Allow viewing versions

[juliusknorr]

Is your feature request related to a problem? Please describe.
Currently versions can only be downloaded in the files app, so a user will need to open them locally in order to see what the state of the file is.

Describe the solution you'd like
The viewer app should be able to handle opening specific versions of a file. This should be already possible from the backend side as the versions are exposed as a WebDAV collection. The version is identified by the file id and their timestamp, after that the file can be downloaded through:

/remote.php/dav/versions/julius/versions/6713781/1668462795

The version to load (timestamp) could become an additional parameter on the open() call:

viewer/src/services/Viewer.js

Line 224 in 8c58437

open({ path, fileInfo, list = [], loadMore = () => ([]), canLoop = true, onPrev = () => {}, onNext = () => {}, onClose = () => {} } = {}) {

Then this version could get passed to any mimetype handler.

Related to ongoing server development in nextcloud/server#34769

cc @skjnldsv @nextcloud/office

[skjnldsv]

I initially planned to cover that by forcing the use of the new File API to open Viewer (for 26)
With this we would load the source straight away if the preview is not existing/defined

[skjnldsv]

Since that would be a breaking change, 26 would be nice for a Viewer 2.0.0

[skjnldsv]

If your team have room to push this forward, we can team up to plan this accordingly :)

[juliusknorr]

Sounds good, thanks. I'll align on the priorities and then reach out to you in case we pick that up.

[skjnldsv]

So you know, I already started this work a few weeks ago. But didn't continue because other priorities came up.

[PVince81]

to dodge the breaking change maybe we can first add a second method with the new API and leave the old one with an adapter to give app devs more time to migrate, and we could deprecate for NC 27 (add a deprecation note in NC 26 that we'll remove to NC 27)

[PVince81]

@juliushaertl is this something the office team would take over ?

[juliusknorr]

Generally yes, but we currently don't have it scheduled due to other tasks with higher prio.

[juliusknorr]

Was done with nextcloud/server#39171