode() {
        return descriptor.hashCode();
    }
}
