/**
* OpenAPI specification cache - file-based caching with TTL
*/
import { readFile, writeFile, mkdir } from "node:fs/promises";
import { join, dirname } from "node:path";
import { tmpdir } from "node:os";
import type { OpenAPISpec, CachedSpec } from "./types.js";
/**
* Cache interface (allows alternative implementations)
*/
export interface SpecCache {
get(): Promise<CachedSpec | null>;
set(spec: OpenAPISpec, ttlMs: number): Promise<void>;
clear(): Promise<void>;
}
/**
* File-based cache implementation
*/
export class FileSpecCache implements SpecCache {
private readonly cachePath: string;
constructor(cacheDir?: string) {
const dir = cacheDir || join(tmpdir(), "openapi-mcp");
this.cachePath = join(dir, "openapi-cache.json");
}
async get(): Promise<CachedSpec | null> {
try {
const content = await readFile(this.cachePath, "utf-8");
const cached = JSON.parse(content) as CachedSpec;
// Validate structure
if (!cached.spec || !cached.fetchedAt || !cached.expiresAt) {
return null;
}
// Check expiry
if (Date.now() > cached.expiresAt) {
return null;
}
return cached;
} catch {
// File doesn't exist or is invalid
return null;
}
}
async set(spec: OpenAPISpec, ttlMs: number): Promise<void> {
const cached: CachedSpec = {
spec,
fetchedAt: Date.now(),
expiresAt: Date.now() + ttlMs,
};
try {
await mkdir(dirname(this.cachePath), { recursive: true });
await writeFile(this.cachePath, JSON.stringify(cached, null, 2), "utf-8");
} catch (error) {
// Cache write failures are non-fatal
console.error(
"[openapi-mcp] Failed to write cache:",
error instanceof Error ? error.message : error
);
}
}
async clear(): Promise<void> {
try {
const { unlink } = await import("node:fs/promises");
await unlink(this.cachePath);
} catch {
// File might not exist
}
}
}
/**
* In-memory cache for testing
*/
export class MemorySpecCache implements SpecCache {
private cached: CachedSpec | null = null;
async get(): Promise<CachedSpec | null> {
if (!this.cached) return null;
if (Date.now() > this.cached.expiresAt) {
this.cached = null;
return null;
}
return this.cached;
}
async set(spec: OpenAPISpec, ttlMs: number): Promise<void> {
this.cached = {
spec,
fetchedAt: Date.now(),
expiresAt: Date.now() + ttlMs,
};
}
async clear(): Promise<void> {
this.cached = null;
}
}
