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package org.scijava.util;


/**
 * Utility methods for working with units.
 * 
 * @author Barry DeZonia
 * @author Curtis Rueden
 */
public final class UnitUtils {

	private static final String[] BYTE_UNITS = { "B", "KiB", "MiB", "GiB", "TiB",
		"PiB", "EiB", "ZiB", "YiB" };

	private static final double LOG1024 = Math.log(1024);

	private UnitUtils() {
		// prevent instantiation of utility class
	}

	/**
	 * @return A properly formatted String representation of the given bytes, in
	 *         the default {@link java.util.Locale} for this JVM.
	 */
	public static String getAbbreviatedByteLabel(final double totBytes) {
		if (totBytes < 0) {
			throw new IllegalArgumentException("Bytes must be non-negative");
		}
		if (totBytes == 0) return "0B";

		// compute unit
		final int rawPow = (int) (Math.log(totBytes) / LOG1024);
		final int pow = Math.min(rawPow, BYTE_UNITS.length - 1);

		// compute value from unit
		final double value = totBytes / Math.pow(1024.0, pow);

		final String format = format(pow);
		return String.format(format, value, BYTE_UNITS[pow]);
	}

	/**
	 * @return Format result with 0 decimal places for bytes, or 1 for larger values
	 */
	public static String format(final double power) {
		return power == 0 ? "%.0f%s" : "%.1f%s";
	}
}