In 2009 we released a Google Analytics API client in PHP. It was the first library released in PHP. Six years later, this software is outdated. Google changed the API and it’s no longer of use.
As an alternative you can use GAPI (Github). Go to github.com/erebusnz/gapi-google-analytics-php-interface for instructions and to get the source code.
Since you are interested in this stuff and might like what we did here, it is good to know that we have several job openings. Interested in applying at SWIS? Check out our vacancies!