/**
* In-memory cache with TTL for Text-TV data
*/
interface CacheEntry<T> {
value: T;
expiresAt: number;
}
/**
* Simple in-memory cache with TTL support
*/
export class Cache {
private store = new Map<string, CacheEntry<unknown>>();
private cleanupInterval: NodeJS.Timeout | null = null;
constructor(cleanupIntervalMs: number = 60_000) {
// Periodic cleanup of expired entries
this.cleanupInterval = setInterval(() => {
this.cleanup();
}, cleanupIntervalMs);
// Allow process to exit
if (this.cleanupInterval.unref) {
this.cleanupInterval.unref();
}
}
/**
* Get a value from cache
*/
get<T>(key: string): T | undefined {
const entry = this.store.get(key) as CacheEntry<T> | undefined;
if (!entry) {
return undefined;
}
if (Date.now() > entry.expiresAt) {
this.store.delete(key);
return undefined;
}
return entry.value;
}
/**
* Set a value in cache with TTL
*/
set<T>(key: string, value: T, ttlMs: number): void {
this.store.set(key, {
value,
expiresAt: Date.now() + ttlMs,
});
}
/**
* Check if key exists and is not expired
*/
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 a specific key
*/
delete(key: string): boolean {
return this.store.delete(key);
}
/**
* Clear all entries
*/
clear(): void {
this.store.clear();
}
/**
* Get cache size
*/
get size(): number {
return this.store.size;
}
/**
* Cleanup expired entries
*/
private cleanup(): void {
const now = Date.now();
for (const [key, entry] of this.store.entries()) {
if (now > entry.expiresAt) {
this.store.delete(key);
}
}
}
/**
* Stop cleanup interval
*/
destroy(): void {
if (this.cleanupInterval) {
clearInterval(this.cleanupInterval);
this.cleanupInterval = null;
}
this.clear();
}
}
/**
* Generate cache key for page requests
*/
export function pageKey(pageNum: number, includePlainText: boolean = false): string {
return `page:${pageNum}:${includePlainText ? 'plain' : 'html'}`;
}
/**
* Generate cache key for page range requests
*/
export function pageRangeKey(start: number, end: number, includePlainText: boolean = false): string {
return `range:${start}-${end}:${includePlainText ? 'plain' : 'html'}`;
}
/**
* Generate cache key for search requests
*/
export function searchKey(query: string, startPage: number, endPage: number): string {
return `search:${query}:${startPage}-${endPage}`;
}
/**
* Generate cache key for category browse
*/
export function categoryKey(category: string, includeContent: boolean = false): string {
return `category:${category}:${includeContent ? 'content' : 'meta'}`;
}
// Singleton cache instance
export const cache = new Cache();
