class ParallelTests::Grouper

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

def by_scenarios(tests, num_groups, options={})
  scenarios = group_by_scenarios(tests, options)
  in_even_groups_by_size(scenarios, num_groups)
end

def by_steps(tests, num_groups, options)
  features_with_steps = group_by_features_with_steps(tests, options)
  in_even_groups_by_size(features_with_steps, num_groups)
end

def group_by_features_with_steps(tests, options)
  require 'parallel_tests/cucumber/features_with_steps'
  ParallelTests::Cucumber::FeaturesWithSteps.all(tests, options)
end

def group_by_scenarios(tests, options={})
  require 'parallel_tests/cucumber/scenarios'
  ParallelTests::Cucumber::Scenarios.all(tests, options)
end

def group_features_by_size(items, groups_to_fill)
  items.each do |item, size|
    size ||= 1
    smallest = smallest_group(groups_to_fill)
    add_to_group(smallest, item, size)
  end
end

def in_even_groups_by_size(items, 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 = items.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)
  group_features_by_size(items_to_group(items), groups_to_fill)
  groups.map! { |g| g[:items].sort }
end

def items_to_group(items)
  items.first && items.first.size == 2 ? largest_first(items) : items
end

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

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