/**
* WPCS MCP Server - File Hash Cache
* Provides incremental checking by caching results keyed by file hash + checker.
*/
import { createHash } from 'crypto';
import { existsSync, readFileSync, writeFileSync } from 'fs';
import { join } from 'path';
import type { CacheStore, CacheEntry } from './types.js';
const CACHE_VERSION = '2.0.0';
const CACHE_FILE_NAME = '.wpcs-cache.json';
export class FileCache {
private store: CacheStore;
private cachePath: string;
private dirty = false;
constructor(projectPath: string) {
this.cachePath = join(projectPath, CACHE_FILE_NAME);
this.store = this.load();
}
private load(): CacheStore {
if (!existsSync(this.cachePath)) {
return { version: CACHE_VERSION, entries: {} };
}
try {
const raw = readFileSync(this.cachePath, 'utf-8');
const data = JSON.parse(raw) as CacheStore;
if (data.version !== CACHE_VERSION) {
return { version: CACHE_VERSION, entries: {} };
}
return data;
} catch {
return { version: CACHE_VERSION, entries: {} };
}
}
/**
* Compute an MD5 hash of a file's contents.
*/
hashFile(filePath: string): string {
try {
const content = readFileSync(filePath);
return createHash('md5').update(content).digest('hex');
} catch {
return '';
}
}
/**
* Build a cache key from file path, checker name, and config hash.
*/
private buildKey(filePath: string, checkerName: string, configHash: string): string {
return `${filePath}:${checkerName}:${configHash}`;
}
/**
* Check if a file has changed since last check.
* Returns the cached results if unchanged, or null if the file needs re-checking.
*/
get(filePath: string, checkerName: string, configHash: string): Record<string, unknown> | null {
const key = this.buildKey(filePath, checkerName, configHash);
const entry = this.store.entries[key];
if (!entry) return null;
const currentHash = this.hashFile(filePath);
if (currentHash === entry.hash) {
return entry.results;
}
return null;
}
/**
* Store results for a file + checker combination.
*/
set(filePath: string, checkerName: string, configHash: string, results: Record<string, unknown>): void {
const key = this.buildKey(filePath, checkerName, configHash);
const hash = this.hashFile(filePath);
this.store.entries[key] = {
hash,
timestamp: Date.now(),
results,
};
this.dirty = true;
}
/**
* Persist the cache to disk.
*/
save(): void {
if (!this.dirty) return;
try {
writeFileSync(this.cachePath, JSON.stringify(this.store, null, 2));
this.dirty = false;
} catch {
// Ignore write errors (read-only fs, permissions, etc.)
}
}
/**
* Clear all cached entries.
*/
clear(): void {
this.store.entries = {};
this.dirty = true;
}
/**
* Hash the config object to detect config changes.
*/
static hashConfig(config: Record<string, unknown>): string {
return createHash('md5').update(JSON.stringify(config)).digest('hex');
}
}
