class ParallelTests::Grouper

def self.add_to_group(group, item, size)
  group[:items] << item
  group[:size] += size
end

def self.build_features_with_steps(tests, options)
  require 'parallel_tests/cucumber/gherkin_listener'
  listener = Cucumber::GherkinListener.new
  listener.ignore_tag_pattern = Regexp.compile(options[:ignore_tag_pattern]) if options[:ignore_tag_pattern]
  parser = Gherkin::Parser::Parser.new(listener, true, 'root')
  tests.each{|file|
    parser.parse(File.read(file), file, 0)
  }
  listener.collect.sort_by{|_,value| -value }
end

def self.by_steps(tests, num_groups, options)
  features_with_steps = build_features_with_steps(tests, options)
  in_even_groups_by_size(features_with_steps, num_groups)
end

def self.in_even_groups_by_size(items_with_sizes, num_groups, options = {})
  groups = Array.new(num_groups) { {:items => [], :size => 0} }
  # add all files that should run in a single process to one group
  (options[:single_process] || []).each do |pattern|
    matched, items_with_sizes = items_with_sizes.partition { |item, size| item =~ pattern }
    matched.each { |item, size| add_to_group(groups.first, item, size) }
  end
  groups_to_fill = (options[:isolate] ? groups[1..-1] : groups)
  # add all other files
  largest_first(items_with_sizes).each do |item, size|
    smallest = smallest_group(groups_to_fill)
    add_to_group(smallest, item, size)
  end
  groups.map!{|g| g[:items].sort }
end

def self.largest_first(files)
  files.sort_by{|item, size| size }.reverse
end

def self.smallest_group(groups)
  groups.min_by{|g| g[:size] }
end