/*
 *  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
 *
 *    https://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.grails.charsequences;

/**
 * Wraps a part of a String and implements the CharSequence interface
 * 
 * 
 * @author Lari Hotari
 * @since 2.3.10
 *
 */
class SubCharSequence implements CharSequence, CharArrayAccessible {
    private final CharSequence str;
    private final int count;
    private final int start;

    SubCharSequence(CharSequence str, int start, int count) {
        if (start + count > str.length())
            throw new StringIndexOutOfBoundsException(start);
        this.str = str;
        this.start = start;
        this.count = count;
    }

    public char charAt(int index) {
        if ((index < 0) || (index + start >= str.length()))
            throw new StringIndexOutOfBoundsException(index);
        return str.charAt(index + start);
    }

    public int length() {
        return count;
    }

    public CharSequence subSequence(int start, int end) {
        if (start < 0)
            throw new StringIndexOutOfBoundsException(start);
        if (end > count)
            throw new StringIndexOutOfBoundsException(end);
        if (start > end)
            throw new StringIndexOutOfBoundsException(end - start);
        if (start == 0 && end == count) {
            return this;
        }
        return new SubCharSequence(str, this.start + start, end - start);
    }

    @Override
    public String toString() {
        return str.subSequence(start, start + count).toString();
    }

    public void getChars(int srcBegin, int srcEnd, char[] dst, int dstBegin) {
        if (srcBegin < 0)
            throw new StringIndexOutOfBoundsException(srcBegin);
        if ((srcEnd < 0) || (srcEnd > start + count))
            throw new StringIndexOutOfBoundsException(srcEnd);
        if (srcBegin > srcEnd)
            throw new StringIndexOutOfBoundsException("srcBegin > srcEnd");
        CharSequences.getChars(str, start + srcBegin, start + srcEnd, dst, dstBegin);
    }
}
