package org.apache.archiva.policies;

/*
 * 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 org.apache.archiva.checksum.ChecksumAlgorithm;
import org.apache.archiva.checksum.ChecksummedFile;
import org.apache.archiva.checksum.UpdateStatus;
import org.apache.archiva.repository.storage.StorageAsset;
import org.apache.commons.lang3.StringUtils;
import org.slf4j.Logger;
import org.slf4j.LoggerFactory;
import org.springframework.stereotype.Service;

import java.io.IOException;
import java.nio.file.Files;
import java.nio.file.Path;
import java.util.ArrayList;
import java.util.Arrays;
import java.util.List;
import java.util.Properties;

/**
 * ChecksumPolicy - a policy applied after the download to see if the file has been downloaded
 * successfully and completely (or not).
 *
 *
 */
@Service( "postDownloadPolicy#checksum" )
public class ChecksumPolicy
    extends AbstractPolicy implements PostDownloadPolicy
{
    private Logger log = LoggerFactory.getLogger( ChecksumPolicy.class );

    private static final String ID = "checksum";

    /**
     * The IGNORE policy indicates that if the checksum policy is ignored, and
     * the state of, contents of, or validity of the checksum files are not
     * checked.
     */
    public static final ChecksumOption IGNORE = ChecksumOption.IGNORE;

    /**
     * The FAIL policy indicates that if the checksum does not match the
     * downloaded file, then remove the downloaded artifact, and checksum
     * files, and fail the transfer to the client side.
     */
    public static final ChecksumOption FAIL = ChecksumOption.FAIL;

    /**
     * The FIX policy indicates that if the checksum does not match the
     * downloaded file, then fix the checksum file locally, and return
     * to the client side the corrected checksum.
     */
    public static final ChecksumOption FIX = ChecksumOption.FIX;

    private List<ChecksumAlgorithm> algorithms = Arrays.asList( ChecksumAlgorithm.SHA256, ChecksumAlgorithm.SHA1, ChecksumAlgorithm.MD5 );

    private List<PolicyOption> options = new ArrayList<>( 3 );

    public ChecksumPolicy()
    {
        super();
        options.add( FAIL );
        options.add( FIX );
        options.add( IGNORE );
    }

    @Override
    public void applyPolicy( PolicyOption policySetting, Properties request, StorageAsset localFile )
        throws PolicyViolationException, PolicyConfigurationException
    {
        if ( "resource".equals( request.getProperty( "filetype" ) ) )
        {
            return;
        }

        if ( !options.contains( policySetting ) )
        {
            // Not a valid code. 
            throw new PolicyConfigurationException(
                "Unknown checksum policy setting [" + policySetting + "], valid settings are [" + StringUtils.join(
                    options.iterator(), "," ) + "]" );
        }

        if ( IGNORE.equals( policySetting ) )
        {
            // Ignore.
            log.debug( "Checksum policy set to IGNORE." );
            return;
        }

        if ( !localFile.exists() )
        {
            // Local File does not exist.
            throw new PolicyViolationException(
                "Checksum policy failure, local file " + localFile.getPath() + " does not exist to check." );
        }

        if ( FAIL.equals( policySetting ) && localFile.isFileBased() )
        {
            ChecksummedFile checksum = new ChecksummedFile( localFile.getFilePath() );
            if ( checksum.isValidChecksums( algorithms ) )
            {
                return;
            }

            for ( ChecksumAlgorithm algorithm : algorithms )
            {
                Path file = checksum.getChecksumFile( algorithm );
                try
                {
                    Files.deleteIfExists( file );
                }
                catch ( IOException e )
                {
                    log.error("Could not delete file {}", file);
                }
            }

            try
            {
                localFile.getStorage().removeAsset( localFile );
            }
            catch ( IOException e )
            {
                log.error("Could not delete file {}", localFile);
            }
            throw new PolicyViolationException(
                "Checksums do not match, policy set to FAIL, " + "deleting checksum files and local file "
                    + localFile.getPath() + "." );
        }

        if ( FIX.equals( policySetting ) && localFile.isFileBased())
        {
            ChecksummedFile checksum = new ChecksummedFile( localFile.getFilePath() );
            if ( checksum.fixChecksums( algorithms ).getTotalStatus() != UpdateStatus.ERROR )
            {
                log.debug( "Checksum policy set to FIX, checksum files have been updated." );
                return;
            }
            else
            {
                throw new PolicyViolationException(
                    "Checksum policy set to FIX, " + "yet unable to update checksums for local file "
                        + localFile.getPath() + "." );
            }
        }

        throw new PolicyConfigurationException(
            "Unable to process checksum policy of [" + policySetting + "], please file a bug report." );
    }

    @Override
    public PolicyOption getDefaultOption()
    {
        return FIX;
    }

    @Override
    public String getId()
    {
        return ID;
    }

    @Override
    public List<PolicyOption> getOptions()
    {
        return options;
    }
}