boonya/rtsp-video-recorder

import { BytesFactor, DirSizeThresholdOption } from '../types';

const DIR_SIZE_THRESHOLD_PATTERN = /^(\d+)(M|G|T)?$/;

export default function transformDirSizeThreshold(value: DirSizeThresholdOption) {
    if (typeof value === 'number') return value;
    const [operand, factor] = matchDirSizeThreshold(value);
    return getBytesSize(operand, factor);
}

function matchDirSizeThreshold(value: string): [number, BytesFactor] {
    const match = value.match(DIR_SIZE_THRESHOLD_PATTERN);
    if (!match) {
        throw new Error(`dirSizeThreshold value has to match to pattern ${DIR_SIZE_THRESHOLD_PATTERN.toString()}.`);
    }
    const operand = Number(match[1]);
    if (!operand) {
        throw new Error('dirSizeThreshold value has to be more than zero.');
    }

    const factor = match[2] as BytesFactor;
    return [operand, factor];
}

/**
 * @returns bytes
 */
function getBytesSize(operand: number, factor: BytesFactor): number {
    switch (factor) {
    case BytesFactor.Gigabytes:
        return operand * Math.pow(1024, 3);
    case BytesFactor.Terabytes:
        return operand * Math.pow(1024, 4);
    case BytesFactor.Megabytes:
    default:
        return operand * Math.pow(1024, 2);
    }
}