Implement Stellar Asset Whitelist Manager

src/assets/whitelist/stellar/asset-whitelist.service.ts

@@ -0,0 +1,56 @@
+export interface StellarAsset {
+  code: string;
+  issuer: string | null; // null = native XLM
+}
+
+export interface WhitelistEntry extends StellarAsset {
+  addedAt: Date;
+  trustedIssuer: boolean;
+}
+
+export class StellarAssetWhitelistManager {
+  private readonly whitelist = new Map<string, WhitelistEntry>();
+  private readonly horizonUrl: string;
+
+  constructor(horizonUrl = 'https://horizon-testnet.stellar.org') {
+    this.horizonUrl = horizonUrl;
+  }
+
+  private key(asset: StellarAsset): string {
+    return asset.issuer ? `${asset.code}:${asset.issuer}` : 'XLM:native';
+  }
+
+  /** Adds an asset to the whitelist after validating issuer trust. */
+  async add(asset: StellarAsset): Promise<WhitelistEntry> {
+    const trustedIssuer = asset.issuer ? await this.validateIssuer(asset.issuer) : true;
+    const entry: WhitelistEntry = { ...asset, addedAt: new Date(), trustedIssuer };
+    this.whitelist.set(this.key(asset), entry);
+    return entry;
+  }
+
+  /** Removes an asset from the whitelist. */
+  remove(asset: StellarAsset): boolean {
+    return this.whitelist.delete(this.key(asset));
+  }
+
+  /** Returns true if the asset is whitelisted and its issuer is trusted. */
+  isAllowed(asset: StellarAsset): boolean {
+    const entry = this.whitelist.get(this.key(asset));
+    return entry != null && entry.trustedIssuer;
+  }
+
+  /** Returns all whitelisted assets. */
+  getAll(): WhitelistEntry[] {
+    return Array.from(this.whitelist.values());
+  }
+
+  /** Validates that an issuer account exists on the Stellar network. */
+  async validateIssuer(issuer: string): Promise<boolean> {
+    try {
+      const res = await fetch(`${this.horizonUrl}/accounts/${issuer}`);
+      return res.ok;
+    } catch {
+      return false;
+    }
+  }
+}