/*
 *    RegexSearchReplace.java
 *    A task to replace occurences of a given pattern with a given replacement in a given file
 *
 *    Copyright (C) 2005 New Zealand Digital Library, http://www.nzdl.org
 *
 *    This program is free software; you can redistribute it and/or modify
 *    it under the terms of the GNU General Public License as published by
 *    the Free Software Foundation; either version 2 of the License, or
 *    (at your option) any later version.
 *
 *    This program 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 General Public License for more details.
 *
 *    You should have received a copy of the GNU General Public License
 *    along with this program; if not, write to the Free Software
 *    Foundation, Inc., 675 Mass Ave, Cambridge, MA 02139, USA.
 */
package org.greenstone.anttasks;

import java.util.ArrayList;
import org.apache.tools.ant.*;
import org.apache.tools.ant.taskdefs.*;
import java.util.*;
import java.io.*;
import java.util.regex.*;

public class RegexSearchReplace extends Task {

	private File file = null;
	private ArrayList jobs = null;
	private String pattern = null;
	private String replacement = null;
	private boolean winPath = false;

	public static void main( String[] args ) {

		RegexSearchReplace rsr = new RegexSearchReplace();
		rsr.setFile(new File (args[0]));
		rsr.setPattern(args[1]);
		rsr.setReplacement(args[2]);

		rsr.execute();

	}

	public void execute() {

		if ( file == null ) {
			throw new BuildException( "Error - No file specified !!" );
		}

		if ( !file.exists() ) {
			throw new BuildException( "Error - File not found !!" );
		}

		if ( jobs == null && pattern == null ) {
			throw new BuildException( "Error - No pattern attribute and no nested jobs !!" );
		}

		if ( jobs != null && pattern != null ) {
			throw new BuildException( "Error - Both pattern attribute and nested jobs given !!" );
		}

		if ( pattern != null && replacement == null ) {
			throw new BuildException( "Error - pattern attribute given but no replacement attribute given !!" );
		}

		if ( jobs != null ) {
			for ( int i=0; i<jobs.size(); i++ ) {
				if ( ((RegexSearchReplaceJob)(jobs.get(i))).getPattern() == null ) {
					throw new BuildException( "Error - One of the jobs lacks a pattern!!" );
				}
				if ( ((RegexSearchReplaceJob)(jobs.get(i))).getReplacement() == null ) {
					throw new BuildException( "Error - One of the jobs lacks a replacement!!" );
				}
			}
		}

		System.out.println( "Replace in file: " + file );
		if ( pattern != null ) {
			System.out.println( " " + pattern + " -> " + replacement );
		} else {
			for ( int i=0; i<jobs.size(); i++ ) {
				System.out.println( " " + ((RegexSearchReplaceJob)(jobs.get(i))).getPattern() + " -> " + ((RegexSearchReplaceJob)(jobs.get(i))).getReplacement() );
			}
		}

		int noReplaces = 0;

		//create the output stream
		BufferedWriter out = null;
		File temp = null;
		try {
			//create temp file.
			temp = File.createTempFile("rsr", ".tmp");

			//delete temp file when program exits.
			temp.deleteOnExit();

			//writer to temp file
			out = new BufferedWriter( new OutputStreamWriter(new FileOutputStream(temp), "UTF8") );

		} catch (IOException e) {
			throw new BuildException( "Error - Couldn't create or open the temp file" );
		}


		//create the input stream
		BufferedReader in = null;
		try {
			in = new BufferedReader( new InputStreamReader(new FileInputStream(file), "UTF8") );
		} catch ( Exception e ) {
			throw new BuildException( "Error - Couldn't open the specified file" );
		}

		//pass the file through, searching and replacing
		String line = null;
		boolean hasMoreLines = true;
		while ( hasMoreLines ) {

			try {
				line = in.readLine();
			} catch ( Exception e ) {
				System.err.println( e.getMessage() );
				throw new BuildException( "Error - Couldn't read from the specified file" );
			}

			if ( line == null ) {
				hasMoreLines = false;
			} else {

				String oldLine = line;
				if ( pattern != null ) {
					String rp = replacement;
					if ( winPath ) {
						rp = rp.replaceAll("\\\\","\\\\\\\\");
					}
					line = line.replaceAll((String)pattern, (String)rp);
				} else {
					for ( int i=0; i<jobs.size(); i++ ) {
						String rp = ((RegexSearchReplaceJob)(jobs.get(i))).getReplacement();
						if ( ((RegexSearchReplaceJob)(jobs.get(i))).getWinPath() ) {
							rp = rp.replaceAll("\\\\","\\\\\\\\");
						}
						line = line.replaceAll( ((RegexSearchReplaceJob)(jobs.get(i))).getPattern(), rp );
					}
				}

				if ( !oldLine.equals( line ) ) {
					noReplaces++;
				}

				try {
					out.write( line );
					out.newLine();
				} catch ( Exception e ) {
					throw new BuildException( "Error - Couldn't write to the temp file" );
				}
			}
		}
		
		try {
			//close them both up
			in.close();
			out.close();
		} catch ( Exception e ) {
			throw new BuildException( "Error - Couldn't close a file" );
		}


		//copy the new file (temp) over the original
		InputStream i;
		OutputStream o;
		try {
			i = new FileInputStream(temp);
			o = new FileOutputStream(file);

		} catch ( Exception e ) {
			throw new BuildException( "Error - Couldn't open the temp file" );
		}

		try {
	
			// Transfer bytes from in to out
			byte[] buf = new byte[1024];
			int len;
			while ((len = i.read(buf)) > 0) {
			   o.write(buf, 0, len);
			}

			//close them up
			i.close();
			o.close();
		} catch ( Exception e ) {
			throw new BuildException( "Error - Couldn't write to the specified file" );
		}

		if ( noReplaces == 0 ) {
			System.out.println( "No Changes Made" );
		} else if ( noReplaces == 1 ) {
			System.out.println( "Successfully changed 1 line" );
		} else {
			System.out.println( "Successfully changed " + noReplaces + " lines" );
		}

	}

	public void setFile(File file) {
		this.file = file;
	}

	public void setPattern(String pattern) {
		this.pattern = pattern;
	}

	public void setReplacement(String replacement) {
		replacement = replacement.replaceAll( "\\\\", "\\\\\\\\" );
		this.replacement = replacement;
	}

	public void setWinPath( boolean isWinPath ) {
		this.winPath = isWinPath;
	}

	public RegexSearchReplaceJob createJob() {
		RegexSearchReplaceJob job = new RegexSearchReplaceJob();
		if ( jobs == null ) {
			jobs = new ArrayList();
		}
		jobs.add( job );
		return job;

	}

}