/*

 * Copyright (c) 1996, 2013, 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.  Oracle designates this

 * particular file as subject to the "Classpath" exception as provided

 * by Oracle in the LICENSE file that accompanied this code.

 *

 * 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.

 */

package java.beans;

import java.lang.ref.Reference;

import java.lang.ref.WeakReference;

import java.lang.reflect.Method;

import java.util.List;

import java.util.ArrayList;

/**

 * A MethodDescriptor describes a particular method that a Java Bean

 * supports for external access from other components.

 */

public class MethodDescriptor extends FeatureDescriptor {

    private final MethodRef methodRef = new MethodRef();

    private String[] paramNames;

    private List<WeakReference<Class<?>>> params;

    private ParameterDescriptor parameterDescriptors[];

    /**

     * Constructs a <code>MethodDescriptor</code> from a

     * <code>Method</code>.

     *

     * @param method    The low-level method information.

     */

    public MethodDescriptor(Method method) {

        this(method, null);

    }

    /**

     * Constructs a <code>MethodDescriptor</code> from a

     * <code>Method</code> providing descriptive information for each

     * of the method's parameters.

     *

     * @param method    The low-level method information.

     * @param parameterDescriptors  Descriptive information for each of the

     *                          method's parameters.

     */

    public MethodDescriptor(Method method,

                ParameterDescriptor parameterDescriptors[]) {

        setName(method.getName());

        setMethod(method);

        this.parameterDescriptors = (parameterDescriptors != null)

                ? parameterDescriptors.clone()

                : null;

    }

    /**

     * Gets the method that this MethodDescriptor encapsulates.

     *

     * @return The low-level description of the method

     */

    public synchronized Method getMethod() {

        Method method = this.methodRef.get();

        if (method == null) {

            Class<?> cls = getClass0();

            String name = getName();

            if ((cls != null) && (name != null)) {

                Class<?>[] params = getParams();

                if (params == null) {

                    for (int i = 0; i < 3; i++) {

                        // Find methods for up to 2 params. We are guessing here.

                        // This block should never execute unless the classloader

                        // that loaded the argument classes disappears.

                        method = Introspector.findMethod(cls, name, i, null);

                        if (method != null) {

                            break;

                        }

                    }

                } else {

                    method = Introspector.findMethod(cls, name, params.length, params);

                }

                setMethod(method);

            }

        }

        return method;

    }

    private synchronized void setMethod(Method method) {

        if (method == null) {

            return;

        }

        if (getClass0() == null) {

            setClass0(method.getDeclaringClass());

        }

        setParams(getParameterTypes(getClass0(), method));

        this.methodRef.set(method);

    }

    private synchronized void setParams(Class<?>[] param) {

        if (param == null) {

            return;

        }

        paramNames = new String[param.length];

        params = new ArrayList<>(param.length);

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

            paramNames[i] = param[i].getName();

            params.add(new WeakReference<Class<?>>(param[i]));

        }

    }

    // pp getParamNames used as an optimization to avoid method.getParameterTypes.

    String[] getParamNames() {

        return paramNames;

    }

    private synchronized Class<?>[] getParams() {

        Class<?>[] clss = new Class<?>[params.size()];

        for (int i = 0; i < params.size(); i++) {

            Reference<? extends Class<?>> ref = (Reference<? extends Class<?>>)params.get(i);

            Class<?> cls = ref.get();

            if (cls == null) {

                return null;

            } else {

                clss[i] = cls;

            }

        }

        return clss;

    }

    /**

     * Gets the ParameterDescriptor for each of this MethodDescriptor's

     * method's parameters.

     *

     * @return The locale-independent names of the parameters.  May return

     *          a null array if the parameter names aren't known.

     */

    public ParameterDescriptor[] getParameterDescriptors() {

        return (this.parameterDescriptors != null)

                ? this.parameterDescriptors.clone()

                : null;

    }

    /*

     * Package-private constructor

     * Merge two method descriptors.  Where they conflict, give the

     * second argument (y) priority over the first argument (x).

     * @param x  The first (lower priority) MethodDescriptor

     * @param y  The second (higher priority) MethodDescriptor

     */

    MethodDescriptor(MethodDescriptor x, MethodDescriptor y) {

        super(x, y);

        params = x.params;

        if (y.params != null) {

            params = y.params;

        }

        paramNames = x.paramNames;

        if (y.paramNames != null) {

            paramNames = y.paramNames;

        }

        parameterDescriptors = x.parameterDescriptors;

        if (y.parameterDescriptors != null) {

            parameterDescriptors = y.parameterDescriptors;

        }

    }

    /*

     * Package-private dup constructor

     * This must isolate the new object from any changes to the old object.

     */

    MethodDescriptor(MethodDescriptor old) {

        super(old);

        this.methodRef.set(old.getMethod());

        params = old.params;

        paramNames = old.paramNames;

        if (old.parameterDescriptors != null) {

            int len = old.parameterDescriptors.length;

            parameterDescriptors = new ParameterDescriptor[len];

            for (int i = 0; i < len ; i++) {

                parameterDescriptors[i] = new ParameterDescriptor(old.parameterDescriptors[i]);

            }

        }

    }

    void appendTo(StringBuilder sb) {

        appendTo(sb, "method", this.methodRef.get());

        if (this.parameterDescriptors != null) {

            sb.append("; parameterDescriptors={");

            for (ParameterDescriptor pd : this.parameterDescriptors) {

                sb.append(pd).append(", ");

            }

            sb.setLength(sb.length() - 2);

            sb.append("}");

        }

    }

}