/*
 * 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 javax.faces.component;

import java.lang.reflect.Array;
import java.util.Arrays;
import java.util.ArrayList;
import java.util.Collection;
import java.util.Collections;
import java.util.Iterator;
import java.util.List;

import javax.faces.application.FacesMessage;
import javax.faces.context.FacesContext;
import javax.faces.convert.ConverterException;
import javax.faces.el.ValueBinding;
import javax.faces.render.Renderer;

/**
 * Base class for the various component classes that allow a user to select zero or
 * more options from a set.
 * <p>
 * This is not an abstract class; java code can create an instance of this, configure
 * its rendererType appropriately, and add it to a view. However there is no tag class
 * for this component, ie it cannot be added directly to a page when using JSP (and
 * other presentation technologies are expected to behave similarly). Instead, there
 * is a family of subclasses that extend this base functionality, and they do have
 * tag classes. 
 * <p>
 * See Javadoc of <a href="http://java.sun.com/j2ee/javaserverfaces/1.1_01/docs/api/index.html">JSF Specification</a>
 *
 * @JSFComponent
 *   type = "javax.faces.SelectMany"
 *   family = "javax.faces.SelectMany"
 *   desc = "UISelectMany"
 *
 * @author Manfred Geiler (latest modification by $Author$)
 * @version $Revision$ $Date$
 */
public class UISelectMany extends UIInput
{
    public static final String COMPONENT_TYPE = "javax.faces.SelectMany";
    public static final String COMPONENT_FAMILY = "javax.faces.SelectMany";
    public static final String INVALID_MESSAGE_ID = "javax.faces.component.UISelectMany.INVALID";

    private static final String DEFAULT_RENDERER_TYPE = "javax.faces.Listbox";

    public UISelectMany()
    {
        setRendererType(DEFAULT_RENDERER_TYPE);
    }

    public String getFamily()
    {
        return COMPONENT_FAMILY;
    }

    public Object[] getSelectedValues()
    {
        return (Object[]) getValue();
    }

    public void setSelectedValues(Object[] selectedValues)
    {
        setValue(selectedValues);
    }

    public ValueBinding getValueBinding(String name)
    {
        if (name == null)
            throw new NullPointerException("name");
        if (name.equals("selectedValues"))
        {
            return super.getValueBinding("value");
        }
        else
        {
            return super.getValueBinding(name);
        }
    }

    public void setValueBinding(String name, ValueBinding binding)
    {
        if (name == null)
            throw new NullPointerException("name");
        if (name.equals("selectedValues"))
        {
            super.setValueBinding("value", binding);
        }
        else
        {
            super.setValueBinding(name, binding);
        }
    }

    /**
     * @return true if Objects are different (!)
     */
    protected boolean compareValues(Object previous, Object value)
    {
        if (previous == null)
        {
            // one is null, the other not
            return value != null;
        }
        else if (value == null)
        {
            // one is null, the other not
            return previous != null;
        }
        else
        {
            if (previous instanceof Object[] && value instanceof Object[])
            {
                return compareObjectArrays((Object[]) previous,
                                (Object[]) value);
            }
            else if (previous instanceof List && value instanceof List)
            {
                return compareLists((List) previous, (List) value);
            }
            else if (previous.getClass().isArray()
                            && value.getClass().isArray())
            {
                return comparePrimitiveArrays(previous, value);
            }
            else
            {
                //Objects have different classes
                return true;
            }
        }
    }

    private boolean compareObjectArrays(Object[] previous, Object[] value)
    {
        int length = value.length;
        if (previous.length != length)
        {
            //different length
            return true;
        }

        boolean[] scoreBoard = new boolean[length];
        for (int i = 0; i < length; i++)
        {
            Object p = previous[i];
            boolean found = false;
            for (int j = 0; j < length; j++)
            {
                if (scoreBoard[j] == false)
                {
                    Object v = value[j];
                    if ((p == null && v == null)
                                    || (p != null && v != null && p.equals(v)))
                    {
                        scoreBoard[j] = true;
                        found = true;
                        break;
                    }
                }
            }
            if (!found)
            {
                return true; //current element of previous array not found in new array
            }
        }

        return false; // arrays are identical
    }

    private boolean compareLists(List previous, List value)
    {
        int length = value.size();
        if (previous.size() != length)
        {
            //different length
            return true;
        }

        boolean[] scoreBoard = new boolean[length];
        for (int i = 0; i < length; i++)
        {
            Object p = previous.get(i);
            boolean found = false;
            for (int j = 0; j < length; j++)
            {
                if (scoreBoard[j] == false)
                {
                    Object v = value.get(j);
                    if ((p == null && v == null)
                                    || (p != null && v != null && p.equals(v)))
                    {
                        scoreBoard[j] = true;
                        found = true;
                        break;
                    }
                }
            }
            if (!found)
            {
                return true; //current element of previous List not found in new List
            }
        }

        return false; // Lists are identical
    }

    private boolean comparePrimitiveArrays(Object previous, Object value)
    {
        int length = Array.getLength(value);
        if (Array.getLength(previous) != length)
        {
            //different length
            return true;
        }

        boolean[] scoreBoard = new boolean[length];
        for (int i = 0; i < length; i++)
        {
            Object p = Array.get(previous, i);
            boolean found = false;
            for (int j = 0; j < length; j++)
            {
                if (scoreBoard[j] == false)
                {
                    Object v = Array.get(value, j);
                    if ((p == null && v == null)
                                    || (p != null && v != null && p.equals(v)))
                    {
                        scoreBoard[j] = true;
                        found = true;
                        break;
                    }
                }
            }
            if (!found)
            {
                return true; //current element of previous array not found in new array
            }
        }

        return false; // arrays are identical
    }

    protected void validateValue(FacesContext context, Object convertedValue)
    {
        Iterator itemValues = _createItemValuesIterator(convertedValue);

        // verify that iterator was successfully created for convertedValue type
        if (itemValues == null)
        {
            _MessageUtils.addErrorMessage(context, this,
                                          INVALID_MESSAGE_ID,
                                          new Object[] {getId()});
            setValid(false);
            return;
        }

        boolean hasValues = itemValues.hasNext();

        // if UISelectMany is required, then there must be some selected values
        if (isRequired() && !hasValues)
        {
            _MessageUtils.addErrorMessage(context, this, REQUIRED_MESSAGE_ID,
                            new Object[] {getId()});
            setValid(false);
            return;
        }

        // run the validators only if there are item values to validate
        if (hasValues)
        {
            _ComponentUtils.callValidators(context, this, convertedValue);
        }

        if (isValid() && hasValues)
        {
            Collection items = new ArrayList();
            for (Iterator iter = new _SelectItemsIterator(this); iter.hasNext();)
            {
                items.add( iter.next() );
            }
            while (itemValues.hasNext())
            {
                Object itemValue = itemValues.next();

                if (!_SelectItemsUtil.matchValue(itemValue, items.iterator()))
                {
                    _MessageUtils.addErrorMessage(context, this,
                                    INVALID_MESSAGE_ID,
                                    new Object[] {getId()});
                    setValid(false);
                    return;
                }
            }
        }
    }

    /**
     * First part is identical to super.validate except the empty condition.
     * Second part: iterate through UISelectItem and UISelectItems and check
     *              current values against these items
     */
    public void validate(FacesContext context)
    {
        // TODO : Setting the submitted value to null in the super class causes a bug, if set to null, you'll get the following error :
        // java.lang.NullPointerException at org.apache.myfaces.renderkit._SharedRendererUtils.getConvertedUISelectManyValue(_SharedRendererUtils.java:118)
        super.validate(context);
    }

    protected Object getConvertedValue(FacesContext context,
                    Object submittedValue)
    {
        try
        {
            Renderer renderer = getRenderer(context);
            if (renderer != null)
            {
                return renderer
                                .getConvertedValue(context, this,
                                                submittedValue);
            }
            else if (submittedValue == null)
            {
                return null;
            }
            else if (submittedValue instanceof String[])
            {
                return _SharedRendererUtils.getConvertedUISelectManyValue(
                                context, this, (String[]) submittedValue);
            }
        }
        catch (ConverterException e)
        {
            FacesMessage facesMessage = e.getFacesMessage();
            if (facesMessage != null)
            {
                context.addMessage(getClientId(context), facesMessage);
            }
            else
            {
                _MessageUtils.addErrorMessage(context, this,
                                CONVERSION_MESSAGE_ID, new Object[] {getId()});
            }
            setValid(false);
        }
        return submittedValue;
    }

    private Iterator _createItemValuesIterator(Object convertedValue)
    {
        if (convertedValue == null)
        {
            return Collections.EMPTY_LIST.iterator();
        }
        else
        {
            Class valueClass = convertedValue.getClass();
            if (valueClass.isArray())
            {
                return new _PrimitiveArrayIterator(convertedValue);
            }
            else if (convertedValue instanceof Object[])
            {
                Object[] values = (Object[]) convertedValue;
                return Arrays.asList(values).iterator();
            }
            else if (convertedValue instanceof List)
            {
                List values = (List) convertedValue;
                return values.iterator();
            }
            else
            {
                // unsupported type for iteration
                return null;
            }
        }
    }
}