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import axios from 'axios';
import * as R from 'ramda';
// URL to use for getting dex trades from Bloxy.
export const BLOXY_DEX_TRADES_URL = 'https://bloxy.info/api/dex/trades';
// Number of trades to get at once. Must be less than or equal to MAX_OFFSET.
const TRADES_PER_QUERY = 10000;
// Maximum offset supported by the Bloxy API.
const MAX_OFFSET = 100000;
// Buffer to subtract from offset. This means we will request some trades twice
// but we have less chance on missing out on any data.
const OFFSET_BUFFER = 1000;
// Maximum number of days supported by the Bloxy API.
const MAX_DAYS = 30;
// Buffer used for comparing the last seen timestamp to the last returned
// timestamp. Increasing this reduces chances of data loss but also creates more
// redundancy and can impact performance.
// tslint:disable-next-line:custom-no-magic-numbers
const LAST_SEEN_TIMESTAMP_BUFFER_MS = 1000 * 60 * 30; // 30 minutes
// tslint:disable-next-line:custom-no-magic-numbers
const millisecondsPerDay = 1000 * 60 * 60 * 24; // ms/d = ms/s * s/m * m/h * h/d
export interface BloxyTrade {
tx_hash: string;
tx_time: string;
tx_date: string;
tx_sender: string;
smart_contract_id: number;
smart_contract_address: string;
contract_type: string;
maker: string;
taker: string;
amountBuy: number;
makerFee: number;
buyCurrencyId: number;
buySymbol: string;
amountSell: number;
takerFee: number;
sellCurrencyId: number;
sellSymbol: string;
maker_annotation: string;
taker_annotation: string;
protocol: string;
buyAddress: string | null;
sellAddress: string | null;
}
interface BloxyError {
error: string;
}
type BloxyResponse<T> = T | BloxyError;
type BloxyTradeResponse = BloxyResponse<BloxyTrade[]>;
function isError<T>(response: BloxyResponse<T>): response is BloxyError {
return (response as BloxyError).error !== undefined;
}
export class BloxySource {
private readonly _apiKey: string;
constructor(apiKey: string) {
this._apiKey = apiKey;
}
/**
* Gets all latest trades between the lastSeenTimestamp (minus some buffer)
* and the current time. Note that because the Bloxy API has some hard
* limits it might not always be possible to get *all* the trades in the
* desired time range.
* @param lastSeenTimestamp The latest timestamp for trades that have
* already been seen.
*/
public async getDexTradesAsync(lastSeenTimestamp: number): Promise<BloxyTrade[]> {
let allTrades: BloxyTrade[] = [];
// Clamp numberOfDays so that it is always between 1 and MAX_DAYS (inclusive)
const numberOfDays = R.clamp(1, MAX_DAYS, getDaysSinceTimestamp(lastSeenTimestamp));
// Keep getting trades until we hit one of the following conditions:
//
// 1. Offset hits MAX_OFFSET (we can't go back any further).
// 2. There are no more trades in the response.
// 3. We see a tx_time equal to or earlier than lastSeenTimestamp (plus
// some buffer).
//
for (let offset = 0; offset <= MAX_OFFSET; offset += TRADES_PER_QUERY - OFFSET_BUFFER) {
const trades = await this._getTradesWithOffsetAsync(numberOfDays, offset);
if (trades.length === 0) {
// There are no more trades left for the days we are querying.
// This means we are done.
return filterDuplicateTrades(allTrades);
}
const sortedTrades = R.reverse(R.sortBy(trade => trade.tx_time, trades));
allTrades = allTrades.concat(sortedTrades);
// Check if lastReturnedTimestamp < lastSeenTimestamp
const lastReturnedTimestamp = new Date(sortedTrades[0].tx_time).getTime();
if (lastReturnedTimestamp < lastSeenTimestamp - LAST_SEEN_TIMESTAMP_BUFFER_MS) {
// We are at the point where we have already seen trades for the
// timestamp range that is being returned. We're done.
return filterDuplicateTrades(allTrades);
}
}
return filterDuplicateTrades(allTrades);
}
private async _getTradesWithOffsetAsync(numberOfDays: number, offset: number): Promise<BloxyTrade[]> {
const resp = await axios.get<BloxyTradeResponse>(BLOXY_DEX_TRADES_URL, {
params: {
key: this._apiKey,
days: numberOfDays,
limit: TRADES_PER_QUERY,
offset,
},
});
if (isError(resp.data)) {
throw new Error(`Error in Bloxy API response: ${resp.data.error}`);
}
return resp.data;
}
}
// Computes the number of days between the given timestamp and the current
// timestamp (rounded up).
function getDaysSinceTimestamp(timestamp: number): number {
const msSinceTimestamp = Date.now() - timestamp;
const daysSinceTimestamp = msSinceTimestamp / millisecondsPerDay;
return Math.ceil(daysSinceTimestamp);
}
const filterDuplicateTrades = R.uniqBy((trade: BloxyTrade) => trade.tx_hash);
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