Drop support for s2Member

Today i did some work for the following issue:

https://github.com/pronamic/wp-pronamic-pay/issues/242

It is currently possible to start payments again, but I have not yet been able to test everything properly. If i understand correctly a WordPress user can only have 1 s2Member 'subscription'.

WordPress admin user profile

What should happen if a logged in WordPress user with already a s2Member 'subscription' makes a new payment via a different or the same shortcode?

But I wonder whether we should put further energy into this issue. The plugin has 20.000+ active install according to: https://wordpress.org/plugins/s2member/. I think the number of Pronamic Pay users can be counted on one hand 🖐. I think we should ask ourselves whether there is any added value to continue to support this plugin. I also find it very difficult to understand the s2Member codebase, certain lines of code are indented with 50+ tabs 😱:

We always try to keep the indentation level as low as possible.

The plan:

[ ] Mark s2Member extension as deprecated in 8.0.
[ ] Write and share a blog post about dropping s2Member support.
[ ] Current implementation is good enough for 8.0, probably somewhat buggy, but good enough for now.
[ ] If users experience problems with s2Member integration in 8.0 advise to switch to Gravity Forms.
[ ] Drop support for s2Member in 8.1.

pronamic / wp-pronamic-pay

Drop support for s2Member #292