/*
 * 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.flink.types.parser;

import org.apache.flink.annotation.PublicEvolving;

/**
 * Parses a decimal text field into a {@link Short}.
 * Only characters '1' to '0' and '-' are allowed.
 * The parser does not check for the maximum value.
 */
@PublicEvolving
public class ShortParser extends FieldParser<Short> {

	private static final int OVERFLOW_BOUND = 0x7fff;
	private static final int UNDERFLOW_BOUND = 0x8000;

	private short result;

	@Override
	public int parseField(byte[] bytes, int startPos, int limit, byte[] delimiter, Short reusable) {
		int val = 0;
		boolean neg = false;

		final int delimLimit = limit - delimiter.length + 1;

		if (bytes[startPos] == '-') {
			neg = true;
			startPos++;

			// check for empty field with only the sign
			if (startPos == limit || (startPos < delimLimit && delimiterNext(bytes, startPos, delimiter))) {
				setErrorState(ParseErrorState.NUMERIC_VALUE_ORPHAN_SIGN);
				return -1;
			}
		}

		for (int i = startPos; i < limit; i++) {
			if (i < delimLimit && delimiterNext(bytes, i, delimiter)) {
				if (i == startPos) {
					setErrorState(ParseErrorState.EMPTY_COLUMN);
					return -1;
				}
				this.result = (short) (neg ? -val : val);
				return i + delimiter.length;
			}
			if (bytes[i] < 48 || bytes[i] > 57) {
				setErrorState(ParseErrorState.NUMERIC_VALUE_ILLEGAL_CHARACTER);
				return -1;
			}
			val *= 10;
			val += bytes[i] - 48;

			if (val > OVERFLOW_BOUND && (!neg || val > UNDERFLOW_BOUND)) {
				setErrorState(ParseErrorState.NUMERIC_VALUE_OVERFLOW_UNDERFLOW);
				return -1;
			}
		}

		this.result = (short) (neg ? -val : val);
		return limit;
	}

	@Override
	public Short createValue() {
		return Short.MIN_VALUE;
	}

	@Override
	public Short getLastResult() {
		return Short.valueOf(this.result);
	}

	/**
	 * Static utility to parse a field of type short from a byte sequence that represents text characters
	 * (such as when read from a file stream).
	 *
	 * @param bytes The bytes containing the text data that should be parsed.
	 * @param startPos The offset to start the parsing.
	 * @param length The length of the byte sequence (counting from the offset).
	 *
	 * @return The parsed value.
	 *
	 * @throws NumberFormatException Thrown when the value cannot be parsed because the text represents not a correct number.
	 */
	public static final short parseField(byte[] bytes, int startPos, int length) {
		return parseField(bytes, startPos, length, (char) 0xffff);
	}

	/**
	 * Static utility to parse a field of type short from a byte sequence that represents text characters
	 * (such as when read from a file stream).
	 *
	 * @param bytes The bytes containing the text data that should be parsed.
	 * @param startPos The offset to start the parsing.
	 * @param length The length of the byte sequence (counting from the offset).
	 * @param delimiter The delimiter that terminates the field.
	 *
	 * @return The parsed value.
	 *
	 * @throws NumberFormatException Thrown when the value cannot be parsed because the text represents not a correct number.
	 */
	public static final short parseField(byte[] bytes, int startPos, int length, char delimiter) {
		long val = 0;
		boolean neg = false;

		if (bytes[startPos] == delimiter) {
			throw new NumberFormatException("Empty field.");
		}

		if (bytes[startPos] == '-') {
			neg = true;
			startPos++;
			length--;
			if (length == 0 || bytes[startPos] == delimiter) {
				throw new NumberFormatException("Orphaned minus sign.");
			}
		}

		for (; length > 0; startPos++, length--) {
			if (bytes[startPos] == delimiter) {
				return (short) (neg ? -val : val);
			}
			if (bytes[startPos] < 48 || bytes[startPos] > 57) {
				throw new NumberFormatException("Invalid character.");
			}
			val *= 10;
			val += bytes[startPos] - 48;

			if (val > OVERFLOW_BOUND && (!neg || val > UNDERFLOW_BOUND)) {
				throw new NumberFormatException("Value overflow/underflow");
			}
		}
		return (short) (neg ? -val : val);
	}
}