// 105 -> 3
const orderOfMagnitudeNum = (n) => {
  return Math.pow(10, n);
};

// 105 -> 3
const orderOfMagnitude = (n) => {
  return Math.floor(Math.log(n) / Math.LN10 + 0.000000001);
};

function withXSigFigs(number, sigFigs) {
  const withPrecision = number.toPrecision(sigFigs);
  const formatted = Number(withPrecision);
  return `${formatted}`;
}

class NumberShower {
  constructor(number, precision = 2) {
    this.number = number;
    this.precision = precision;
  }

  convert() {
    const number = Math.abs(this.number);
    const response = this.evaluate(number);
    if (this.number < 0) {
      response.value = '-' + response.value;
    }
    return response
  }

  metricSystem(number, order) {
    const newNumber = number / orderOfMagnitudeNum(order);
    const precision = this.precision;
    return `${withXSigFigs(newNumber, precision)}`;
  }

  evaluate(number) {
    if (number === 0) {
      return { value: this.metricSystem(0, 0) }
    }

    const order = orderOfMagnitude(number);
    if (order < -2) {
      return { value: this.metricSystem(number, order), power: order };
    } else if (order < 4) {
      return { value: this.metricSystem(number, 0) };
    } else if (order < 6) {
      return { value: this.metricSystem(number, 3), symbol: 'K' };
    } else if (order < 9) {
      return { value: this.metricSystem(number, 6), symbol: 'M' };
    } else if (order < 12) {
      return { value: this.metricSystem(number, 9), symbol: 'B' };
    } else if (order < 15) {
      return { value: this.metricSystem(number, 12), symbol: 'T' };
    } else {
      return { value: this.metricSystem(number, order), power: order };
    }
  }
}

export function numberShow(number, precision = 2) {
  const ns = new NumberShower(number, precision);
  return ns.convert();
}