import { mkdir, mkdtemp, readFile, rm, writeFile } from 'node:fs/promises'
import { tmpdir } from 'node:os'
import { dirname, join, normalize, sep } from 'node:path'
import { prepareSpine38SkeletonJson } from './spine38-project.mjs'

const MAX_JSON_BYTES = 64 * 1024 * 1024
const MAX_IMAGE_BYTES = 32 * 1024 * 1024
const MAX_TOTAL_IMAGE_BYTES = 128 * 1024 * 1024

export function safeProjectName(value) {
  const name = String(value || 'SpineParticle').trim().replace(/[\\/:*?"<>|\x00-\x1f]+/g, '_').replace(/^\.+/, '')
  return name.slice(0, 100) || 'SpineParticle'
}

function safeImagePath(value) {
  const raw = String(value || '').replace(/\\/g, '/')
  if (!raw || raw.startsWith('/') || raw.includes('\0')) throw new Error('图片路径无效')
  const path = normalize(raw)
  if (path === '..' || path.startsWith(`..${sep}`)) throw new Error('图片路径不能超出 images 目录')
  return path
}

function safeImagesDirectory(value) {
  const raw = String(value || './images/').replace(/\\/g, '/').replace(/^\.\//, '').replace(/\/$/, '') || 'images'
  if (raw.startsWith('/') || /^[a-z]+:/i.test(raw)) throw new Error('Spine 图片路径必须是工程内的相对路径')
  return safeImagePath(raw)
}

function decodeBase64(value) {
  if (typeof value !== 'string' || !/^[A-Za-z0-9+/]*={0,2}$/.test(value)) throw new Error('图片数据格式无效')
  const data = Buffer.from(value, 'base64')
  if (data.length > MAX_IMAGE_BYTES) throw new Error('单张图片不能超过 32MB')
  return data
}

export async function createConversionWorkspace(payload) {
  if (!payload || payload.schemaVersion !== 1) throw new Error('不支持的连接器请求格式')
  if (typeof payload.skeletonJson !== 'string' || Buffer.byteLength(payload.skeletonJson) > MAX_JSON_BYTES) throw new Error('Spine JSON 缺失或超过 64MB')
  let skeleton
  try { skeleton = JSON.parse(payload.skeletonJson) } catch { throw new Error('Spine JSON 格式无效') }
  const jsonVersion = String(skeleton?.skeleton?.spine || '')
  const spineVersion = /^(3\.8|4\.[0-3])(?:\.\d+)?$/.exec(jsonVersion)?.[1]
  if (!spineVersion) throw new Error(`JSON 中的 Spine 版本不受支持：${jsonVersion || '未知'}`)
  const requestedVersion = String(payload.spineVersion || spineVersion)
  if (requestedVersion !== spineVersion) throw new Error(`请求版本 ${requestedVersion} 与 JSON 版本 ${jsonVersion} 不一致`)
  const imagesDirectory = safeImagesDirectory(skeleton?.skeleton?.images)

  const root = await mkdtemp(join(tmpdir(), 'spine-particle-'))
  try {
    const projectName = safeProjectName(payload.projectName)
    const inputPath = join(root, `${projectName}.json`)
    const outputPath = join(root, `${projectName}.spine`)
    const importJson = spineVersion === '3.8'
      ? prepareSpine38SkeletonJson(skeleton, imagesDirectory)
      : payload.skeletonJson
    await mkdir(join(root, imagesDirectory), { recursive: true })
    await writeFile(inputPath, importJson, 'utf8')
    let total = 0
    const archiveImages = []
    for (const image of Array.isArray(payload.images) ? payload.images : []) {
      const data = decodeBase64(image?.dataBase64)
      total += data.length
      if (total > MAX_TOTAL_IMAGE_BYTES) throw new Error('图片总大小不能超过 128MB')
      const relativeImagePath = safeImagePath(image?.path)
      const target = join(root, imagesDirectory, relativeImagePath)
      await mkdir(dirname(target), { recursive: true })
      await writeFile(target, data)
      archiveImages.push({ name: `${imagesDirectory.replace(/\\/g, '/')}/${relativeImagePath.replace(/\\/g, '/')}`, data })
    }
    return {
      root,
      projectName,
      spineVersion,
      archiveImages,
      inputPath,
      outputPath,
      readOutput: () => readFile(outputPath),
      cleanup: () => rm(root, { recursive: true, force: true }),
    }
  } catch (error) {
    await rm(root, { recursive: true, force: true })
    throw error
  }
}