/*
 * Copyright 2015-Present Entando S.r.l. (http://www.entando.com) All rights reserved.
 *
 * This library is free software; you can redistribute it and/or modify it under
 * the terms of the GNU Lesser General Public License as published by the Free
 * Software Foundation; either version 2.1 of the License, or (at your option)
 * any later version.
 *
 * This library 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 Lesser General Public License for more
 * details.
 */
package org.entando.entando.aps.system.services.storage;

import java.io.File;
import java.util.regex.Matcher;
import java.util.regex.Pattern;

import org.apache.commons.io.FilenameUtils;
import org.apache.commons.lang3.StringUtils;
import org.slf4j.Logger;
import org.slf4j.LoggerFactory;

public class StorageManagerUtil {

	private static final Logger _logger =  LoggerFactory.getLogger(StorageManagerUtil.class);
	
	public static boolean isValidFilename(String fullname) {
		if (StringUtils.isBlank(fullname)) return false;
		String basename = FilenameUtils.getBaseName(fullname);
		String extension = FilenameUtils.getExtension(fullname);
		return isValidFilename(basename, extension);
	}
	
	public static boolean isValidFilename(String basename, String extension) {
		if (StringUtils.isBlank(basename)) return false;
		if (!isValidPath(basename)) return false;
		if (!isValidFilenameNoExtension(basename)) return false;
		if (StringUtils.isNotBlank(extension)) {
			if (!isValidExtension(extension)) return false;
		}
		return true;
	}
	
	public static boolean isValidFilenameNoExtension(String basename) {
		if (StringUtils.isBlank(basename)) return false;
		Pattern pattern = Pattern.compile(REGEXP_FILE_BASENAME);
		Matcher matcher = pattern.matcher(basename);
		return matcher.matches();
	}

	public static boolean isValidDirName(String basename) {
		if (StringUtils.isBlank(basename)) return true;
		if (!isValidPath(basename)) return false;
		Pattern pattern = Pattern.compile(REGEXP_DIR);
		Matcher matcher = pattern.matcher(basename);
		boolean check = matcher.matches();
		if (!check) return check;
		return endWithParentDir(basename);
	}
	
	public static boolean isValidExtension(String extension) {
		if (StringUtils.isBlank(extension)) return false;
		Pattern pattern = Pattern.compile(REGEXP_FILE_EXTENSION);
		Matcher matcher = pattern.matcher(extension);
		return matcher.matches();
	}
	
	public static boolean isValidPath(String path) {
		final boolean check = true;
		if (StringUtils.isBlank(path)) return check;
		if (path.contains("../") 
				|| path.contains("%2e%2e%2f") 
				|| path.contains("..%2f") 
				|| path.contains(".."+File.separator) 
				|| path.contains("%2e%2e/") 
				|| path.contains("%2e%2e"+File.separator)) {
			_logger.info("Attack avoided - requested path {}", path);
			return !check;
		}
		return check;
	}

	private static boolean endWithParentDir(String path) {
		if (StringUtils.isBlank(path)) return true;
		if (path.endsWith("..") 
				|| path.endsWith("..") 
				|| path.endsWith("%2e%2e")) {
			_logger.info("Attack avoided - requested path {}", path);
			return false;
		}
		return true;
	}
	
	private static final String REGEXP_FILE_EXTENSION = "([\\w|\\-]+?$)";
	private static final String REGEXP_FILE_BASENAME = "(^[\\w|\\.|\\-|\\_| ]+?)";
	private static final String REGEXP_DIR = "(^[\\w|\\.|\\-|\\_|/| ]+?)";
}