/*
 * 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.util;

import com.ibm.icu.text.Bidi;
import com.ibm.icu.text.Normalizer;

/**
 * This class is an implementation the the ICU4J class. TextNormalize 
 * will call this only if the ICU4J library exists in the classpath.
 * @author <a href="mailto:carrier@digital-evidence.org">Brian Carrier</a>
 * @version $Revision: 1.0 $
 */
public class ICU4JImpl 
{
    Bidi bidi;

    /**
     * Constructor.
     */
    public ICU4JImpl() 
    {
        bidi = new Bidi();

        /* We do not use bidi.setInverse() because that uses
         * Bidi.REORDER_INVERSE_NUMBERS_AS_L, which caused problems
         * in some test files. For example, a file had a line of:
         * 0 1 / ARABIC
         * and the 0 and 1 were reversed in the end result.  
         * REORDER_INVERSE_LIKE_DIRECT is the inverse Bidi mode 
         * that more closely reflects the Unicode spec.
         */
        bidi.setReorderingMode(Bidi.REORDER_INVERSE_LIKE_DIRECT);
    }

    /**
     * Takes a line of text in presentation order and converts it to logical order.
     * @see TextNormalize.makeLineLogicalOrder(String, boolean)     
     *  
     * @param str String to convert
     * @param isRtlDominant RTL (right-to-left) will be the dominant text direction
     * @return The converted string
     */
    public String makeLineLogicalOrder(String str, boolean isRtlDominant) 
    {    
        bidi.setPara(str, isRtlDominant?Bidi.RTL:Bidi.LTR, null);

        /* Set the mirror flag so that parentheses and other mirror symbols
         * are properly reversed, when needed.  With this removed, lines
         * such as (CBA) in the PDF file will come out like )ABC( in logical
         * order.
         */
        return bidi.writeReordered(Bidi.DO_MIRRORING);
    }

    /**
     * Normalize presentation forms of characters to the separate parts. 
     * @see TextNormalize.normalizePres(String)
     * 
     * @param str String to normalize
     * @return Normalized form
     */
    public String normalizePres(String str)
    {
        StringBuilder builder = null;
        int p = 0;
        int q = 0;
        int strLength = str.length();
        for (; q < strLength; q++) 
        {
            // We only normalize if the codepoint is in a given range.
            // Otherwise, NFKC converts too many things that would cause
            // confusion. For example, it converts the micro symbol in
            // extended Latin to the value in the Greek script. We normalize
            // the Unicode Alphabetic and Arabic A&B Presentation forms.
            char c = str.charAt(q);
            if ((0xFB00 <= c && c <= 0xFDFF) || (0xFE70 <= c && c <= 0xFEFF))
            {
                if (builder == null) 
                {
                    builder = new StringBuilder(strLength * 2);
                }
                builder.append(str.substring(p, q));
                // Some fonts map U+FDF2 differently than the Unicode spec.
                // They add an extra U+0627 character to compensate.
                // This removes the extra character for those fonts. 
                if(c == 0xFDF2 && q > 0 && (str.charAt(q-1) == 0x0627 || str.charAt(q-1) == 0xFE8D))
                {
                    builder.append("\u0644\u0644\u0647");
                }
                else
                {
                    // Trim because some decompositions have an extra space,
                    // such as U+FC5E
                    builder.append(
                            Normalizer.normalize(c, Normalizer.NFKC).trim());
                }
                p = q + 1;
            }
        }
        if (builder == null) 
        {
            return str;
        } 
        else 
        {
            builder.append(str.substring(p, q));
            return builder.toString();
        }
    }
    
    /**
     * Decomposes Diacritic characters to their combining forms.
     * 
     * @param str String to be Normalized
     * @return A Normalized String
     */      
    public String normalizeDiac(String str)
    {
        StringBuilder retStr = new StringBuilder();
        int strLength = str.length();
        for (int i = 0; i < strLength; i++) 
        {
            char c = str.charAt(i);
            int type = Character.getType(c);
            if(type == Character.NON_SPACING_MARK 
                    || type == Character.MODIFIER_SYMBOL
                    || type == Character.MODIFIER_LETTER)
            {
                /*
                 * Trim because some decompositions have an extra space, such as
                 * U+00B4
                 */
                retStr.append(Normalizer.normalize(c, Normalizer.NFKC).trim());
            }
            else
            {
                retStr.append(str.charAt(i));
            }
        }
        return retStr.toString();
    }
}