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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 {

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

	static {
		FILESIZE_POWMAP.put("EB", 5);
		FILESIZE_POWMAP.put("TB", 4);
		FILESIZE_POWMAP.put("GB", 3);
		FILESIZE_POWMAP.put("MB", 2);
		FILESIZE_POWMAP.put("KB", 1);
		FILESIZE_POWMAP.put("E", 5);
		FILESIZE_POWMAP.put("T", 4);
		FILESIZE_POWMAP.put("G", 3);
		FILESIZE_POWMAP.put("M", 2);
		FILESIZE_POWMAP.put("K", 1);
	}

	private ParseUtils() {
	}

	/**
	 * Parse filesize given as String (e.g. 0.003EB, 2.3GB, 5M, 30, 705.23kB) and return the size in bytes as {@link BigDecimal}.
	 * 
	 * @param filesize
	 *            Size as 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 (-1, if the 'filesize' could not be parsed)
	 */
	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 = FILESIZE_POWMAP.get(matcher.group(2).toUpperCase());
			BigDecimal bytes = new BigDecimal(number);
			bytes = bytes.multiply(BigDecimal.valueOf(1024).pow(pow));
			return bytes;
		}
		try {
			return new BigDecimal(filesize);
		} catch (NumberFormatException e) {
			return new BigDecimal(-1);
		}
	}
}