chore: migrate swaps controller to typescript (#25063)

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## **Description**

This PR refactors the SwapsController class to be rewritten in
typescript. For the sake of making sure all functionality stays the
same, the tests have not been affected
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also include relevant motivation and context. Have in mind the following
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1. What is the reason for the change?
2. What is the improvement/solution?
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## **Related issues**

Fixes:

## **Manual testing steps**

Go to swaps. Swap on the following scenarios:

ETH -> WETH
WETH -> ETH
ETH -> ERC20
ERC20 -> ETH
ERC20 -> ERC20

## **Screenshots/Recordings**

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before and after of your change. -->
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### **Before**

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### **After**

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## **Pre-merge author checklist**

- [x] I’ve followed [MetaMask Coding
Standards](https://github.com/MetaMask/metamask-extension/blob/develop/.github/guidelines/CODING_GUIDELINES.md).
- [x] I've completed the PR template to the best of my ability
- [x] I’ve included tests if applicable
- [x] I’ve documented my code using [JSDoc](https://jsdoc.app/) format
if applicable
- [x] I’ve applied the right labels on the PR (see [labeling
guidelines](https://github.com/MetaMask/metamask-extension/blob/develop/.github/guidelines/LABELING_GUIDELINES.md)).
Not required for external contributors.

## **Pre-merge reviewer checklist**

- [x] I've manually tested the PR (e.g. pull and build branch, run the
app, test code being changed).
- [x] I confirm that this PR addresses all acceptance criteria described
in the ticket it closes and includes the necessary testing evidence such
as recordings and or screenshots.

app/scripts/controllers/swaps.constants.ts

@@ -0,0 +1,50 @@
+import {
+  FALLBACK_SMART_TRANSACTIONS_MAX_FEE_MULTIPLIER,
+  FALLBACK_SMART_TRANSACTIONS_REFRESH_TIME,
+} from '../../../shared/constants/smartTransactions';
+import { MINUTE } from '../../../shared/constants/time';
+
+import type { SwapsControllerState } from './swaps.types';
+
+// The MAX_GAS_LIMIT is a number that is higher than the maximum gas costs we have observed on any aggregator
+export const MAX_GAS_LIMIT = 2500000;
+
+// To ensure that our serves are not spammed if MetaMask is left idle, we limit the number of fetches for quotes that are made on timed intervals.
+// 3 seems to be an appropriate balance of giving users the time they need when MetaMask is not left idle, and turning polling off when it is.
+export const POLL_COUNT_LIMIT = 3;
+
+// If for any reason the MetaSwap API fails to provide a refresh time,
+// provide a reasonable fallback to avoid further errors
+export const FALLBACK_QUOTE_REFRESH_TIME = MINUTE;
+
+export const swapsControllerInitialState: { swapsState: SwapsControllerState } =
+  {
+    swapsState: {
+      quotes: {},
+      quotesPollingLimitEnabled: false,
+      fetchParams: null,
+      tokens: null,
+      tradeTxId: null,
+      approveTxId: null,
+      quotesLastFetched: null,
+      customMaxGas: '',
+      customGasPrice: null,
+      customMaxFeePerGas: null,
+      customMaxPriorityFeePerGas: null,
+      swapsUserFeeLevel: '',
+      selectedAggId: null,
+      customApproveTxData: '',
+      errorKey: '',
+      topAggId: null,
+      routeState: '',
+      swapsFeatureIsLive: true,
+      saveFetchedQuotes: false,
+      swapsQuoteRefreshTime: FALLBACK_QUOTE_REFRESH_TIME,
+      swapsQuotePrefetchingRefreshTime: FALLBACK_QUOTE_REFRESH_TIME,
+      swapsStxBatchStatusRefreshTime: FALLBACK_SMART_TRANSACTIONS_REFRESH_TIME,
+      swapsStxGetTransactionsRefreshTime:
+        FALLBACK_SMART_TRANSACTIONS_REFRESH_TIME,
+      swapsStxMaxFeeMultiplier: FALLBACK_SMART_TRANSACTIONS_MAX_FEE_MULTIPLIER,
+      swapsFeatureFlags: {},
+    },
+  };

app/scripts/controllers/swaps.test.js

@@ -10,7 +10,8 @@ import {
   FALLBACK_SMART_TRANSACTIONS_REFRESH_TIME,
   FALLBACK_SMART_TRANSACTIONS_MAX_FEE_MULTIPLIER,
 } from '../../../shared/constants/smartTransactions';
-import SwapsController, { utils } from './swaps';
+import SwapsController from './swaps';
+import { getMedianEthValueQuote } from './swaps.utils';
 
 const MOCK_FETCH_PARAMS = {
   slippage: 3,
@@ -179,7 +180,7 @@ describe('SwapsController', function () {
       expect(swapsController.getBufferedGasLimit).toStrictEqual(
         MOCK_GET_BUFFERED_GAS_LIMIT,
       );
-      expect(swapsController.pollCount).toStrictEqual(0);
+      expect(swapsController._pollCount).toStrictEqual(0);
       expect(swapsController.getProviderConfig).toStrictEqual(
         MOCK_GET_PROVIDER_CONFIG,
       );
@@ -716,7 +717,7 @@ describe('SwapsController', function () {
 
         const timedoutGasReturnResult = { gasLimit: 1000000 };
         const timedoutGasReturnSpy = jest
-          .spyOn(swapsController, 'timedoutGasReturn')
+          .spyOn(swapsController, '_timedoutGasReturn')
           .mockReturnValue(timedoutGasReturnResult);
 
         await swapsController.fetchAndSetQuotes(
@@ -820,7 +821,7 @@ describe('SwapsController', function () {
 
         const _swapsController = getSwapsController();
 
-        const currentEthersInstance = _swapsController.ethersProvider;
+        const currentEthersInstance = _swapsController._ethersProvider;
 
         // Make the network fetch error message disappear
         jest
@@ -832,7 +833,7 @@ describe('SwapsController', function () {
           chainId: CHAIN_IDS.GOERLI,
         });
 
-        const newEthersInstance = _swapsController.ethersProvider;
+        const newEthersInstance = _swapsController._ethersProvider;
         expect(currentEthersInstance).not.toStrictEqual(newEthersInstance);
       });
 
@@ -845,7 +846,7 @@ describe('SwapsController', function () {
           fetchTradesInfo: fetchTradesInfoStub,
           getCurrentChainId: getCurrentChainIdStub,
         });
-        const currentEthersInstance = _swapsController.ethersProvider;
+        const currentEthersInstance = _swapsController._ethersProvider;
 
         // Make the network fetch error message disappear
         jest.spyOn(swapsController, '_setSwapsNetworkConfig').mockReturnValue();
@@ -855,7 +856,7 @@ describe('SwapsController', function () {
           chainId: CHAIN_IDS.MAINNET,
         });
 
-        const newEthersInstance = _swapsController.ethersProvider;
+        const newEthersInstance = _swapsController._ethersProvider;
         expect(currentEthersInstance).toStrictEqual(newEthersInstance);
       });
 
@@ -870,7 +871,7 @@ describe('SwapsController', function () {
           getLayer1GasFee: getLayer1GasFeeStub,
           getNetworkClientId: getNetworkClientIdStub,
         });
-        const firstEthersInstance = _swapsController.ethersProvider;
+        const firstEthersInstance = _swapsController._ethersProvider;
         const firstEthersProviderChainId =
           _swapsController._ethersProviderChainId;
 
@@ -884,7 +885,7 @@ describe('SwapsController', function () {
           chainId: CHAIN_IDS.GOERLI,
         });
 
-        const secondEthersInstance = _swapsController.ethersProvider;
+        const secondEthersInstance = _swapsController._ethersProvider;
         const secondEthersProviderChainId =
           _swapsController._ethersProviderChainId;
 
@@ -898,7 +899,7 @@ describe('SwapsController', function () {
           chainId: CHAIN_IDS.LOCALHOST,
         });
 
-        const thirdEthersInstance = _swapsController.ethersProvider;
+        const thirdEthersInstance = _swapsController._ethersProvider;
         const thirdEthersProviderChainId =
           _swapsController._ethersProviderChainId;
 
@@ -946,7 +947,7 @@ describe('SwapsController', function () {
       });
 
       it('clears polling timeout', function () {
-        swapsController.pollingTimeout = setTimeout(() => {
+        swapsController._pollingTimeout = setTimeout(() => {
           throw new Error('Polling timeout not cleared');
         }, POLLING_TIMEOUT);
 
@@ -960,7 +961,7 @@ describe('SwapsController', function () {
 
     describe('stopPollingForQuotes', function () {
       it('clears polling timeout', function () {
-        swapsController.pollingTimeout = setTimeout(() => {
+        swapsController._pollingTimeout = setTimeout(() => {
           throw new Error('Polling timeout not cleared');
         }, POLLING_TIMEOUT);
 
@@ -981,7 +982,7 @@ describe('SwapsController', function () {
 
     describe('resetPostFetchState', function () {
       it('clears polling timeout', function () {
-        swapsController.pollingTimeout = setTimeout(() => {
+        swapsController._pollingTimeout = setTimeout(() => {
           throw new Error('Polling timeout not cleared');
         }, POLLING_TIMEOUT);
 
@@ -1031,8 +1032,6 @@ describe('SwapsController', function () {
 
   describe('utils', function () {
     describe('getMedianEthValueQuote', function () {
-      const { getMedianEthValueQuote } = utils;
-
       it('calculates median correctly with uneven sample', function () {
         const expectedResult = {
           ethFee: '10',