package org.eclipse.aether.internal.impl;

/*
 * 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.
 */

import javax.inject.Named;
import javax.inject.Singleton;

import java.io.BufferedInputStream;
import java.io.BufferedOutputStream;
import java.io.File;
import java.io.IOException;
import java.io.InputStream;
import java.io.OutputStream;
import java.io.UncheckedIOException;
import java.nio.ByteBuffer;
import java.nio.charset.StandardCharsets;
import java.nio.file.Files;
import java.nio.file.StandardCopyOption;

import org.eclipse.aether.spi.io.FileProcessor;
import org.eclipse.aether.util.ChecksumUtils;
import org.eclipse.aether.util.FileUtils;

/**
 * A utility class helping with file-based operations.
 */
@Singleton
@Named
public class DefaultFileProcessor
        implements FileProcessor
{

    /**
     * Thread-safe variant of {@link File#mkdirs()}. Creates the directory named by the given abstract pathname,
     * including any necessary but nonexistent parent directories. Note that if this operation fails it may have
     * succeeded in creating some of the necessary parent directories.
     *
     * @param directory The directory to create, may be {@code null}.
     * @return {@code true} if and only if the directory was created, along with all necessary parent directories;
     * {@code false} otherwise
     */
    public boolean mkdirs( File directory )
    {
        if ( directory == null )
        {
            return false;
        }

        if ( directory.exists() )
        {
            return false;
        }
        if ( directory.mkdir() )
        {
            return true;
        }

        File canonDir;
        try
        {
            canonDir = directory.getCanonicalFile();
        }
        catch ( IOException e )
        {
            throw new UncheckedIOException( e );
        }

        File parentDir = canonDir.getParentFile();
        return ( parentDir != null && ( mkdirs( parentDir ) || parentDir.exists() ) && canonDir.mkdir() );
    }

    public void write( File target, String data )
            throws IOException
    {
        FileUtils.writeFile( target.toPath(), p -> Files.write( p, data.getBytes( StandardCharsets.UTF_8 ) ) );
    }

    public void write( File target, InputStream source )
            throws IOException
    {
        FileUtils.writeFile( target.toPath(), p -> Files.copy( source, p, StandardCopyOption.REPLACE_EXISTING ) );
    }

    public void copy( File source, File target )
            throws IOException
    {
        copy( source, target, null );
    }

    public long copy( File source, File target, ProgressListener listener )
            throws IOException
    {
        try ( InputStream in = new BufferedInputStream( Files.newInputStream( source.toPath() ) );
              FileUtils.CollocatedTempFile tempTarget = FileUtils.newTempFile( target.toPath() );
              OutputStream out = new BufferedOutputStream( Files.newOutputStream( tempTarget.getPath() ) ) )
        {
            long result = copy( out, in, listener );
            tempTarget.move();
            return result;
        }
    }

    private long copy( OutputStream os, InputStream is, ProgressListener listener )
            throws IOException
    {
        long total = 0L;
        byte[] buffer = new byte[1024 * 32];
        while ( true )
        {
            int bytes = is.read( buffer );
            if ( bytes < 0 )
            {
                break;
            }

            os.write( buffer, 0, bytes );

            total += bytes;

            if ( listener != null && bytes > 0 )
            {
                try
                {
                    listener.progressed( ByteBuffer.wrap( buffer, 0, bytes ) );
                }
                catch ( Exception e )
                {
                    // too bad
                }
            }
        }

        return total;
    }

    public void move( File source, File target )
            throws IOException
    {
        if ( !source.renameTo( target ) )
        {
            copy( source, target );

            target.setLastModified( source.lastModified() );

            source.delete();
        }
    }

    @Override
    public String readChecksum( final File checksumFile ) throws IOException
    {
        // for now do exactly same as happened before, but FileProcessor is a component and can be replaced
        return ChecksumUtils.read( checksumFile );
    }

    @Override
    public void writeChecksum( final File checksumFile, final String checksum ) throws IOException
    {
        // for now do exactly same as happened before, but FileProcessor is a component and can be replaced
        write( checksumFile, checksum );
    }
}