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 } }
  return specify_groups(items, num_groups, options, groups) if options[:specify_groups]
  # 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 >= total 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..])
  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

def specified_groups(options)
  groups = options[:specify_groups]
  return groups if groups != '-'
  $stdin.read.chomp
end

def specify_groups(items, num_groups, options, groups)
  specify_test_process_groups = specified_groups(options).split('|')
  if specify_test_process_groups.count > num_groups
    raise 'Number of processes separated by pipe must be less than or equal to the total number of processes'
  end
  all_specified_tests = specify_test_process_groups.map { |group| group.split(',') }.flatten
  specified_items_found, items = items.partition { |item, _size| all_specified_tests.include?(item) }
  specified_specs_not_found = all_specified_tests - specified_items_found.map(&:first)
  if specified_specs_not_found.any?
    raise "Could not find #{specified_specs_not_found} from --specify-groups in the selected files & folders"
  end
  if specify_test_process_groups.count == num_groups && items.flatten.any?
    raise(
      <<~ERROR
        The number of groups in --specify-groups matches the number of groups from -n but there were other specs
        found in the selected files & folders not specified in --specify-groups. Make sure -n is larger than the
        number of processes in --specify-groups if there are other specs that need to be run. The specs that aren't run:
        #{items.map(&:first)}
      ERROR
    )
  end
  # First order the specify_groups into the main groups array
  specify_test_process_groups.each_with_index do |specify_test_process, i|
    groups[i] = specify_test_process.split(',')
  end
  # Return early when processed specify_groups tests exactly match the items passed in
  return groups if specify_test_process_groups.count == num_groups
  # Now sort the rest of the items into the main groups array
  specified_range = specify_test_process_groups.count..-1
  remaining_groups = groups[specified_range]
  group_features_by_size(items_to_group(items), remaining_groups)
  # Don't sort all the groups, only sort the ones not specified in specify_groups
  sorted_groups = remaining_groups.map { |g| g[:items].sort }
  groups[specified_range] = sorted_groups
  groups
end