/*
 * Copyright 2008-2021 the original author or authors.
 *
 * Licensed 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.springframework.data.mongodb.util.json;

import org.bson.json.JsonParseException;

/**
 * JsonBuffer implementation borrowed from <a href=
 * "https://github.com/mongodb/mongo-java-driver/blob/master/bson/src/main/org/bson/json/JsonBuffer.java">MongoDB
 * Inc.</a> licensed under the Apache License, Version 2.0. <br />
 * Formatted and modified.
 *
 * @author Jeff Yemin
 * @author Ross Lawley
 * @since 2.2
 */
class JsonBuffer {

	private final String buffer;
	private int position;
	private boolean eof;

	JsonBuffer(final String buffer) {
		this.buffer = buffer;
	}

	public int getPosition() {
		return position;
	}

	public void setPosition(final int position) {
		this.position = position;
	}

	public int read() {
		if (eof) {
			throw new JsonParseException("Trying to read past EOF.");
		} else if (position >= buffer.length()) {
			eof = true;
			return -1;
		} else {
			return buffer.charAt(position++);
		}
	}

	public void unread(final int c) {
		eof = false;
		if (c != -1 && buffer.charAt(position - 1) == c) {
			position--;
		}
	}

	public String substring(final int beginIndex) {
		return buffer.substring(beginIndex);
	}

	public String substring(final int beginIndex, final int endIndex) {
		return buffer.substring(beginIndex, endIndex);
	}
}
