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/*************************************************************************
 * ADOBE CONFIDENTIAL
 * ___________________
 *
 * Copyright 2016 Adobe
 * All Rights Reserved.
 *
 * NOTICE: All information contained herein is, and remains
 * the property of Adobe and its suppliers, if any. The intellectual
 * and technical concepts contained herein are proprietary to Adobe
 * and its suppliers and are protected by all applicable intellectual
 * property laws, including trade secret and copyright laws.
 * Dissemination of this information or reproduction of this material
 * is strictly forbidden unless prior written permission is obtained
 * from Adobe.
 **************************************************************************/
package com.adobe.granite.crx2oak.util.filesystem;

import com.adobe.granite.crx2oak.model.Topics;
import com.adobe.granite.crx2oak.pipeline.InputAggregatingComponent;
import com.adobe.granite.crx2oak.pipeline.PipeData;
import com.google.common.base.Optional;
import org.slf4j.Logger;
import org.slf4j.LoggerFactory;

import javax.annotation.Nonnull;
import java.io.File;
import java.io.IOException;

import static com.adobe.granite.crx2oak.util.FilesystemUtils.getCurrentTimestampFilenameSuffix;
import static com.google.common.base.Preconditions.checkNotNull;
import static java.lang.String.format;

/**
 * The processor that activates the candidate directory (if exist) into a blessed directory (that might
 * exist or not). If blessed directory exists it will be deactivated as the old backup directory.
 *
 * FIXME change to support move operation across filesystems instead of just rename
 */
public class DirectoryActivator extends InputAggregatingComponent {

    private static final String LOGGER_PLACEHOLDER = "{}";
    private static final String STRING_FORMAT_PLACEHOLDER = "%s";
    private final Logger log = LoggerFactory.getLogger(DirectoryActivator.class);
    private final String ERROR_MSG = "Could not move directory: {} into: {}. You need to manually swap directories";

    private final File blessedDirectory;
    private final File candidateDirectory;
    private final File backupDirectory;

    /**
     * Create a processor with the specific directories: candidate one and blessed one and with backup suffix
     * that will be used optionally if blessed directory needs to be first archived.
     *
     * @param blessedDirectory the blessed directory (might exist or not)
     * @param candidateDirectory the candidate directory (that should exist before using {@linkplain #process(com.adobe.granite.crx2oak.pipeline.PipeData)})
     * @param partialBackupSuffix the mandatory backup suffix that will be used only in some cases
     * @throws IOException when there is a problem with calculating canonical paths from the given directories
     */
    public DirectoryActivator(@Nonnull final File blessedDirectory,
                              @Nonnull final File candidateDirectory,
                              @Nonnull final String partialBackupSuffix) throws IOException {
        checkNotNull(blessedDirectory);
        checkNotNull(candidateDirectory);
        checkNotNull(partialBackupSuffix);
        this.blessedDirectory = blessedDirectory.getCanonicalFile();
        this.candidateDirectory = candidateDirectory.getCanonicalFile();
        final String fullSuffix = "-" + partialBackupSuffix + "backup-" + getCurrentTimestampFilenameSuffix();
        backupDirectory = new File(this.blessedDirectory.getAbsolutePath() + fullSuffix);
    }

    @Override
    protected PipeData preprocess(final PipeData input) {
        final Optional optWarning = blessedDirectory.exists()
                ? deactivatePreviouslyBlessedAndBlessACandidate() : blessACandidateDirectory();
        return optWarning.isPresent()
                ? PipeData.join(input, Topics.WARNINGS, optWarning.get()).toPipe()
                : PipeData.EMPTY;
    }

    private Optional deactivatePreviouslyBlessedAndBlessACandidate() {
        return blessedDirectory.renameTo(backupDirectory)
                ? blessACandidateDirectory() : announceMoveError(this.blessedDirectory, this.backupDirectory);
    }

    private Optional blessACandidateDirectory() {
        return !candidateDirectory.renameTo(blessedDirectory)
                ? announceMoveError(candidateDirectory, blessedDirectory) : Optional.absent();
    }

    private Optional announceMoveError(final File fromDir, final File toDir) {
        log.error(ERROR_MSG, fromDir, toDir);
        return Optional.of(format(getStringFormatMessage(ERROR_MSG), fromDir, toDir));
    }

    private String getStringFormatMessage(final String loggerErrorMessage) {
        return loggerErrorMessage.replace(LOGGER_PLACEHOLDER, STRING_FORMAT_PLACEHOLDER);
    }
}