Setting the ranking parameters

If we are going to choose two simple factors to rate the headlines, I would say lets do it based on the freshness of the news and the important keywords available in each headline. We don't want to investigate yesterday's news, so let's say if the news belongs to a timestamp within 24 hours from now, we give them a score of 1 and any news older than that won't score any points.

Keywords are important as well. A headline with important keywords deserves to receive a higher rate compared to bland and uninteresting topics. But how can we decide which keywords are important?

We can define a dictionary of keywords and save it into our Firebase db. That might be a good - temporary - solution, but in the long term it won't be practical or reliable. First, as the dictionary grows, analyzing the headlines and looking for keywords takes longer time. Secondly, how can we be certain that the keywords we have selected are trending globally and have...