/**
* @license
* Copyright 2026 Google LLC
* SPDX-License-Identifier: Apache-2.0
*/
import fs from 'node:fs/promises';
import os from 'node:os';
import path from 'node:path';
import process from 'node:process';
import {logger} from '../logger.js';
export interface LocalState {
lastActive: string; // ISO 8601 UTC date string
}
const STATE_FILE_NAME = 'telemetry_state.json';
function getDataFolder(): string {
const homedir = os.homedir();
const {env} = process;
const name = 'chrome-devtools-mcp';
if (process.platform === 'darwin') {
return path.join(homedir, 'Library', 'Application Support', name);
}
if (process.platform === 'win32') {
const localAppData =
env.LOCALAPPDATA || path.join(homedir, 'AppData', 'Local');
return path.join(localAppData, name, 'Data');
}
return path.join(
env.XDG_DATA_HOME || path.join(homedir, '.local', 'share'),
name,
);
}
export interface Persistence {
loadState(): Promise<LocalState>;
saveState(state: LocalState): Promise<void>;
}
export class FilePersistence implements Persistence {
#dataFolder: string;
constructor(dataFolderOverride?: string) {
this.#dataFolder = dataFolderOverride ?? getDataFolder();
}
async loadState(): Promise<LocalState> {
try {
const filePath = path.join(this.#dataFolder, STATE_FILE_NAME);
const content = await fs.readFile(filePath, 'utf-8');
return JSON.parse(content) as LocalState;
} catch {
return {
lastActive: '',
};
}
}
async saveState(state: LocalState): Promise<void> {
const filePath = path.join(this.#dataFolder, STATE_FILE_NAME);
try {
await fs.mkdir(this.#dataFolder, {recursive: true});
await fs.writeFile(filePath, JSON.stringify(state, null, 2), 'utf-8');
} catch (error) {
// Ignore errors during state saving to avoid crashing the server
logger(`Failed to save telemetry state to ${filePath}:`, error);
}
}
}
