Resolve "feat(Rates): Composite Adapter should be able to add/remove adapters"

packages/stack/src/rates/rates-composite.ts

@@ -1,28 +1,32 @@
 import { BaseRates } from './base-rates.js';
+import { UUIDV7 } from '../utils/uuid.js';
 
 /**
  * A composite rate adapter that combines rates from multiple rate sources
  * using a configurable policy.
  */
 export class RatesComposite extends BaseRates {
+  // List of the adapters with a unique ID for each adapter
+  private adapters: { id: string; adapter: BaseRates }[] = [];
+
   // Track available pairs across all rate adapters
   private availablePairs: Set<string> = new Set();
 
   // Cache of the latest rates from each adapter
-  private rateCache: Map<string, Map<string, Map<number, number>>> = new Map();
+  private rateCache: Map<string, Map<string, Map<string, number>>> = new Map();
 
   // Off callbacks for unsubscribing from events
-  private unsubscribeFunctions: (() => void)[] = [];
+  private unsubscribeFunctions: Map<string, () => void> = new Map();
 
   /**
    * Creates a new RatesComposite instance
    *
    * @param adapters Array of BaseRates adapters to combine
    * @param policy Policy to determine how to combine rates (defaults to average)
-   * @param refreshIntervalMs How often to emit combined rates (defaults to 1000ms)
+   * @param refreshIntervalMs How often to emit combined rates (defaults to 60000ms)
    */
   constructor(
-    private adapters: BaseRates[],
+    adapters: BaseRates[],
     private policy: RatesCompositePolicy = ratesAveragePolicy,
     private refreshIntervalMs: number = 60000,
   ) {
@@ -30,34 +34,17 @@ export class RatesComposite extends BaseRates {
 
     // Initialize rate cache
     this.rateCache = new Map();
+
+    // Add all adapters to the composite
+    adapters.forEach((adapter) => this.addAdapter(adapter, false));
   }
 
   /**
    * Start all rate adapters and setup event listeners
    */
   public async start(): Promise<void> {
-    // Setup event listeners for all adapters
-    for (let i = 0; i < this.adapters.length; i++) {
-      const adapter = this.adapters[i];
-      const adapterIndex = i;
-
-      const listener = (event: {
-        denominatorUnitCode: string;
-        numeratorUnitCode: string;
-        price: number;
-      }) => {
-        this.handleRateUpdate(adapterIndex, event);
-      };
-
-      // Use the returned unsubscribe function from the custom EventEmitter
-      const unsubscribe = adapter.on('rateUpdated', listener);
-
-      // Store unsubscribe function for cleanup
-      this.unsubscribeFunctions.push(unsubscribe);
-    }
-
     // Start all adapters
-    await Promise.all(this.adapters.map((adapter) => adapter.start()));
+    await Promise.all(this.adapters.map(({ adapter }) => adapter.start()));
 
     // Start periodic refresh to emit combined rates
     this.startPeriodicRefresh();
@@ -74,13 +61,86 @@ export class RatesComposite extends BaseRates {
     }
 
     // Clean up all event listeners by calling their unsubscribe functions
-    for (const unsubscribe of this.unsubscribeFunctions) {
+    for (const unsubscribe of this.unsubscribeFunctions.values()) {
       unsubscribe();
     }
-    this.unsubscribeFunctions = [];
+    this.unsubscribeFunctions.clear();
 
     // Stop all adapters
-    await Promise.all(this.adapters.map((adapter) => adapter.stop()));
+    await Promise.all(this.adapters.map(({ adapter }) => adapter.stop()));
+  }
+
+  /**
+   * Adds a new rate adapter to the composite
+   */
+  public addAdapter(adapter: BaseRates, start: boolean = true): void {
+    // Generate a random ID for the adapter
+    const adapterId = UUIDV7.generateRandom().toString();
+
+    // Add the adapter to the list
+    this.adapters.push({ id: adapterId, adapter });
+
+    const listener = (event: {
+      denominatorUnitCode: string;
+      numeratorUnitCode: string;
+      price: number;
+    }) => {
+      this.handleRateUpdate(adapterId, event);
+    };
+
+    // Use the returned unsubscribe function from the custom EventEmitter
+    const unsubscribe = adapter.on('rateUpdated', listener);
+
+    // Store unsubscribe function associated with the adapter ID
+    this.unsubscribeFunctions.set(adapterId, unsubscribe);
+
+    // Start the adapter if requested
+    if (start) {
+      adapter.start();
+    }
+  }
+
+  /**
+   * Removes a rate adapter from the composite
+   */
+  public removeAdapter(adapter: BaseRates, stop: boolean = true): void {
+    // Get the index of the adapter
+    const adapterId = this.adapters.find(
+      ({ adapter: storedAdapter }) => storedAdapter === adapter,
+    )?.id;
+
+    // If the adapter is not found, do nothing
+    if (!adapterId) {
+      return;
+    }
+
+    // Call the unsubscribe function for the adapter
+    this.unsubscribeFunctions.get(adapterId)?.();
+
+    // Remove the adapter's rates from the cache
+    this.rateCache.forEach((numeratorMap) => {
+      numeratorMap.forEach((rateMap) => {
+        rateMap.delete(adapterId);
+      });
+    });
+
+    // Remove the unsubscribe function for the adapter
+    this.unsubscribeFunctions.delete(adapterId);
+
+    // Remove the adapter from the list
+    this.adapters = this.adapters.filter(({ id }) => id !== adapterId);
+
+    // Stop the adapter if requested
+    if (stop) {
+      adapter.stop();
+    }
+  }
+
+  /**
+   * Sets the policy for how to combine rates
+   */
+  public setPolicy(policy: RatesCompositePolicy): void {
+    this.policy = policy;
   }
 
   /**
@@ -88,7 +148,9 @@ export class RatesComposite extends BaseRates {
    */
   public async listPairs(): Promise<Set<string>> {
     // Get available pairs from all adapters
-    const pairPromises = this.adapters.map((adapter) => adapter.listPairs());
+    const pairPromises = this.adapters.map(({ adapter }) =>
+      adapter.listPairs(),
+    );
     const pairSets = await Promise.all(pairPromises);
 
     // Combine all pairs
@@ -127,7 +189,7 @@ export class RatesComposite extends BaseRates {
    * Handles a rate update from an adapter
    */
   private handleRateUpdate(
-    adapterIndex: number,
+    adapterId: string,
     event: {
       denominatorUnitCode: string;
       numeratorUnitCode: string;
@@ -148,7 +210,7 @@ export class RatesComposite extends BaseRates {
 
     // Store the rate in the cache
     const rateMap = denomMap.get(numeratorUnitCode)!;
-    rateMap.set(adapterIndex, price);
+    rateMap.set(adapterId, price);
 
     // Add pair to available pairs
     this.availablePairs.add(`${numeratorUnitCode}/${denominatorUnitCode}`);
@@ -162,8 +224,10 @@ export class RatesComposite extends BaseRates {
     for (const [denominator, numeratorMap] of this.rateCache.entries()) {
       // Process each numerator currency
       for (const [numerator, rateMap] of numeratorMap.entries()) {
-        // Get all rates for this pair
-        const rates = Array.from(rateMap.values());
+        // Go through our adapters in order, plucking the rate for each adapter
+        const rates = this.adapters
+          .map(({ id }) => rateMap.get(id))
+          .filter((rate) => rate !== undefined);
 
         // Apply policy to get combined rate
         const combinedRate = this.policy(rates);