import { mkdir, readFile, rename, writeFile } from 'node:fs/promises'
import { join } from 'node:path'
import { dataDirectory } from './files.js'

export async function ensureDataDirectory() {
  await mkdir(dataDirectory, { recursive: true })
}

export async function readData<T>(name: string, fallback: T): Promise<T> {
  await ensureDataDirectory()
  try {
    const raw = await readFile(join(dataDirectory, name), 'utf8')
    return JSON.parse(raw) as T
  } catch (error) {
    if ((error as NodeJS.ErrnoException).code !== 'ENOENT') throw new Error(`无法读取 ${name}：${String(error)}`)
    await writeData(name, fallback)
    return fallback
  }
}

export async function writeData<T>(name: string, data: T) {
  await ensureDataDirectory()
  const target = join(dataDirectory, name)
  const temp = `${target}.tmp`
  await writeFile(temp, `${JSON.stringify(data, null, 2)}\n`, 'utf8')
  await rename(temp, target)
}

export async function updateData<T>(name: string, fallback: T, updater: (data: T) => T) {
  const current = await readData(name, fallback)
  const next = updater(current)
  await writeData(name, next)
  return next
}