Allow sending visits to a matomo analytics instance

[acelaya]

https://github.com/matomo-org/matomo-php-tracker

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FAQ:

• How to generate the API token and get the Site ID. Instructions with screenshot/s.
• How to find the site ID: https://matomo.org/faq/general/faq_19212/
• Matomo tracks unique visits in intervals of 30 min. New visits from the same visitor within that interval are considered actions of the same visit: https://matomo.org/faq/general/faq_36/#:~:text=If%20a%20visitor%20enters%20to,it%20in%20a%20new%20Visit.
  This can make visits in Shlink and matomo not match, so it should be documented how it works, and how to change it.
• Matomo uses IP + User agent to determine unique visitors: https://matomo.org/faq/general/faq_43/#:~:text=Unique%20visitors%20are%20determined%20using,will%20detect%20two%20unique%20visitors.
• Matomo obfuscates IP addresses by discarding last two octets: https://forum.matomo.org/t/how-matomo-anonymises-ip-addresses/34006/2

TODO

• Visits should be sent using a background job when possible.
• Make sure there's a reasonable timeout. If the matomo instance goes away, it should not have a big impact on visitors, specially when not using an async runtime.
• Make dev env more straightforward. Right now you need to go over the installation process and generate some info manually.
• Document integration with matomo

Nice to have (for future versions):

• Support different site IDs per domain
• Matomo integration: Add console command to send existing visits to Matomo #1925
• Allow customizing the timeout (MATOMO_TIMEOUT)
• Detect if token is invalid. Right now it fails to track visit, but Matomo does not return an error (see How to know if site ID or auth token are incorrect matomo-org/matomo-php-tracker#127)
• Detect if site ID is invalid. Right now it fails to track visit, but Matomo does not return an error (see How to know if site ID or auth token are incorrect matomo-org/matomo-php-tracker#127)

[acelaya]

Send a visit to matomo:

$matomoToken = '...'; // Must be admin/superuser
$matomoSiteId = '3';
$matomoUrl = 'http://shlink_matomo';

// Create a new MatomoTracker on every request, because it infers request info during construction
$tracker = new MatomoTracker($matomoSiteId, $matomoUrl);
$tracker->setTokenAuth($matomoToken);
$tracker->disableBulkTracking(); // We don't want to bulk send, as every request to Shlink will create a new tracker

$tracker
    ->setUrl('http://localhost:8800/foo') // Set absolute short URL for the visit to be tracked
    ->setCity('Zaragoza')
    ->setCountry('Spain')
    ->setRegion('Aragón')
    ->setLatitude(41.656840)
    ->setLongitude(-0.879420)
    ->setIp('1.2.3.4') // Set not obfuscated, as matomo handles obfuscation on itself
    ->setUserAgent('bar')
    ->setRequestMethodNonBulk('POST') // Ensure params are not sent in the URL, for security reasons
    ->setCustomTrackingParameter('type', VisitType::INVALID_SHORT_URL->value)
    ->setCustomTrackingParameter('orphan', 'true') // Set only for orphan visits?
    ->doTrackPageView('http://localhost:8800/foo'); // Use same short URL as action