// const Decimal = require('decimal.js');
import Decimal from 'decimal.js-light';

Decimal.set({ precision: 40 });

export function getAmountFromUNI(amount): string {
  return new Decimal(amount).times(new Decimal(10).pow(-18)).toFixed();
}
export function getAmountToUNI(amount): string {
  return new Decimal(amount).times(new Decimal(10).pow(18)).toFixed(0);
}
export function calculateSaleReturn({ volume, reserve, crr, inputSellAmount }): Decimal | number {
  const decimalReserve = new Decimal(reserve);
  const sellAmount = new Decimal(inputSellAmount);

  if (decimalReserve.isZero()) {
    return 0;
  }

  if (sellAmount.eq(volume)) {
    return decimalReserve;
  }

  if (crr === 100) {
    return new Decimal(1).mul(decimalReserve).mul(sellAmount).div(volume);
  }

  let res = sellAmount.div(volume); // sellAmount / supply

  res = new Decimal(1).minus(res); // 1 - sellAmount / supply
  const pow = new Decimal(100).div(crr); // 100 / crr

  res = res.toPower(pow); // (1 - sellAmount / supply) ^ (100 / crr)
  res = new Decimal(1).minus(res); // 1 - (1 - sellAmount / supply) ^ (100 / crr)
  res = decimalReserve.mul(res); // reserve * (1 - (1 - sellAmount / supply) ^ (100 / crr))

  return res;
}

export function getDelegationPrice({ volume, reserve, crr, delegated }, shifted = false): string {
  const returnAmount = calculateSaleReturn({
    crr,
    volume,
    reserve,
    inputSellAmount: delegated,
  });
  const price = new Decimal(returnAmount).div(delegated);

  return shifted ? getAmountToUNI(price) : price.toFixed();
}

export function getCoinPrice({ volume, reserve, crr }, shifted = false): string {
  const price = calculateSaleReturn({
    crr,
    volume,
    reserve,
    inputSellAmount: '1',
  });

  return shifted ? getAmountToUNI(price) : price.toFixed();
}