/*

 * Copyright (c) 2004, Oracle and/or its affiliates. All rights reserved.

 * DO NOT ALTER OR REMOVE COPYRIGHT NOTICES OR THIS FILE HEADER.

 *

 * This code is free software; you can redistribute it and/or modify it

 * under the terms of the GNU General Public License version 2 only, as

 * published by the Free Software Foundation.

 *

 * This code is distributed in the hope that it will be useful, but WITHOUT

 * ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or

 * FITNESS FOR A PARTICULAR PURPOSE.  See the GNU General Public License

 * version 2 for more details (a copy is included in the LICENSE file that

 * accompanied this code).

 *

 * You should have received a copy of the GNU General Public License version

 * 2 along with this work; if not, write to the Free Software Foundation,

 * Inc., 51 Franklin St, Fifth Floor, Boston, MA 02110-1301 USA.

 *

 * Please contact Oracle, 500 Oracle Parkway, Redwood Shores, CA 94065 USA

 * or visit www.oracle.com if you need additional information or have any

 * questions.

 */

/*

 * @bug     5024531

 * @summary Utility class to convert a struct-like class to a CompositeData.

 * @author Mandy Chung

 */

import java.lang.reflect.*;

import java.util.*;

import javax.management.*;

import javax.management.openmbean.*;

import static javax.management.openmbean.SimpleType.*;

/**

 * A converter utiltiy class to automatically convert a given

 * class to a CompositeType.

 */

public class OpenTypeConverter {

    private static final WeakHashMap<Class,OpenType> convertedTypes =

        new WeakHashMap<Class,OpenType>();

    private static final OpenType[] simpleTypes = {

        BIGDECIMAL, BIGINTEGER, BOOLEAN, BYTE, CHARACTER, DATE,

        DOUBLE, FLOAT, INTEGER, LONG, OBJECTNAME, SHORT, STRING,

        VOID,

    };

    static {

        for (int i = 0; i < simpleTypes.length; i++) {

            final OpenType t = simpleTypes[i];

            Class c;

            try {

                c = Class.forName(t.getClassName(), false,

                                  String.class.getClassLoader());

            } catch (ClassNotFoundException e) {

                // the classes that these predefined types declare must exist!

                assert(false);

                c = null; // not reached

            }

            convertedTypes.put(c, t);

            if (c.getName().startsWith("java.lang.")) {

                try {

                    final Field typeField = c.getField("TYPE");

                    final Class primitiveType = (Class) typeField.get(null);

                    convertedTypes.put(primitiveType, t);

                } catch (NoSuchFieldException e) {

                    // OK: must not be a primitive wrapper

                } catch (IllegalAccessException e) {

                    // Should not reach here

                    throw new AssertionError(e);

                }

            }

        }

    }

    private static class InProgress extends OpenType {

        private static final String description =

                  "Marker to detect recursive type use -- internal use only!";

        InProgress() throws OpenDataException {

            super("java.lang.String", "java.lang.String", description);

        }

        public String toString() {

            return description;

        }

        public int hashCode() {

            return 0;

        }

        public boolean equals(Object o) {

            return false;

        }

        public boolean isValue(Object o) {

            return false;

        }

    }

    private static final OpenType inProgress;

    static {

        OpenType t;

        try {

            t = new InProgress();

        } catch (OpenDataException e) {

            // Should not reach here

            throw new AssertionError(e);

        }

        inProgress = t;

    }

    // Convert a class to an OpenType

    public static synchronized OpenType toOpenType(Class c)

            throws OpenDataException {

        OpenType t;

        t = convertedTypes.get(c);

        if (t != null) {

            if (t instanceof InProgress)

                throw new OpenDataException("Recursive data structure");

            return t;

        }

        convertedTypes.put(c, inProgress);

        if (Enum.class.isAssignableFrom(c))

            t = STRING;

        else if (c.isArray())

            t = makeArrayType(c);

        else

            t = makeCompositeType(c);

        convertedTypes.put(c, t);

        return t;

    }

    private static OpenType makeArrayType(Class c) throws OpenDataException {

        int dim;

        for (dim = 0; c.isArray(); dim++)

            c = c.getComponentType();

        return new ArrayType(dim, toOpenType(c));

    }

    private static OpenType makeCompositeType(Class c)

            throws OpenDataException {

        // Make a CompositeData containing all the getters

        final Method[] methods = c.getMethods();

        final List<String> names = new ArrayList<String>();

        final List<OpenType> types = new ArrayList<OpenType>();

        /* Select public methods that look like "T getX()" or "boolean

           isX() or hasX()", where T is not void and X is not the empty

           string.  Exclude "Class getClass()" inherited from Object.  */

        for (int i = 0; i < methods.length; i++) {

            final Method method = methods[i];

            final String name = method.getName();

            final Class type = method.getReturnType();

            final String rest;

            if (name.startsWith("get"))

                rest = name.substring(3);

            else if (name.startsWith("is") && type == boolean.class)

                rest = name.substring(2);

            else if (name.startsWith("has") && type == boolean.class)

                rest = name.substring(3);

            else

                continue;

            if (rest.equals("") || method.getParameterTypes().length > 0

                || type == void.class || rest.equals("Class"))

                continue;

            names.add(decapitalize(rest));

            types.add(toOpenType(type));

        }

        final String[] nameArray = names.toArray(new String[0]);

        return new CompositeType(c.getName(),

                                 c.getName(),

                                 nameArray, // field names

                                 nameArray, // field descriptions

                                 types.toArray(new OpenType[0]));

    }

    /**

     * Utility method to take a string and convert it to normal Java variable

     * name capitalization.  This normally means converting the first

     * character from upper case to lower case, but in the (unusual) special

     * case when there is more than one character and both the first and

     * second characters are upper case, we leave it alone.

     * <p>

     * Thus "FooBah" becomes "fooBah" and "X" becomes "x", but "URL" stays

     * as "URL".

     *

     * @param  name The string to be decapitalized.

     * @return  The decapitalized version of the string.

     */

    private static String decapitalize(String name) {

        if (name == null || name.length() == 0) {

            return name;

        }

        if (name.length() > 1 && Character.isUpperCase(name.charAt(1)) &&

                        Character.isUpperCase(name.charAt(0))){

            return name;

        }

        char chars[] = name.toCharArray();

        chars[0] = Character.toLowerCase(chars[0]);

        return new String(chars);

    }

}