/*
 * @(#)ObjectStreamClassUtil_1_3.java	1.7 03/12/19
 *
 * Copyright 2004 Sun Microsystems, Inc. All rights reserved.
 * SUN PROPRIETARY/CONFIDENTIAL. Use is subject to license terms.
 */

package com.sun.corba.se.impl.orbutil;

// for computing the structural UID
import java.security.MessageDigest;
import java.security.NoSuchAlgorithmException;
import java.security.DigestOutputStream;
import java.security.AccessController;
import java.security.PrivilegedExceptionAction;
import java.security.PrivilegedActionException;
import java.security.PrivilegedAction;
import java.io.DataOutputStream;
import java.io.ByteArrayOutputStream;
import java.io.IOException;

import java.util.Arrays;
import java.util.Comparator;
import java.lang.reflect.Field;
import java.lang.reflect.Modifier;
import java.lang.reflect.Array;
import java.lang.reflect.Member;
import java.lang.reflect.Method;
import java.lang.reflect.Constructor;


import com.sun.corba.se.impl.io.ObjectStreamClass;

public final class ObjectStreamClassUtil_1_3 {

    // maintained here for backward compatability with JDK 1.3, where
    // writeObject method was not being checked at all, so there is
    // no need to lookup the ObjectStreamClass

    public static long computeSerialVersionUID(final Class cl) {
	
	long csuid = ObjectStreamClass.getSerialVersionUID(cl);
	if (csuid == 0)
	    return csuid; // for non-serializable/proxy classes

	csuid = (ObjectStreamClassUtil_1_3.getSerialVersion(csuid, cl).longValue());
	return csuid;
    }
	

    // to maintain same suid as the JDK 1.3, we pick
    // up suid only for classes with private,static,final
    // declarations, and compute it for all others

    private static Long getSerialVersion(final long csuid, final Class cl)
    {
        return (Long) AccessController.doPrivileged(new PrivilegedAction() {
          public Object run() {
	    long suid;
	    try {
                final Field f = cl.getDeclaredField("serialVersionUID");
	        int mods = f.getModifiers();
	        if (Modifier.isStatic(mods) && 
                    Modifier.isFinal(mods) && Modifier.isPrivate(mods)) {
	            suid = csuid;
	         } else {
		    suid = _computeSerialVersionUID(cl);
	         }
	      } catch (NoSuchFieldException ex) {
	          suid = _computeSerialVersionUID(cl);
              //} catch (IllegalAccessException ex) {
              //     suid = _computeSerialVersionUID(cl);
              }
	      return new Long(suid);
	   }
	});
    }

    public static long computeStructuralUID(boolean hasWriteObject, Class cl) {
	ByteArrayOutputStream devnull = new ByteArrayOutputStream(512);
		
	long h = 0;
	try {

	    if ((!java.io.Serializable.class.isAssignableFrom(cl)) ||
		(cl.isInterface())){
		return 0;
	    }
			
	    if (java.io.Externalizable.class.isAssignableFrom(cl)) {
		return 1;
	    }

	    MessageDigest md = MessageDigest.getInstance("SHA");
	    DigestOutputStream mdo = new DigestOutputStream(devnull, md);
	    DataOutputStream data = new DataOutputStream(mdo);

	    //In the old case, for the caller class, the write Method wasn't considered
	    // for rep-id calculations correctly, but for parent classes it was taken
	    // into account.  That is the reason there is the klude of getting the write
	    // Object method in there

	    // Get SUID of parent
	    Class parent = cl.getSuperclass();
	    if ((parent != null) && (parent != java.lang.Object.class)) {
	        boolean hasWriteObjectFlag = false;
	        Class [] args = {java.io.ObjectOutputStream.class};
                Method hasWriteObjectMethod = ObjectStreamClassUtil_1_3.getDeclaredMethod(parent, "writeObject", args,
	               Modifier.PRIVATE, Modifier.STATIC);
	        if (hasWriteObjectMethod != null)
	            hasWriteObjectFlag = true; 
		data.writeLong(ObjectStreamClassUtil_1_3.computeStructuralUID(hasWriteObjectFlag, parent));
	    }

	    if (hasWriteObject)
	        data.writeInt(2);
	    else
	        data.writeInt(1);

	    /* Sort the field names to get a deterministic order */
	    Field[] field = ObjectStreamClassUtil_1_3.getDeclaredFields(cl);
	    Arrays.sort(field, compareMemberByName);
			
	    for (int i = 0; i < field.length; i++) {
		Field f = field[i];
				
				/* Include in the hash all fields except those that are
				 * transient or static.
				 */
		int m = f.getModifiers();
		if (Modifier.isTransient(m) || Modifier.isStatic(m))
		    continue;
				
		data.writeUTF(f.getName());
		data.writeUTF(getSignature(f.getType()));
	    }
			
	    /* Compute the hash value for this class.
	     * Use only the first 64 bits of the hash.
	     */
	    data.flush();
	    byte hasharray[] = md.digest();
	    int minimum = Math.min(8, hasharray.length);
	    for (int i = minimum; i > 0; i--) {
		h += (long)(hasharray[i] & 255) << (i * 8);
	    }
	} catch (IOException ignore) {
	    /* can't happen, but be deterministic anyway. */
	    h = -1;
	} catch (NoSuchAlgorithmException complain) {
	    throw new SecurityException(complain.getMessage());
	}
	return h;
    }

    /*
     * Compute a hash for the specified class.  Incrementally add
     * items to the hash accumulating in the digest stream.
     * Fold the hash into a long.  Use the SHA secure hash function.
     */
    private static long _computeSerialVersionUID(Class cl) {
	ByteArrayOutputStream devnull = new ByteArrayOutputStream(512);

	long h = 0;
	try {
	    MessageDigest md = MessageDigest.getInstance("SHA");
	    DigestOutputStream mdo = new DigestOutputStream(devnull, md);
	    DataOutputStream data = new DataOutputStream(mdo);


	    data.writeUTF(cl.getName());

	    int classaccess = cl.getModifiers();
	    classaccess &= (Modifier.PUBLIC | Modifier.FINAL |
			    Modifier.INTERFACE | Modifier.ABSTRACT);

	    /* Workaround for javac bug that only set ABSTRACT for
	     * interfaces if the interface had some methods.
	     * The ABSTRACT bit reflects that the number of methods > 0.
	     * This is required so correct hashes can be computed
	     * for existing class files.
	     * Previously this hack was previously present in the VM.
	     */
            Method[] method = cl.getDeclaredMethods();
	    if ((classaccess & Modifier.INTERFACE) != 0) {
		classaccess &= (~Modifier.ABSTRACT);
		if (method.length > 0) {
		    classaccess |= Modifier.ABSTRACT;
		}
	    }

	    data.writeInt(classaccess);

	    /*
	     * Get the list of interfaces supported,
	     * Accumulate their names their names in Lexical order
	     * and add them to the hash
	     */
            if (!cl.isArray()) {
                /* In 1.2fcs, getInterfaces() was modified to return
                 * {java.lang.Cloneable, java.io.Serializable} when
                 * called on array classes.  These values would upset
                 * the computation of the hash, so we explicitly omit
                 * them from its computation.
                 */

	        Class interfaces[] = cl.getInterfaces();
	        Arrays.sort(interfaces, compareClassByName);

	        for (int i = 0; i < interfaces.length; i++) {
		    data.writeUTF(interfaces[i].getName());
	        }
	    }

	    /* Sort the field names to get a deterministic order */
            Field[] field = cl.getDeclaredFields();
	    Arrays.sort(field, compareMemberByName);

	    for (int i = 0; i < field.length; i++) {
		Field f = field[i];

		/* Include in the hash all fields except those that are
		 * private transient and private static.
		 */
		int m = f.getModifiers();
		if (Modifier.isPrivate(m) &&
		    (Modifier.isTransient(m) || Modifier.isStatic(m)))
		    continue;

		data.writeUTF(f.getName());
		data.writeInt(m);
		data.writeUTF(getSignature(f.getType()));
	    }

	    // need to find the java replacement for hasStaticInitializer
	    if (hasStaticInitializer(cl)) {
	 	data.writeUTF("<clinit>");
	 	data.writeInt(Modifier.STATIC); // TBD: what modifiers does it have
	 	data.writeUTF("()V");
	    }

	    /*
	     * Get the list of constructors including name and signature
	     * Sort lexically, add all except the private constructors
	     * to the hash with their access flags
	     */

	    MethodSignature[] constructors =
		MethodSignature.removePrivateAndSort(cl.getDeclaredConstructors());
	    for (int i = 0; i < constructors.length; i++) {
		MethodSignature c = constructors[i];
		String mname = "<init>";
		String desc = c.signature;
		desc = desc.replace('/', '.');
		data.writeUTF(mname);
		data.writeInt(c.member.getModifiers());
		data.writeUTF(desc);
	    }

	    /* Include in the hash all methods except those that are
	     * private transient and private static.
	     */
	    MethodSignature[] methods =
		MethodSignature.removePrivateAndSort(method);
	    for (int i = 0; i < methods.length; i++ ) {
		MethodSignature m = methods[i];
		String desc = m.signature;
		desc = desc.replace('/', '.');
		data.writeUTF(m.member.getName());
		data.writeInt(m.member.getModifiers());
		data.writeUTF(desc);
	    }

	    /* Compute the hash value for this class.
	     * Use only the first 64 bits of the hash.
	     */
	    data.flush();
	    byte hasharray[] = md.digest();
	    for (int i = 0; i < Math.min(8, hasharray.length); i++) {
		h += (long)(hasharray[i] & 255) << (i * 8);
	    }
	} catch (IOException ignore) {
	    /* can't happen, but be deterministic anyway. */
	    h = -1;
	} catch (NoSuchAlgorithmException complain) {
	    throw new SecurityException(complain.getMessage());
	}
	return h;
    }

    /*
     * Comparator object for Classes and Interfaces
     */
    private static Comparator compareClassByName =
    	new CompareClassByName();

    private static class CompareClassByName implements Comparator {
	public int compare(Object o1, Object o2) {
	    Class c1 = (Class)o1;
	    Class c2 = (Class)o2;
	    return (c1.getName()).compareTo(c2.getName());
	}
    }

    /*
     * Comparator object for Members, Fields, and Methods
     */
    private static Comparator compareMemberByName =
        new CompareMemberByName();

    private static class CompareMemberByName implements Comparator {
        public int compare(Object o1, Object o2) {
            String s1 = ((Member)o1).getName();
            String s2 = ((Member)o2).getName();

            if (o1 instanceof Method) {
                s1 += getSignature((Method)o1);
                s2 += getSignature((Method)o2);
            } else if (o1 instanceof Constructor) {
                s1 += getSignature((Constructor)o1);
                s2 += getSignature((Constructor)o2);
            }
            return s1.compareTo(s2);
        }
    }

    /**
     * Compute the JVM signature for the class.
     */
    private static String getSignature(Class clazz) {
	String type = null;
	if (clazz.isArray()) {
	    Class cl = clazz;
	    int dimensions = 0;
	    while (cl.isArray()) {
		dimensions++;
		cl = cl.getComponentType();
	    }
	    StringBuffer sb = new StringBuffer();
	    for (int i = 0; i < dimensions; i++) {
		sb.append("[");
	    }
	    sb.append(getSignature(cl));
	    type = sb.toString();
	} else if (clazz.isPrimitive()) {
	    if (clazz == Integer.TYPE) {
		type = "I";
	    } else if (clazz == Byte.TYPE) {
		type = "B";
	    } else if (clazz == Long.TYPE) {
		type = "J";
	    } else if (clazz == Float.TYPE) {
		type = "F";
	    } else if (clazz == Double.TYPE) {
		type = "D";
	    } else if (clazz == Short.TYPE) {
		type = "S";
	    } else if (clazz == Character.TYPE) {
		type = "C";
	    } else if (clazz == Boolean.TYPE) {
		type = "Z";
	    } else if (clazz == Void.TYPE) {
		type = "V";
	    }
	} else {
	    type = "L" + clazz.getName().replace('.', '/') + ";";
	}
	return type;
    }

    /*
     * Compute the JVM method descriptor for the method.
     */
    private static String getSignature(Method meth) {
	StringBuffer sb = new StringBuffer();

	sb.append("(");

	Class[] params = meth.getParameterTypes(); // avoid clone
	for (int j = 0; j < params.length; j++) {
	    sb.append(getSignature(params[j]));
	}
	sb.append(")");
	sb.append(getSignature(meth.getReturnType()));
	return sb.toString();
    }

    /*
     * Compute the JVM constructor descriptor for the constructor.
     */
    private static String getSignature(Constructor cons) {
	StringBuffer sb = new StringBuffer();

	sb.append("(");

	Class[] params = cons.getParameterTypes(); // avoid clone
	for (int j = 0; j < params.length; j++) {
	    sb.append(getSignature(params[j]));
	}
	sb.append(")V");
	return sb.toString();
    }

    private static Field[] getDeclaredFields(final Class clz) {
        return (Field[]) AccessController.doPrivileged(new PrivilegedAction() {
            public Object run() {
                return clz.getDeclaredFields();
            }
        });
    }

    private static class MethodSignature implements Comparator {
	Member member;
	String signature;      // cached parameter signature

	/* Given an array of Method or Constructor members,
	   return a sorted array of the non-private members.*/
	/* A better implementation would be to implement the returned data
	   structure as an insertion sorted link list.*/
	static MethodSignature[] removePrivateAndSort(Member[] m) {
	    int numNonPrivate = 0;
	    for (int i = 0; i < m.length; i++) {
		if (! Modifier.isPrivate(m[i].getModifiers())) {
		    numNonPrivate++;
		}
	    }
	    MethodSignature[] cm = new MethodSignature[numNonPrivate];
	    int cmi = 0;
	    for (int i = 0; i < m.length; i++) {
		if (! Modifier.isPrivate(m[i].getModifiers())) {
		    cm[cmi] = new MethodSignature(m[i]);
		    cmi++;
		}
	    }
	    if (cmi > 0)
		Arrays.sort(cm, cm[0]);
	    return cm;
	}

	/* Assumes that o1 and o2 are either both methods
	   or both constructors.*/
	public int compare(Object o1, Object o2) {
	    /* Arrays.sort calls compare when o1 and o2 are equal.*/
	    if (o1 == o2)
		return 0;

	    MethodSignature c1 = (MethodSignature)o1;
	    MethodSignature c2 = (MethodSignature)o2;

	    int result;
	    if (isConstructor()) {
		result = c1.signature.compareTo(c2.signature);
	    } else { // is a Method.
		result = c1.member.getName().compareTo(c2.member.getName());
		if (result == 0)
		    result = c1.signature.compareTo(c2.signature);
	    }
	    return result;
	}

	final private boolean isConstructor() {
	    return member instanceof Constructor;
	}
	private MethodSignature(Member m) {
	    member = m;
	    if (isConstructor()) {
		signature = ObjectStreamClassUtil_1_3.getSignature((Constructor)m);
	    } else {
		signature = ObjectStreamClassUtil_1_3.getSignature((Method)m);
	    }
	}
    }

    /* Find out if the class has a static class initializer <clinit> */
    // use java.io.ObjectStream's hasStaticInitializer method
    // private static native boolean hasStaticInitializer(Class cl);

    private static Method hasStaticInitializerMethod = null;
    /**
     * Returns true if the given class defines a static initializer method,
     * false otherwise.
     */
    private static boolean hasStaticInitializer(Class cl) {
        if (hasStaticInitializerMethod == null) {
            Class classWithThisMethod = null;
            
            try {
                try {
                    // When using rip-int with Merlin or when this is a Merlin
                    // workspace, the method we want is in sun.misc.ClassReflector
                    // and absent from java.io.ObjectStreamClass.
                    //
                    // When compiling rip-int with JDK 1.3.x, we have to get it
                    // from java.io.ObjectStreamClass.
                    classWithThisMethod = Class.forName("sun.misc.ClassReflector");
                } catch (ClassNotFoundException cnfe) {
                    // Do nothing.  This is either not a Merlin workspace,
                    // or rip-int is being compiled with something other than
                    // Merlin, probably JDK 1.3.  Fall back on java.io.ObjectStreaClass.
                }
                if (classWithThisMethod == null)
                    classWithThisMethod = java.io.ObjectStreamClass.class;
                
                hasStaticInitializerMethod =
                    classWithThisMethod.getDeclaredMethod("hasStaticInitializer",
                                                          new Class[] { Class.class });
            } catch (NoSuchMethodException ex) {
            }
            
            if (hasStaticInitializerMethod == null) {
                throw new InternalError("Can't find hasStaticInitializer method on "
                                        + classWithThisMethod.getName());
            }
            hasStaticInitializerMethod.setAccessible(true);
        }
        try {
            Boolean retval = (Boolean)
                hasStaticInitializerMethod.invoke(null, new Object[] { cl });
            return retval.booleanValue();
        } catch (Exception ex) {
            throw new InternalError("Error invoking hasStaticInitializer: "
                                    + ex);
        }
    }

    private static Method getDeclaredMethod(final Class cl, final String methodName, final Class[] args,
                                     final int requiredModifierMask,
                                     final int disallowedModifierMask) {
        return (Method) AccessController.doPrivileged(new PrivilegedAction() {
            public Object run() {
                Method method = null;
                try {
                    method =
                        cl.getDeclaredMethod(methodName, args);
                        int mods = method.getModifiers();
                        if ((mods & disallowedModifierMask) != 0 ||
                            (mods & requiredModifierMask) != requiredModifierMask) {
                            method = null;
                        } 
	                //if (!Modifier.isPrivate(mods) ||
	                //    Modifier.isStatic(mods)) {
	                //    method = null;
	                //}
                } catch (NoSuchMethodException e) {
                // Since it is alright if methodName does not exist,
                // no need to do anything special here.
                }
                return method;
	    }
	});
    }

}