Tags with dashes not working

[timonsky]

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• This is not a feature request
• This is not an image-provider request

Describe the bug:
Using keywords that contain dashes ('-') does not work. It seems the dashes are stripped before being passed to the URL builder.

To Reproduce:
Steps to reproduce the behavior:

1. Go to the Splash section in admin theming
2. enter a keyword containing dashes (eg. 'picos-de-europa')
3. reload the page
4. right-clicking in the browser where the picture is visible (for me it was in the empty space next to the app tray; at the very edge should also work)
5. getting the url from the 'Copy Image Link' shows that the url called is https://source.unsplash.com/featured/1920x1080?picosdeeuropa as in the tag had the dashes stripped

Expected behavior:
Images should be taken from the tag containing dashes (e.g. https://source.unsplash.com/featured/1920x1080?picos-de-europa)

Server:

• Nextcloud version: 27.0.1
• Splash-App version: 2.2.1

Additional Information:

• Might be related to Handle search keywords containing characters outside the latin alphabet #125
• with the tag 'picos-de-europa' it's especially noticeable as the tag 'picosdeeuropa' only has one image associated compared to 10k for the dashed one
• 'aurora-borealis' vs 'auroraborealis' is another example

[timonsky]

guessing it's this line that's responsible

Line 116 in lib/ProviderHandler/Provider.php
$term = preg_replace('/[^a-z]/i','', $term);