This app is a solution for the test: https://github.com/armel/GlobTest

Answers:

1. The function foo takes all the intervals given as input and factors them all by combining the intervals that have an intersection. It returns the new collection of factored intervals.
2. 1. Clone the project
   2. run composer install
   3. run test: vendor/bin/phpunit tests/BarTest.php
3. It takes me 3 hours :(