const map: any = {
    b: 1,
    kb: 1 << 10,
    mb: 1 << 20,
    gb: 1 << 30,
    tb: Math.pow(1024, 4),
    pb: Math.pow(1024, 5),
}

/**
 * 通过文件尺寸字符串解析字节数 "1KB" => 1024
 * @param sizeString
 */
export function toByte(sizeString: string | number): number {
    if (typeof sizeString === "number") return sizeString

    const parseRegExp = /^((-|\+)?(\d+(?:\.\d+)?)) *(kb|mb|gb|tb|pb)$/i

    // Test if the string passed is valid
    var results = parseRegExp.exec(sizeString)
    var floatValue
    var unit = "b"

    if (!results) {
        // Nothing could be extracted from the given string
        floatValue = parseInt(sizeString, 10)
        unit = "b"
    } else {
        // Retrieve the value and the unit
        floatValue = parseFloat(results[1])
        unit = results[4].toLowerCase()
    }

    return Math.floor(map[unit] * floatValue)
}