/*
 * Copyright (c) 2000, 2012, Oracle and/or its affiliates. All rights reserved.
 * DO NOT ALTER OR REMOVE COPYRIGHT NOTICES OR THIS FILE HEADER.
 *
 * This code is free software; you can redistribute it and/or modify it
 * under the terms of the GNU General Public License version 2 only, as
 * published by the Free Software Foundation.  Oracle designates this
 * particular file as subject to the "Classpath" exception as provided
 * by Oracle in the LICENSE file that accompanied this code.
 *
 * This code is distributed in the hope that it will be useful, but WITHOUT
 * ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or
 * FITNESS FOR A PARTICULAR PURPOSE.  See the GNU General Public License
 * version 2 for more details (a copy is included in the LICENSE file that
 * accompanied this code).
 *
 * You should have received a copy of the GNU General Public License version
 * 2 along with this work; if not, write to the Free Software Foundation,
 * Inc., 51 Franklin St, Fifth Floor, Boston, MA 02110-1301 USA.
 *
 * Please contact Oracle, 500 Oracle Parkway, Redwood Shores, CA 94065 USA
 * or visit www.oracle.com if you need additional information or have any
 * questions.
 */
package com.moparisthebest.text;

import java.lang.reflect.Constructor;
import java.lang.reflect.InvocationTargetException;
import java.lang.reflect.Method;
import java.text.AttributedCharacterIterator;
import java.text.AttributedString;
import java.text.Format;
import java.util.ArrayList;

/**
 * CharacterIteratorFieldDelegate combines the notifications from a Format
 * into a resulting <code>AttributedCharacterIterator</code>. The resulting
 * <code>AttributedCharacterIterator</code> can be retrieved by way of
 * the <code>getIterator</code> method.
 */
class CharacterIteratorFieldDelegate extends FieldDelegate {

    private static final Constructor<AttributedString> iterableConstructor;
    private static final Method length;

    static {
        Constructor<AttributedString> cons = null;
        Method l = null;
        try {
            cons = AttributedString.class.getDeclaredConstructor(AttributedCharacterIterator[].class);
            cons.setAccessible(true);

            l = AttributedString.class.getDeclaredMethod("length");
            l.setAccessible(true);
        } catch (NoSuchMethodException e) {
            throw new RuntimeException(DecimalFormat.DECIMAL_FORMAT_EXCEPTION, e);
        }
        iterableConstructor = cons;
        length = l;
    }

    /**
     * Array of AttributeStrings. Whenever <code>formatted</code> is invoked
     * for a region > size, a new instance of AttributedString is added to
     * attributedStrings. Subsequent invocations of <code>formatted</code>
     * for existing regions result in invoking addAttribute on the existing
     * AttributedStrings.
     */
    private ArrayList<AttributedString> attributedStrings;
    /**
     * Running count of the number of characters that have
     * been encountered.
     */
    private int size;


    CharacterIteratorFieldDelegate() {
        super((Object)null);
        attributedStrings = new ArrayList<>();
    }

    public void formatted(Format.Field attr, Object value, int start, int end,
                          StringBuffer buffer) {
        if (start != end) {
            if (start < size) {
                // Adjust attributes of existing runs
                int index = size;
                int asIndex = attributedStrings.size() - 1;

                while (start < index) {
                    AttributedString as = attributedStrings.
                            get(asIndex--);
                    int asLength;
                    try {
                        asLength = (Integer) length.invoke(as); // was: as.length();
                    } catch (Throwable e) {
                        throw new RuntimeException(DecimalFormat.DECIMAL_FORMAT_EXCEPTION, e);
                    }
                    int newIndex = index - asLength;
                    int aStart = Math.max(0, start - newIndex);

                    as.addAttribute(attr, value, aStart, Math.min(
                            end - start, asLength - aStart) +
                            aStart);
                    index = newIndex;
                }
            }
            if (size < start) {
                // Pad attributes
                attributedStrings.add(new AttributedString(
                                          buffer.substring(size, start)));
                size = start;
            }
            if (size < end) {
                // Add new string
                int aStart = Math.max(start, size);
                AttributedString string = new AttributedString(
                                   buffer.substring(aStart, end));

                string.addAttribute(attr, value);
                attributedStrings.add(string);
                size = end;
            }
        }
    }

    public void formatted(int fieldID, Format.Field attr, Object value,
                          int start, int end, StringBuffer buffer) {
        formatted(attr, value, start, end, buffer);
    }

    /**
     * Returns an <code>AttributedCharacterIterator</code> that can be used
     * to iterate over the resulting formatted String.
     *
     * @pararm string Result of formatting.
     */
    public AttributedCharacterIterator getIterator(String string) {
        // Add the last AttributedCharacterIterator if necessary
        // assert(size <= string.length());
        if (string.length() > size) {
            attributedStrings.add(new AttributedString(
                                  string.substring(size)));
            size = string.length();
        }
        int iCount = attributedStrings.size();
        AttributedCharacterIterator iterators[] = new
                                    AttributedCharacterIterator[iCount];

        for (int counter = 0; counter < iCount; counter++) {
            iterators[counter] = attributedStrings.
                                  get(counter).getIterator();
        }
        try {
            return iterableConstructor.newInstance(iterators).getIterator(); // was: new AttributedString(iterators).getIterator();
        } catch (InstantiationException | IllegalAccessException | InvocationTargetException e) {
            throw new RuntimeException(DecimalFormat.DECIMAL_FORMAT_EXCEPTION, e);
        }

    }
}