/*
 *  Copyright 2001-2004 The Apache Software Foundation
 *
 *  Licensed 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.commons.collections;

import java.beans.BeanInfo;
import java.beans.IntrospectionException;
import java.beans.Introspector;
import java.beans.PropertyDescriptor;
import java.lang.reflect.Constructor;
import java.lang.reflect.InvocationTargetException;
import java.lang.reflect.Method;
import java.util.AbstractMap;
import java.util.AbstractSet;
import java.util.ArrayList;
import java.util.Collection;
import java.util.HashMap;
import java.util.Iterator;
import java.util.Set;

import org.apache.commons.collections.list.UnmodifiableList;
import org.apache.commons.collections.keyvalue.AbstractMapEntry;
import org.apache.commons.collections.set.UnmodifiableSet;

/** 
 * An implementation of Map for JavaBeans which uses introspection to
 * get and put properties in the bean.
 * <p>
 * If an exception occurs during attempts to get or set a property then the
 * property is considered non existent in the Map
 *
 * @since Commons Collections 1.0
 * @version $Revision: 1.29 $ $Date: 2004/02/18 01:15:42 $
 * 
 * @author James Strachan
 * @author Stephen Colebourne
 */
public class BeanMap extends AbstractMap implements Cloneable {

    private transient Object bean;

    private transient HashMap readMethods = new HashMap();
    private transient HashMap writeMethods = new HashMap();
    private transient HashMap types = new HashMap();

    /**
     * An empty array.  Used to invoke accessors via reflection.
     */
    public static final Object[] NULL_ARGUMENTS = {};

    /**
     * Maps primitive Class types to transformers.  The transformer
     * transform strings into the appropriate primitive wrapper.
     */
    public static HashMap defaultTransformers = new HashMap();
    
    static {
        defaultTransformers.put( 
            Boolean.TYPE, 
            new Transformer() {
                public Object transform( Object input ) {
                    return Boolean.valueOf( input.toString() );
                }
            }
        );
        defaultTransformers.put( 
            Character.TYPE, 
            new Transformer() {
                public Object transform( Object input ) {
                    return new Character( input.toString().charAt( 0 ) );
                }
            }
        );
        defaultTransformers.put( 
            Byte.TYPE, 
            new Transformer() {
                public Object transform( Object input ) {
                    return Byte.valueOf( input.toString() );
                }
            }
        );
        defaultTransformers.put( 
            Short.TYPE, 
            new Transformer() {
                public Object transform( Object input ) {
                    return Short.valueOf( input.toString() );
                }
            }
        );
        defaultTransformers.put( 
            Integer.TYPE, 
            new Transformer() {
                public Object transform( Object input ) {
                    return Integer.valueOf( input.toString() );
                }
            }
        );
        defaultTransformers.put( 
            Long.TYPE, 
            new Transformer() {
                public Object transform( Object input ) {
                    return Long.valueOf( input.toString() );
                }
            }
        );
        defaultTransformers.put( 
            Float.TYPE, 
            new Transformer() {
                public Object transform( Object input ) {
                    return Float.valueOf( input.toString() );
                }
            }
        );
        defaultTransformers.put( 
            Double.TYPE, 
            new Transformer() {
                public Object transform( Object input ) {
                    return Double.valueOf( input.toString() );
                }
            }
        );
    }
    
    
    // Constructors
    //-------------------------------------------------------------------------

    /**
     * Constructs a new empty <code>BeanMap</code>.
     */
    public BeanMap() {
    }

    /**
     * Constructs a new <code>BeanMap</code> that operates on the 
     * specified bean.  If the given bean is <code>null</code>, then
     * this map will be empty.
     *
     * @param bean  the bean for this map to operate on
     */
    public BeanMap(Object bean) {
        this.bean = bean;
        initialise();
    }

    // Map interface
    //-------------------------------------------------------------------------

    public String toString() {
        return "BeanMap<" + String.valueOf(bean) + ">";
    }
    
    /**
     * Clone this bean map using the following process: 
     *
     * <ul>
     * <li>If there is no underlying bean, return a cloned BeanMap without a
     * bean.
     *
     * <li>Since there is an underlying bean, try to instantiate a new bean of
     * the same type using Class.newInstance().
     * 
     * <li>If the instantiation fails, throw a CloneNotSupportedException
     *
     * <li>Clone the bean map and set the newly instantiated bean as the
     * underlying bean for the bean map.
     *
     * <li>Copy each property that is both readable and writable from the
     * existing object to a cloned bean map.  
     *
     * <li>If anything fails along the way, throw a
     * CloneNotSupportedException.
     *
     * <ul>
     */
    public Object clone() throws CloneNotSupportedException {
        BeanMap newMap = (BeanMap)super.clone();

        if(bean == null) {
            // no bean, just an empty bean map at the moment.  return a newly
            // cloned and empty bean map.
            return newMap;
        }

        Object newBean = null;            
        Class beanClass = null;
        try {
            beanClass = bean.getClass();
            newBean = beanClass.newInstance();
        } catch (Exception e) {
            // unable to instantiate
            throw new CloneNotSupportedException
                ("Unable to instantiate the underlying bean \"" +
                 beanClass.getName() + "\": " + e);
        }
            
        try {
            newMap.setBean(newBean);
        } catch (Exception exception) {
            throw new CloneNotSupportedException
                ("Unable to set bean in the cloned bean map: " + 
                 exception);
        }
            
        try {
            // copy only properties that are readable and writable.  If its
            // not readable, we can't get the value from the old map.  If
            // its not writable, we can't write a value into the new map.
            Iterator readableKeys = readMethods.keySet().iterator();
            while(readableKeys.hasNext()) {
                Object key = readableKeys.next();
                if(getWriteMethod(key) != null) {
                    newMap.put(key, get(key));
                }
            }
        } catch (Exception exception) {
            throw new CloneNotSupportedException
                ("Unable to copy bean values to cloned bean map: " +
                 exception);
        }

        return newMap;
    }

    /**
     * Puts all of the writable properties from the given BeanMap into this
     * BeanMap. Read-only and Write-only properties will be ignored.
     *
     * @param map  the BeanMap whose properties to put
     */
    public void putAllWriteable(BeanMap map) {
        Iterator readableKeys = map.readMethods.keySet().iterator();
        while (readableKeys.hasNext()) {
            Object key = readableKeys.next();
            if (getWriteMethod(key) != null) {
                this.put(key, map.get(key));
            }
        }
    }


    /**
     * This method reinitializes the bean map to have default values for the
     * bean's properties.  This is accomplished by constructing a new instance
     * of the bean which the map uses as its underlying data source.  This
     * behavior for <code>clear()</code> differs from the Map contract in that
     * the mappings are not actually removed from the map (the mappings for a
     * BeanMap are fixed).
     */
    public void clear() {
        if(bean == null) return;

        Class beanClass = null;
        try {
            beanClass = bean.getClass();
            bean = beanClass.newInstance();
        }
        catch (Exception e) {
            throw new UnsupportedOperationException( "Could not create new instance of class: " + beanClass );
        }
    }

    /**
     * Returns true if the bean defines a property with the given name.
     * <p>
     * The given name must be a <code>String</code> if not, this method
     * returns false. This method will also return false if the bean
     * does not define a property with that name.
     * <p>
     * Write-only properties will not be matched as the test operates against
     * property read methods.
     *
     * @param name  the name of the property to check
     * @return false if the given name is null or is not a <code>String</code>
     *   false if the bean does not define a property with that name; or
     *   true if the bean does define a property with that name
     */
    public boolean containsKey(Object name) {
        Method method = getReadMethod(name);
        return method != null;
    }

    /**
     * Returns true if the bean defines a property whose current value is
     * the given object.
     *
     * @param value  the value to check
     * @return false  true if the bean has at least one property whose 
     *   current value is that object, false otherwise
     */
    public boolean containsValue(Object value) {
        // use default implementation
        return super.containsValue(value);
    }

    /**
     * Returns the value of the bean's property with the given name.
     * <p>
     * The given name must be a {@link String} and must not be 
     * null; otherwise, this method returns <code>null</code>.
     * If the bean defines a property with the given name, the value of
     * that property is returned.  Otherwise, <code>null</code> is 
     * returned.
     * <p>
     * Write-only properties will not be matched as the test operates against
     * property read methods.
     *
     * @param name  the name of the property whose value to return
     * @return  the value of the property with that name
     */
    public Object get(Object name) {
        if ( bean != null ) {
            Method method = getReadMethod( name );
            if ( method != null ) {
                try {
                    return method.invoke( bean, NULL_ARGUMENTS );
                }
                catch (  IllegalAccessException e ) {
                    logWarn( e );
                }
                catch ( IllegalArgumentException e ) {
                    logWarn(  e );
                }
                catch ( InvocationTargetException e ) {
                    logWarn(  e );
                }
                catch ( NullPointerException e ) {
                    logWarn(  e );
                }
            }
        }
        return null;
    }

    /**
     * Sets the bean property with the given name to the given value.
     *
     * @param name  the name of the property to set
     * @param value  the value to set that property to
     * @return  the previous value of that property
     * @throws IllegalArgumentException  if the given name is null;
     *   if the given name is not a {@link String}; if the bean doesn't
     *   define a property with that name; or if the bean property with
     *   that name is read-only
     */
    public Object put(Object name, Object value) throws IllegalArgumentException, ClassCastException {
        if ( bean != null ) {
            Object oldValue = get( name );
            Method method = getWriteMethod( name );
            if ( method == null ) {
                throw new IllegalArgumentException( "The bean of type: "+ bean.getClass().getName() + " has no property called: " + name );
            }
            try {
                Object[] arguments = createWriteMethodArguments( method, value );
                method.invoke( bean, arguments );

                Object newValue = get( name );
                firePropertyChange( name, oldValue, newValue );
            }
            catch ( InvocationTargetException e ) {
                logInfo( e );
                throw new IllegalArgumentException( e.getMessage() );
            }
            catch ( IllegalAccessException e ) {
                logInfo( e );
                throw new IllegalArgumentException( e.getMessage() );
            }
            return oldValue;
        }
        return null;
    }
                    
    /**
     * Returns the number of properties defined by the bean.
     *
     * @return  the number of properties defined by the bean
     */
    public int size() {
        return readMethods.size();
    }

    
    /**
     * Get the keys for this BeanMap.
     * <p>
     * Write-only properties are <b>not</b> included in the returned set of
     * property names, although it is possible to set their value and to get 
     * their type.
     * 
     * @return BeanMap keys.  The Set returned by this method is not
     *        modifiable.
     */
    public Set keySet() {
        return UnmodifiableSet.decorate(readMethods.keySet());
    }

    /**
     * Gets a Set of MapEntry objects that are the mappings for this BeanMap.
     * <p>
     * Each MapEntry can be set but not removed.
     * 
     * @return the unmodifiable set of mappings
     */
    public Set entrySet() {
        return UnmodifiableSet.decorate(new AbstractSet() {
            public Iterator iterator() {
                return entryIterator();
            }
            public int size() {
              return BeanMap.this.readMethods.size();
            }
        });
    }

    /**
     * Returns the values for the BeanMap.
     * 
     * @return values for the BeanMap.  The returned collection is not
     *        modifiable.
     */
    public Collection values() {
        ArrayList answer = new ArrayList( readMethods.size() );
        for ( Iterator iter = valueIterator(); iter.hasNext(); ) {
            answer.add( iter.next() );
        }
        return UnmodifiableList.decorate(answer);
    }


    // Helper methods
    //-------------------------------------------------------------------------

    /**
     * Returns the type of the property with the given name.
     *
     * @param name  the name of the property
     * @return  the type of the property, or <code>null</code> if no such
     *  property exists
     */
    public Class getType(String name) {
        return (Class) types.get( name );
    }

    /**
     * Convenience method for getting an iterator over the keys.
     * <p>
     * Write-only properties will not be returned in the iterator.
     *
     * @return an iterator over the keys
     */
    public Iterator keyIterator() {
        return readMethods.keySet().iterator();
    }

    /**
     * Convenience method for getting an iterator over the values.
     *
     * @return an iterator over the values
     */
    public Iterator valueIterator() {
        final Iterator iter = keyIterator();
        return new Iterator() {            
            public boolean hasNext() {
                return iter.hasNext();
            }
            public Object next() {
                Object key = iter.next();
                return get(key);
            }
            public void remove() {
                throw new UnsupportedOperationException( "remove() not supported for BeanMap" );
            }
        };
    }

    /**
     * Convenience method for getting an iterator over the entries.
     *
     * @return an iterator over the entries
     */
    public Iterator entryIterator() {
        final Iterator iter = keyIterator();
        return new Iterator() {            
            public boolean hasNext() {
                return iter.hasNext();
            }            
            public Object next() {
                Object key = iter.next();
                Object value = get(key);
                return new MyMapEntry( BeanMap.this, key, value );
            }            
            public void remove() {
                throw new UnsupportedOperationException( "remove() not supported for BeanMap" );
            }
        };
    }


    // Properties
    //-------------------------------------------------------------------------

    /**
     * Returns the bean currently being operated on.  The return value may
     * be null if this map is empty.
     *
     * @return the bean being operated on by this map
     */
    public Object getBean() {
        return bean;
    }

    /**
     * Sets the bean to be operated on by this map.  The given value may
     * be null, in which case this map will be empty.
     *
     * @param newBean  the new bean to operate on
     */
    public void setBean( Object newBean ) {
        bean = newBean;
        reinitialise();
    }

    /**
     * Returns the accessor for the property with the given name.
     *
     * @param name  the name of the property 
     * @return the accessor method for the property, or null
     */
    public Method getReadMethod(String name) {
        return (Method) readMethods.get(name);
    }

    /**
     * Returns the mutator for the property with the given name.
     *
     * @param name  the name of the property
     * @return the mutator method for the property, or null
     */
    public Method getWriteMethod(String name) {
        return (Method) writeMethods.get(name);
    }


    // Implementation methods
    //-------------------------------------------------------------------------

    /**
     * Returns the accessor for the property with the given name.
     *
     * @param name  the name of the property 
     * @return null if the name is null; null if the name is not a 
     * {@link String}; null if no such property exists; or the accessor
     *  method for that property
     */
    protected Method getReadMethod( Object name ) {
        return (Method) readMethods.get( name );
    }

    /**
     * Returns the mutator for the property with the given name.
     *
     * @param name  the name of the 
     * @return null if the name is null; null if the name is not a 
     * {@link String}; null if no such property exists; null if the 
     * property is read-only; or the mutator method for that property
     */
    protected Method getWriteMethod( Object name ) {
        return (Method) writeMethods.get( name );
    }

    /**
     * Reinitializes this bean.  Called during {@link #setBean(Object)}.
     * Does introspection to find properties.
     */
    protected void reinitialise() {
        readMethods.clear();
        writeMethods.clear();
        types.clear();
        initialise();
    }

    private void initialise() {
        if(getBean() == null) return;

        Class  beanClass = getBean().getClass();
        try {
            //BeanInfo beanInfo = Introspector.getBeanInfo( bean, null );
            BeanInfo beanInfo = Introspector.getBeanInfo( beanClass );
            PropertyDescriptor[] propertyDescriptors = beanInfo.getPropertyDescriptors();
            if ( propertyDescriptors != null ) {
                for ( int i = 0; i < propertyDescriptors.length; i++ ) {
                    PropertyDescriptor propertyDescriptor = propertyDescriptors[i];
                    if ( propertyDescriptor != null ) {
                        String name = propertyDescriptor.getName();
                        Method readMethod = propertyDescriptor.getReadMethod();
                        Method writeMethod = propertyDescriptor.getWriteMethod();
                        Class aType = propertyDescriptor.getPropertyType();

                        if ( readMethod != null ) {
                            readMethods.put( name, readMethod );
                        }
                        if ( writeMethods != null ) {
                            writeMethods.put( name, writeMethod );
                        }
                        types.put( name, aType );
                    }
                }
            }
        }
        catch ( IntrospectionException e ) {
            logWarn(  e );
        }
    }

    /**
     * Called during a successful {@link #put(Object,Object)} operation.
     * Default implementation does nothing.  Override to be notified of
     * property changes in the bean caused by this map.
     *
     * @param key  the name of the property that changed
     * @param oldValue  the old value for that property
     * @param newValue  the new value for that property
     */
    protected void firePropertyChange( Object key, Object oldValue, Object newValue ) {
    }

    // Implementation classes
    //-------------------------------------------------------------------------

    /**
     * Map entry used by {@link BeanMap}.
     */
    protected static class MyMapEntry extends AbstractMapEntry {        
        private BeanMap owner;
        
        /**
         * Constructs a new <code>MyMapEntry</code>.
         *
         * @param owner  the BeanMap this entry belongs to
         * @param key  the key for this entry
         * @param value  the value for this entry
         */
        protected MyMapEntry( BeanMap owner, Object key, Object value ) {
            super( key, value );
            this.owner = owner;
        }

        /**
         * Sets the value.
         *
         * @param value  the new value for the entry
         * @return the old value for the entry
         */
        public Object setValue(Object value) {
            Object key = getKey();
            Object oldValue = owner.get( key );

            owner.put( key, value );
            Object newValue = owner.get( key );
            super.setValue( newValue );
            return oldValue;
        }
    }

    /**
     * Creates an array of parameters to pass to the given mutator method.
     * If the given object is not the right type to pass to the method 
     * directly, it will be converted using {@link #convertType(Class,Object)}.
     *
     * @param method  the mutator method
     * @param value  the value to pass to the mutator method
     * @return an array containing one object that is either the given value
     *   or a transformed value
     * @throws IllegalAccessException if {@link #convertType(Class,Object)}
     *   raises it
     * @throws IllegalArgumentException if any other exception is raised
     *   by {@link #convertType(Class,Object)}
     */
    protected Object[] createWriteMethodArguments( Method method, Object value ) throws IllegalAccessException, ClassCastException {            
        try {
            if ( value != null ) {
                Class[] types = method.getParameterTypes();
                if ( types != null && types.length > 0 ) {
                    Class paramType = types[0];
                    if ( ! paramType.isAssignableFrom( value.getClass() ) ) {
                        value = convertType( paramType, value );
                    }
                }
            }
            Object[] answer = { value };
            return answer;
        }
        catch ( InvocationTargetException e ) {
            logInfo( e );
            throw new IllegalArgumentException( e.getMessage() );
        }
        catch ( InstantiationException e ) {
            logInfo( e );
            throw new IllegalArgumentException( e.getMessage() );
        }
    }

    /**
     * Converts the given value to the given type.  First, reflection is
     * is used to find a public constructor declared by the given class 
     * that takes one argument, which must be the precise type of the 
     * given value.  If such a constructor is found, a new object is
     * created by passing the given value to that constructor, and the
     * newly constructed object is returned.<P>
     *
     * If no such constructor exists, and the given type is a primitive
     * type, then the given value is converted to a string using its 
     * {@link Object#toString() toString()} method, and that string is
     * parsed into the correct primitive type using, for instance, 
     * {@link Integer#valueOf(String)} to convert the string into an
     * <code>int</code>.<P>
     *
     * If no special constructor exists and the given type is not a 
     * primitive type, this method returns the original value.
     *
     * @param newType  the type to convert the value to
     * @param value  the value to convert
     * @return the converted value
     * @throws NumberFormatException if newType is a primitive type, and 
     *  the string representation of the given value cannot be converted
     *  to that type
     * @throws InstantiationException  if the constructor found with 
     *  reflection raises it
     * @throws InvocationTargetException  if the constructor found with
     *  reflection raises it
     * @throws IllegalAccessException  never
     * @throws IllegalArgumentException  never
     */
    protected Object convertType( Class newType, Object value ) 
        throws InstantiationException, IllegalAccessException, IllegalArgumentException, InvocationTargetException {
        
        // try call constructor
        Class[] types = { value.getClass() };
        try {
            Constructor constructor = newType.getConstructor( types );        
            Object[] arguments = { value };
            return constructor.newInstance( arguments );
        }
        catch ( NoSuchMethodException e ) {
            // try using the transformers
            Transformer transformer = getTypeTransformer( newType );
            if ( transformer != null ) {
                return transformer.transform( value );
            }
            return value;
        }
    }

    /**
     * Returns a transformer for the given primitive type.
     *
     * @param aType  the primitive type whose transformer to return
     * @return a transformer that will convert strings into that type,
     *  or null if the given type is not a primitive type
     */
    protected Transformer getTypeTransformer( Class aType ) {
        return (Transformer) defaultTransformers.get( aType );
    }

    /**
     * Logs the given exception to <code>System.out</code>.  Used to display
     * warnings while accessing/mutating the bean.
     *
     * @param ex  the exception to log
     */
    protected void logInfo(Exception ex) {
        // Deliberately do not use LOG4J or Commons Logging to avoid dependencies
        System.out.println( "INFO: Exception: " + ex );
    }

    /**
     * Logs the given exception to <code>System.err</code>.  Used to display
     * errors while accessing/mutating the bean.
     *
     * @param ex  the exception to log
     */
    protected void logWarn(Exception ex) {
        // Deliberately do not use LOG4J or Commons Logging to avoid dependencies
        System.out.println( "WARN: Exception: " + ex );
        ex.printStackTrace();
    }
}