Handlers based on file extension, rather than MIME

[ChristophWurst]

Is your feature request related to a problem? Please describe.

I would like to extend the Viewer with a new file type. Unfortunately the file doesn't have a standardized MIME type. On Linux it is detected as application/octet-stream.

Describe the solution you'd like

Allow registering handlers based on file extensions as well:

 OCA.Viewer.registerHandler({
     // unique id
     id: 'emf',

    // optional, it will group every view of this group and
    // use the proper view when building the file list
    // of the slideshow.
    // e.g. you open an image/jpeg that have the `media` group
    // you will be able to see the video/mpeg from the `video` handler
    // files that also have the `media` group set.
    group: 'media',

    // the list of mimes your component is able to display
    mimes: [],

    fileExtensions: [
        'emf',
    ],

     // your vue component view
     component: VideoView
 })

Describe alternatives you've considered

N/a

Additional context

nextcloud/files_emfviewer#1 is the feature.

[skjnldsv]

For me this would be for Viewer 3.0, where, following the same pattern as FileAction and NewFileEntry APIs, you can register conditional handlers with whatever you need. We would expose this as a library and only allow a Node with optional array of Node

new FileAction({
	...
	enabled(nodes: Node[]) {
		// Only works on single node
		if (nodes.length !== 1) {
			return false
		}

		return (nodes[0].permissions & Permission.UPDATE) !== 0
	},
	...
})

[ChristophWurst]

This is obsolete