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Commons for lang, crypto, dom, text, csv, reflection, parsing, xtreams...

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/*
 * tksCommons
 * 
 * Author  : Thomas Kuhlmann (ThK-Systems, http://www.thk-systems.de)
 * License : LGPL (https://www.gnu.org/licenses/lgpl.html)
 */
package de.thksystems.util.text;

import java.math.BigDecimal;
import java.util.HashMap;
import java.util.Map;
import java.util.regex.Matcher;
import java.util.regex.Pattern;

/**
 * Just about parsing text ...
 */
public final class ParseUtils {

	public static final BigDecimal VALUE_BIGDECIMAL_MINUSONE = new BigDecimal("-1");

	private static final Pattern FILESIZE_PATTERN = Pattern.compile("^([0-9.]+)([ETGMK]B?)$", Pattern.CASE_INSENSITIVE);

	private static Map fileSizePowMap = null;

	private ParseUtils() {
	}

	/**
	 * Parse filesize given as a {@link String} (e.g. '0.003EB', '2.3GB', '5M', '30', '705.23kB') and return the size in bytes as
	 * {@link BigDecimal}.
	 * 
	 * @param filesize
	 *            Size as {@link String} (KB, MB, GB, TB, EB are supported as suffixes, case-insensitive, the 'B' may be omitted; If no
	 *            suffix is given, the filesize is interpreted as bytes; Negative values are not supported.)
	 * @return size in bytes as {@link BigDecimal} (null, if a invalid 'filesize' is given.)
	 */
	public static BigDecimal parseFileSize(String filesize) {
		if (filesize == null || filesize.length() == 0) {
			return null;
		}
		Matcher matcher = FILESIZE_PATTERN.matcher(filesize);
		if (matcher.find()) {
			String number = matcher.group(1);
			int pow = getFileSizePowMap().get(matcher.group(2).toUpperCase());
			BigDecimal bytes = new BigDecimal(number);
			bytes = bytes.multiply(BigDecimal.valueOf(1024).pow(pow));
			return bytes;
		}
		try {
			BigDecimal value = new BigDecimal(filesize);
			if (value.compareTo(VALUE_BIGDECIMAL_MINUSONE) <= 0) {
				return null;
			} else {
				return value;
			}
		} catch (NumberFormatException e) {
			return null;
		}
	}

	/** Lazy get fileSizePowMap. */
	private static Map getFileSizePowMap() {
		if (fileSizePowMap == null) {
			fileSizePowMap = new HashMap<>();
			fileSizePowMap.put("EB", 5);
			fileSizePowMap.put("TB", 4);
			fileSizePowMap.put("GB", 3);
			fileSizePowMap.put("MB", 2);
			fileSizePowMap.put("KB", 1);
			fileSizePowMap.put("E", 5);
			fileSizePowMap.put("T", 4);
			fileSizePowMap.put("G", 3);
			fileSizePowMap.put("M", 2);
			fileSizePowMap.put("K", 1);
		}
		return fileSizePowMap;
	}
}