import java.io.File;
import java.io.IOException;
import java.nio.file.FileVisitResult;
import java.nio.file.Files;
import java.nio.file.Path;
import java.nio.file.Paths;
import java.nio.file.SimpleFileVisitor;
import java.nio.file.attribute.BasicFileAttributes;
import java.util.Set;
import java.util.Date;

public class FIter2 {
    
    public static void main(String[] args) throws IOException {

        System.out.println("java.io.File iteration");
        Info info = null;
        long t = 0;

        nioIter(args[0], new Info());
        t = 0;
        System.out.println("------------------");        
        for (int i = 0; i < 10; i++) {
            info = new Info();    
            long t0 = System.currentTimeMillis();
            nioIter(args[0], info);
            long t1 = System.currentTimeMillis();
            t += (t1 - t0);
        }

        System.out.println("  nio.totalSize:" + info.size);
        System.out.println("        fileNum:" + info.num);
        System.out.println("       checkSum:" + info.csum);
        System.out.println("           Time:" + t/10);

        // fs warmup
        ioIter(new File[] { new File(args[0])}, new Info());
        System.out.println("------------------");        
        for (int i = 0; i < 10; i++) {
            info = new Info();    
            long t0 = System.currentTimeMillis();
            ioIter(new File[] { new File(args[0])}, info);
            long t1 = System.currentTimeMillis();
            t += (t1 - t0);
        }

        System.out.println("  io.totalSize:" + info.size);
        System.out.println("        fileNum:" + info.num);
        System.out.println("       checkSum:" + info.csum);
        System.out.println("          Time:" + t/10);


        ioIter2(null, new String[] { args[0]}, new Info());
        System.out.println("------------------");        
        for (int i = 0; i < 10; i++) {
            info = new Info();    
            long t0 = System.currentTimeMillis();
            ioIter2(null, new String[] { args[0]}, info);
            long t1 = System.currentTimeMillis();
            t += (t1 - t0);
        }

        System.out.println(" io2.totalSize:" + info.size);
        System.out.println("        fileNum:" + info.num);
        System.out.println("       checkSum:" + info.csum);
        System.out.println("          Time:" + t/10);
    }
    
    static class Info {
        long size;
        int  num;
        long csum;
    }
    
    private static void ioIter(File[] files, Info info) {
        if (files == null)
            return;
        
        for (File f : files) {
            info.num++;            
            //info.csum += f.lastModified();            
            info.csum += javaToDosTime(f.lastModified());            
            if (f.isFile()) {
                info.size += f.length();

            } else if (f.isDirectory()) {
                ioIter(f.listFiles(), info);

            } else {}  // just ignore
         }
    }

    private static void ioIter2(File dir, String[] files, Info info) {
        if (files == null)
            return;
        
        for (String fn : files) {
            File f;
            if (dir == null) {
                f = new File(fn);
            } else {
                f = new File(dir, fn);
            }
            info.num++;            
            //info.csum += f.lastModified();            
            info.csum += javaToDosTime(f.lastModified());            

            if (f.isFile()) {
                info.size += f.length();

            } else if (f.isDirectory()) {
                ioIter2(f, f.list(), info);

            } else {}  // just ignore
         }
    }

    
    private static void nioIter(String dir, final Info info) throws IOException {
        Path path = Paths.get(dir);
        Files.walkFileTree(
            path,
            new SimpleFileVisitor<Path>() {
                @Override
                public FileVisitResult visitFile(Path file,
                                                 BasicFileAttributes attrs)
                {
                    info.size += attrs.size();
                    //info.csum += attrs.lastModifiedTime().toMillis();
                    info.csum += javaToDosTime(attrs.lastModifiedTime().toMillis());
                    info.num++;
                    return FileVisitResult.CONTINUE;
                }

                @Override
                public FileVisitResult preVisitDirectory(Path dir,
                                                         BasicFileAttributes attrs)
                {
                     info.num++;
                     //info.csum += attrs.lastModifiedTime().toMillis();              
                     info.csum += javaToDosTime(attrs.lastModifiedTime().toMillis());       
                     return FileVisitResult.CONTINUE;
                }
        });        
    }

    private static long javaToDosTime(long time) {
        Date d = new Date(time);
        int year = d.getYear() + 1900;
        if (year < 1980) {
            return (1 << 21) | (1 << 16);
        }
        return (year - 1980) << 25 | (d.getMonth() + 1) << 21 |
               d.getDate() << 16 | d.getHours() << 11 | d.getMinutes() << 5 |
               d.getSeconds() >> 1;
    }

}