CORSrequest.coffee

createCORSRequest = (method, url) ->
  xhr = new XMLHttpRequest()
  if "withCredentials" of xhr
    xhr.open method, url, true
  else unless typeof XDomainRequest is "undefined"
    xhr = new XDomainRequest()
    xhr.open method, url
  else
    xhr = null
  xhr

handleFileSelect = (evt) ->
  setProgress 0, "Upload started."
  files = evt.target.files
  output = []
  i = 0
  f = undefined

  while f = files[i]
    uploadFile f
    i++

###
Execute the given callback with the signed response.
###
executeOnSignedUrl = (file, callback) ->
  xhr = new XMLHttpRequest()
  xhr.open "GET", "signput.php?name=" + file.name + "&type=" + file.type, true
  
  # Hack to pass bytes through unprocessed.
  xhr.overrideMimeType "text/plain; charset=x-user-defined"
  xhr.onreadystatechange = (e) ->
    if @readyState is 4 and @status is 200
      callback decodeURIComponent(@responseText)
    else setProgress 0, "Could not contact signing script. Status = " + @status  if @readyState is 4 and @status isnt 200

  xhr.send()

uploadFile = (file) ->
  executeOnSignedUrl file, (signedURL) ->
    uploadToS3 file, signedURL


###
Use a CORS call to upload the given file to S3. Assumes the url
parameter has been signed and is accessible for upload.
###
uploadToS3 = (file, url) ->
  xhr = createCORSRequest("PUT", url)
  unless xhr
    setProgress 0, "CORS not supported"
  else
    xhr.onload = ->
      if xhr.status is 200
        setProgress 100, "Upload completed."
      else
        setProgress 0, "Upload error: " + xhr.status

    xhr.onerror = ->
      setProgress 0, "XHR error."

    xhr.upload.onprogress = (e) ->
      if e.lengthComputable
        percentLoaded = Math.round((e.loaded / e.total) * 100)
        setProgress percentLoaded, (if percentLoaded is 100 then "Finalizing." else "Uploading.")

    xhr.setRequestHeader "Content-Type", file.type
    xhr.setRequestHeader "x-amz-acl", "public-read"
    xhr.send file

setProgress = (percent, statusLabel) ->
  progress = document.querySelector(".percent")
  progress.style.width = percent + "%"
  progress.textContent = percent + "%"
  document.getElementById("progress_bar").className = "loading"
  document.getElementById("status").innerText = statusLabel