tuplo/numberfmt

import {
    rgUnitSystem,
    rgBitSystem,
    rgByteSystem,
    rgMetricSystem,
    rgKiloSystem,
} from "../helpers/regex";

type IBit = "bit" | "kilobit" | "megabit" | "gigabit" | "terabit";

type IByte =
    | "byte"
    | "kilobyte"
    | "megabyte"
    | "gigabyte"
    | "terabyte"
    | "petabyte";

type IMetric = "millimeter" | "centimeter" | "meter" | "kilometer";

type IKilo = "gram" | "kilogram";

type IUnit = IBit | IByte | IMetric | IKilo;

export function getUnitFromPowerOfTwo(
    value: number,
    units: (IBit | IByte)[]
): IBit | IByte {
    const idx = Math.floor(Math.log(value) / Math.log(1024));
    return units[idx];
}

export function getMetricUnit(value: number): IMetric {
    const absValue = Math.abs(value);

    if (absValue > 999.9999) return "kilometer";
    if (absValue >= 0.01 && absValue <= 0.0999) return "centimeter";
    if (absValue >= 0.001 && absValue <= 0.00999) return "millimeter";

    return "meter";
}

export function getKiloUnit(value: number): IKilo {
    const absValue = Math.abs(value);

    if (absValue >= 0.001 && absValue <= 0.00999) return "gram";

    return "kilogram";
}

export function getUnit(value: number, format: string): IUnit | undefined {
    if (!rgUnitSystem.test(format)) return undefined;

    if (rgMetricSystem.test(format)) return getMetricUnit(value);
    if (rgKiloSystem.test(format)) return getKiloUnit(value);

    if (rgBitSystem.test(format))
        return getUnitFromPowerOfTwo(value, [
            "bit",
            "kilobit",
            "megabit",
            "gigabit",
            "terabit",
        ]);

    if (rgByteSystem.test(format))
        return getUnitFromPowerOfTwo(value, [
            "byte",
            "kilobyte",
            "megabyte",
            "gigabyte",
            "terabyte",
            "petabyte",
        ]);

    return undefined;
}