/*
 * Copyright (C) 2023 Laurent CLOUET
 * Author Laurent CLOUET <laurent.clouet@nopnop.net>
 *
 * This program is free software; you can redistribute it and/or
 * modify it under the terms of the GNU General Public License
 * as published by the Free Software Foundation; version 2
 * of the License.
 *
 * This program is distributed in the hope that it will be useful,
 * but WITHOUT ANY WARRANTY; without even the implied warranty of
 * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
 * GNU General Public License for more details.
 *
 * You should have received a copy of the GNU General Public License
 * along with this program; if not, write to the Free Software
 * Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA  02110-1301, USA.
 */

package com.sheepit.client;

import com.sheepit.client.datamodel.Chunk;
import lombok.AllArgsConstructor;

import java.io.File;
import java.io.IOException;
import java.nio.file.FileSystemException;
import java.nio.file.Files;
import java.nio.file.Path;
import java.nio.file.Paths;
import java.nio.file.StandardCopyOption;

@AllArgsConstructor
public class DirectoryManager {
	private Configuration configuration;
	private Log log;
	
	public String getActualStoragePathFor(Chunk chunk) {
		return isSharedEnabled() ? getSharedPathFor(chunk) : getCachePathFor(chunk);
	}
	
	public String getCachePathFor(Chunk chunk) {
		return configuration.getWoolCacheDirectory().getAbsolutePath() + File.separator + chunk.getId() + ".wool";
	}
	
	public String getSharedPathFor(Chunk chunk) {
		return configuration.getSharedDownloadsDirectory().getAbsolutePath() + File.separator + chunk.getId() + ".wool";
	}
	
	public boolean isSharedEnabled() {
		return configuration.getSharedDownloadsDirectory() != null && configuration.getSharedDownloadsDirectory().exists();
	}
	
	public boolean copyChunkFromSharedToCache(Chunk chunk) {
		return copyFileFromSharedToCache(getSharedPathFor(chunk), getCachePathFor(chunk));
	}
	
	private boolean copyFileFromSharedToCache(String source, String target) {
		Path existingArchivePath = Paths.get(source);
		Path targetArchivePath = Paths.get(target);
		
		if (existingArchivePath.equals(targetArchivePath)) {
			// target are the same, do nothing
			return true;
		}
		
		try {
			Files.deleteIfExists(targetArchivePath);  // createLink only works if the target does not exist
			try {
				Files.createLink(targetArchivePath, existingArchivePath);
				log.debug("Created hardlink from " + targetArchivePath + " to " + existingArchivePath);
			}
			catch (UnsupportedOperationException // underlying file system does not support hard-linking
				   | FileSystemException       // cache-dir and shared-zip are on separate file systems, even though hard-linking is supported
				   | SecurityException         // user is not allowed to create hard-links
				ignore) {
				// Creating hardlinks might not be supported on some filesystems
				log.debug("Failed to create hardlink, falling back to copying file to " + targetArchivePath);
				Files.copy(existingArchivePath, targetArchivePath, StandardCopyOption.REPLACE_EXISTING);
			}
		}
		catch (IOException e) {
			log.error("Error while copying " + source + " from shared downloads directory to working dir");
			return false;
		}
		
		return true;
	}
}