import JSBI from "jsbi";
import {
  Currency,
  CurrencyAmount,
  Percent,
  TradeType,
} from "@uniswap/sdk-core";
import { Trade as V2Trade } from "@uniswap/v2-sdk";
import {
  ALLOWED_PRICE_IMPACT_HIGH,
  ALLOWED_PRICE_IMPACT_LOW,
  ALLOWED_PRICE_IMPACT_MEDIUM,
  BLOCKED_PRICE_IMPACT_NON_EXPERT,
} from "../constants/misc";

const THIRTY_BIPS_FEE = new Percent(JSBI.BigInt(30), JSBI.BigInt(10000));
const ONE_HUNDRED_PERCENT = new Percent(JSBI.BigInt(10000), JSBI.BigInt(10000));
const INPUT_FRACTION_AFTER_FEE = (bpsFee?: Percent) =>
  ONE_HUNDRED_PERCENT.subtract(bpsFee ?? THIRTY_BIPS_FEE);

// computes realized lp fee as a percent
export function computeRealizedLPFeePercent(
  trade: V2Trade<Currency, Currency, TradeType>,
  bpsLpFee?: number | string
): Percent {
  // for each hop in our trade, take away the x*y=k price impact from 0.3% fees
  // e.g. for 3 tokens/2 hops: 1 - ((1 - .03) * (1-.03))
  const percent = ONE_HUNDRED_PERCENT.subtract(
    trade.route.pairs.reduce<Percent>(
      (currentFee: Percent): Percent =>
        currentFee.multiply(
          INPUT_FRACTION_AFTER_FEE(
            bpsLpFee
              ? new Percent(JSBI.BigInt(bpsLpFee), JSBI.BigInt(10000))
              : undefined
          )
        ),
      ONE_HUNDRED_PERCENT
    )
  );

  return new Percent(percent.numerator, percent.denominator);
}

// computes price breakdown for the trade
export function computeRealizedLPFeeAmount(
  trade?: V2Trade<Currency, Currency, TradeType> | null
): CurrencyAmount<Currency> | undefined {
  if (trade) {
    const realizedLPFee = computeRealizedLPFeePercent(trade);

    // the amount of the input that accrues to LPs
    return CurrencyAmount.fromRawAmount(
      trade.inputAmount.currency,
      trade.inputAmount.multiply(realizedLPFee).quotient
    );
  }

  return undefined;
}

const IMPACT_TIERS = [
  BLOCKED_PRICE_IMPACT_NON_EXPERT,
  ALLOWED_PRICE_IMPACT_HIGH,
  ALLOWED_PRICE_IMPACT_MEDIUM,
  ALLOWED_PRICE_IMPACT_LOW,
];

type WarningSeverity = 0 | 1 | 2 | 3 | 4;
export function warningSeverity(
  priceImpact: Percent | undefined
): WarningSeverity {
  if (!priceImpact) return 4;
  let impact: WarningSeverity = IMPACT_TIERS.length as WarningSeverity;
  for (const impactLevel of IMPACT_TIERS) {
    if (impactLevel.lessThan(priceImpact)) return impact;
    impact--;
  }
  return 0;
}