The simple answer is none.
The only way I know of would be to get a Hauppauge HD PVR which has a Windows Media Center add on. I know it can be made to work with several different receivers, but I'm not familiar with how the Roku channels are selected.
In theory you would use the Roku as the tuner and attach it to the HD PVR via HDMI or component video and optical audio. If the Roku has only an HDMI output you may need a converter to go from HDMI to component if the digital protection causes you an issue. Then the Media Center add on would be installed in a PC (used as a DVR) and the HD PVR connected to the PC via USB. The HD PVR comes with IR blasters to change the channels on the receiver/tuner. That's where the Roku may take some investigation and may just not work if the Roku uses a RF or Bluetooth remote.
Once set up the Windows Media Center DVR can have programs scheduled just like a DVR. Hook up the TV with a PC HDMI cable.
I've used this with a Dish Network receiver and it worked pretty well. Essentially, it becomes a one channel DVR. With OTA, DirectTV, Dish or cable box where there is guide data available on the internet the media center guide will work like other DVRs.
What's Needed is any dual core or higher PC with HDMI video and 4 USB ports.
The Hauppauge HD PVR: https://smile.amazon.com/Hauppauge-1...uppauge+hd+pvr
HDMI to component video: http://www.gang-hu.com/gh_shop/index.aspx
may not be necessary if the Roku allows the HDMI connection to work with the HD PVR. No protection error.
IR remote for the Windows Media Center: https://smile.amazon.com/gp/product/...?ie=UTF8&psc=1
Windows Media Center support for WinTV products
If you want to use a Windows 10 PC, Microsoft has discontinued Windows Media Center for Windows 10. Here is how to get windows Media Center installed: How to Install Windows Media Center on Windows 10
Having typed all of this it should be noted there are many issues that would need to be worked out, but if you have the technical ability to add software if necessary it could be worked out in theory.