Picker

[Thatoo]

This is a draft to make Nextcloud Picker very handy within Element for Nextcloud to answer this issue.
The idea is to add a button that would open an iframe to select a file and get one of the three link :

• internal link of the file
• read only public link of the file
• editable public link of the file
  It requires to install the app https://github.com/nextcloud/picker on version 1.0.11 or above.

So far, it is a POC.
The way the button is added, using const interval = setInterval(() => {... }, 100); isn't satisfying.
I don't know how to make

function closePickerIframe() {
  const pickerFrame = document.getElementById('pickerFrame');
  document.body.removeChild(pickerFrame); // Remove the iframe
}

survive the webpack building operation. Indeed, this function isn't directly used by Element for Nextcloud but it needs to exist for the Picker app to be able to call this function (window.parent.closePickerIframe()) and close the iframe once the link has been copied. Webpack delete this function at building time as it consider it being unused.