WPML compatibility issue with LL BG image in specific scenarios

[Mai-Saad]

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• Made sure you’re on the latest version =>3.15.2
• Used the search feature to ensure that the bug hasn’t been reported before

Describe the bug
1- Console error for external absolute URL CSS files in scenario 1
2- A console error is there when trying to switch language in scenario 2

To Reproduce
Steps to reproduce the behavior:
Scenario1:
1- WPML activated on domain base setup
2- install /activate WPR, then cache LL BG template (containing absolute URL of CSS file)
3- enable LL BG I then access the sub language FE and hard refresh => We will have a console error for some CSS files

Scenario 2:
1- WPML is domain base, WPR LL BG image enabled
2- cache the page in both languages
3- WPML changed to a directory
4- access the main language page and click on language switch to sub-lang => console error

Expected behavior
No console error when accessing page/switching language with WPML while LL BG image is enabled

Screenshots
If applicable, add screenshots to help explain your problem.
scenario1:

scenario 2:

Additional context
Add any other context about the problem here.

• Using Rocketlabs env
• For scenario 2, if we clear the cache and then repeat step 4, we will have no console error => shall we automatically clear the cache when changing the WPML setup? @wp-media/productrocket

Acceptance Criteria (for WP Media team use only)
Clear instructions for developers, to be added before the grooming

• No console error for main/sub language using domain base setup /directory setup and string setup
• Switch language is working with no console error
• Lazy load BG images working correctly with CDN on a regular and on a WPML environments
• No regressions to regular environment LL BG images feature

[CrochetFeve0251]

rocketlabs is using WPML and the issue is repoducable there.

[CrochetFeve0251]

Reproduce the issue

I cannot reproduce the second scenario.

Root issue

For the first scenario is due to that line

wp-rocket/inc/Engine/Optimization/Minify/AbstractMinifySubscriber.php

Line 131 in cfc26a3

return str_replace( $url_host, sanitize_text_field( $_SERVER['HTTP_HOST'] ), $url ); // phpcs:ignore WordPress.Security.ValidatedSanitizedInput.MissingUnslash

which add the new host url in all occurence in the url instead of just the domain leading to a extension added twice to the ll css generated file.

Scope a solution

We should change str_replace by preg_replace with the parameter one to stop at the first occurence.

Estimate effort

Effort XS

[remyperona]

Fix for first scenario looks good to me