import { readFile, writeFile, mkdir } from 'fs/promises';import { existsSync } from 'fs';import path from 'path'; export interface ApiSettings {  backendUrl: string;  apiKey: string;  voiceUrl: string;  voiceModel: string;} const DEFAULT_SETTINGS: ApiSettings = {  backendUrl: process.env.BACKEND_URL || process.env.NEXT_PUBLIC_API_URL || 'http://localhost:8080',  apiKey: process.env.API_KEY || '',  voiceUrl: process.env.VOICE_URL || process.env.NEXT_PUBLIC_VOICE_URL || '',  voiceModel: process.env.VOICE_MODEL || process.env.NEXT_PUBLIC_VOICE_MODEL || 'whisper-1',}; // Settings file path - relative to frontend directoryconst DATA_DIR = path.join(process.cwd(), 'data');const SETTINGS_FILE = path.join(DATA_DIR, 'api-settings.json'); export async function getApiSettings(): Promise<ApiSettings> {  try {    if (existsSync(SETTINGS_FILE)) {      const content = await readFile(SETTINGS_FILE, 'utf-8');      const saved = JSON.parse(content) as Partial<ApiSettings>;      // Merge with defaults (env vars still take precedence if settings file has empty values)      return {        backendUrl: saved.backendUrl || DEFAULT_SETTINGS.backendUrl,        apiKey: saved.apiKey || DEFAULT_SETTINGS.apiKey,        voiceUrl: saved.voiceUrl || DEFAULT_SETTINGS.voiceUrl,        voiceModel: saved.voiceModel || DEFAULT_SETTINGS.voiceModel,      };    }  } catch (error) {    console.error('[API Settings] Failed to read settings file:', error);  }  return DEFAULT_SETTINGS;} export async function saveApiSettings(settings: ApiSettings): Promise<void> {  try {    // Ensure data directory exists    if (!existsSync(DATA_DIR)) {      await mkdir(DATA_DIR, { recursive: true });    }    await writeFile(SETTINGS_FILE, JSON.stringify(settings, null, 2), 'utf-8');  } catch (error) {    console.error('[API Settings] Failed to save settings file:', error);    throw error;  }} // Mask API key for display (show first 4 and last 4 chars)export function maskApiKey(key: string): string {  if (!key || key.length < 12) return key ? '••••••••' : '';  return `${key.slice(0, 4)}••••${key.slice(-4)}`;}