# COSArrayList.java

    /*
     * 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 org.apache.pdfbox.pdmodel.common;

    import org.apache.pdfbox.cos.COSArray;
    import org.apache.pdfbox.cos.COSBase;
    import org.apache.pdfbox.cos.COSDictionary;
    import org.apache.pdfbox.cos.COSInteger;
    import org.apache.pdfbox.cos.COSFloat;
    import org.apache.pdfbox.cos.COSString;
    import org.apache.pdfbox.cos.COSName;
    import org.apache.pdfbox.cos.COSNull;

    import java.util.ArrayList;
    import java.util.Collection;
    import java.util.Iterator;
    import java.util.List;
    import java.util.ListIterator;

    /**
     * This is an implementation of a List that will sync its contents to a COSArray.
     *
     * @author Ben Litchfield
     * @param <E> Element type.
     */
    public class COSArrayList<E> implements List<E>
    {
        private final COSArray array;
        private final List<E> actual;

        // indicates that the list has been filtered
        // i.e. the number of entries in array and actual differ
        private boolean isFiltered = false;

        private COSDictionary parentDict;
        private COSName dictKey;

        /**
         * Default constructor.
         */
        public COSArrayList()
        {
            array = new COSArray();
            actual = new ArrayList<>();
        }

        /**
         * Create the COSArrayList specifying the List and the backing COSArray.
         *
         * <p>User of this constructor need to ensure that the entries in the List and
         * the backing COSArray are matching i.e. the COSObject of the List entry is
         * included in the COSArray.
         *
         * <p>If the number of entries in the List and the COSArray differ
         * it is assumed that the List has been filtered. In that case the COSArrayList
         * shall only be used for reading purposes and no longer for updating.
         *
         * @param actualList The list of standard java objects
         * @param cosArray The COS array object to sync to.
         */
        public COSArrayList( List<E> actualList, COSArray cosArray )
        {
            actual = actualList;
            array = cosArray;

            // if the number of entries differs this may come from a filter being
            // applied at the PDModel level
            if (actual.size() != array.size()) {
                isFiltered = true;
            }
        }

        /**
         * This constructor is to be used if the array doesn't exist, but is to be created and added to
         * the parent dictionary as soon as the first element is added to the array.
         *
         * @param dictionary The dictionary that holds the item, and will hold the array if an item is
         * added.
         * @param dictionaryKey The key into the dictionary to set the item.
         */
        public COSArrayList(COSDictionary dictionary, COSName dictionaryKey)
        {
            array = new COSArray();
            actual = new ArrayList<>();
            parentDict = dictionary;
            dictKey = dictionaryKey;
        }

        /**
         * This is a really special constructor.  Sometimes the PDF spec says
         * that a dictionary entry can either be a single item or an array of those
         * items.  But in the PDModel interface we really just want to always return
         * a java.util.List.  In the case were we get the list and never modify it
         * we don't want to convert to COSArray and put one element, unless we append
         * to the list.  So here we are going to create this object with a single
         * item instead of a list, but allow more items to be added and then converted
         * to an array.
         *
         * @param actualObject The PDModel object.
         * @param item The COS Model object.
         * @param dictionary The dictionary that holds the item, and will hold the array if an item is added.
         * @param dictionaryKey The key into the dictionary to set the item.
         */
        public COSArrayList( E actualObject, COSBase item, COSDictionary dictionary, COSName dictionaryKey )
        {
            array = new COSArray();
            array.add( item );
            actual = new ArrayList<>();
            actual.add( actualObject );

            parentDict = dictionary;
            dictKey = dictionaryKey;
        }

        /**
         * {@inheritDoc}
         */
        @Override
        public int size()
        {
            return actual.size();
        }

        /**
         * {@inheritDoc}
         */
        @Override
        public boolean isEmpty()
        {
            return actual.isEmpty();
        }

        /**
         * {@inheritDoc}
         */
        @Override
        public boolean contains(Object o)
        {
            return actual.contains(o);
        }

        /**
         * {@inheritDoc}
         */
        @Override
        public Iterator<E> iterator()
        {
            return actual.iterator();
        }

        /**
         * {@inheritDoc}
         */
        @Override
        public Object[] toArray()
        {
            return actual.toArray();
        }

        /**
         * {@inheritDoc}
         */
        @Override
        public <X>X[] toArray(X[] a)
        {
            return actual.toArray(a);

        }

        /**
         * {@inheritDoc}
         */
        @Override
        public boolean add(E o)
        {
            //when adding if there is a parentDict then change the item
            //in the dictionary from a single item to an array.
            if( parentDict != null )
            {
                parentDict.setItem( dictKey, array );
                //clear the parent dict so it doesn't happen again, there might be
                //a usecase for keeping the parentDict around but not now.
                parentDict = null;
            }
            //string is a special case because we can't subclass to be COSObjectable
            if( o instanceof String )
            {
                array.add( new COSString( (String)o ) );
            }
            else
            {
                if(array != null)
                {
                    array.add(((COSObjectable)o).getCOSObject());
                }
            }
            return actual.add(o);
        }

        /**
         * {@inheritDoc}
         */
        @Override
        public boolean remove(Object o)
        {

            if (isFiltered) {
                throw new UnsupportedOperationException("removing entries from a filtered List is not permitted");
            }

            boolean retval = true;
            int index = actual.indexOf( o );
            if( index >= 0 )
            {
                actual.remove( index );
                array.remove( index );
            }
            else
            {
                retval = false;
            }
            return retval;
        }

        /**
         * {@inheritDoc}
         */
        @Override
        public boolean containsAll(Collection<?> c)
        {
            return actual.containsAll( c );
        }

        /**
         * {@inheritDoc}
         */
        @Override
        public boolean addAll(Collection<? extends E> c)
        {
            if (isFiltered) {
                throw new UnsupportedOperationException("Adding to a filtered List is not permitted");
            }

            //when adding if there is a parentDict then change the item
            //in the dictionary from a single item to an array.
            if( parentDict != null && c.size() > 0)
            {
                parentDict.setItem( dictKey, array );
                //clear the parent dict so it doesn't happen again, there might be
                //a usecase for keeping the parentDict around but not now.
                parentDict = null;
            }
            array.addAll( toCOSObjectList( c ) );
            return actual.addAll( c );
        }

        /**
         * {@inheritDoc}
         */
        @Override
        public boolean addAll(int index, Collection<? extends E> c)
        {
            if (isFiltered) {
                throw new UnsupportedOperationException("Inserting to a filtered List is not permitted");
            }

            //when adding if there is a parentDict then change the item
            //in the dictionary from a single item to an array.
            if( parentDict != null && c.size() > 0)
            {
                parentDict.setItem( dictKey, array );
                //clear the parent dict so it doesn't happen again, there might be
                //a usecase for keeping the parentDict around but not now.
                parentDict = null;
            }

            array.addAll( index, toCOSObjectList( c ) );
            return actual.addAll( index, c );
        }

        /**
         * This will convert a list of COSObjectables to an array list of COSBase objects.
         *
         * @param cosObjectableList A list of COSObjectable.
         *
         * @return A list of COSBase.
         * @throws IllegalArgumentException if an object type is not supported for conversion to a
         * COSBase object.
         */
        public static COSArray converterToCOSArray(List<?> cosObjectableList)
        {
            COSArray array = null;
            if( cosObjectableList != null )
            {
                if( cosObjectableList instanceof COSArrayList )
                {
                    //if it is already a COSArrayList then we don't want to recreate the array, we want to reuse it.
                    array = ((COSArrayList<?>)cosObjectableList).array;
                }
                else
                {
                    array = new COSArray();
                    for (Object next : cosObjectableList)
                    {
                        if( next instanceof String )
                        {
                            array.add( new COSString( (String)next ) );
                        }
                        else if( next instanceof Integer || next instanceof Long )
                        {
                            array.add( COSInteger.get( ((Number)next).longValue() ) );
                        }
                        else if( next instanceof Float || next instanceof Double )
                        {
                            array.add( new COSFloat( ((Number)next).floatValue() ) );
                        }
                        else if( next instanceof COSObjectable )
                        {
                            COSObjectable object = (COSObjectable)next;
                            array.add( object.getCOSObject() );
                        }
                        else if( next == null )
                        {
                            array.add( COSNull.NULL );
                        }
                        else
                        {
                            throw new IllegalArgumentException( "Error: Don't know how to convert type to COSBase '" +
                            next.getClass().getName() + "'" );
                        }
                    }
                }
            }
            return array;
        }

        private List<COSBase> toCOSObjectList( Collection<?> list )
        {
            List<COSBase> cosObjects = new ArrayList<>(list.size());
            list.forEach(next ->
            {
                if( next instanceof String )
                {
                    cosObjects.add( new COSString( (String)next ) );
                }
                else
                {
                    COSObjectable cos = (COSObjectable)next;
                    cosObjects.add( cos.getCOSObject() );
                }
            });
            return cosObjects;
        }

        /**
         * {@inheritDoc}
         */
        @Override
        public boolean removeAll(Collection<?> c)
        {
            c.forEach(item -> {
                COSBase itemCOSBase = ((COSObjectable)item).getCOSObject();
                // remove all indirect objects too by dereferencing them
                // before doing the comparison
                for (int i=array.size()-1; i>=0; i--)
                {
                    if (itemCOSBase.equals(array.getObject(i)))
                    {
                        array.remove(i);
                    }
                }
            });

            return actual.removeAll( c );
        }

        /**
         * {@inheritDoc}
         */
        @Override
        public boolean retainAll(Collection<?> c)
        {
            c.forEach(item -> {
                COSBase itemCOSBase = ((COSObjectable)item).getCOSObject();
                // remove all indirect objects too by dereferencing them
                // before doing the comparison
                for (int i=array.size()-1; i>=0; i--)
                {
                    if (!itemCOSBase.equals(array.getObject(i)))
                    {
                        array.remove(i);
                    }
                }
            });

            return actual.retainAll( c );
        }

        /**
         * {@inheritDoc}
         */
        @Override
        public void clear()
        {
            //when adding if there is a parentDict then change the item
            //in the dictionary from a single item to an array.
            if( parentDict != null )
            {
                parentDict.setItem( dictKey, null );
            }
            actual.clear();
            array.clear();
        }

        /**
         * {@inheritDoc}
         */
        @Override
        public boolean equals(Object o)
        {
            return actual.equals( o );
        }

        /**
         * {@inheritDoc}
         */
        @Override
        public int hashCode()
        {
            return actual.hashCode();
        }

        /**
         * {@inheritDoc}
         */
        @Override
        public E get(int index)
        {
            return actual.get( index );

        }

        /**
         * {@inheritDoc}
         */
        @Override
        public E set(int index, E element)
        {
            if (isFiltered) {
                throw new UnsupportedOperationException("Replacing an element in a filtered List is not permitted");
            }

            if( element instanceof String )
            {
                COSString item = new COSString( (String)element );
                if( parentDict != null && index == 0 )
                {
                    parentDict.setItem( dictKey, item );
                }
                array.set( index, item );
            }
            else
            {
                if( parentDict != null && index == 0 )
                {
                    parentDict.setItem( dictKey, ((COSObjectable)element).getCOSObject() );
                }
                array.set( index, ((COSObjectable)element).getCOSObject() );
            }
            return actual.set( index, element );
        }

        /**
         * {@inheritDoc}
         */
        @Override
        public void add(int index, E element)
        {
            if (isFiltered) {
                throw new UnsupportedOperationException("Adding an element in a filtered List is not permitted");
            }

            //when adding if there is a parentDict then change the item
            //in the dictionary from a single item to an array.
            if( parentDict != null )
            {
                parentDict.setItem( dictKey, array );
                //clear the parent dict so it doesn't happen again, there might be
                //a usecase for keeping the parentDict around but not now.
                parentDict = null;
            }
            actual.add( index, element );
            if( element instanceof String )
            {
                array.add( index, new COSString( (String)element ) );
            }
            else
            {
                array.add( index, ((COSObjectable)element).getCOSObject() );
            }
        }

        /**
         * {@inheritDoc}
         */
        @Override
        public E remove(int index)
        {
            if (isFiltered) {
                throw new UnsupportedOperationException("removing entries from a filtered List is not permitted");
            }

            array.remove( index );
            return actual.remove( index );
        }

        /**
         * {@inheritDoc}
         */
        @Override
        public int indexOf(Object o)
        {
            return actual.indexOf( o );
        }

        /**
         * {@inheritDoc}
         */
        @Override
        public int lastIndexOf(Object o)
        {
            return actual.lastIndexOf( o );

        }

        /**
         * {@inheritDoc}
         */
        @Override
        public ListIterator<E> listIterator()
        {
            return actual.listIterator();
        }

        /**
         * {@inheritDoc}
         */
        @Override
        public ListIterator<E> listIterator(int index)
        {
            return actual.listIterator( index );
        }

        /**
         * {@inheritDoc}
         */
        @Override
        public List<E> subList(int fromIndex, int toIndex)
        {
            return actual.subList( fromIndex, toIndex );
        }

        /**
         * {@inheritDoc}
         */
        @Override
        public String toString()
        {
            return "COSArrayList{" + array.toString() + "}";
        }

        /**
         * This will return then underlying COSArray.
         *
         * @return the COSArray
         */
        public COSArray toList()
        {
            return array;
        }

    }