Looking for a way to create a report. Long story...

Basically, I need to generate reports which contains more than 300 tables, over 100 charts and many images. Until now this was done manually in docx, so I was asked to build an RoR app where the user could add all the images and data, and with one button click get the report. Here is the problem. The user wants to be able to download the report, and be able to edit that file manually.
So I looked for gems. Many of them just fill spaces in docx files. At the moment I use axlsx to generate my charts, tables and images, everything is saved into excel file. It works pretty well. I was thinking if there is some kind of format that ruby can edit (insert tables, bar charts, styles…) and the same format could be opened in the office… why ? because I could open the file and convert it to docx…
I am a little lost. My web app have database ready, just need some way of generating that file for the user. Any tips would be nice. I thought about html reports, but I cant edit them later, or can I ?
Thanks community.

I believe LibreOffice can open html files, which could then be saved
as doc. I guess the MS equivalent can also do that, but I don't know.
Easy enough to try it.

Colin

Actually LibreOffice don’t save html file in doc format. =/

Actually LibreOffice don't save html file in doc format. =/

Mine does (5.0.2.2 and I am confident it has for all the versions I
have used over a number of years). One of the format options when
saving is "Microsoft Word 97-2003(.doc)". I have just checked by
opening an html file then using File > Save As to save it.

Colin