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
  single_process_patterns = options[:single_process] || []
  single_items, items = items.partition do |item, _size|
    single_process_patterns.any? { |pattern| item =~ pattern }
  end
  isolate_count = isolate_count(options)
  if isolate_count >= num_groups
    raise 'Number of isolated processes must be less than total the number of processes'
  end
  if isolate_count >= 1
    # add all files that should run in a multiple isolated processes to their own groups
    group_features_by_size(items_to_group(single_items), groups[0..(isolate_count - 1)])
    # group the non-isolated by size
    group_features_by_size(items_to_group(items), groups[isolate_count..-1])
  else
    # add all files that should run in a single non-isolated process to first group
    single_items.each { |item, size| add_to_group(groups.first, item, size) }
    # group all by size
    group_features_by_size(items_to_group(items), groups)
  end
  groups.map! { |g| g[:items].sort }
end

def isolate_count(options)
  if options[:isolate_count] && options[:isolate_count] > 1
    options[:isolate_count]
  elsif options[:isolate]
    1
  else
    0
  end
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