package org.apache.torque.util;
   
   import java.io.File;
   import java.util.List;
   
   import org.apache.commons.logging.Log;
   import org.apache.commons.logging.LogFactory;
   
   public class ChangeDetector {
  
  	private static final Log log = LogFactory.getLog(ChangeDetector.class);
  	File controlFile;
  	List<File> files;
  
  	public ChangeDetector() {
  		this(null, null);
  	}
  
  	public ChangeDetector(File controlFile, List<File> files) {
  		super();
  		this.controlFile = controlFile;
  		this.files = files;
  	}
  
  	/**
  	 * Return true if any file in the list of files has a last modified timestamp newer than the control file or if the
  	 * control file does not exist
  	 */
  	public boolean isChanged() {
  		if (!getControlFile().exists()) {
  			log.debug("File " + getControlFile().getAbsolutePath() + " does not exist.  Returning true");
  			return true;
  		}
  		long lastModified = getControlFile().lastModified();
  		for (File file : getFiles()) {
  			if (file.lastModified() > lastModified) {
  				log.debug("File " + file.getAbsolutePath() + " was modified after " + getControlFile().getAbsolutePath() + " was last modified");
  				return true;
  			}
  		}
  		log.debug("No files were modified.");
  		return false;
  	}
  
  	public File getControlFile() {
  		return controlFile;
  	}
  
  	public void setControlFile(File controlFile) {
  		this.controlFile = controlFile;
  	}
  
  	public List<File> getFiles() {
  		return files;
  	}
  
  	public void setFiles(List<File> files) {
  		this.files = files;
  	}
  }