import os from 'node:os';
import path from 'node:path';

// ---------------------------------------------------------------------------
// Helpers
// ---------------------------------------------------------------------------

function envString(key: string, fallback: string): string {
  return process.env[key] ?? fallback;
}

function envInt(key: string, fallback: number): number {
  const raw = process.env[key];
  if (raw === undefined) return fallback;
  const parsed = Number.parseInt(raw, 10);
  if (Number.isNaN(parsed)) {
    // eslint-disable-next-line no-console
    console.error(`[config] Invalid integer for ${key}="${raw}", using default ${fallback}`);
    return fallback;
  }
  return parsed;
}

function envBool(key: string, fallback: boolean): boolean {
  const raw = process.env[key];
  if (raw === undefined) return fallback;
  // Accept common truthy / falsy strings
  if (['true', '1', 'yes'].includes(raw.toLowerCase())) return true;
  if (['false', '0', 'no'].includes(raw.toLowerCase())) return false;
  return fallback;
}

// ---------------------------------------------------------------------------
// HOST safety check — must run before exporting config
// ---------------------------------------------------------------------------

const host = envString('HOST', '127.0.0.1');

if (host === '0.0.0.0' || host === '::') {
  const allow = process.env['ALLOW_REMOTE'];
  if (allow !== 'yes-i-understand-the-risk') {
    // Use console.error directly — the logger module depends on config,
    // so it is not available yet at this point.
    // eslint-disable-next-line no-console
    console.error(
      `[FATAL] HOST is set to "${host}" which exposes the service to the network.\n` +
      `If you really intend to do this, set ALLOW_REMOTE=yes-i-understand-the-risk\n` +
      `Refusing to start.`,
    );
    process.exit(1);
  }
}

// ---------------------------------------------------------------------------
// Operation timeouts (milliseconds)
// Matches the tiers described in PLAN.md section 6.1
// ---------------------------------------------------------------------------

const operationTimeouts: Record<string, number> = {
  like:        15_000,   // 15s  — quick interactions
  favorite:    15_000,   // 15s
  comment:     20_000,   // 20s
  reply:       20_000,   // 20s
  feed_list:   30_000,   // 30s  — page load + extraction
  search:      30_000,   // 30s
  feed_detail: 60_000,   // 60s  — includes scroll loading
  user_profile: 60_000,  // 60s
  publish:    300_000,   // 5min — upload may be slow
  login:      300_000,   // 5min — user interaction
  default:     60_000,   // 1min — fallback
};

// ---------------------------------------------------------------------------
// Config type
// ---------------------------------------------------------------------------

export interface AppConfig {
  /** HTTP port */
  port: number;
  /** HTTP bind address */
  host: string;
  /** Run browser in headless mode */
  headless: boolean;
  /** Custom browser executable path (optional) */
  browserBin: string | undefined;
  /** Pino log level */
  logLevel: string;
  /** NODE_ENV */
  nodeEnv: string;
  /** Directory for per-platform cookie storage */
  cookieDir: string;
  /** Max pending operations per platform queue */
  maxQueueDepth: number;
  /** Per-operation-type timeout in ms */
  operationTimeouts: Record<string, number>;
}

// ---------------------------------------------------------------------------
// Exported config singleton
// ---------------------------------------------------------------------------

export const config: AppConfig = {
  port:              envInt('PORT', 9527),
  host,
  headless:          envBool('HEADLESS', true),
  browserBin:        process.env['BROWSER_BIN'] || undefined,
  logLevel:          envString('LOG_LEVEL', 'info'),
  nodeEnv:           envString('NODE_ENV', 'development'),
  cookieDir:         envString('COOKIE_DIR', path.join(os.homedir(), '.social-mcp')),
  maxQueueDepth:     envInt('MAX_QUEUE_DEPTH', 10),
  operationTimeouts,
};