/**
    * Copyright 2010-2013 The Kuali Foundation
    *
    * Licensed under the Educational Community 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.opensource.org/licenses/ecl2.php
    *
   * 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.
   */
  package org.kuali.common.util;
  
  import java.io.File;
  import java.io.IOException;
  import java.util.ArrayList;
  import java.util.Arrays;
  import java.util.List;
  
  import org.apache.commons.io.FileUtils;
  import org.apache.commons.lang3.StringUtils;
  import org.slf4j.Logger;
  import org.slf4j.LoggerFactory;
  
  public class FileSystemUtils {
  
  	private static final Logger logger = LoggerFactory.getLogger(FileSystemUtils.class);
  
  	/**
  	 * Examine the contents of a text file, stopping as soon as it contains <code>token</code>, or <code>timeout</code> is exceeded, whichever comes first.
  	 */
  	public static MonitorTextFileResult monitorTextFile(File file, String token, int intervalMillis, int timeoutMillis, String encoding) {
  
  		// Make sure we are configured correctly
  		Assert.notNull(file, "file is null");
  		Assert.hasText(token, "token has no text");
  		Assert.hasText(encoding, "encoding has no text");
  		Assert.isTrue(intervalMillis > 0, "interval must be a positive integer");
  		Assert.isTrue(intervalMillis > 0, "timeout must be a positive integer");
  
  		// Setup some member variables to record what happens
  		long start = System.currentTimeMillis();
  		long stop = start + timeoutMillis;
  		boolean exists = false;
  		boolean contains = false;
  		boolean timeoutExceeded = false;
  		long now = -1;
  		String content = null;
  
  		// loop until timeout is exceeded or we find the token inside the file
  		for (;;) {
  
  			// Always pause (unless this is the first iteration)
  			if (now != -1) {
  				ThreadUtils.sleep(intervalMillis);
  			}
  
  			// Check to make sure we haven't exceeded our timeout limit
  			now = System.currentTimeMillis();
  			if (now > stop) {
  				timeoutExceeded = true;
  				break;
  			}
  
  			// If the file does not exist, no point in going any further
  			exists = LocationUtils.exists(file);
  			if (!exists) {
  				continue;
  			}
  
  			// The file exists, check to see if the token we are looking for is present in the file
  			content = LocationUtils.toString(file, encoding);
  			contains = StringUtils.contains(content, token);
  			if (contains) {
  				// We found what we are looking for, we are done
  				break;
  			}
  		}
  
  		// Record how long the overall process took
  		long elapsed = now - start;
  
  		// Fill in a pojo detailing what happened
  		MonitorTextFileResult mtfr = new MonitorTextFileResult(exists, contains, timeoutExceeded, elapsed);
  		mtfr.setAbsolutePath(LocationUtils.getCanonicalPath(file));
  		mtfr.setContent(content);
  		return mtfr;
  	}
  
  	public static List<SyncResult> syncFiles(List<SyncRequest> requests) throws IOException {
  		List<SyncResult> results = new ArrayList<SyncResult>();
  		for (SyncRequest request : requests) {
  			SyncResult result = syncFiles(request);
  			results.add(result);
  		}
 		return results;
 	}
 
 	public static SyncResult syncFiles(SyncRequest request) throws IOException {
 		logger.info("Sync [{}] -> [{}]", request.getSrcDir(), request.getDstDir());
 		List<File> dstFiles = getAllFiles(request.getDstDir());
 		List<File> srcFiles = request.getSrcFiles();
 
 		List<String> dstPaths = getRelativePaths(request.getDstDir(), dstFiles);
 		List<String> srcPaths = getRelativePaths(request.getSrcDir(), srcFiles);
 
 		List<String> adds = new ArrayList<String>();
 		List<String> updates = new ArrayList<String>();
 		List<String> deletes = new ArrayList<String>();
 
 		for (String srcPath : srcPaths) {
 			boolean existing = dstPaths.contains(srcPath);
 			if (existing) {
 				updates.add(srcPath);
 			} else {
 				adds.add(srcPath);
 			}
 		}
 		for (String dstPath : dstPaths) {
 			boolean extra = !srcPaths.contains(dstPath);
 			if (extra) {
 				deletes.add(dstPath);
 			}
 		}
 
 		copyFiles(request.getSrcDir(), request.getSrcFiles(), request.getDstDir());
 
 		SyncResult result = new SyncResult();
 		result.setAdds(getFullPaths(request.getDstDir(), adds));
 		result.setUpdates(getFullPaths(request.getDstDir(), updates));
 		result.setDeletes(getFullPaths(request.getDstDir(), deletes));
 		return result;
 	}
 
 	protected static void copyFiles(File srcDir, List<File> files, File dstDir) throws IOException {
 		for (File file : files) {
 			String relativePath = getRelativePath(srcDir, file);
 			File dstFile = new File(dstDir, relativePath);
 			FileUtils.copyFile(file, dstFile);
 		}
 	}
 
 	protected static List<File> getFullPaths(File dir, List<String> relativePaths) {
 		List<File> files = new ArrayList<File>();
 		for (String relativePath : relativePaths) {
 			File file = new File(dir, relativePath);
 			files.add(file);
 		}
 		return files;
 	}
 
 	protected static List<String> getRelativePaths(File dir, List<File> files) {
 		List<String> relativePaths = new ArrayList<String>();
 		for (File file : files) {
 			String relativePath = getRelativePath(dir, file);
 			relativePaths.add(relativePath);
 		}
 		return relativePaths;
 	}
 
 	protected static String getRelativePath(File dir, File file) {
 		String dirPath = LocationUtils.getCanonicalPath(dir);
 		String filePath = LocationUtils.getCanonicalPath(file);
 		if (!StringUtils.contains(filePath, dirPath)) {
 			throw new IllegalArgumentException(file + " does not reside under " + dir);
 		}
 		return StringUtils.remove(filePath, dirPath);
 	}
 
 	protected static List<File> getAllFiles(File dir) {
 		SimpleScanner scanner = new SimpleScanner(dir, Arrays.asList("**/*"), Arrays.asList("**/.svn/**", "**/.git/**"));
 		return scanner.getFiles();
 	}
 
 }