AbstractShellLogAccessService.java

package org.lognavigator.service;

import java.io.BufferedReader;
import java.io.IOException;
import java.io.InputStream;
import java.io.InputStreamReader;
import java.nio.charset.Charset;
import java.text.MessageFormat;
import java.util.Date;
import java.util.Set;
import java.util.TreeSet;

import net.schmizz.sshj.common.IOUtils;

import org.lognavigator.bean.FileInfo;
import org.lognavigator.bean.LogAccessConfig;
import org.lognavigator.bean.OsType;
import org.lognavigator.exception.LogAccessException;

import static org.lognavigator.util.Constants.*;

import org.springframework.beans.factory.annotation.Autowired;
import org.springframework.util.FileCopyUtils;

/**
 * Abstract class defining common methods for LogAccessService based on shell commands 
 */
public abstract class AbstractShellLogAccessService implements LogAccessService {
	
	private static final String DIRECTORY_MARKER = "4000";

	private static final String GET_PERL_INFO_COMMAND = "echo DIRECTORY_OK && perl -v";
	private static final String DIRECTORY_OK_MARKER = "DIRECTORY_OK";
	private static final String PERL_INSTALLED_MARKER = "this is perl";
	
	private static final String LS_WITH_GROUP_DIRECTORIES_FIRST_CHECK_COMMAND = "ls -a --group-directories-first | head -1";
	private static final String LS_WITH_GROUP_DIRECTORIES_FIRST_SUPPORTED_MARKER = ".\n";
	

	@Autowired
	protected ConfigService configService;
	
	
	/**
	 * Check and return if host referenced by 'logAccessConfig' has perl installed
	 * @param logAccessConfig log access config to test
	 * @return true if referenced host has perl installed
	 * @throws LogAccessException if a technical error occurs
	 */
	protected boolean isPerlInstalled(LogAccessConfig logAccessConfig) throws LogAccessException {
		if (logAccessConfig.isPerlInstalled() == null) {
			try {
				// Execute command to know if perl is installed
				InputStream resultStream = executeCommand(logAccessConfig.getId(), GET_PERL_INFO_COMMAND);
				// Check if perl is installed
				String result = FileCopyUtils.copyToString(new InputStreamReader(resultStream));
				if (!result.contains(DIRECTORY_OK_MARKER)) {
					throw new LogAccessException("Configuration is invalid : directory " + logAccessConfig.getDirectory() + " does not exist");
				}
				boolean isPerlInstalled = result.toLowerCase().contains(PERL_INSTALLED_MARKER);
				// Update logAccessConfig to cache the information (and not execute command every time)
				logAccessConfig.setPerlInstalled(isPerlInstalled);
			}
			catch (IOException ioe) {
				throw new LogAccessException("Error while reading response of command : " + GET_PERL_INFO_COMMAND, ioe);
			}
		}
		return logAccessConfig.isPerlInstalled();
	}

	/**
	 * Check and return if host referenced by 'logAccessConfig' supports command {@value #LS_WITH_GROUP_DIRECTORIES_FIRST_CHECK_COMMAND}
	 * @param logAccessConfig log access config to test
	 * @return true if referenced host supports command {@value #LS_WITH_GROUP_DIRECTORIES_FIRST_CHECK_COMMAND}
	 * @throws LogAccessException if a technical error occurs
	 */
	protected boolean isLsWithGroupDirectoriesFirstSupported(LogAccessConfig logAccessConfig) throws LogAccessException {
		if (logAccessConfig.isLsWithGroupDirectoriesFirstSupported() == null) {
			try {
				// Execute command to know if command {@value #LS_WITH_GROUP_DIRECTORIES_FIRST_CHECK_COMMAND} is supported
				InputStream resultStream = executeCommand(logAccessConfig.getId(), LS_WITH_GROUP_DIRECTORIES_FIRST_CHECK_COMMAND);
				// Check if command {@value #LS_WITH_GROUP_DIRECTORIES_FIRST_CHECK_COMMAND} is supported
				String result = FileCopyUtils.copyToString(new InputStreamReader(resultStream));
				boolean isLsWithGroupDirectoriesFirstSupported = result.equals(LS_WITH_GROUP_DIRECTORIES_FIRST_SUPPORTED_MARKER);
				// Update logAccessConfig to cache the information (and not execute command every time)
				logAccessConfig.setLsWithGroupDirectoriesFirstSupported(isLsWithGroupDirectoriesFirstSupported);
			}
			catch (IOException ioe) {
				throw new LogAccessException("Error while reading response of command : " + LS_WITH_GROUP_DIRECTORIES_FIRST_CHECK_COMMAND, ioe);
			}
		}
		return logAccessConfig.isLsWithGroupDirectoriesFirstSupported();
	}
	
	@Override
	public Set<FileInfo> listFiles(String logAccessConfigId, String subPath) throws LogAccessException {
		
		// Get the LogAccessConfig
		LogAccessConfig logAccessConfig = configService.getLogAccessConfig(logAccessConfigId);

		// If Perl is not installed : execute a simple 'ls' command
		if (!isPerlInstalled(logAccessConfig)) {
			return listFilesUsingNativeSystem(logAccessConfig, subPath);
		}

		// Avoid trailing / at end of subPath
		if (subPath != null && subPath.endsWith("/") && subPath.length() > 1) {
			subPath = subPath.substring(0, subPath.length() - 1);
		}

		// Construct perl list command based path and maximum file count
		String path = (subPath != null) ? subPath : ".";
		OsType osType = getOSType(logAccessConfig);
		String listCommandPattern = isLsWithGroupDirectoriesFirstSupported(logAccessConfig) ? PERL_LIST_COMMAND_LINUX_GROUP_DIRECTORIES_FIRST : PERL_LIST_COMMAND_FALLBACK;
		String listCommand = MessageFormat.format(listCommandPattern, path, configService.getFileListMaxCount());
		if (osType == OsType.WINDOWS) {
			listCommand = listCommand.replace("\"", "\\\"")
					                 .replace('\'', '"');
		}

		// Execute perl command
		InputStream resultStream = executeCommand(logAccessConfigId, listCommand);
		BufferedReader resultReader = new BufferedReader(new InputStreamReader(resultStream, Charset.forName("UTF-8")));
		
		// Parse the result lines to build FileInfo list
		Set<FileInfo> fileInfos = new TreeSet<FileInfo>();
		StringBuilder potentialErrorMessage = new StringBuilder();
		String line = null;
		
		try {
			while ((line = resultReader.readLine()) != null) {
				
				potentialErrorMessage.append(line).append("\n");

				// Parse the line
				String[] lineTokens = line.split(" ");
				boolean isDirectory = lineTokens[0].equals(DIRECTORY_MARKER);
				long fileSize = Long.parseLong(lineTokens[1]);
				Date lastModified = new Date(Long.parseLong(lineTokens[2]));
				String fileName = lineTokens[3];
				int tokenIndex = 4;
				while (tokenIndex < lineTokens.length) {
					fileName += " " + lineTokens[tokenIndex];
					++tokenIndex;
				}
				
				// Compute relative path prefix
				String relativePathPrefix = "";
				if ("/".equals(subPath)) {
					relativePathPrefix = subPath;
				}
				else if (subPath != null) {
					relativePathPrefix = subPath + "/";
				}
				
				// Build FileInfo bean
				FileInfo fileInfo = new FileInfo();
				fileInfo.setDirectory(isDirectory);
				fileInfo.setFileSize(isDirectory ? 0L : fileSize);
				fileInfo.setLastModified(lastModified);
				fileInfo.setFileName(fileName);
				fileInfo.setLogAccessType(logAccessConfig.getType());
				fileInfo.setRelativePath(relativePathPrefix + fileName);
				fileInfos.add(fileInfo);
			}
			
			// Return list of files
			return fileInfos;
		}
		catch (RuntimeException e) {
			try {
				potentialErrorMessage.append(FileCopyUtils.copyToString(resultReader));
			}
			catch (IOException ioe) {}
			throw new LogAccessException("Error while executing list command.\n " + potentialErrorMessage.toString(), e);
		}
		catch (IOException e) {
			throw new LogAccessException("I/O Error while listing files in path '" + subPath + "'\n" + e.getMessage(), e);
		}
		finally {
			IOUtils.closeQuietly(resultReader);
		}
	}
	
	/**
	 * list files of a path, using native underlying system
	 * @see #listFiles(String, String)
	 */
	protected abstract Set<FileInfo> listFilesUsingNativeSystem(LogAccessConfig logAccessConfig, String subPath) throws LogAccessException;

	/**
	 * Compute and return which OS Type is isntalled on host referenced by 'logAccessConfig'
	 * @param logAccessConfig log access config to test
	 * @return which OS Type is installed on host referenced by 'logAccessConfig'
	 * @throws LogAccessException if a technical error occurs
	 */
	protected abstract OsType getOSType(LogAccessConfig logAccessConfig) throws LogAccessException;

}