import enforcePrecision from './enforcePrecision';

const _defaultDict = {
    thousand: 'K',
    million: 'M',
    billion: 'B'
};

/**
 * Abbreviate number if bigger than 1000. (eg: 2.5K, 17.5M, 3.4B, ...)
 */
function abbreviateNumber(val: number, nDecimals?: number, dict?: typeof _defaultDict): string {
    nDecimals = nDecimals != null ? nDecimals : 1;
    dict = dict || _defaultDict;
    val = enforcePrecision(val, nDecimals);

    let str;
    let mod;

    if (val < 1000000) {
        mod = enforcePrecision(val / 1000, nDecimals);
        // might overflow to next scale during rounding
        str = mod < 1000 ? mod + dict.thousand : 1 + dict.million;
    } else if (val < 1000000000) {
        mod = enforcePrecision(val / 1000000, nDecimals);
        str = mod < 1000 ? mod + dict.million : 1 + dict.billion;
    } else {
        str = enforcePrecision(val / 1000000000, nDecimals) + dict.billion;
    }

    return str;
}

export default abbreviateNumber;