// Copyright 2000-2005 the Contributors, as shown in the revision logs.
// Licensed under the Apache Public Source License 2.0 ("the License").
// You may not use this file except in compliance with the License.

package org.ibex.nestedvm.util;

import java.io.*;
import java.nio.channels.*;
import java.net.*;
import java.util.*;

import java.text.DateFormatSymbols;

/*
 GCCLASS_HINT: org.ibex.nestedvm.util.Platform.<clinit> org.ibex.nestedvm.util.Platform$Jdk11.<init>
 GCCLASS_HINT: org.ibex.nestedvm.util.Platform.<clinit> org.ibex.nestedvm.util.Platform$Jdk12.<init>
 GCCLASS_HINT: org.ibex.nestedvm.util.Platform.<clinit> org.ibex.nestedvm.util.Platform$Jdk13.<init>
 GCCLASS_HINT: org.ibex.nestedvm.util.Platform.<clinit> org.ibex.nestedvm.util.Platform$Jdk14.<init>
*/

public abstract class Platform {
    Platform() { }
    private static final Platform p;
    
    static {
        float version;
        try {
            if(getProperty("java.vm.name").equals("SableVM"))
                version = 1.2f;
            else
                version = Float.valueOf(getProperty("java.specification.version")).floatValue();
        } catch(Exception e) {
            System.err.println("WARNING: " + e + " while trying to find jvm version -  assuming 1.1");
            version = 1.1f;
        }
        String platformClass;
        if(version >= 1.4f) platformClass = "Jdk14";
        else if(version >= 1.3f) platformClass = "Jdk13";
        else if(version >= 1.2f) platformClass = "Jdk12";
        else if(version >= 1.1f) platformClass = "Jdk11";
        else throw new Error("JVM Specification version: " + version + " is too old. (see org.ibex.util.Platform to add support)");
        
        try {
            p = (Platform) Class.forName(Platform.class.getName() + "$" + platformClass).newInstance();
        } catch(Exception e) {
            e.printStackTrace();
            throw new Error("Error instansiating platform class");
        }
    }
    
    public static String getProperty(String key) {
        try {
            if ("user.dir".equals(key)) {
                return "/tmp";
            }
            return System.getProperty(key);
        } catch(SecurityException e) {
            return null;
        }
    }
    
    
    abstract boolean _atomicCreateFile(File f) throws IOException;
    public static boolean atomicCreateFile(File f) throws IOException { return p._atomicCreateFile(f); }

    abstract Seekable.Lock _lockFile(Seekable s, RandomAccessFile raf, long pos, long size, boolean shared) throws IOException;
    public static Seekable.Lock lockFile(Seekable s, RandomAccessFile raf, long pos, long size, boolean shared) throws IOException {
        return p._lockFile(s, raf, pos, size, shared); }
    
    abstract void _socketHalfClose(Socket s, boolean output) throws IOException;
    public static void socketHalfClose(Socket s, boolean output) throws IOException { p._socketHalfClose(s,output); }
    
    abstract void _socketSetKeepAlive(Socket s, boolean on) throws SocketException;
    public static void socketSetKeepAlive(Socket s, boolean on) throws SocketException { p._socketSetKeepAlive(s,on); }
    
    abstract InetAddress _inetAddressFromBytes(byte[] a) throws UnknownHostException;
    public static InetAddress inetAddressFromBytes(byte[] a) throws UnknownHostException { return p._inetAddressFromBytes(a); }
    
    abstract String _timeZoneGetDisplayName(TimeZone tz, boolean dst, boolean showlong, Locale l);
    public static String timeZoneGetDisplayName(TimeZone tz, boolean dst, boolean showlong, Locale l) { return p._timeZoneGetDisplayName(tz,dst,showlong,l); }
    public static String timeZoneGetDisplayName(TimeZone tz, boolean dst, boolean showlong) { return timeZoneGetDisplayName(tz,dst,showlong,Locale.getDefault()); }

    abstract void _setFileLength(RandomAccessFile f, int length)
        throws IOException;
    public static void setFileLength(RandomAccessFile f, int length)
        throws IOException { p._setFileLength(f, length); }
    
    abstract File[] _listRoots();
    public static File[] listRoots() { return p._listRoots(); }
    
    abstract File _getRoot(File f);
    public static File getRoot(File f) { return p._getRoot(f); }
    
    static class Jdk11 extends Platform {
        boolean _atomicCreateFile(File f) throws IOException {
            // This is not atomic, but its the best we can do on jdk 1.1
            if(f.exists()) return false;
            new FileOutputStream(f).close();
            return true;
        }
        Seekable.Lock _lockFile(Seekable s, RandomAccessFile raf, long p, long size, boolean shared) throws IOException {
            throw new IOException("file locking requires jdk 1.4+");
        }
        void _socketHalfClose(Socket s, boolean output) throws IOException {
            throw new IOException("half closing sockets not supported");
        }
        InetAddress _inetAddressFromBytes(byte[] a) throws UnknownHostException {
            if(a.length != 4) throw new UnknownHostException("only ipv4 addrs supported");
            return InetAddress.getByName(""+(a[0]&0xff)+"."+(a[1]&0xff)+"."+(a[2]&0xff)+"."+(a[3]&0xff));
        }
        void _socketSetKeepAlive(Socket s, boolean on) throws SocketException {
            if(on) throw new SocketException("keepalive not supported");
        }
        String _timeZoneGetDisplayName(TimeZone tz, boolean dst, boolean showlong, Locale l) {
            String[][] zs  = new DateFormatSymbols(l).getZoneStrings();
            String id = tz.getID();
            for(int i=0;i<zs.length;i++)
                if(zs[i][0].equals(id))
                    return zs[i][dst ? (showlong ? 3 : 4) : (showlong ? 1 : 2)];
            StringBuffer sb = new StringBuffer("GMT");
            int off = tz.getRawOffset() / 1000;
            if(off < 0) { sb.append("-"); off = -off; }
            else sb.append("+");
            sb.append(off/3600); off = off%3600;
            if(off > 0) sb.append(":").append(off/60); off=off%60;
            if(off > 0) sb.append(":").append(off);
            return sb.toString();
        }

        void _setFileLength(RandomAccessFile f, int length) throws IOException{
            InputStream in = new FileInputStream(f.getFD());
            OutputStream out = new FileOutputStream(f.getFD());

            byte[] buf = new byte[1024];
            for (int len; length > 0; length -= len) {
                len = in.read(buf, 0, Math.min(length, buf.length));
                if (len == -1) break;
                out.write(buf, 0, len);
            }
            if (length == 0) return;

            // fill the rest of the space with zeros
            for (int i=0; i < buf.length; i++) buf[i] = 0;
            while (length > 0) {
                out.write(buf, 0, Math.min(length, buf.length));
                length -= buf.length;
            }
        }

        RandomAccessFile _truncatedRandomAccessFile(File f, String mode) throws IOException {
            new FileOutputStream(f).close();
            return new RandomAccessFile(f,mode);
        }
        
        File[] _listRoots() {
            String[] rootProps = new String[]{"java.home","java.class.path","java.library.path","java.io.tmpdir","java.ext.dirs","user.home","user.dir" };
            Hashtable known = new Hashtable();
            for(int i=0;i<rootProps.length;i++) {
                String prop = getProperty(rootProps[i]);
                if(prop == null) continue;
                for(;;) {
                    String path = prop;
                    int p;
                    if((p = prop.indexOf(File.pathSeparatorChar)) != -1) {
                        path = prop.substring(0,p);
                        prop = prop.substring(p+1);
                    }
                    File root = getRoot(new File(path));
                    //System.err.println(rootProps[i] + ": " + path + " -> " + root);
                    known.put(root,Boolean.TRUE);
                    if(p == -1) break;
                }
            }
            File[] ret = new File[known.size()];
            int i=0;
            for(Enumeration e = known.keys();e.hasMoreElements();)
                ret[i++] = (File) e.nextElement();
            return ret;
        }
        
        File _getRoot(File f) {
            if(!f.isAbsolute()) f = new File(f.getAbsolutePath());
            String p;
            while((p = f.getParent()) != null) f = new File(p);
            if(f.getPath().length() == 0) f = new File("/"); // work around a classpath bug
            return f;
        }
    }
    
    static class Jdk12 extends Jdk11 {
        boolean _atomicCreateFile(File f) throws IOException {
            return f.createNewFile();
        }
        
        String _timeZoneGetDisplayName(TimeZone tz, boolean dst, boolean showlong, Locale l) {
            return tz.getDisplayName(dst,showlong ? TimeZone.LONG : TimeZone.SHORT, l);
        }

        void _setFileLength(RandomAccessFile f, int length) throws IOException {
            f.setLength(length);
        }

        File[] _listRoots() { return File.listRoots(); }
    }
    
    static class Jdk13 extends Jdk12 {
        void _socketHalfClose(Socket s, boolean output) throws IOException {
            if(output) s.shutdownOutput();
            else s.shutdownInput();
        }
        
        void _socketSetKeepAlive(Socket s, boolean on) throws SocketException {
            s.setKeepAlive(on);
        }
    }
    
    static class Jdk14 extends Jdk13 {
        InetAddress _inetAddressFromBytes(byte[] a) throws UnknownHostException { return InetAddress.getByAddress(a); } 

        Seekable.Lock _lockFile(Seekable s, RandomAccessFile r, long pos, long size, boolean shared) throws IOException {
            FileLock flock;
            try {
                flock = pos == 0 && size == 0 ? r.getChannel().lock() :
                    r.getChannel().tryLock(pos, size, shared);
            } catch (OverlappingFileLockException e) { flock = null; }
            if (flock == null) return null; // region already locked
            return new Jdk14FileLock(s, flock);
        }
    }

    private static final class Jdk14FileLock extends Seekable.Lock {
        private final Seekable s;
        private final FileLock l;

        Jdk14FileLock(Seekable sk, FileLock flock) { s = sk; l = flock; }
        public Seekable seekable() { return s; }
        public boolean isShared() { return l.isShared(); }
        public boolean isValid() { return l.isValid(); }
        public void release() throws IOException { l.release(); }
        public long position() { return l.position(); }
        public long size() { return l.size(); }
        public String toString() { return l.toString(); }
    }
}