import java.util.zip.*;				// for Zip classes
import java.util.*;					// for Date
import java.io.*;   				// for File, IOException

public class ZipInfo {

protected long totalBytes = 0;		// uncompressed bytes in ZIP
protected long zipFileLength;

//-------------------------------------------------------------------
// static main delegates all work to object so we're not stuck in a
// "static universe"
//-------------------------------------------------------------------
public static void main (String[] args) {

	try {
		new ZipInfo().go(args);
	} catch (IOException ioError) {
		System.out.println("An I/O error occurred: " + ioError);
	}
}
//-------------------------------------------------------------------
// ZipInfo main entry point.
//-------------------------------------------------------------------
protected void go(String[] args) throws IOException {
File file;
String tentativeFilename, zipFilename = null;
ZipFile zip = null;
ZipEntry entry;

	if ( args.length != 1 ) {
		System.out.println(
		"Please specify a JAR or ZIP filename (with or without extension).");
		System.exit(10);
	}

	// grab sole command line argument
	tentativeFilename = args[0];

	// turn it into definitive filename
	zipFilename = completeFilename(tentativeFilename);

	file = new File(zipFilename);
	zipFileLength = file.length();

	// open ZIP-compatible file
	try {
		zip = new ZipFile(file);
	} catch (ZipException zipError) {
		System.out.print("ERROR: Problem with zip file: ");
		System.out.println(zipError);
		System.exit(10);
	}

	System.out.println("");
	System.out.println("File : "+ zipFilename);
	System.out.println("");

	// dump neat report on all entries
	System.out.println("Filename\t\tSize\tModification Date");
	System.out.println("--------\t\t----\t-----------------");

	Enumeration zipEntries = zip.entries();
	while ( zipEntries.hasMoreElements() ) {
		entry = (ZipEntry) zipEntries.nextElement();
		dumpInfo(entry);
	}

	System.out.println("");

	// summarize compression efficiency
	float ratio = 100 - ((float)zipFileLength / totalBytes * 100);

	System.out.println("Total bytes ..... : " + totalBytes);
	System.out.println("Compressed to ... : " + zipFileLength);
	System.out.println("Compression ratio : " + ratio + " %");
}
//-------------------------------------------------------------------
// Dump summary information for a ZIP entry.
//-------------------------------------------------------------------
protected void dumpInfo(ZipEntry entry) {

String entryName = entry.getName();
String padding;
long size = entry.getSize();

	// pad the entry name out with spaces to align columns neatly.
	padding = columnPadding(3*8, entryName);

	System.out.print(entryName + padding + size + "\t");
	System.out.print( new Date(entry.getTime()) );
	System.out.println("");

	String comment = entry.getComment();
	if ( comment != null ) {
		System.out.println("\tcomment : " + comment);
	}

	totalBytes += size;			// keep track of total uncompressed bytes
}
//-------------------------------------------------------------------
// Pad a text column out to a certain width
//-------------------------------------------------------------------
private static String spaces = "                   ";

public static String columnPadding(int columnWidth, String string) {
int numberOfPaddingSpaces;

	numberOfPaddingSpaces = columnWidth - string.length();

	// if no padding required, or string is wider than column, return
	// a single space so that columns dont "stick" to each other.
	if ( numberOfPaddingSpaces < 1 ) {
		numberOfPaddingSpaces = 1;
	}

	return spaces.substring(0, numberOfPaddingSpaces);
}
//-------------------------------------------------------------------
// Determine filename
//-------------------------------------------------------------------
protected String completeFilename(String tentativeFilename) {
String zipFilename = null;

boolean zipExtension	 = tentativeFilename.endsWith(".zip");
boolean jarExtension	 = tentativeFilename.endsWith(".jar");
boolean noExtensionAtAll = (! zipExtension) && (! jarExtension);

	if ( noExtensionAtAll ) {
		if ( fileExists(tentativeFilename + ".zip")) {
			zipFilename = tentativeFilename + ".zip";
		} else
		if ( fileExists(tentativeFilename + ".jar")) {
			zipFilename = tentativeFilename + ".jar";
		}
	} else {
		if ( fileExists(tentativeFilename) ) {
			zipFilename = tentativeFilename;
		}
	}
	if ( zipFilename == null ) {
		System.out.print("Sorry, could not find file '");
		if ( noExtensionAtAll ) {
			System.out.println(tentativeFilename + "[.jar][.zip]'");
		} else {
			System.out.println(tentativeFilename + "'");
		}
		System.exit(10);
	}
	return zipFilename;
}
//-------------------------------------------------------------------
// See if a given file exists
//-------------------------------------------------------------------
public static boolean fileExists (String filename) {
File file = new File(filename);

	if ( !file.exists() ) {
		return false;
	}
	return ! file.isDirectory();	// dont let directories trip us up
}
} // End of Class ZipInfo