Add 'activestorage/' from commit '3f4a7218a4a4923a0e7ce1b2eb0d2888ce30da58'

git-subtree-dir: activestorage
git-subtree-mainline: 0d58e7e478e79c2d6b2a39a4444d2a17a903b2a6
git-subtree-split: 3f4a7218a4a4923a0e7ce1b2eb0d2888ce30da58

21 files changed, 983 insertions, 0 deletions

diff --git a/activestorage/app/assets/javascripts/activestorage.js b/activestorage/app/assets/javascripts/activestorage.js
new file mode 100644
index 0000000000..33dc5cdc58
--- /dev/null
+++ b/activestorage/app/assets/javascripts/activestorage.js
@@ -0,0 +1 @@
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t.buff=f(t.buff,!0),d.prototype.setState.call(this,t)},d.ArrayBuffer.prototype.destroy=d.prototype.destroy,d.ArrayBuffer.prototype._finish=d.prototype._finish,d.ArrayBuffer.hash=function(t,e){var r=a(new Uint8Array(t)),n=o(r);return e?l(n):n},d})},function(t,e,r){"use strict";function n(t,e){if(!(t instanceof e))throw new TypeError("Cannot call a class as a function")}r.d(e,"a",function(){return u});var i=r(0),a=function(){function t(t,e){for(var r=0;r<e.length;r++){var n=e[r];n.enumerable=n.enumerable||!1,n.configurable=!0,"value"in n&&(n.writable=!0),Object.defineProperty(t,n.key,n)}}return function(e,r,n){return r&&t(e.prototype,r),n&&t(e,n),e}}(),u=function(){function t(e,r,a){var u=this;n(this,t),this.file=e,this.attributes={filename:e.name,content_type:e.type,byte_size:e.size,checksum:r},this.xhr=new XMLHttpRequest,this.xhr.open("POST",a,!0),this.xhr.responseType="json",this.xhr.setRequestHeader("Content-Type","application/json"),this.xhr.setRequestHeader("Accept","application/json"),this.xhr.setRequestHeader("X-Requested-With","XMLHttpRequest"),this.xhr.setRequestHeader("X-CSRF-Token",Object(i.d)("csrf-token")),this.xhr.addEventListener("load",function(t){return u.requestDidLoad(t)}),this.xhr.addEventListener("error",function(t){return u.requestDidError(t)})}return a(t,[{key:"create",value:function(t){this.callback=t,this.xhr.send(JSON.stringify({blob:this.attributes}))}},{key:"requestDidLoad",value:function(t){var e=this.xhr,r=e.status,n=e.response;if(r>=200&&r<300){var i=n.direct_upload;delete n.direct_upload,this.attributes=n,this.directUploadData=i,this.callback(null,this.toJSON())}else this.requestDidError(t)}},{key:"requestDidError",value:function(t){this.callback('Error creating Blob for "'+this.file.name+'". Status: '+this.xhr.status)}},{key:"toJSON",value:function(){var t={};for(var e in this.attributes)t[e]=this.attributes[e];return t}}]),t}()},function(t,e,r){"use strict";function n(t,e){if(!(t instanceof e))throw new TypeError("Cannot call a class as a function")}r.d(e,"a",function(){return a});var i=function(){function t(t,e){for(var r=0;r<e.length;r++){var n=e[r];n.enumerable=n.enumerable||!1,n.configurable=!0,"value"in n&&(n.writable=!0),Object.defineProperty(t,n.key,n)}}return function(e,r,n){return r&&t(e.prototype,r),n&&t(e,n),e}}(),a=function(){function t(e){var r=this;n(this,t),this.blob=e,this.file=e.file;var i=e.directUploadData,a=i.url,u=i.headers;this.xhr=new XMLHttpRequest,this.xhr.open("PUT",a,!0);for(var o in u)this.xhr.setRequestHeader(o,u[o]);this.xhr.addEventListener("load",function(t){return r.requestDidLoad(t)}),this.xhr.addEventListener("error",function(t){return r.requestDidError(t)})}return i(t,[{key:"create",value:function(t){this.callback=t,this.xhr.send(this.file)}},{key:"requestDidLoad",value:function(t){var e=this.xhr,r=e.status,n=e.response;r>=200&&r<300?this.callback(null,n):this.requestDidError(t)}},{key:"requestDidError",value:function(t){this.callback('Error storing "'+this.file.name+'". Status: '+this.xhr.status)}}]),t}()}])});
\ No newline at end of file
diff --git a/activestorage/app/controllers/active_storage/blobs_controller.rb b/activestorage/app/controllers/active_storage/blobs_controller.rb
new file mode 100644
index 0000000000..05af29f8b2
--- /dev/null
+++ b/activestorage/app/controllers/active_storage/blobs_controller.rb
@@ -0,0 +1,22 @@
+# Take a signed permanent reference for a blob and turn it into an expiring service URL for download.
+# Note: These URLs are publicly accessible. If you need to enforce access protection beyond the
+# security-through-obscurity factor of the signed blob references, you'll need to implement your own
+# authenticated redirection controller.
+class ActiveStorage::BlobsController < ActionController::Base
+  def show
+    if blob = find_signed_blob
+      redirect_to blob.service_url(disposition: disposition_param)
+    else
+      head :not_found
+    end
+  end
+
+  private
+    def find_signed_blob
+      ActiveStorage::Blob.find_signed(params[:signed_id])
+    end
+
+    def disposition_param
+      params[:disposition].presence_in(%w( inline attachment )) || "inline"
+    end
+end
diff --git a/activestorage/app/controllers/active_storage/direct_uploads_controller.rb b/activestorage/app/controllers/active_storage/direct_uploads_controller.rb
new file mode 100644
index 0000000000..0d93985897
--- /dev/null
+++ b/activestorage/app/controllers/active_storage/direct_uploads_controller.rb
@@ -0,0 +1,21 @@
+# Creates a new blob on the server side in anticipation of a direct-to-service upload from the client side.
+# When the client-side upload is completed, the signed_blob_id can be submitted as part of the form to reference
+# the blob that was created up front.
+class ActiveStorage::DirectUploadsController < ActionController::Base
+  def create
+    blob = ActiveStorage::Blob.create_before_direct_upload!(blob_args)
+    render json: direct_upload_json(blob)
+  end
+
+  private
+    def blob_args
+      params.require(:blob).permit(:filename, :byte_size, :checksum, :content_type, :metadata).to_h.symbolize_keys
+    end
+
+    def direct_upload_json(blob)
+      blob.as_json(methods: :signed_id).merge(direct_upload: {
+        url: blob.service_url_for_direct_upload,
+        headers: blob.service_headers_for_direct_upload
+      })
+    end
+end
diff --git a/activestorage/app/controllers/active_storage/disk_controller.rb b/activestorage/app/controllers/active_storage/disk_controller.rb
new file mode 100644
index 0000000000..76377a0f20
--- /dev/null
+++ b/activestorage/app/controllers/active_storage/disk_controller.rb
@@ -0,0 +1,51 @@
+# Serves files stored with the disk service in the same way that the cloud services do.
+# This means using expiring, signed URLs that are meant for immediate access, not permanent linking.
+# Always go through the BlobsController, or your own authenticated controller, rather than directly
+# to the service url.
+class ActiveStorage::DiskController < ActionController::Base
+  def show
+    if key = decode_verified_key
+      send_data disk_service.download(key),
+        filename: params[:filename], disposition: disposition_param, content_type: params[:content_type]
+    else
+      head :not_found
+    end
+  end
+
+  def update
+    if token = decode_verified_token
+      if acceptable_content?(token)
+        disk_service.upload token[:key], request.body, checksum: token[:checksum]
+      else
+        head :unprocessable_entity
+      end
+    else
+      head :not_found
+    end
+  rescue ActiveStorage::IntegrityError
+    head :unprocessable_entity
+  end
+
+  private
+    def disk_service
+      ActiveStorage::Blob.service
+    end
+
+
+    def decode_verified_key
+      ActiveStorage.verifier.verified(params[:encoded_key], purpose: :blob_key)
+    end
+
+    def disposition_param
+      params[:disposition].presence_in(%w( inline attachment )) || "inline"
+    end
+
+
+    def decode_verified_token
+      ActiveStorage.verifier.verified(params[:encoded_token], purpose: :blob_token)
+    end
+
+    def acceptable_content?(token)
+      token[:content_type] == request.content_type && token[:content_length] == request.content_length
+    end
+end
diff --git a/activestorage/app/controllers/active_storage/variants_controller.rb b/activestorage/app/controllers/active_storage/variants_controller.rb
new file mode 100644
index 0000000000..aa38f8e928
--- /dev/null
+++ b/activestorage/app/controllers/active_storage/variants_controller.rb
@@ -0,0 +1,28 @@
+require "active_storage/variant"
+
+# Take a signed permanent reference for a variant and turn it into an expiring service URL for download.
+# Note: These URLs are publicly accessible. If you need to enforce access protection beyond the
+# security-through-obscurity factor of the signed blob and variation reference, you'll need to implement your own
+# authenticated redirection controller.
+class ActiveStorage::VariantsController < ActionController::Base
+  def show
+    if blob = find_signed_blob
+      redirect_to ActiveStorage::Variant.new(blob, decoded_variation).processed.service_url(disposition: disposition_param)
+    else
+      head :not_found
+    end
+  end
+
+  private
+    def find_signed_blob
+      ActiveStorage::Blob.find_signed(params[:signed_blob_id])
+    end
+
+    def decoded_variation
+      ActiveStorage::Variation.decode(params[:variation_key])
+    end
+
+    def disposition_param
+      params[:disposition].presence_in(%w( inline attachment )) || "inline"
+    end
+end
diff --git a/activestorage/app/helpers/active_storage/file_field_with_direct_upload_helper.rb b/activestorage/app/helpers/active_storage/file_field_with_direct_upload_helper.rb
new file mode 100644
index 0000000000..7c5fd0eb55
--- /dev/null
+++ b/activestorage/app/helpers/active_storage/file_field_with_direct_upload_helper.rb
@@ -0,0 +1,18 @@
+module ActiveStorage
+  # Temporary hack to overwrite the default file_field_tag and Form#file_field to accept a direct_upload: true option
+  # that then gets replaced with a data-direct-upload-url attribute with the route prefilled.
+  module FileFieldWithDirectUploadHelper
+    def file_field_tag(name, options = {})
+      text_field_tag(name, nil, convert_direct_upload_option_to_url(options.merge(type: :file)))
+    end
+
+    def file_field(object_name, method, options = {})
+      ActionView::Helpers::Tags::FileField.new(object_name, method, self, convert_direct_upload_option_to_url(options)).render
+    end
+
+    private
+      def convert_direct_upload_option_to_url(options)
+        options.merge('data-direct-upload-url': options.delete(:direct_upload) ? rails_direct_uploads_url : nil).compact
+      end
+  end
+end
diff --git a/activestorage/app/javascript/activestorage/blob_record.js b/activestorage/app/javascript/activestorage/blob_record.js
new file mode 100644
index 0000000000..3c6e6b6ba1
--- /dev/null
+++ b/activestorage/app/javascript/activestorage/blob_record.js
@@ -0,0 +1,54 @@
+import { getMetaValue } from "./helpers"
+
+export class BlobRecord {
+  constructor(file, checksum, url) {
+    this.file = file
+
+    this.attributes = {
+      filename: file.name,
+      content_type: file.type,
+      byte_size: file.size,
+      checksum: checksum
+    }
+
+    this.xhr = new XMLHttpRequest
+    this.xhr.open("POST", url, true)
+    this.xhr.responseType = "json"
+    this.xhr.setRequestHeader("Content-Type", "application/json")
+    this.xhr.setRequestHeader("Accept", "application/json")
+    this.xhr.setRequestHeader("X-Requested-With", "XMLHttpRequest")
+    this.xhr.setRequestHeader("X-CSRF-Token", getMetaValue("csrf-token"))
+    this.xhr.addEventListener("load", event => this.requestDidLoad(event))
+    this.xhr.addEventListener("error", event => this.requestDidError(event))
+  }
+
+  create(callback) {
+    this.callback = callback
+    this.xhr.send(JSON.stringify({ blob: this.attributes }))
+  }
+
+  requestDidLoad(event) {
+    const { status, response } = this.xhr
+    if (status >= 200 && status < 300) {
+      const { direct_upload } = response
+      delete response.direct_upload
+      this.attributes = response
+      this.directUploadData = direct_upload
+      this.callback(null, this.toJSON())
+    } else {
+      this.requestDidError(event)
+    }
+  }
+
+  requestDidError(event) {
+    this.callback(`Error creating Blob for "${this.file.name}". Status: ${this.xhr.status}`)
+  }
+
+  toJSON() {
+    const result = {}
+    for (const key in this.attributes) {
+      result[key] = this.attributes[key]
+    }
+    return result
+  }
+}
diff --git a/activestorage/app/javascript/activestorage/blob_upload.js b/activestorage/app/javascript/activestorage/blob_upload.js
new file mode 100644
index 0000000000..99bf0c9e30
--- /dev/null
+++ b/activestorage/app/javascript/activestorage/blob_upload.js
@@ -0,0 +1,34 @@
+export class BlobUpload {
+  constructor(blob) {
+    this.blob = blob
+    this.file = blob.file
+
+    const { url, headers } = blob.directUploadData
+
+    this.xhr = new XMLHttpRequest
+    this.xhr.open("PUT", url, true)
+    for (const key in headers) {
+      this.xhr.setRequestHeader(key, headers[key])
+    }
+    this.xhr.addEventListener("load", event => this.requestDidLoad(event))
+    this.xhr.addEventListener("error", event => this.requestDidError(event))
+  }
+
+  create(callback) {
+    this.callback = callback
+    this.xhr.send(this.file)
+  }
+
+  requestDidLoad(event) {
+    const { status, response } = this.xhr
+    if (status >= 200 && status < 300) {
+      this.callback(null, response)
+    } else {
+      this.requestDidError(event)
+    }
+  }
+
+  requestDidError(event) {
+    this.callback(`Error storing "${this.file.name}". Status: ${this.xhr.status}`)
+  }
+}
diff --git a/activestorage/app/javascript/activestorage/direct_upload.js b/activestorage/app/javascript/activestorage/direct_upload.js
new file mode 100644
index 0000000000..7085e0a4ab
--- /dev/null
+++ b/activestorage/app/javascript/activestorage/direct_upload.js
@@ -0,0 +1,42 @@
+import { FileChecksum } from "./file_checksum"
+import { BlobRecord } from "./blob_record"
+import { BlobUpload } from "./blob_upload"
+
+let id = 0
+
+export class DirectUpload {
+  constructor(file, url, delegate) {
+    this.id = ++id
+    this.file = file
+    this.url = url
+    this.delegate = delegate
+  }
+
+  create(callback) {
+    FileChecksum.create(this.file, (error, checksum) => {
+      const blob = new BlobRecord(this.file, checksum, this.url)
+      notify(this.delegate, "directUploadWillCreateBlobWithXHR", blob.xhr)
+      blob.create(error => {
+        if (error) {
+          callback(error)
+        } else {
+          const upload = new BlobUpload(blob)
+          notify(this.delegate, "directUploadWillStoreFileWithXHR", upload.xhr)
+          upload.create(error => {
+            if (error) {
+              callback(error)
+            } else {
+              callback(null, blob.toJSON())
+            }
+          })
+        }
+      })
+    })
+  }
+}
+
+function notify(object, methodName, ...messages) {
+  if (object && typeof object[methodName] == "function") {
+    return object[methodName](...messages)
+  }
+}
diff --git a/activestorage/app/javascript/activestorage/direct_upload_controller.js b/activestorage/app/javascript/activestorage/direct_upload_controller.js
new file mode 100644
index 0000000000..987050889a
--- /dev/null
+++ b/activestorage/app/javascript/activestorage/direct_upload_controller.js
@@ -0,0 +1,67 @@
+import { DirectUpload } from "./direct_upload"
+import { dispatchEvent } from "./helpers"
+
+export class DirectUploadController {
+  constructor(input, file) {
+    this.input = input
+    this.file = file
+    this.directUpload = new DirectUpload(this.file, this.url, this)
+    this.dispatch("initialize")
+  }
+
+  start(callback) {
+    const hiddenInput = document.createElement("input")
+    hiddenInput.type = "hidden"
+    hiddenInput.name = this.input.name
+    this.input.insertAdjacentElement("beforebegin", hiddenInput)
+
+    this.dispatch("start")
+
+    this.directUpload.create((error, attributes) => {
+      if (error) {
+        hiddenInput.parentNode.removeChild(hiddenInput)
+        this.dispatchError(error)
+      } else {
+        hiddenInput.value = attributes.signed_id
+      }
+
+      this.dispatch("end")
+      callback(error)
+    })
+  }
+
+  uploadRequestDidProgress(event) {
+    const progress = event.loaded / event.total * 100
+    if (progress) {
+      this.dispatch("progress", { progress })
+    }
+  }
+
+  get url() {
+    return this.input.getAttribute("data-direct-upload-url")
+  }
+
+  dispatch(name, detail = {}) {
+    detail.file = this.file
+    detail.id = this.directUpload.id
+    return dispatchEvent(this.input, `direct-upload:${name}`, { detail })
+  }
+
+  dispatchError(error) {
+    const event = this.dispatch("error", { error })
+    if (!event.defaultPrevented) {
+      alert(error)
+    }
+  }
+
+  // DirectUpload delegate
+
+  directUploadWillCreateBlobWithXHR(xhr) {
+    this.dispatch("before-blob-request", { xhr })
+  }
+
+  directUploadWillStoreFileWithXHR(xhr) {
+    this.dispatch("before-storage-request", { xhr })
+    xhr.upload.addEventListener("progress", event => this.uploadRequestDidProgress(event))
+  }
+}
diff --git a/activestorage/app/javascript/activestorage/direct_uploads_controller.js b/activestorage/app/javascript/activestorage/direct_uploads_controller.js
new file mode 100644
index 0000000000..94b89c9119
--- /dev/null
+++ b/activestorage/app/javascript/activestorage/direct_uploads_controller.js
@@ -0,0 +1,50 @@
+import { DirectUploadController } from "./direct_upload_controller"
+import { findElements, dispatchEvent, toArray } from "./helpers"
+
+const inputSelector = "input[type=file][data-direct-upload-url]:not([disabled])"
+
+export class DirectUploadsController {
+  constructor(form) {
+    this.form = form
+    this.inputs = findElements(form, inputSelector).filter(input => input.files.length)
+  }
+
+  start(callback) {
+    const controllers = this.createDirectUploadControllers()
+
+    const startNextController = () => {
+      const controller = controllers.shift()
+      if (controller) {
+        controller.start(error => {
+          if (error) {
+            callback(error)
+            this.dispatch("end")
+          } else {
+            startNextController()
+          }
+        })
+      } else {
+        callback()
+        this.dispatch("end")
+      }
+    }
+
+    this.dispatch("start")
+    startNextController()
+  }
+
+  createDirectUploadControllers() {
+    const controllers = []
+    this.inputs.forEach(input => {
+      toArray(input.files).forEach(file => {
+        const controller = new DirectUploadController(input, file)
+        controllers.push(controller)
+      })
+    })
+    return controllers
+  }
+
+  dispatch(name, detail = {}) {
+    return dispatchEvent(this.form, `direct-uploads:${name}`, { detail })
+  }
+}
diff --git a/activestorage/app/javascript/activestorage/file_checksum.js b/activestorage/app/javascript/activestorage/file_checksum.js
new file mode 100644
index 0000000000..ffaec1a128
--- /dev/null
+++ b/activestorage/app/javascript/activestorage/file_checksum.js
@@ -0,0 +1,53 @@
+import SparkMD5 from "spark-md5"
+
+const fileSlice = File.prototype.slice || File.prototype.mozSlice || File.prototype.webkitSlice
+
+export class FileChecksum {
+  static create(file, callback) {
+    const instance = new FileChecksum(file)
+    instance.create(callback)
+  }
+
+  constructor(file) {
+    this.file = file
+    this.chunkSize = 2097152 // 2MB
+    this.chunkCount = Math.ceil(this.file.size / this.chunkSize)
+    this.chunkIndex = 0
+  }
+
+  create(callback) {
+    this.callback = callback
+    this.md5Buffer = new SparkMD5.ArrayBuffer
+    this.fileReader = new FileReader
+    this.fileReader.addEventListener("load", event => this.fileReaderDidLoad(event))
+    this.fileReader.addEventListener("error", event => this.fileReaderDidError(event))
+    this.readNextChunk()
+  }
+
+  fileReaderDidLoad(event) {
+    this.md5Buffer.append(event.target.result)
+
+    if (!this.readNextChunk()) {
+      const binaryDigest = this.md5Buffer.end(true)
+      const base64digest = btoa(binaryDigest)
+      this.callback(null, base64digest)
+    }
+  }
+
+  fileReaderDidError(event) {
+    this.callback(`Error reading ${this.file.name}`)
+  }
+
+  readNextChunk() {
+    if (this.chunkIndex < this.chunkCount) {
+      const start = this.chunkIndex * this.chunkSize
+      const end = Math.min(start + this.chunkSize, this.file.size)
+      const bytes = fileSlice.call(this.file, start, end)
+      this.fileReader.readAsArrayBuffer(bytes)
+      this.chunkIndex++
+      return true
+    } else {
+      return false
+    }
+  }
+}
diff --git a/activestorage/app/javascript/activestorage/helpers.js b/activestorage/app/javascript/activestorage/helpers.js
new file mode 100644
index 0000000000..52fec8f6f1
--- /dev/null
+++ b/activestorage/app/javascript/activestorage/helpers.js
@@ -0,0 +1,42 @@
+export function getMetaValue(name) {
+  const element = findElement(document.head, `meta[name="${name}"]`)
+  if (element) {
+    return element.getAttribute("content")
+  }
+}
+
+export function findElements(root, selector) {
+  if (typeof root == "string") {
+    selector = root
+    root = document
+  }
+  const elements = root.querySelectorAll(selector)
+  return toArray(elements)
+}
+
+export function findElement(root, selector) {
+  if (typeof root == "string") {
+    selector = root
+    root = document
+  }
+  return root.querySelector(selector)
+}
+
+export function dispatchEvent(element, type, eventInit = {}) {
+  const { bubbles, cancelable, detail } = eventInit
+  const event = document.createEvent("Event")
+  event.initEvent(type, bubbles || true, cancelable || true)
+  event.detail = detail || {}
+  element.dispatchEvent(event)
+  return event
+}
+
+export function toArray(value) {
+  if (Array.isArray(value)) {
+    return value
+  } else if (Array.from) {
+    return Array.from(value)
+  } else {
+    return [].slice.call(value)
+  }
+}
diff --git a/activestorage/app/javascript/activestorage/index.js b/activestorage/app/javascript/activestorage/index.js
new file mode 100644
index 0000000000..a340008fb9
--- /dev/null
+++ b/activestorage/app/javascript/activestorage/index.js
@@ -0,0 +1,11 @@
+import { start } from "./ujs"
+import { DirectUpload } from "./direct_upload"
+export { start, DirectUpload }
+
+function autostart() {
+  if (window.ActiveStorage) {
+    start()
+  }
+}
+
+setTimeout(autostart, 1)
diff --git a/activestorage/app/javascript/activestorage/ujs.js b/activestorage/app/javascript/activestorage/ujs.js
new file mode 100644
index 0000000000..a2ce2cfc58
--- /dev/null
+++ b/activestorage/app/javascript/activestorage/ujs.js
@@ -0,0 +1,74 @@
+import { DirectUploadsController } from "./direct_uploads_controller"
+import { findElement } from "./helpers"
+
+const processingAttribute = "data-direct-uploads-processing"
+let started = false
+
+export function start() {
+  if (!started) {
+    started = true
+    document.addEventListener("submit", didSubmitForm)
+    document.addEventListener("ajax:before", didSubmitRemoteElement)
+  }
+}
+
+function didSubmitForm(event) {
+  handleFormSubmissionEvent(event)
+}
+
+function didSubmitRemoteElement(event) {
+  if (event.target.tagName == "FORM") {
+    handleFormSubmissionEvent(event)
+  }
+}
+
+function handleFormSubmissionEvent(event) {
+  const form = event.target
+
+  if (form.hasAttribute(processingAttribute)) {
+    event.preventDefault()
+    return
+  }
+
+  const controller = new DirectUploadsController(form)
+  const { inputs } = controller
+
+  if (inputs.length) {
+    event.preventDefault()
+    form.setAttribute(processingAttribute, "")
+    inputs.forEach(disable)
+    controller.start(error => {
+      form.removeAttribute(processingAttribute)
+      if (error) {
+        inputs.forEach(enable)
+      } else {
+        submitForm(form)
+      }
+    })
+  }
+}
+
+function submitForm(form) {
+  let button = findElement(form, "input[type=submit]")
+  if (button) {
+    const { disabled } = button
+    button.disabled = false
+    button.click()
+    button.disabled = disabled
+  } else {
+    button = document.createElement("input")
+    button.type = "submit"
+    button.style = "display:none"
+    form.appendChild(button)
+    button.click()
+    form.removeChild(button)
+  }
+}
+
+function disable(input) {
+  input.disabled = true
+}
+
+function enable(input) {
+  input.disabled = false
+}
diff --git a/activestorage/app/jobs/active_storage/purge_job.rb b/activestorage/app/jobs/active_storage/purge_job.rb
new file mode 100644
index 0000000000..815f908e6c
--- /dev/null
+++ b/activestorage/app/jobs/active_storage/purge_job.rb
@@ -0,0 +1,9 @@
+# Provides delayed purging of attachments or blobs using their `#purge_later` method.
+class ActiveStorage::PurgeJob < ActiveJob::Base
+  # FIXME: Limit this to a custom ActiveStorage error
+  retry_on StandardError
+
+  def perform(attachment_or_blob)
+    attachment_or_blob.purge
+  end
+end
diff --git a/activestorage/app/models/active_storage/attachment.rb b/activestorage/app/models/active_storage/attachment.rb
new file mode 100644
index 0000000000..2c8b7a9cf2
--- /dev/null
+++ b/activestorage/app/models/active_storage/attachment.rb
@@ -0,0 +1,29 @@
+require "active_storage/blob"
+require "active_support/core_ext/module/delegation"
+
+# Attachments associate records with blobs. Usually that's a one record-many blobs relationship, 
+# but it is possible to associate many different records with the same blob. If you're doing that,
+# you'll want to declare with `has_one/many_attached :thingy, dependent: false`, so that destroying
+# any one record won't destroy the blob as well. (Then you'll need to do your own garbage collecting, though).
+class ActiveStorage::Attachment < ActiveRecord::Base
+  self.table_name = "active_storage_attachments"
+
+  belongs_to :record, polymorphic: true
+  belongs_to :blob, class_name: "ActiveStorage::Blob"
+
+  delegate_missing_to :blob
+
+  # Purging an attachment will purge the blob (delete the file on the service, then destroy the record)
+  # and then destroy the attachment itself.
+  def purge
+    blob.purge
+    destroy
+  end
+
+  # Purging an attachment means purging the blob, which means talking to the service, which means
+  # talking over the internet. Whenever you're doing that, it's a good idea to put that work in a job,
+  # so it doesn't hold up other operations. That's what #purge_later provides.
+  def purge_later
+    ActiveStorage::PurgeJob.perform_later(self)
+  end
+end
diff --git a/activestorage/app/models/active_storage/blob.rb b/activestorage/app/models/active_storage/blob.rb
new file mode 100644
index 0000000000..9208d36ee3
--- /dev/null
+++ b/activestorage/app/models/active_storage/blob.rb
@@ -0,0 +1,193 @@
+require "active_storage/service"
+require "active_storage/filename"
+require "active_storage/purge_job"
+require "active_storage/variant"
+require "active_storage/variation"
+
+# A blob is a record that contains the metadata about a file and a key for where that file resides on the service.
+# Blobs can be created in two ways:
+#
+# 1) Subsequent to the file being uploaded server-side to the service via #create_after_upload!
+# 2) Ahead of the file being directly uploaded client-side to the service via #create_before_direct_upload!
+#
+# The first option doesn't require any client-side JavaScript integration, and can be used by any other back-end
+# service that deals with files. The second option is faster, since you're not using your own server as a staging
+# point for uploads, and can work with deployments like Heroku that do not provide large amounts of disk space.
+#
+# Blobs are intended to be immutable in as-so-far as their reference to a specific file goes. You're allowed to
+# update a blob's metadata on a subsequent pass, but you should not update the key or change the uploaded file.
+# If you need to create a derivative or otherwise change the blob, simply create a new blob and purge the old.
+class ActiveStorage::Blob < ActiveRecord::Base
+  self.table_name = "active_storage_blobs"
+
+  has_secure_token :key
+  store :metadata, coder: JSON
+
+  class_attribute :service
+
+  class << self
+    # You can used the signed id of a blob to refer to it on the client side without fear of tampering.
+    # This is particularly helpful for direct uploads where the client side needs to refer to the blob
+    # that was created ahead of the upload itself on form submission.
+    #
+    # The signed id is also used to create stable URLs for the blob through the BlobsController.
+    def find_signed(id)
+      find ActiveStorage.verifier.verify(id, purpose: :blob_id)
+    end
+
+    # Returns a new, unsaved blob instance after the `io` has been uploaded to the service.
+    def build_after_upload(io:, filename:, content_type: nil, metadata: nil)
+      new.tap do |blob|
+        blob.filename     = filename
+        blob.content_type = content_type
+        blob.metadata     = metadata
+
+        blob.upload io
+      end
+    end
+
+    # Returns a saved blob instance after the `io` has been uploaded to the service. Note, the blob is first built,
+    # then the `io` is uploaded, then the blob is saved. This is doing to avoid opening a transaction and talking to
+    # the service during that (which is a bad idea and leads to deadlocks).
+    def create_after_upload!(io:, filename:, content_type: nil, metadata: nil)
+      build_after_upload(io: io, filename: filename, content_type: content_type, metadata: metadata).tap(&:save!)
+    end
+
+    # Returns a saved blob _without_ uploading a file to the service. This blob will point to a key where there is
+    # no file yet. It's intended to be used together with a client-side upload, which will first create the blob
+    # in order to produce the signed URL for uploading. This signed URL points to the key generated by the blob.
+    # Once the form using the direct upload is submitted, the blob can be associated with the right record using
+    # the signed ID.
+    def create_before_direct_upload!(filename:, byte_size:, checksum:, content_type: nil, metadata: nil)
+      create! filename: filename, byte_size: byte_size, checksum: checksum, content_type: content_type, metadata: metadata
+    end
+  end
+
+
+  # Returns a signed ID for this blob that's suitable for reference on the client-side without fear of tampering.
+  # It uses the framework-wide verifier on `ActiveStorage.verifier`, but with a dedicated purpose.
+  def signed_id
+    ActiveStorage.verifier.generate(id, purpose: :blob_id)
+  end
+
+  # Returns the key pointing to the file on the service that's associated with this blob. The key is in the
+  # standard secure-token format from Rails. So it'll look like: XTAPjJCJiuDrLk3TmwyJGpUo. This key is not intended
+  # to be revealed directly to the user. Always refer to blobs using the signed_id or a verified form of the key.
+  def key
+    # We can't wait until the record is first saved to have a key for it
+    self[:key] ||= self.class.generate_unique_secure_token
+  end
+
+  # Returns a `ActiveStorage::Filename` instance of the filename that can be queried for basename, extension, and
+  # a sanitized version of the filename that's safe to use in URLs.
+  def filename
+    ActiveStorage::Filename.new(self[:filename])
+  end
+
+  # Returns true if the content_type of this blob is in the image range, like image/png.
+  def image?() content_type =~ /^image/ end
+
+  # Returns true if the content_type of this blob is in the audio range, like audio/mpeg.
+  def audio?() content_type =~ /^audio/ end
+
+  # Returns true if the content_type of this blob is in the video range, like video/mp4.
+  def video?() content_type =~ /^video/ end
+
+  # Returns true if the content_type of this blob is in the text range, like text/plain.
+  def text?()  content_type =~ /^text/  end
+
+  # Returns a `ActiveStorage::Variant` instance with the set of `transformations` passed in. This is only relevant
+  # for image files, and it allows any image to be transformed for size, colors, and the like. Example:
+  #
+  #   avatar.variant(resize: "100x100").processed.service_url
+  #
+  # This will create and process a variant of the avatar blob that's constrained to a height and width of 100.
+  # Then it'll upload said variant to the service according to a derivative key of the blob and the transformations.
+  #
+  # Frequently, though, you don't actually want to transform the variant right away. But rather simply refer to a
+  # specific variant that can be created by a controller on-demand. Like so:
+  #
+  #   <%= image_tag url_for(Current.user.avatar.variant(resize: "100x100")) %>
+  #
+  # This will create a URL for that specific blob with that specific variant, which the `ActiveStorage::VariantsController`
+  # can then produce on-demand.
+  def variant(transformations)
+    ActiveStorage::Variant.new(self, ActiveStorage::Variation.new(transformations))
+  end
+
+
+  # Returns the URL of the blob on the service. This URL is intended to be short-lived for security and not used directly
+  # with users. Instead, the `service_url` should only be exposed as a redirect from a stable, possibly authenticated URL.
+  # Hiding the `service_url` behind a redirect also gives you the power to change services without updating all URLs. And
+  # it allows permanent URLs that redirect to the `service_url` to be cached in the view.
+  def service_url(expires_in: 5.minutes, disposition: :inline)
+    service.url key, expires_in: expires_in, disposition: disposition, filename: filename, content_type: content_type
+  end
+
+  # Returns a URL that can be used to directly upload a file for this blob on the service. This URL is intended to be
+  # short-lived for security and only generated on-demand by the client-side JavaScript responsible for doing the uploading.
+  def service_url_for_direct_upload(expires_in: 5.minutes)
+    service.url_for_direct_upload key, expires_in: expires_in, content_type: content_type, content_length: byte_size, checksum: checksum
+  end
+
+  # Returns a Hash of headers for `service_url_for_direct_upload` requests.
+  def service_headers_for_direct_upload
+    service.headers_for_direct_upload key, filename: filename, content_type: content_type, content_length: byte_size, checksum: checksum
+  end
+
+  # Uploads the `io` to the service on the `key` for this blob. Blobs are intended to be immutable, so you shouldn't be
+  # using this method after a file has already been uploaded to fit with a blob. If you want to create a derivative blob,
+  # you should instead simply create a new blob based on the old one.
+  #
+  # Prior to uploading, we compute the checksum, which is sent to the service for transit integrity validation. If the
+  # checksum does not match what the service receives, an exception will be raised. We also measure the size of the `io`
+  # and store that in `byte_size` on the blob record.
+  #
+  # Normally, you do not have to call this method directly at all. Use the factory class methods of `build_after_upload`
+  # and `create_after_upload!`.
+  def upload(io)
+    self.checksum  = compute_checksum_in_chunks(io)
+    self.byte_size = io.size
+
+    service.upload(key, io, checksum: checksum)
+  end
+
+  # Downloads the file associated with this blob. If no block is given, the entire file is read into memory and returned.
+  # That'll use a lot of RAM for very large files. If a block is given, then the download is streamed and yielded in chunks.
+  def download(&block)
+    service.download key, &block
+  end
+
+
+  # Deletes the file on the service that's associated with this blob. This should only be done if the blob is going to be
+  # deleted as well or you will essentially have a dead reference. It's recommended to use the `#purge` and `#purge_later`
+  # methods in most circumstances.
+  def delete
+    service.delete key
+  end
+
+  # Deletes the file on the service and then destroys the blob record. This is the recommended way to dispose of unwanted
+  # blobs. Note, though, that deleting the file off the service will initiate a HTTP connection to the service, which may
+  # be slow or prevented, so you should not use this method inside a transaction or in callbacks. Use `#purge_later` instead.
+  def purge
+    delete
+    destroy
+  end
+
+  # Enqueues a `ActiveStorage::PurgeJob` job that'll call `#purge`. This is the recommended way to purge blobs when the call
+  # needs to be made from a transaction, a callback, or any other real-time scenario.
+  def purge_later
+    ActiveStorage::PurgeJob.perform_later(self)
+  end
+
+  private
+    def compute_checksum_in_chunks(io)
+      Digest::MD5.new.tap do |checksum|
+        while chunk = io.read(5.megabytes)
+          checksum << chunk
+        end
+
+        io.rewind
+      end.base64digest
+    end
+end
diff --git a/activestorage/app/models/active_storage/filename.rb b/activestorage/app/models/active_storage/filename.rb
new file mode 100644
index 0000000000..35f4a8ac59
--- /dev/null
+++ b/activestorage/app/models/active_storage/filename.rb
@@ -0,0 +1,49 @@
+# Encapsulates a string representing a filename to provide convenience access to parts of it and a sanitized version.
+# This is what's returned by `ActiveStorage::Blob#filename`. A Filename instance is comparable so it can be used for sorting.
+class ActiveStorage::Filename
+  include Comparable
+
+  def initialize(filename)
+    @filename = filename
+  end
+
+  # Filename.new("racecar.jpg").extname # => ".jpg"
+  def extname
+    File.extname(@filename)
+  end
+
+  # Filename.new("racecar.jpg").extension # => "jpg"
+  def extension
+    extname.from(1)
+  end
+
+  # Filename.new("racecar.jpg").base # => "racecar"
+  def base
+    File.basename(@filename, extname)
+  end
+
+  # Filename.new("foo:bar.jpg").sanitized # => "foo-bar.jpg"
+  # Filename.new("foo/bar.jpg").sanitized # => "foo-bar.jpg"
+  #
+  # ...and any other character unsafe for URLs or storage is converted or stripped.
+  def sanitized
+    @filename.encode(Encoding::UTF_8, invalid: :replace, undef: :replace, replace: "�").strip.tr("\u{202E}%$|:;/\t\r\n\\", "-")
+  end
+
+  # Returns the sanitized version of the filename.
+  def to_s
+    sanitized.to_s
+  end
+
+  def as_json(*)
+    to_s
+  end
+
+  def to_json
+    to_s
+  end
+
+  def <=>(other)
+    to_s.downcase <=> other.to_s.downcase
+  end
+end
diff --git a/activestorage/app/models/active_storage/variant.rb b/activestorage/app/models/active_storage/variant.rb
new file mode 100644
index 0000000000..a8e64f781e
--- /dev/null
+++ b/activestorage/app/models/active_storage/variant.rb
@@ -0,0 +1,82 @@
+require "active_storage/blob"
+
+# Image blobs can have variants that are the result of a set of transformations applied to the original.
+# These variants are used to create thumbnails, fixed-size avatars, or any other derivative image from the
+# original.
+#
+# Variants rely on `MiniMagick` for the actual transformations of the file, so you must add `gem "mini_magick"`
+# to your Gemfile if you wish to use variants.
+#
+# Note that to create a variant it's necessary to download the entire blob file from the service and load it
+# into memory. The larger the image, the more memory is used. Because of this process, you also want to be
+# considerate about when the variant is actually processed. You shouldn't be processing variants inline in a
+# template, for example. Delay the processing to an on-demand controller, like the one provided in
+# `ActiveStorage::VariantsController`.
+#
+# To refer to such a delayed on-demand variant, simply link to the variant through the resolved route provided
+# by Active Storage like so:
+#
+#   <%= image_tag url_for(Current.user.avatar.variant(resize: "100x100")) %>
+#
+# This will create a URL for that specific blob with that specific variant, which the `ActiveStorage::VariantsController`
+# can then produce on-demand.
+#
+# When you do want to actually produce the variant needed, call `#processed`. This will check that the variant
+# has already been processed and uploaded to the service, and, if so, just return that. Otherwise it will perform
+# the transformations, upload the variant to the service, and return itself again. Example:
+#
+#   avatar.variant(resize: "100x100").processed.service_url
+#
+# This will create and process a variant of the avatar blob that's constrained to a height and width of 100.
+# Then it'll upload said variant to the service according to a derivative key of the blob and the transformations.
+#
+# A list of all possible transformations is available at https://www.imagemagick.org/script/mogrify.php. You can
+# combine as many as you like freely:
+#
+#   avatar.variant(resize: "100x100", monochrome: true, flip: "-90")
+class ActiveStorage::Variant
+  attr_reader :blob, :variation
+  delegate :service, to: :blob
+
+  def initialize(blob, variation)
+    @blob, @variation = blob, variation
+  end
+
+  # Returns the variant instance itself after it's been processed or an existing processing has been found on the service.
+  def processed
+    process unless processed?
+    self
+  end
+
+  # Returns a combination key of the blob and the variation that together identifies a specific variant.
+  def key
+    "variants/#{blob.key}/#{variation.key}"
+  end
+
+  # Returns the URL of the variant on the service. This URL is intended to be short-lived for security and not used directly
+  # with users. Instead, the `service_url` should only be exposed as a redirect from a stable, possibly authenticated URL.
+  # Hiding the `service_url` behind a redirect also gives you the power to change services without updating all URLs. And
+  # it allows permanent URLs that redirec to the `service_url` to be cached in the view.
+  #
+  # Use `url_for(variant)` (or the implied form, like `link_to variant` or `redirect_to variant`) to get the stable URL
+  # for a variant that points to the `ActiveStorage::VariantsController`, which in turn will use this `#service_call` method
+  # for its redirection.
+  def service_url(expires_in: 5.minutes, disposition: :inline)
+    service.url key, expires_in: expires_in, disposition: disposition, filename: blob.filename, content_type: blob.content_type
+  end
+
+
+  private
+    def processed?
+      service.exist?(key)
+    end
+
+    def process
+      service.upload key, transform(service.download(blob.key))
+    end
+
+    def transform(io)
+      require "mini_magick"
+      File.open MiniMagick::Image.read(io).tap { |image| variation.transform(image) }.path
+    end
+end
diff --git a/activestorage/app/models/active_storage/variation.rb b/activestorage/app/models/active_storage/variation.rb
new file mode 100644
index 0000000000..34b854fd9f
--- /dev/null
+++ b/activestorage/app/models/active_storage/variation.rb
@@ -0,0 +1,53 @@
+require "active_support/core_ext/object/inclusion"
+
+# A set of transformations that can be applied to a blob to create a variant. This class is exposed via 
+# the `ActiveStorage::Blob#variant` method and should rarely be used directly.
+#
+# In case you do need to use this directly, it's instantiated using a hash of transformations where
+# the key is the command and the value is the arguments. Example:
+#
+#   ActiveStorage::Variation.new(resize: "100x100", monochrome: true, trim: true, rotate: "-90")
+#
+# A list of all possible transformations is available at https://www.imagemagick.org/script/mogrify.php.
+class ActiveStorage::Variation
+  attr_reader :transformations
+
+  class << self
+    # Returns a variation instance with the transformations that were encoded by `#encode`.
+    def decode(key)
+      new ActiveStorage.verifier.verify(key, purpose: :variation)
+    end
+
+    # Returns a signed key for the `transformations`, which can be used to refer to a specific
+    # variation in a URL or combined key (like `ActiveStorage::Variant#key`).
+    def encode(transformations)
+      ActiveStorage.verifier.generate(transformations, purpose: :variation)
+    end
+  end
+
+  def initialize(transformations)
+    @transformations = transformations
+  end
+
+  # Accepts an open MiniMagick image instance, like what's return by `MiniMagick::Image.read(io)`,
+  # and performs the `transformations` against it. The transformed image instance is then returned.
+  def transform(image)
+    transformations.each do |(method, argument)|
+      if eligible_argument?(argument)
+        image.public_send(method, argument)
+      else
+        image.public_send(method)
+      end
+    end
+  end
+
+  # Returns a signed key for all the `transformations` that this variation was instantiated with.
+  def key
+    self.class.encode(transformations)
+  end
+
+  private
+    def eligible_argument?(argument)
+      argument.present? && argument != true
+    end
+end