[JS->TS] Migrate ensure_owl_liquidity.js (#820)

* Migrate ensure_owl_liquidity.js
* improve return type and capture all possible script outcomes

scripts/ensure_owl_liquidity.ts

@@ -0,0 +1,117 @@
+import BN from "bn.js";
+import { placeFeeTokenLiquidityOrders } from "../src/fee_token_liquidity";
+import { getOrdersPaginated } from "../src/onchain_reading";
+import type { Order } from "../src/encoding";
+import { factory } from "../src/logging";
+const log = factory.getLogger("scripts.owl_liquidity");
+
+const BatchExchange = artifacts.require("BatchExchange");
+const MAXU32 = new BN(2).pow(new BN(32)).sub(new BN(1));
+const MIN_OWL_LIQUIDITY = new BN(10).pow(new BN(17));
+const SELL_AMOUNT_OWL = new BN(10).pow(new BN(18)).mul(new BN(5));
+
+// All orders provided by this liquidity script will sell OWL for a very high price:
+// At 1000 [token]/[OWL]. In most of the cases this will ensure that 1 [OWL] is valued
+// higher than 1 dollar. For tokens valued below 1/10000 USD, OWL can be extracted profitably
+// from these orders. However, since we only sell 5 OWL and 10 OWL have to be spent to add one token,
+// stealing OWL by adding new tokens is not profitable.
+const PRICE_FOR_PROVISION = new BN(10000);
+
+const containsSellOrderProvidingLiquidity = function (orders: Order<BN>[]) {
+  return orders.some(
+    (order) =>
+      order.sellTokenBalance.gt(MIN_OWL_LIQUIDITY) &&
+      order.remainingAmount.gt(MIN_OWL_LIQUIDITY),
+  );
+};
+
+// This function checks whether it is likely that Gnosis has already provided liquidity for this token
+// with a liquidity-order. The check depends on the match of two order criteria: SellAmount and validUntil.
+// Despite being just an heuristic check, it should be sufficient for now.
+const hasOWLLiquidityOrderAlreadyBeenPlaced = function (orders: Order<BN>[]) {
+  return orders.some(
+    (order) =>
+      order.priceDenominator.eq(SELL_AMOUNT_OWL) &&
+      new BN(order.validUntil).eq(MAXU32),
+  );
+};
+
+module.exports = async (callback: Truffle.ScriptCallback) => {
+  try {
+    const exchange = await BatchExchange.deployed();
+    const owlTokenAddress = await exchange.tokenIdToAddressMap(0);
+    const [liquidityEnsurer] = await web3.eth.getAccounts();
+    log.info(`Using account ${liquidityEnsurer}`);
+    // check that liquidityEnsurer has sufficient OWL in the exchange:
+    const owlBalance = await exchange.getBalance(
+      liquidityEnsurer,
+      owlTokenAddress,
+    );
+    if (new BN(10).pow(new BN(18)).gt(owlBalance)) {
+      callback(
+        "Error: OWL balance is below the 10 OWL threshold, please stock it up again",
+      );
+    }
+
+    // Get the order data
+    const numTokens = (await exchange.numTokens()).toNumber();
+    const batchId = (await exchange.getCurrentBatchId()).toNumber();
+    log.info("Retrieving orders from exchange. This may take a while...");
+    let orders = await getOrdersPaginated(exchange.contract, 100);
+    orders = orders.filter(
+      (order) => order.validUntil >= batchId && order.validFrom <= batchId,
+    );
+
+    // Ensure OWL-liquidity is given
+    const tokensRequiringLiquidity = [];
+    for (let tokenId = 1; tokenId < numTokens; tokenId++) {
+      const tokenAddress = await exchange.tokenIdToAddressMap(tokenId);
+      log.info(`Checking liquidity for token ${tokenId} - ${tokenAddress}`);
+      const ordersForTokenId = orders.filter(
+        (order) => order.buyToken == tokenId && order.sellToken == 0,
+      );
+      if (
+        !containsSellOrderProvidingLiquidity(ordersForTokenId) &&
+        !hasOWLLiquidityOrderAlreadyBeenPlaced(ordersForTokenId)
+      ) {
+        tokensRequiringLiquidity.push(tokenId);
+      } else {
+        log.info(
+          `    Liquidity for ${tokenAddress} is given or has been provided in the past`,
+        );
+      }
+    }
+    if (tokensRequiringLiquidity) {
+      log.info(
+        `Attempting to place orders for tokens ${tokensRequiringLiquidity}`,
+      );
+      const successTokens = await placeFeeTokenLiquidityOrders(
+        exchange,
+        tokensRequiringLiquidity,
+        PRICE_FOR_PROVISION,
+        SELL_AMOUNT_OWL,
+        artifacts,
+      );
+      if (successTokens && successTokens.length) {
+        log.info(
+          `Successfully placed fee token liquidity orders for tokens: ${successTokens}`,
+        );
+      }
+      // This scenario is actually quite common. In fact, always
+      // happens once a non-ERC20 token has been registered on exchange.
+      const failedTokens = tokensRequiringLiquidity.filter(
+        (x) => !successTokens.includes(x),
+      );
+      if (failedTokens && failedTokens.length) {
+        log.warn(
+          `No orders placed for ${failedTokens} (Likely not ERC20s on this network).`,
+        );
+      }
+    } else {
+      log.info("Did not detect any tokens requiring liquidity");
+    }
+    callback();
+  } catch (error) {
+    callback(error);
+  }
+};

src/fee_token_liquidity.ts

@@ -69,9 +69,9 @@ export async function placeFeeTokenLiquidityOrders(
   provisionPrice: BN,
   sellAmountOwl: BN,
   artifacts: Truffle.Artifacts,
-): Promise<(string | undefined)[]> {
+): Promise<number[]> {
   const minBuyAmounts = [];
-  const validTokenIds = [];
+  const validTokenIds: number[] = [];
   const feeToken = await fetchTokenInfoFromExchange(exchange, [0], artifacts);
   // This is expected to always be OWL which has 18 digits.
   const feeDigits = feeToken.get(0)?.decimals || 18;
@@ -82,7 +82,7 @@ export async function placeFeeTokenLiquidityOrders(
   );
   for (const tokenId of tokenIds) {
     const numDigits = tokenInfo.get(tokenId)?.decimals;
-    if (numDigits && numDigits != -1) {
+    if (numDigits) {
       validTokenIds.push(tokenId);
       if (numDigits < feeDigits) {
         minBuyAmounts.push(
@@ -113,5 +113,5 @@ export async function placeFeeTokenLiquidityOrders(
     Array(numOrders).fill(sellAmountOwl), // sellAmount
   );
 
-  return await Promise.all(validTokenIds.map((i) => tokenInfo.get(i)?.address));
+  return validTokenIds;
 }