import java.io.File;
import java.io.FileReader;
import java.io.FileWriter;
import java.io.IOException;
import java.io.PrintWriter;
import java.util.Scanner;

import javax.swing.JFileChooser;
import javax.swing.JOptionPane;

/*
 * Created on Apr 26, 2006
 * Demonstration of String handling via Regular Expressions
 */
public class BasicRegEx {

	/**
	 * Standard entry for all Java programs
	 * @param args
	 */
	public static void main(String[] args) {
		new BasicRegEx().start();
	}

	private void start() {
		String filename = null; // without path spec, JVM assumes the file is in the project directory

//		JFileChooser jfc = new JFileChooser(); // starts in My Documents folder
		JFileChooser jfc = new JFileChooser("."); // starts in working folder (project folder)
		jfc.setDialogTitle("Please enter the name of a text file to read");
		jfc.setFileFilter( new CustomFilter() );

		int status;
		status = jfc.showDialog(null, "Press me!"); // "generic" dialog with customizable "approve" button
		//			status = jfc.showOpenDialog(null); // has an "open" button 
		//			status = jfc.showSaveDialog(null); // has a "save" button

		if( status == JFileChooser.APPROVE_OPTION ) { // "Open" button was pressed
			File selected = jfc.getSelectedFile();
			filename = selected.getName();
			System.out.println(filename);
		} else { // Cancel was pressed
			System.exit(0);
		}

		// try reading or writing a file, based on the user's choice
		try {
			String contents = readTextFile( filename );
			saveTextFile( "copy of " + filename, contents );
		} catch( IOException e ) { // catch only IOExceptions during read or write
			System.out.println( "IO Error: " + e );
		} catch( Exception e ) { // catch any and all other exceptions during read or write
			System.out.println( "General Error: " + e );
		} // end try
	}

	// read a text file and create a roster from it
	private String readTextFile( String filename ) throws Exception {
		FileReader fr = new FileReader( filename );
		Scanner reader = new Scanner( fr );
		String contents = ""; // initially empty
		try {
			while( reader.hasNextLine() ) { // keep reading as long as there's something to read
				String line = reader.nextLine();
				assert(0==1):"ERROR";
				if( containsPattern(line ) )
					System.out.println(line + " :contains Pattern");
				contents += line + "\n";
			}
			return contents;
		} finally { // guarantees that this code block will execute before exiting the method,
			// whether an exception was thrown or not.
			System.out.println("Closing file reader");
			reader.close();
		}
	}

	// save the roster to a text file
	private void saveTextFile(String filename, String contents) throws Exception {
		// attach to a File object (file or directory) 
		File fileObject = new File( filename );
		FileWriter fw = new FileWriter( fileObject, false ); // use 'false' to overwrite an existing file
		//		FileWriter fw = new FileWriter( filename, true ); // alternate FileWriter construction
		PrintWriter pw = new PrintWriter(fw);
		//		PrintWriter pw = new PrintWriter(filename); // alternate PrintWriter construction

		try {
			pw.print( contents );
		} finally {
			pw.close(); // good behavior + it guarantees the data is flushed to the file
		}
	}

	private boolean containsPattern( String s) {
		if( s.matches(".*[0-9].*") ) // any occurrence of digits 
// 		if( s.matches("[a-zA-Z ]*") ) // any occurrence of letters or blanks
//		if( s.matches(".*[jJ]ava.*") ) // any occurrence of "Java" or "java"
//		if( s.matches( ".*[a-zA-Z ]+[0-9][0-9].*" )) // any letters or blank followed by 2 digits
//			if( s.matches( ".*[a-zA-Z ]{2}[0-9]{4}.*" )) // two letters or blank followed by 2 digits
			return true;
		else
			return false;
	}

	/*

		for( String s : myList ) {
			// replaces entire line containing a time sequence
			// If we want to replace just the time sequence and leave the remaining
			// components of the line in place, we have to use find() instead.
			s=s.replaceAll(".*[1-9]:[0-9][0-9]","time TBD");
			   System.out.println(s);
		}
	 */

	/**
	 * Custom FileFilter
	 * @author hornick
	 *
	 */
	private class CustomFilter extends javax.swing.filechooser.FileFilter {

		@Override
		/*
		 * sets what files are accepted
		 */
		public boolean accept(File file) {
			if( file.isDirectory() ) // directory
				return true;

			if( file.getName().toLowerCase().endsWith(".txt") ) // text file
				return true;

			return false;
		}

		@Override
		/*
		 * the label of the filter
		 */
		public String getDescription(){
			return ".txt files";
		}
	}
}