Integrating Mermaid in Gitiles markdown renderer

[Réda Housni Alaoui]

Hello everyone,

As part of the #gothenburg2023 hackaton, I'd like to integrate Mermaid into Gitiles.

Mermaid is a javascript program that converts a diagram text representation into an SVG representation. It is already supported by GitHub markdown renderer.

I took a look at Gitiles source code. Currently, Gitiles only performs markdown rendering on the server-side, therefore using java. 

I think there are multiple (naive?) solutions to add Mermaid to the Markdown rendering:

1. the easiest: add Mermaid Npm Package to the browser-side to perform the mermaid FencedCodeBlock rendering on the browser-side
2. use Puppeteer to execute Mermaid Npm Package on the server-side
3. the hardest/highly unlikely: re-implement Mermaid in java

I think we should pick option 1.

But it seems that Gitiles was designed with browser-side security in mind. Currently, there isn't a single third party javascript module loaded by Gitiles. So I am not sure that integrating Mermaid Npm Package would be accepted by the community.

If we think that some people/organizations will refuse to reference a third party javascript library, I suggest 2 ways of implementing option 1:

1. Adding a configuration flag controlling Mermaid activation. It would be disabled by default.
2. Adding an extension point to Gitiles at https://gerrit.googlesource.com/gitiles/+/refs/heads/master/java/com/google/gitiles/doc/MarkdownToHtml.java#312

What do you think? Please share your suggestions/interrogations/observations !

[Réda Housni Alaoui]

Here is video of the demo => https://drive.google.com/file/d/17RUWCp0OahjT3kdxVLz9zsiuBkq-m8hg/view?usp=sharing

[Réda Housni Alaoui]

I am not used to Bazel. I don't know where to start to add an npm dependency.
Should I add a Mermaid npm module dependency, or should I add https://github.com/mermaid-js/mermaid as a submodule? Is there any example of such frontend dependency I could take inspiration from?

[Réda Housni Alaoui]

Given the project already rely heavily on Maven Central, I am going to pull the dependency via https://www.webjars.org/ .

[Vitaly Bordyug DE]

Hi all,  

Sorry to pull out an old thread, just would be generally interested if anything came out of this initiative (even if it is not yet mergeable/buildable state)

TIA!

-Vitaly