export enum Unit {

	/** B */
	B = "B",

	/** KB */
	KB = "KB",

	/** MB */
	MB = "MB",

	/** GB */
	GB = "GB",

	/** TB */
	TB = "TB",

	/** PB */
	PB = "PB",

	/** EB */
	EB = "EB"
}

/** 储存单位 */
export default class IOSize {

	/** 1 字节 */
	public static BYTE = 1;

	/** 1 KB */
	public static KB = IOSize.BYTE << 10;

	/** 1 MB */
	public static MB = IOSize.KB << 10;

	/** 1 GB */
	public static GB = IOSize.MB << 10;

	/** 1 TB */
	public static TB = IOSize.GB << 10;

	/** 1 PB */
	public static PB = IOSize.TB << 10;

	/** 1 EB */
	public static EB = IOSize.PB << 10;

	public static Unit = Unit;

	/**
	 * <p>格式化一个储存容量，保留两位小数
	 * <pre>
	 *     // 返回 100.01 KB
	 *     format(102411, 2);
	 * </pre>
	 *
	 * @param size     字节大小
	 * @param fixed    保留小数
	 * @param stopUnit 停止单位
	 * @return
	 */
	public static format(size: number, fixed = 2, stopUnit?: Unit): string {
		const units = Object.keys(Unit);
		if (0 < size) {
			for (let i = 0; i < units.length; i++, size /= 1024) {
				const unit = units[i];
				if (size <= 1000 || i === units.length - 1 || unit === stopUnit) {
					if (i === 0) {
						// 最小单位不需要小数
						return size + " B";
					} else {
						return `${size.toFixed(fixed)} ${unit}`;
					}
				}
			}
		}
		return "0 B";
	}
	

	/**
	 * <p>格式化一个储存容量，保留两位小数，不带单位
	 * <pre>
	 *     // 返回 100.01
	 *     format(102411, 2);
	 * </pre>
	 *
	 * @param size     字节大小
	 * @param fixed    保留小数
	 * @param stopUnit 停止单位
	 * @return
	 */
	public static formatWithoutUnit(size: number, fixed = 2, stopUnit?: Unit): string {
		const units = Object.keys(Unit);
		if (0 < size) {
			for (let i = 0; i < units.length; i++, size /= 1024) {
				const unit = units[i];
				if (size <= 1000 || i === units.length - 1 || unit === stopUnit) {
					if (i === 0) {
						// 最小单位不需要小数
						return size.toFixed(0);
					} else {
						return size.toFixed(fixed);
					}
				}
			}
		}
		return "0";
	}
}