lightsaver/local_packages/from.js

import {
  realpathSync,
  statSync,
  rmdirSync,
  createReadStream,
  promises as fs
} from 'node:fs'
import { basename, sep, join } from 'node:path'
import { tmpdir } from 'node:os'
import process from 'node:process'

import { File } from './file.js'
import { Blob } from './index.js'

const { stat, mkdtemp } = fs
let i = 0, tempDir, registry



/**
 * @param {string} path filepath on the disk
 * @param {string} [type] mimetype to use
 */
const blobFromSync = (path, type) => fromBlob(statSync(path), path, type)

/**
 * @param {string} path filepath on the disk
 * @param {string} [type] mimetype to use
 * @returns {Promise<Blob>}
 */
const blobFrom = (path, type) => stat(path).then(stat => fromBlob(stat, path, type))

/**
 * @param {string} path filepath on the disk
 * @param {string} [type] mimetype to use
 * @returns {Promise<File>}
 */
const fileFrom = (path, type) => stat(path).then(stat => fromFile(stat, path, type))

/**
 * @param {string} path filepath on the disk
 * @param {string} [type] mimetype to use
 */
const fileFromSync = (path, type) => fromFile(statSync(path), path, type)

// @ts-ignore
const fromBlob = (stat, path, type = '') => new Blob([new BlobDataItem({
  path,
  size: stat.size,
  lastModified: stat.mtimeMs,
  start: 0
})], { type })

// @ts-ignore
const fromFile = (stat, path, type = '') => new File([new BlobDataItem({
  path,
  size: stat.size,
  lastModified: stat.mtimeMs,
  start: 0
})], basename(path), { type, lastModified: stat.mtimeMs })

/**
 * Creates a temporary blob backed by the filesystem.
 * NOTE: requires node.js v14 or higher to use FinalizationRegistry
 *
 * @param {*} data Same as fs.writeFile data
 * @param {BlobPropertyBag & {signal?: AbortSignal}} options
 * @param {AbortSignal} [signal] in case you wish to cancel the write operation
 * @returns {Promise<Blob>}
 */
const createTemporaryBlob = async (data, {signal, type} = {}) => {
  registry = registry || new FinalizationRegistry(fs.unlink)
  tempDir = tempDir || await mkdtemp(realpathSync(tmpdir()) + sep)
  const id = `${i++}`
  const destination = join(tempDir, id)
  if (data instanceof ArrayBuffer) data = new Uint8Array(data)
  await fs.writeFile(destination, data, { signal })
  const blob = await blobFrom(destination, type)
  registry.register(blob, destination)
  return blob
}

/**
 * Creates a temporary File backed by the filesystem.
 * Pretty much the same as constructing a new File(data, name, options)
 *
 * NOTE: requires node.js v14 or higher to use FinalizationRegistry
 * @param {*} data
 * @param {string} name
 * @param {FilePropertyBag & {signal?: AbortSignal}} opts
 * @returns {Promise<File>}
 */
const createTemporaryFile = async (data, name, opts) => {
  const blob = await createTemporaryBlob(data)
  return new File([blob], name, opts)
}

/**
 * This is a blob backed up by a file on the disk
 * with minium requirement. Its wrapped around a Blob as a blobPart
 * so you have no direct access to this.
 *
 * @private
 */
class BlobDataItem {
  #path
  #start

  constructor (options) {
    this.#path = options.path
    this.#start = options.start
    this.size = options.size
    this.lastModified = options.lastModified
    this.originalSize = options.originalSize === undefined
      ? options.size
      : options.originalSize
  }

  /**
   * Slicing arguments is first validated and formatted
   * to not be out of range by Blob.prototype.slice
   */
  slice (start, end) {
    return new BlobDataItem({
      path: this.#path,
      lastModified: this.lastModified,
      originalSize: this.originalSize,
      size: end - start,
      start: this.#start + start
    })
  }

  async * stream () {
    const { mtimeMs, size } = await stat(this.#path)

    if (mtimeMs > this.lastModified || this.originalSize !== size) {
      throw new DOMException('The requested file could not be read, typically due to permission problems that have occurred after a reference to a file was acquired.', 'NotReadableError')
    }

    yield * createReadStream(this.#path, {
      start: this.#start,
      end: this.#start + this.size - 1
    })
  }

  get [Symbol.toStringTag] () {
    return 'Blob'
  }
}

process.once('exit', () => {
  tempDir && rmdirSync(tempDir, { recursive: true })
})

export default blobFromSync
export {
  Blob,
  blobFrom,
  blobFromSync,
  createTemporaryBlob,
  File,
  fileFrom,
  fileFromSync,
  createTemporaryFile
}