import JSBI from "jsbi";
import { utils } from "ethers/";
import { Currency, CurrencyAmount } from "@uniswap/sdk-core";

// try to parse a user entered amount for a given token
export function tryParseAmount<T extends Currency>(
  value?: string,
  currency?: T
): CurrencyAmount<T> | undefined {
  if (!value || !currency) {
    return undefined;
  }
  try {
    const typedValueParsed = utils
      .parseUnits(value, currency.decimals)
      .toString();

    if (typedValueParsed !== "0") {
      return CurrencyAmount.fromRawAmount(
        currency,
        JSBI.BigInt(typedValueParsed)
      );
    }
  } catch (error) {
    // should fail if the user specifies too many decimal places of precision (or maybe exceed max uint?)
    console.debug(`Failed to parse input amount: "${value}"`, error);
  }
  // necessary for all paths to return a value
  return undefined;
}