Fix too greedy TrackLink regex replacement.

[0xdeb]

Hi there!

First, thank you for developing and maintaining listmonk - it's an awesome tool and very easy to use!

I implemented listmonk at my company a few weeks ago, and one recurring issue reported by the marketing team is that they sometimes cannot save tracked links.

Issue Description

After investigating, I found that the issue stems from the TrackLink regex replacement, which incorrectly matches more characters than intended. This results in template compilation errors like:

{"message":"Error compiling template: error compiling message: template: content:1: unexpected \"\u003e\" in operand"}

A minimal reproducible example is inserting two links in the same line:

<a href="https://google.de">Untracked Link</a><a href="https://google.de@TrackLink">Tracked Link</a>

This causes the campaign to fail rendering.

Root Cause

The issue occurs because the @TrackLink syntax regex matches too many characters, unintentionally breaking the DOM.

As you can see here, the expression starts with the "https://" of the first link and ends with the second tracked link.
Different combinations of imgs and links in the same link can of course also trigger this issue.

Fix

I updated the regex to only match characters that are valid in a URL per RFC 3986, ensuring a clean stop after the URL.

Let me know if you'd like any adjustments. Thanks!

[knadh]

Ah, that's a neat gotcha! Thanks for the well articulated PR.

The Regexp can be simplified as (https?://[\w\-\.~!#$&'()*+,/:;=?@\[\]]*)@TrackLink. Could you please amend the PR with this? This uses aliases for character classes and removes redundant escape chars.

PS: I tried to amend the PR with the GitHub CLI and messed it up somehow.

[0xdeb]

Sure! Integrated the change and rebased on current master to get rid of the merge commit.

On second thought, what so you think about using \p{L} in the expression instead?
\w does not match accented letters and the rich text editor does not save the domain in IDN (xn--...). So if one were to enter a internationalized domain and enable tracking, that wouldn't work with \w.