feat: add TTL cache for API response caching

src/utils/cache.ts

@@ -0,0 +1,88 @@
+export interface CacheEntry<T> {
+	value: T;
+	expiresAt: number;
+}
+
+export class TtlCache<T> {
+	private store = new Map<string, CacheEntry<T>>();
+	private maxSize: number;
+	private defaultTtlMs: number;
+
+	constructor(maxSize = 1000, defaultTtlMs = 300000) {
+		this.maxSize = maxSize;
+		this.defaultTtlMs = defaultTtlMs;
+	}
+
+	get(key: string): T | undefined {
+		const entry = this.store.get(key);
+		if (!entry) return undefined;
+		if (Date.now() > entry.expiresAt) {
+			this.store.delete(key);
+			return undefined;
+		}
+		return entry.value;
+	}
+
+	set(key: string, value: T, ttlMs?: number): void {
+		if (this.store.size >= this.maxSize) {
+			this.evict();
+		}
+		this.store.set(key, {
+			value,
+			expiresAt: Date.now() + (ttlMs ?? this.defaultTtlMs),
+		});
+	}
+
+	has(key: string): boolean {
+		const entry = this.store.get(key);
+		if (!entry) return false;
+		if (Date.now() > entry.expiresAt) {
+			this.store.delete(key);
+			return false;
+		}
+		return true;
+	}
+
+	delete(key: string): boolean {
+		return this.store.delete(key);
+	}
+
+	clear(): void {
+		this.store.clear();
+	}
+
+	get size(): number {
+		return this.store.size;
+	}
+
+	private evict(): void {
+		let oldestKey: string = "";
+		let oldestTime = Infinity;
+
+		for (const [key, entry] of this.store) {
+			if (entry.expiresAt < oldestTime) {
+				oldestTime = entry.expiresAt;
+				oldestKey = key;
+			}
+		}
+
+		if (oldestKey) this.store.delete(oldestKey);
+	}
+}
+
+export function parseCacheControl(header: string): { maxAge: number; noCache: boolean } {
+	const result = { maxAge: 0, noCache: false };
+
+	for (const directive of header.split(",")) {
+		const trimmed = directive.trim().toLowerCase();
+		if (trimmed === "no-cache" || trimmed === "no-store") {
+			result.noCache = true;
+		}
+		if (trimmed.startsWith("max-age=")) {
+			const parsed = Number(trimmed.split("=")[1]);
+			if (Number.isFinite(parsed)) result.maxAge = parsed * 1000;
+		}
+	}
+
+	return result;
+}