module Aperitifilm

# File lib/aperitifilm.rb, line 11
def self.run(usernames, number_of_movies = 20)
  usernames = Array(usernames)

  movie_listings = usernames.map do |username|
    puts "Fetching movies for #{username}"
    fetch_movies(username)
  end

  ranking = create_ranking(movie_listings)

  puts "Found #{ranking.positions.size} movies"

  print_ranking(ranking, number_of_movies)
end

# File lib/aperitifilm.rb, line 67
def self.create_ranking(movie_rankings)
  all_movies = movie_rankings.map { |ranking| ranking.positions.map(&:item) }.flatten.uniq

  ranking = Ranking.new

  all_movies.map do |movie|
    ranking.add_position movie, score_movie(movie, movie_rankings)
  end

  ranking
end

# File lib/aperitifilm.rb, line 30
def self.fetch_movies(username)
  movies_url = "http://www.filmweb.pl/user/#{username}/films/wanna-see"

  doc = Nokogiri::HTML(open(movies_url)) do |config|
    config.noent
  end

  raw_movies = doc.css(".wantToSeeSee td").each_slice(2)

  ranking = Ranking.new

  raw_movies.each do |raw_movie|
    movie_cell, score_cell = raw_movie

    title_attribute = movie_cell.attributes.fetch('sorttable_customkey')

    movie_title = title_attribute.value

    movie_link = movie_cell.at_css('a')

    movie_id = movie_link.attributes.fetch('href').value
    movie_id = movie_id[1..-1] # Cut the first char, which is /

    movie_score = Integer(score_cell.attributes.fetch('sorttable_customkey').value)

    movie = Movie.new(movie_id, movie_title)

    ranking.add_position movie, movie_score
  end

  if ranking.positions.to_a.empty?
    raise "#{username} has no movies that they would like to watch"
  end

  ranking
end

# File lib/aperitifilm.rb, line 89
def self.print_ranking(ranking, number_of_movies = 20)
  string_format = "%-2s %-32s %4s %s"

  puts string_format % %w(# Title Score URL)

  ranking.positions_with_ordinal(number_of_movies) do |position, ordinal|
    puts string_format % [ordinal, position.item.title, position.score.round(2), position.item.url]
  end

  nil
end

# File lib/aperitifilm.rb, line 79
def self.score_movie(movie, rankings)
  scores_sum = rankings.map { |ranking| ranking.find_position(movie.id) { BlankPosition.new }.score }.inject(:+)

  # Bonus is the number of users who also want to watch a particular movie
  # times the number of users.
  bonus = rankings.count { |ranking| ranking.find_position(movie.id) { nil } } / rankings.size.to_f

  scores_sum * bonus
end