export class FileSizeUnit {
    public constructor(
        public readonly bytes: number,
        public readonly longName: string,
        public readonly shortName: string,
        public readonly divisible: boolean = true,
    ) {
    }
}

export class FileSize {
    public static readonly UNITS: Record<string, FileSizeUnit> = {
        B: new FileSizeUnit(1, 'byte', 'B', false),
        KB: new FileSizeUnit(1000, 'kilobyte', 'kB'),
        MB: new FileSizeUnit(1000 * 1000, 'megabyte', 'MB'),
        GB: new FileSizeUnit(1000 * 1000 * 1000, 'gigabyte', 'GB'),
        TB: new FileSizeUnit(1000 * 1000 * 1000 * 1000, 'terabyte', 'TB'),
    };

    public static humanizeFileSize(
        size: number,
        short: boolean = false,
        skipOneUnitNumber: boolean = false,
        units: FileSizeUnit[] = [
            this.UNITS.B,
            this.UNITS.KB,
            this.UNITS.MB,
            this.UNITS.GB,
            this.UNITS.TB,
        ],
    ): string {
        for (let i = units.length - 1; i > 0; i--) {
            const fileSizeUnit = units[i - 1];
            if (size >= fileSizeUnit.bytes && size < units[i].bytes) {
                const amount = size / fileSizeUnit.bytes;
                const unit = short ?
                    fileSizeUnit.shortName :
                    ' ' + fileSizeUnit.longName + (amount > 1 ? 's' : '');
                const strAmount = fileSizeUnit.divisible ?
                    amount.toFixed(1) :
                    Math.floor(amount);
                return (amount > 1 || !skipOneUnitNumber ? strAmount : '') + unit;
            }
        }

        return '0';
    }
}