/*

 * Copyright (c) 1996, 2010, 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.reflect.Method;

import java.lang.reflect.Constructor;

/**

 * A PropertyDescriptor describes one property that a Java Bean

 * exports via a pair of accessor methods.

 */

public class PropertyDescriptor extends FeatureDescriptor {

    private Reference<? extends Class<?>> propertyTypeRef;

    private Reference<Method> readMethodRef;

    private Reference<Method> writeMethodRef;

    private Reference<? extends Class<?>> propertyEditorClassRef;

    private boolean bound;

    private boolean constrained;

    // The base name of the method name which will be prefixed with the

    // read and write method. If name == "foo" then the baseName is "Foo"

    private String baseName;

    private String writeMethodName;

    private String readMethodName;

    /**

     * Constructs a PropertyDescriptor for a property that follows

     * the standard Java convention by having getFoo and setFoo

     * accessor methods.  Thus if the argument name is "fred", it will

     * assume that the writer method is "setFred" and the reader method

     * is "getFred" (or "isFred" for a boolean property).  Note that the

     * property name should start with a lower case character, which will

     * be capitalized in the method names.

     *

     * @param propertyName The programmatic name of the property.

     * @param beanClass The Class object for the target bean.  For

     *          example sun.beans.OurButton.class.

     * @exception IntrospectionException if an exception occurs during

     *              introspection.

     */

    public PropertyDescriptor(String propertyName, Class<?> beanClass)

                throws IntrospectionException {

        this(propertyName, beanClass,

             Introspector.IS_PREFIX + NameGenerator.capitalize(propertyName),

             Introspector.SET_PREFIX + NameGenerator.capitalize(propertyName));

    }

    /**

     * This constructor takes the name of a simple property, and method

     * names for reading and writing the property.

     *

     * @param propertyName The programmatic name of the property.

     * @param beanClass The Class object for the target bean.  For

     *          example sun.beans.OurButton.class.

     * @param readMethodName The name of the method used for reading the property

     *           value.  May be null if the property is write-only.

     * @param writeMethodName The name of the method used for writing the property

     *           value.  May be null if the property is read-only.

     * @exception IntrospectionException if an exception occurs during

     *              introspection.

     */

    public PropertyDescriptor(String propertyName, Class<?> beanClass,

                String readMethodName, String writeMethodName)

                throws IntrospectionException {

        if (beanClass == null) {

            throw new IntrospectionException("Target Bean class is null");

        }

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

            throw new IntrospectionException("bad property name");

        }

        if ("".equals(readMethodName) || "".equals(writeMethodName)) {

            throw new IntrospectionException("read or write method name should not be the empty string");

        }

        setName(propertyName);

        setClass0(beanClass);

        this.readMethodName = readMethodName;

        if (readMethodName != null && getReadMethod() == null) {

            throw new IntrospectionException("Method not found: " + readMethodName);

        }

        this.writeMethodName = writeMethodName;

        if (writeMethodName != null && getWriteMethod() == null) {

            throw new IntrospectionException("Method not found: " + writeMethodName);

        }

        // If this class or one of its base classes allow PropertyChangeListener,

        // then we assume that any properties we discover are "bound".

        // See Introspector.getTargetPropertyInfo() method.

        Class[] args = { PropertyChangeListener.class };

        this.bound = null != Introspector.findMethod(beanClass, "addPropertyChangeListener", args.length, args);

    }

    /**

     * This constructor takes the name of a simple property, and Method

     * objects for reading and writing the property.

     *

     * @param propertyName The programmatic name of the property.

     * @param readMethod The method used for reading the property value.

     *          May be null if the property is write-only.

     * @param writeMethod The method used for writing the property value.

     *          May be null if the property is read-only.

     * @exception IntrospectionException if an exception occurs during

     *              introspection.

     */

    public PropertyDescriptor(String propertyName, Method readMethod, Method writeMethod)

                throws IntrospectionException {

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

            throw new IntrospectionException("bad property name");

        }

        setName(propertyName);

        setReadMethod(readMethod);

        setWriteMethod(writeMethod);

    }

    /**

     * Creates <code>PropertyDescriptor</code> for the specified bean

     * with the specified name and methods to read/write the property value.

     *

     * @param bean   the type of the target bean

     * @param base   the base name of the property (the rest of the method name)

     * @param read   the method used for reading the property value

     * @param write  the method used for writing the property value

     * @exception IntrospectionException if an exception occurs during introspection

     *

     * @since 1.7

     */

    PropertyDescriptor(Class<?> bean, String base, Method read, Method write) throws IntrospectionException {

        if (bean == null) {

            throw new IntrospectionException("Target Bean class is null");

        }

        setClass0(bean);

        setName(Introspector.decapitalize(base));

        setReadMethod(read);

        setWriteMethod(write);

        this.baseName = base;

    }

    /**

     * Returns the Java type info for the property.

     * Note that the {@code Class} object may describe

     * primitive Java types such as {@code int}.

     * This type is returned by the read method

     * or is used as the parameter type of the write method.

     * Returns {@code null} if the type is an indexed property

     * that does not support non-indexed access.

     *

     * @return the {@code Class} object that represents the Java type info,

     *         or {@code null} if the type cannot be determined

     */

    public synchronized Class<?> getPropertyType() {

        Class<?> type = getPropertyType0();

        if (type  == null) {

            try {

                type = findPropertyType(getReadMethod(), getWriteMethod());

                setPropertyType(type);

            } catch (IntrospectionException ex) {

                // Fall

            }

        }

        return type;

    }

    private void setPropertyType(Class<?> type) {

        this.propertyTypeRef = getWeakReference(type);

    }

    private Class<?> getPropertyType0() {

        return (this.propertyTypeRef != null)

                ? this.propertyTypeRef.get()

                : null;

    }

    /**

     * Gets the method that should be used to read the property value.

     *

     * @return The method that should be used to read the property value.

     * May return null if the property can't be read.

     */

    public synchronized Method getReadMethod() {

        Method readMethod = getReadMethod0();

        if (readMethod == null) {

            Class<?> cls = getClass0();

            if (cls == null || (readMethodName == null && readMethodRef == null)) {

                // The read method was explicitly set to null.

                return null;

            }

            if (readMethodName == null) {

                Class<?> type = getPropertyType0();

                if (type == boolean.class || type == null) {

                    readMethodName = Introspector.IS_PREFIX + getBaseName();

                } else {

                }

            }

            // Since there can be multiple write methods but only one getter

            // method, find the getter method first so that you know what the

            // property type is.  For booleans, there can be "is" and "get"

            // methods.  If an "is" method exists, this is the official

            // reader method so look for this one first.

            readMethod = Introspector.findMethod(cls, readMethodName, 0);

                readMethod = Introspector.findMethod(cls, readMethodName, 0);

            }

            try {

                setReadMethod(readMethod);

            } catch (IntrospectionException ex) {

                // fall

            }

        }

        return readMethod;

    }

    /**

     * Sets the method that should be used to read the property value.

     *

     * @param readMethod The new read method.

     */

    public synchronized void setReadMethod(Method readMethod)

                                throws IntrospectionException {

        if (readMethod == null) {

            readMethodName = null;

            readMethodRef = null;

            return;

        }

        // The property type is determined by the read method.

        setPropertyType(findPropertyType(readMethod, getWriteMethod0()));

        setClass0(readMethod.getDeclaringClass());

        readMethodName = readMethod.getName();

        this.readMethodRef = getSoftReference(readMethod);

        setTransient(readMethod.getAnnotation(Transient.class));

    }

    /**

     * Gets the method that should be used to write the property value.

     *

     * @return The method that should be used to write the property value.

     * May return null if the property can't be written.

     */

    public synchronized Method getWriteMethod() {

        Method writeMethod = getWriteMethod0();

        if (writeMethod == null) {

            Class<?> cls = getClass0();

            if (cls == null || (writeMethodName == null && writeMethodRef == null)) {

                // The write method was explicitly set to null.

                return null;

            }

            // We need the type to fetch the correct method.

            Class<?> type = getPropertyType0();

            if (type == null) {

                try {

                    // Can't use getPropertyType since it will lead to recursive loop.

                    type = findPropertyType(getReadMethod(), null);

                    setPropertyType(type);

                } catch (IntrospectionException ex) {

                    // Without the correct property type we can't be guaranteed

                    // to find the correct method.

                    return null;

                }

            }

            if (writeMethodName == null) {

                writeMethodName = Introspector.SET_PREFIX + getBaseName();

            }

            Class<?>[] args = (type == null) ? null : new Class<?>[] { type };

            writeMethod = Introspector.findMethod(cls, writeMethodName, 1, args);

            if (writeMethod != null) {

                if (!writeMethod.getReturnType().equals(void.class)) {

                    writeMethod = null;

                }

            }

            try {

                setWriteMethod(writeMethod);

            } catch (IntrospectionException ex) {

                // fall through

            }

        }

        return writeMethod;

    }

    /**

     * Sets the method that should be used to write the property value.

     *

     * @param writeMethod The new write method.

     */

    public synchronized void setWriteMethod(Method writeMethod)

                                throws IntrospectionException {

        if (writeMethod == null) {

            writeMethodName = null;

            writeMethodRef = null;

            return;

        }

        // Set the property type - which validates the method

        setPropertyType(findPropertyType(getReadMethod(), writeMethod));

        setClass0(writeMethod.getDeclaringClass());

        writeMethodName = writeMethod.getName();

        this.writeMethodRef = getSoftReference(writeMethod);

        setTransient(writeMethod.getAnnotation(Transient.class));

    }

    private Method getReadMethod0() {

        return (this.readMethodRef != null)

                ? this.readMethodRef.get()

                : null;

    }

    private Method getWriteMethod0() {

        return (this.writeMethodRef != null)

                ? this.writeMethodRef.get()

                : null;

    }

    /**

     * Overridden to ensure that a super class doesn't take precedent

     */

    void setClass0(Class<?> clz) {

        if (getClass0() != null && clz.isAssignableFrom(getClass0())) {

            // dont replace a subclass with a superclass

            return;

        }

        super.setClass0(clz);

    }

    /**

     * Updates to "bound" properties will cause a "PropertyChange" event to

     * get fired when the property is changed.

     *

     * @return True if this is a bound property.

     */

    public boolean isBound() {

        return bound;

    }

    /**

     * Updates to "bound" properties will cause a "PropertyChange" event to

     * get fired when the property is changed.

     *

     * @param bound True if this is a bound property.

     */

    public void setBound(boolean bound) {

        this.bound = bound;

    }

    /**

     * Attempted updates to "Constrained" properties will cause a "VetoableChange"

     * event to get fired when the property is changed.

     *

     * @return True if this is a constrained property.

     */

    public boolean isConstrained() {

        return constrained;

    }

    /**

     * Attempted updates to "Constrained" properties will cause a "VetoableChange"

     * event to get fired when the property is changed.

     *

     * @param constrained True if this is a constrained property.

     */

    public void setConstrained(boolean constrained) {

        this.constrained = constrained;

    }

    /**

     * Normally PropertyEditors will be found using the PropertyEditorManager.

     * However if for some reason you want to associate a particular

     * PropertyEditor with a given property, then you can do it with

     * this method.

     *

     * @param propertyEditorClass  The Class for the desired PropertyEditor.

     */

    public void setPropertyEditorClass(Class<?> propertyEditorClass) {

        this.propertyEditorClassRef = getWeakReference(propertyEditorClass);

    }

    /**

     * Gets any explicit PropertyEditor Class that has been registered

     * for this property.

     *

     * @return Any explicit PropertyEditor Class that has been registered

     *          for this property.  Normally this will return "null",

     *          indicating that no special editor has been registered,

     *          so the PropertyEditorManager should be used to locate

     *          a suitable PropertyEditor.

     */

    public Class<?> getPropertyEditorClass() {

        return (this.propertyEditorClassRef != null)

                ? this.propertyEditorClassRef.get()

                : null;

    }

    /**

     * Constructs an instance of a property editor using the current

     * property editor class.

     * <p>

     * If the property editor class has a public constructor that takes an

     * Object argument then it will be invoked using the bean parameter

     * as the argument. Otherwise, the default constructor will be invoked.

     *

     * @param bean the source object

     * @return a property editor instance or null if a property editor has

     *         not been defined or cannot be created

     * @since 1.5

     */

    public PropertyEditor createPropertyEditor(Object bean) {

        Object editor = null;

        Class<?> cls = getPropertyEditorClass();

        if (cls != null) {

            Constructor<?> ctor = null;

            if (bean != null) {

                try {

                    ctor = cls.getConstructor(new Class<?>[] { Object.class });

                } catch (Exception ex) {

                    // Fall through

                }

            }

            try {

                if (ctor == null) {

                    editor = cls.newInstance();

                } else {

                    editor = ctor.newInstance(new Object[] { bean });

                }

            } catch (Exception ex) {

                // Fall through

            }

        }

        return (PropertyEditor)editor;

    }

    /**

     * Compares this <code>PropertyDescriptor</code> against the specified object.

     * Returns true if the objects are the same. Two <code>PropertyDescriptor</code>s

     * are the same if the read, write, property types, property editor and

     * flags  are equivalent.

     *

     * @since 1.4

     */

    public boolean equals(Object obj) {

        if (this == obj) {

            return true;

        }

        if (obj != null && obj instanceof PropertyDescriptor) {

            PropertyDescriptor other = (PropertyDescriptor)obj;

            Method otherReadMethod = other.getReadMethod();

            Method otherWriteMethod = other.getWriteMethod();

            if (!compareMethods(getReadMethod(), otherReadMethod)) {

                return false;

            }

            if (!compareMethods(getWriteMethod(), otherWriteMethod)) {

                return false;

            }

            if (getPropertyType() == other.getPropertyType() &&

                getPropertyEditorClass() == other.getPropertyEditorClass() &&

                bound == other.isBound() && constrained == other.isConstrained() &&

                writeMethodName == other.writeMethodName &&

                readMethodName == other.readMethodName) {

                return true;

            }

        }

        return false;

    }

    /**

     * Package private helper method for Descriptor .equals methods.

     *

     * @param a first method to compare

     * @param b second method to compare

     * @return boolean to indicate that the methods are equivalent

     */

    boolean compareMethods(Method a, Method b) {

        // Note: perhaps this should be a protected method in FeatureDescriptor

        if ((a == null) != (b == null)) {

            return false;

        }

        if (a != null && b != null) {

            if (!a.equals(b)) {

                return false;

            }

        }

        return true;

    }