Google Now - Card proposal

This is a proposal for Google Now card.
With this card Google detects the mood of the user through: topics in the search criteria, social media use, keywords in messaging
apps, speed and pression on the user interaction device and external factors such as weather or things happening arround the user.

After detecting down mood, Google helps to chear the user up through solutions, positive sentences, useful information, playing the favorite song, searching favorite food around them, smiles, and updating the beloveds to text and call the person.

How can Google
detect the mood of the user?