/*
 * 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.encryption;

import java.io.IOException;

import org.apache.pdfbox.cos.COSArray;
import org.apache.pdfbox.cos.COSDictionary;
import org.apache.pdfbox.cos.COSName;
import org.apache.pdfbox.cos.COSString;

/**
 * This class is a specialized view of the crypt filter dictionary of a PDF document. It contains a low level dictionary (COSDictionary) and provides the methods to manage its fields.
 * 
 * 
 * @version $Revision: 1.0 $
 */
public class PDCryptFilterDictionary {

    /**
     * COS crypt filter dictionary.
     */
    protected COSDictionary     cryptFilterDictionary = null;

    private final COSDictionary values;

    /**
     * creates a new empty crypt filter dictionary.
     */
    public PDCryptFilterDictionary() {
        cryptFilterDictionary = new COSDictionary();
        cryptFilterDictionary.setDirect(true);

        values = cryptFilterDictionary;
    }

    /**
     * creates a new crypt filter dictionary from the low level dictionary provided.
     * 
     * @param d
     *            the low level dictionary that will be managed by the newly created object
     */
    public PDCryptFilterDictionary(final COSDictionary d) {
        cryptFilterDictionary = d;
        values = cryptFilterDictionary;
    }

    public PDCryptFilterDictionary(final COSName filterName) {
        this(filterName.getName());
    }

    public PDCryptFilterDictionary(final String filterName) {
        cryptFilterDictionary = new COSDictionary();
        cryptFilterDictionary.setDirect(true);

        values = new COSDictionary();
        values.setDirect(true);

        cryptFilterDictionary.setItem(filterName, values);
    }

    /**
     * This will get the dictionary associated with this crypt filter dictionary.
     * 
     * @return The COS dictionary that this object wraps.
     */
    public COSDictionary getCOSDictionary() {
        return cryptFilterDictionary;
    }

    /**
     * This will return the crypt filter method. Allowed values are: NONE, V2, AESV2
     * 
     * @return the name of the crypt filter method.
     * 
     * @throws IOException
     *             If there is an error accessing the data.
     */
    public COSName getCryptFilterMethod() throws IOException {
        return (COSName) values.getDictionaryObject(COSName.CFM);
    }

    /**
     * This will return the Length entry of the crypt filter dictionary.<br />
     * <br />
     * The length in <b>bits</b> for the crypt filter algorithm. This will return a multiple of 8.
     * 
     * @return The length in bits for the encryption algorithm
     */
    public int getLength() {
        return values.getInt(COSName.LENGTH, 40);
    }

    /**
     * This will set the crypt filter method. Allowed values are: NONE, V2, AESV2
     * 
     * @param cfm
     *            name of the crypt filter method.
     * 
     * @throws IOException
     *             If there is an error setting the data.
     */
    public void setCryptFilterMethod(final COSName cfm) throws IOException {
        values.setItem(COSName.CFM, cfm);
    }

    /**
     * This will set the number of bits to use for the crypt filter algorithm.
     * 
     * @param length
     *            The new key length.
     */
    public void setLength(final int length) {
        values.setInt(COSName.LENGTH, length);
    }

    public void setRecipients(final byte[][] recipients) throws IOException {
        final COSArray array = new COSArray();
        for (int i = 0; i < recipients.length; i++) {
            final COSString recip = new COSString();
            recip.append(recipients[i]);
            recip.setForceLiteralForm(true);
            array.add(recip);
        }
        values.setItem(COSName.RECIPIENTS, array);
    }
}