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/*bin/mkdir /tmp/strip 2> /dev/null
javac -d /tmp/strip $0
java -cp /tmp/strip Strip "$@"
exit
*/

import java.io.BufferedInputStream;
import java.io.BufferedOutputStream;
import java.io.BufferedWriter;
import java.io.File;
import java.io.FileInputStream;
import java.io.FileOutputStream;
import java.io.FileWriter;
import java.io.IOException;
import java.io.RandomAccessFile;
import java.util.ArrayList;
import java.util.Arrays;
import java.util.Iterator;
import java.util.LinkedHashSet;
import java.util.List;
import java.util.Set;
import java.util.regex.Matcher;
import java.util.regex.Pattern;

public class Strip {

  private final Pattern pattern;
  private final Set<File> files;
  private boolean clobber;

  public Strip(Pattern pattern, Set<File> files, boolean clobber) {
    this.pattern = pattern;
    this.files = files;
    this.clobber = clobber;
  }

  private void strip() throws IOException {
    for (File file : files) {
      FileCharSequence fileCharSequence = new FileCharSequence(file);

      File stripped = File.createTempFile(file.getName(), ".strip");
      BufferedWriter out = new BufferedWriter(new FileWriter(stripped));
      int numberFound = 0;

      // strip to a copy
      int position = 0;
      Matcher matcher = pattern.matcher(fileCharSequence);
      while (matcher.find(position)) {
        out.append(fileCharSequence.subSequence(position, matcher.start()));
        position = matcher.end();
        numberFound++;
      }
      out.append(fileCharSequence.subSequence(position, fileCharSequence.length()));
      out.close();
      fileCharSequence.close();

      // move copy over original
      if (numberFound > 0) {
        if (clobber) {
          copy(stripped, file);
          System.out.println("Stripped " + numberFound + " from " + file);
        } else {
          System.out.println("Stripped " + numberFound + " from " + file + " at " + stripped);
        }
      } else {
        System.out.println("No occurrences in " + file + ", stripped file is " + stripped);
      }
    }
  }

  private void copy(File source, File target) throws IOException {
    byte[] buffer = new byte[1024];
    BufferedInputStream in = new BufferedInputStream(new FileInputStream(source));
    BufferedOutputStream out = new BufferedOutputStream(new FileOutputStream(target));

    int read;
    while ((read = in.read(buffer)) != -1) {
      out.write(buffer, 0, read);
    }

    in.close();
    out.close();
  }

  static class FileCharSequence implements CharSequence {

    final RandomAccessFile randomAccess;
    final long start;
    final long end;

    public FileCharSequence(File file) throws IOException {
      randomAccess = new RandomAccessFile(file, "r");
      start = 0;
      end = randomAccess.length();
    }

    private FileCharSequence(FileCharSequence prototype, long start, long end) {
      this.randomAccess = prototype.randomAccess;
      this.start = start;
      this.end = end;
    }

    public int length() {
      return (int) (end - start);
    }

    public char charAt(int index) {
      try {
        randomAccess.seek(start + index);
        return (char) randomAccess.read();
      } catch (IOException e) {
        throw new RuntimeException(e);
      }
    }

    public CharSequence subSequence(int start, int end) {
      return new FileCharSequence(this, this.start + start, this.start + end);
    }

    public void close() throws IOException {
      randomAccess.close();
    }

    @Override public String toString() {
      try {
        byte[] bytes = new byte[length()];
        randomAccess.seek(start);
        randomAccess.readFully(bytes);
        return new String(bytes, "ISO-8859-1");
      } catch (IOException e) {
        throw new RuntimeException(e);
      }
    }
  }

  public static void main(String[] args) throws IOException {
    boolean clobber = false;

    List<String> argsList = new ArrayList<String>(Arrays.asList(args));
    for (Iterator<String> a = argsList.iterator(); a.hasNext(); ) {
      String arg = a.next();
      if ("-c".equals(arg) || "--clobber".equals(arg)) {
        clobber = true;
        a.remove();
      }
    }

    if (argsList.size() < 2) {
      printUsage();
      System.exit(1);
    }

    Pattern pattern = Pattern.compile(argsList.get(0));

    Set<File> files = new LinkedHashSet<File>();
    for (String file : argsList.subList(1, argsList.size())) {
      files.add(new File(file));
    }

    new Strip(pattern, files, clobber).strip();
  }

  public static void printUsage() {
    System.out.println("Usage: Strip <regex> [files]");
    System.out.println();
    System.out.println("  regex: a Java regular expression, with groups");
    System.out.println("  http://java.sun.com/javase/6/docs/api/java/util/regex/Pattern.html");
    System.out.println("         you can (parenthesize) groups");
    System.out.println("         \\s whitespace");
    System.out.println("         \\S non-whitespace");
    System.out.println("         \\w word characters");
    System.out.println("         \\W non-word");
    System.out.println();
    System.out.println("  files: files to strip. These will be overwritten!");
    System.out.println();
    System.out.println("flags:");
    System.out.println("  --clober: overwrite the passed in files rather than creating new ones");
    System.out.println("       -c:");
    System.out.println();
    System.out.println("  Use 'single quotes' to prevent bash from interfering");
    System.out.println();
  }
}