📄💫 File conversion

[juliusknorr]

This has been discussed upfront with @sorbaugh and @AndyScherzinger

We should introduce a file conversion API that apps can register their ability to convert certain file types in certain other ones. In the beginning we will make use of this in richdocuments to be able to convert office files to PDF. The files app will then be able to make use of that API to provide a file action for conversion. Flow can also use this API for automation through OCS endpoints

• Server API to have a plugin architecture where apps can register file convertion handlers @elzody
  • OCP API for apps to register their conversion capabilities and implement logic to convert files
    • Input/output format tuples provided by apps
    • Capabilities exposing possible file conversion formats
    • Capability to limit file conversion to files below a configurable size threshold
    • Add fake provider in the testing app
  • OCS API to do synchronous file conversion
• richdocuments: Implement conversion for office to pdf files
• pandoc: Implement conversion for other types @juliusknorr
• Files app: File action to convert a file to a different type @skjnldsv

Out of scope

• Asynchronous conversion for larger files
• Additional file types (e.g. video, image or more advanced AI related ones) -> should be planned separately

[juliusknorr]

From discussion with @AndyScherzinger

• We should support multiple providers (e.g. pandoc as well)
• We should have a preferred conversion option list to only offer one option per tuple
• Need to make sure this list of preferred options is only loaded once needed when converting to select which provider to prefer (php array)