/*
 * Licensed to the Apache Software Foundation (ASF) under one
 * or more contributor license agreements.  See the NOTICE file
 * distributed with this work for additional information
 * regarding copyright ownership.  The ASF licenses this file
 * to you under the Apache License, Version 2.0 (the
 * "License"); you may not use this file except in compliance
 * with the License.  You may obtain a copy of the License at
 * 
 *   http://www.apache.org/licenses/LICENSE-2.0
 * 
 * Unless required by applicable law or agreed to in writing,
 * software distributed under the License is distributed on an
 * "AS IS" BASIS, WITHOUT WARRANTIES OR CONDITIONS OF ANY
 * KIND, either express or implied.  See the License for the
 * specific language governing permissions and limitations
 * under the License.    
 */
package org.apache.tuscany.sca.binding.ejb.java2idl;

import java.io.ByteArrayOutputStream;
import java.io.DataOutputStream;
import java.io.Externalizable;
import java.io.IOException;
import java.io.ObjectOutputStream;
import java.io.ObjectStreamClass;
import java.io.Serializable;
import java.lang.reflect.Field;
import java.lang.reflect.Method;
import java.lang.reflect.Modifier;
import java.rmi.Remote;
import java.security.MessageDigest;
import java.security.NoSuchAlgorithmException;
import java.util.Collections;
import java.util.Comparator;
import java.util.HashSet;
import java.util.Iterator;
import java.util.Map;
import java.util.Set;
import java.util.SortedSet;
import java.util.TreeSet;
import java.util.WeakHashMap;

import org.omg.CORBA.Any;

/**
 * This is a RMI/IIOP metadata conversion utility class.
 */
public class IDLUtil {

    /**
     * Return the IDL type name for the given class. Here we use the mapping for
     * parameter types and return values.
     */
    public static String getTypeIDLName(Class cls) {
        if (cls.isPrimitive())
            return PrimitiveType.getPrimitiveType(cls).getIDLName();
        if (cls.isArray()) {
            int dimension = 0;
            Class type = cls;
            while (type.isArray()) {
                dimension++;
                type = type.getComponentType();
            }
            String baseName = getTypeIDLName(type);
            int index = baseName.lastIndexOf("::");
            String prefix = "";
            String suffix = baseName;
            if (index != -1) {
                prefix = baseName.substring(0, index);
                suffix = baseName.substring(index + 2);
            }
            String name = "::org::omg::boxedRMI" + prefix + "::seq" + dimension + "_" + suffix;
            return name;
        }

        // special classes
        if (cls == java.lang.String.class)
            return "::CORBA::WStringValue";
        if (cls == java.lang.Object.class)
            return "::java::lang::_Object";
        if (cls == java.lang.Class.class)
            return "::javax::rmi::CORBA::ClassDesc";
        if (cls == java.io.Serializable.class)
            return "::java::io::Serializable";
        if (cls == java.io.Externalizable.class)
            return "::java::io::Externalizable";
        if (cls == java.rmi.Remote.class)
            return "::java::rmi::Remote";
        if (cls == org.omg.CORBA.Object.class)
            return "::CORBA::Object";
        // remote interface?
        if (cls.isInterface() && java.rmi.Remote.class.isAssignableFrom(cls)) {
            InterfaceType ia = InterfaceType.getInterfaceType(cls);
            return ia.getIDLModuleName() + "::" + ia.getIDLName();
        }
        // IDL interface?
        if (cls.isInterface() && org.omg.CORBA.Object.class.isAssignableFrom(cls)
            && org.omg.CORBA.portable.IDLEntity.class.isAssignableFrom(cls)) {
            InterfaceType ia = InterfaceType.getInterfaceType(cls);
            return ia.getIDLModuleName() + "::" + ia.getIDLName();
        }
        // exception?
        if (Throwable.class.isAssignableFrom(cls)) {
            if (Exception.class.isAssignableFrom(cls) && !RuntimeException.class.isAssignableFrom(cls)) {
                ExceptionType ea = ExceptionType.getExceptionType(cls);
                return ea.getIDLModuleName() + "::" + ea.getIDLName();
            }
        }
        // got to be value
        ValueType va = ValueType.getValueType(cls);
        return va.getIDLModuleName() + "::" + va.getIDLName();
    }

    /**
     * Check if this class is valid for RMI/IIOP mapping. This method will
     * either throw an exception or return true.
     */
    public static boolean isValidRMIIIOP(Class cls) {
        if (cls.isPrimitive())
            return true;
        if (cls.isArray())
            return isValidRMIIIOP(cls.getComponentType());
        // special interfaces
        if (cls == Serializable.class || cls == Externalizable.class)
            return true;
        // interface?
        if (cls.isInterface() && Remote.class.isAssignableFrom(cls)) {
            InterfaceType.getInterfaceType(cls);
            return true;
        }
        // exception?
        if (Throwable.class.isAssignableFrom(cls)) {
            if (Exception.class.isAssignableFrom(cls) && (!RuntimeException.class.isAssignableFrom(cls))) {
                ExceptionType.getExceptionType(cls);
            }
            return true;
        }
        // special values
        if (cls == Object.class || cls == String.class || cls == Class.class)
            return true;
        // got to be value
        ValueType.getValueType(cls);
        return true;
    }

    /**
     * Insert a java primitive into an Any. The primitive is assumed to be
     * wrapped in one of the primitive wrapper classes.
     */
    public static void insertAnyPrimitive(Any any, Object primitive) {
        Class type = primitive.getClass();
        if (type == Boolean.class)
            any.insert_boolean(((Boolean)primitive).booleanValue());
        else if (type == Character.class)
            any.insert_wchar(((Character)primitive).charValue());
        else if (type == Byte.class)
            any.insert_octet(((Byte)primitive).byteValue());
        else if (type == Short.class)
            any.insert_short(((Short)primitive).shortValue());
        else if (type == Integer.class)
            any.insert_long(((Integer)primitive).intValue());
        else if (type == Long.class)
            any.insert_longlong(((Long)primitive).longValue());
        else if (type == Float.class)
            any.insert_float(((Float)primitive).floatValue());
        else if (type == Double.class)
            any.insert_double(((Double)primitive).doubleValue());
        else
            throw new IllegalArgumentException(type.getName() + "is not a primitive type");
    }

    /**
     * Map Java name to IDL name, as per sections 1.3.2.3, 1.3.2.4 and 1.3.2.2.
     * This only works for a single name component, without a qualifying dot.
     */
    public static String javaToIDLName(String name) {
        if (name == null || "".equals(name))
            throw new IllegalArgumentException("Illegal name: " + name);
        if (name.indexOf('.') != -1)
            throw new IllegalArgumentException("Qualified name is not supported: " + name);
        StringBuffer res = new StringBuffer(name.length());
        if (name.charAt(0) == '_')
            res.append('J'); // 1.3.2.3
        for (int i = 0; i < name.length(); ++i) {
            char c = name.charAt(i);
            if (isLegalIDLIdentifierChar(c))
                res.append(c);
            else
                // 1.3.2.4
                res.append('U').append(toHexString((int)c));
        }
        String s = res.toString();
        if (isReservedIDLKeyword(s))
            return "_" + s;
        else
            return s;
    }

    /**
     * Return the IR global ID of the given class or interface. This is
     * described in section 1.3.5.7.
     */
    public static String getIRIdentifier(Class cls) {
        if (cls.isPrimitive())
            throw new IllegalArgumentException("Primitive type doesn't have IR IDs.");
        String result = (String)classIRIdentifierCache.get(cls);
        if (result != null)
            return result;
        String name = cls.getName();
        StringBuffer b = new StringBuffer("RMI:");
        for (int i = 0; i < name.length(); ++i) {
            char c = name.charAt(i);
            if (c < 256)
                b.append(c);
            else
                b.append("\\U").append(toHexString((int)c));
        }
        long clsHash = getClassHashCode(cls);
        b.append(':').append(toHexString(clsHash));
        ObjectStreamClass osClass = ObjectStreamClass.lookup(cls);
        if (osClass != null) {
            long serialVersionUID = osClass.getSerialVersionUID();
            if (clsHash != serialVersionUID)
                b.append(':').append(toHexString(serialVersionUID));
        }
        result = b.toString();
        classIRIdentifierCache.put(cls, result);
        return result;
    }

    /**
     * A cache for calculated class hash codes.
     */
    private static Map classHashCodeCache = Collections.synchronizedMap(new WeakHashMap());
    /**
     * A cache for class IR identifiers.
     */
    private static Map classIRIdentifierCache = Collections.synchronizedMap(new WeakHashMap());
    /**
     * Reserved IDL keywords. Section 1.3.2.2 says that Java identifiers with
     * these names should have prepended an underscore.
     */

    private static final Set reservedIDLKeywordSet = new HashSet();
    static {
        String[] reservedIDLKeywords = new String[] {"abstract", "any", "attribute", "boolean", "case", "char",
                                                     "const", "context", "custom", "default", "double", "exception",
                                                     "enum", "factory", "FALSE", "fixed", "float", "in", "inout",
                                                     "interface", "local", "long", "module", "native", "Object",
                                                     "octet", "oneway", "out", "private", "public", "raises",
                                                     "readonly", "sequence", "short", "string", "struct", "supports",
                                                     "switch", "TRUE", "truncatable", "typedef", "unsigned", "union",
                                                     "ValueBase", "valuetype", "void", "wchar", "wstring"};
        for (int i = 0; i < reservedIDLKeywords.length; i++)
            reservedIDLKeywordSet.add(reservedIDLKeywords[i]);
    }

    /**
     * Convert an integer to a 16-digit hex string.
     */
    private static String toHexString(int i) {
        String s = Integer.toHexString(i).toUpperCase();
        if (s.length() < 8)
            return "00000000".substring(8 - s.length()) + s;
        else
            return s;
    }

    /**
     * Convert a long to a 16-digit hex string.
     */
    private static String toHexString(long l) {
        String s = Long.toHexString(l).toUpperCase();
        if (s.length() < 16)
            return "0000000000000000".substring(16 - s.length()) + s;
        else
            return s;
    }

    /**
     * Determine if the argument is a reserved IDL keyword.
     */
    private static boolean isReservedIDLKeyword(String s) {
        return reservedIDLKeywordSet.contains(s);
        /*
         * // TODO: faster lookup for (int i = 0; i <
         * reservedIDLKeywords.length; ++i) if
         * (reservedIDLKeywords[i].equals(s)) return true; return false;
         */
    }

    /**
     * Determine if a <code>char</code> is a legal IDL identifier character.
     */
    private static boolean isLegalIDLIdentifierChar(char c) {
        if (c >= 0x61 && c <= 0x7a)
            return true; // lower case letter
        if (c >= 0x30 && c <= 0x39)
            return true; // digit
        if (c >= 0x41 && c <= 0x5a)
            return true; // upper case letter
        if (c == '_')
            return true; // underscore
        return false;
    }

    /**
     * Return the class hash code, as specified in "The Common Object Request
     * Broker: Architecture and Specification" (01-02-33), section 10.6.2.
     */
    static long getClassHashCode(Class cls) {
        // The simple cases
        if (cls.isInterface())
            return 0;
        if (!Serializable.class.isAssignableFrom(cls))
            return 0;
        if (Externalizable.class.isAssignableFrom(cls))
            return 1;
        // Try cache
        Long l = (Long)classHashCodeCache.get(cls);
        if (l != null)
            return l.longValue();
        // Has to calculate the hash.
        ByteArrayOutputStream baos = new ByteArrayOutputStream(256);
        DataOutputStream dos = new DataOutputStream(baos);
        // Step 1
        Class superClass = cls.getSuperclass();
        if (superClass != null && superClass != Object.class) {
            try {
                dos.writeLong(getClassHashCode(superClass));
            } catch (IOException ex) {
                throw new RuntimeException("Unexpected IOException: " + ex);
            }
        }
        // Step 2
        boolean hasWriteObject = false;
        try {
            Method m;
            int mods;
            m = cls.getDeclaredMethod("writeObject", new Class[] {ObjectOutputStream.class});
            mods = m.getModifiers();
            if (!Modifier.isPrivate(mods) && !Modifier.isStatic(mods))
                hasWriteObject = true;
        } catch (NoSuchMethodException ex) {
            // ignore
        }
        try {
            dos.writeInt(hasWriteObject ? 2 : 1);
        } catch (IOException ex) {
            throw new RuntimeException("Unexpected IOException: " + ex);
        }
        // Step 3
        Field[] fields = cls.getDeclaredFields();
        SortedSet set = new TreeSet(new FieldComparator());
        for (int i = 0; i < fields.length; ++i) {
            int mods = fields[i].getModifiers();
            if (!Modifier.isStatic(mods) && !Modifier.isTransient(mods))
                set.add(fields[i]);
        }
        Iterator iter = set.iterator();
        try {
            while (iter.hasNext()) {
                Field f = (Field)iter.next();
                dos.writeUTF(f.getName());
                dos.writeUTF(getSignature(f.getType()));
            }
        } catch (IOException ex) {
            throw new RuntimeException("Unexpected IOException: " + ex);
        }
        // Convert to byte[]
        try {
            dos.flush();
        } catch (IOException ex) {
            throw new RuntimeException("Unexpected IOException: " + ex);
        }
        byte[] bytes = baos.toByteArray();
        // Calculate SHA digest
        MessageDigest digest;
        try {
            digest = MessageDigest.getInstance("SHA");
        } catch (NoSuchAlgorithmException ex) {
            throw new RuntimeException("No SHA MEssageDigest: " + ex);
        }
        digest.update(bytes);
        byte[] sha = digest.digest();
        // Calculate hash as per section 10.6.2
        long hash = 0;
        for (int i = 0; i < Math.min(8, sha.length); i++) {
            hash += (long)(sha[i] & 255) << (i * 8);
        }
        // Save in cache
        classHashCodeCache.put(cls, new Long(hash));
        return hash;
    }

    /**
     * Calculate the signature of a class, according to the Java VM
     * specification, section 4.3.2.
     */
    private static String getSignature(Class cls) {
        if (cls.isArray())
            return "[" + cls.getComponentType();
        if (cls.isPrimitive()) {
            if (cls == Byte.TYPE)
                return "B";
            if (cls == Character.TYPE)
                return "C";
            if (cls == Double.TYPE)
                return "D";
            if (cls == Float.TYPE)
                return "F";
            if (cls == Integer.TYPE)
                return "I";
            if (cls == Long.TYPE)
                return "J";
            if (cls == Short.TYPE)
                return "S";
            if (cls == Boolean.TYPE)
                return "Z";
            throw new RuntimeException("Unknown primitive class.");
        }
        return "L" + cls.getName().replace('.', '/') + ";";
    }

    /**
     * Handle mappings for primitive types, as per section 1.3.3.
     */
    static String primitiveTypeIDLName(Class type) {
        if (type == Void.TYPE)
            return "void";
        if (type == Boolean.TYPE)
            return "boolean";
        if (type == Character.TYPE)
            return "wchar";
        if (type == Byte.TYPE)
            return "octet";
        if (type == Short.TYPE)
            return "short";
        if (type == Integer.TYPE)
            return "long";
        if (type == Long.TYPE)
            return "long long";
        if (type == Float.TYPE)
            return "float";
        if (type == Double.TYPE)
            return "double";
        throw new IllegalArgumentException(type + "is not a primitive type.");
    }

    /**
     * A <code>Comparator</code> for <code>Field</code>s, ordering the
     * fields according to the lexicographic ordering of their Java names.
     */
    private static class FieldComparator implements Comparator {
        public int compare(Object o1, Object o2) {
            if (o1 == o2)
                return 0;
            String n1 = ((Field)o1).getName();
            String n2 = ((Field)o2).getName();
            return n1.compareTo(n2);
        }
    }
}