import { FeeEstimationFailed } from "@ledgerhq/errors";
import { makeLRUCache } from "@ledgerhq/live-network/cache";
import network from "@ledgerhq/live-network";
import type { CryptoCurrency } from "@ledgerhq/types-cryptoassets";
import { BigNumber } from "bignumber.js";
import invariant from "invariant";
import { blockchainBaseURL } from "@ledgerhq/coin-bitcoin/explorer";
import type { FeeItems } from "../types";

type Fees = Record<string, number>;

const getEstimatedFees: (currency: CryptoCurrency) => Promise<Fees> = makeLRUCache(
  async currency => {
    const baseURL = blockchainBaseURL(currency);
    invariant(baseURL, `Fees for ${currency.id} are not supported`);
    const { data, status } = await network<Fees>({
      method: "GET",
      url: `${baseURL}/fees`,
    });

    if (data) {
      return data;
    }

    throw new FeeEstimationFailed(`FeeEstimationFailed ${status}`, {
      httpStatus: status,
    });
  },
  c => c.id,
);

export const speeds = new Map([
  [1, "fast"],
  [3, "medium"],
  [6, "slow"],
]);

export const defaultBlockCount = 3;

/**
 * Returns the current network fee rate(fast, medium, slow) from our backend for a given currency
 */
export const getFeeItems = async (currency: CryptoCurrency): Promise<FeeItems> => {
  const all: Array<{
    key: string;
    speed: string;
    blockCount: number;
    feePerByte: BigNumber;
  }> = [];
  const fees = await getEstimatedFees(currency);
  let defaultFeePerByte = new BigNumber(0);

  for (const key of Object.keys(fees)) {
    const feePerByte = new BigNumber(Math.ceil(fees[key] / 1000));
    const blockCount = parseInt(key, 10);
    if (blockCount === defaultBlockCount) defaultFeePerByte = feePerByte;

    if (!Number.isNaN(blockCount) && !feePerByte.isNaN() && speeds.has(blockCount)) {
      all.push({
        key,
        speed: speeds.get(blockCount)!,
        blockCount,
        feePerByte,
      });
    }
  }

  const items = all
    .sort((a, b) => a.blockCount - b.blockCount)
    .map(({ key, speed, feePerByte }) => ({
      key,
      speed,
      feePerByte,
    }));
  return {
    items,
    defaultFeePerByte,
  };
};