import { mkdirSync, readFileSync, writeFileSync } from 'node:fs'
import path from 'node:path'
import crypto from 'node:crypto'

export interface Config {
  dataDir: string
  artworkDir: string
  dbPath: string
  port: number
  sessionSecret: string
}

export function loadConfig(env: Record<string, string | undefined> = process.env): Config {
  const dataDir = env.DATA_DIR ?? path.resolve('data')
  mkdirSync(dataDir, { recursive: true })
  const artworkDir = path.join(dataDir, 'artwork-cache')
  mkdirSync(artworkDir, { recursive: true })
  return {
    dataDir,
    artworkDir,
    dbPath: path.join(dataDir, 'record-shop.db'),
    port: Number(env.PORT ?? 3000),
    sessionSecret: getOrCreateSecret(dataDir),
  }
}

function getOrCreateSecret(dataDir: string): string {
  const secretPath = path.join(dataDir, 'session-secret')
  try {
    const existing = readFileSync(secretPath, 'utf8').trim()
    if (existing) return existing
  } catch {
    // first boot — create below
  }
  const secret = crypto.randomBytes(32).toString('hex')
  writeFileSync(secretPath, secret, { mode: 0o600 })
  return secret
}