class Rspec::Core::World

def apply_exclusion_filters(collection, conditions={})
  find(collection, :negative, conditions)
end

def apply_inclusion_filters(collection, conditions={})
  find(collection, :positive, conditions)
end

def example_groups_to_run
  return @example_groups_to_run if @example_groups_to_run
  if filter || exclusion_filter
    @example_groups_to_run = filter_example_groups
    if @example_groups_to_run.size == 0 && Rspec::Core.configuration.run_all_when_everything_filtered?
      Rspec::Core.configuration.puts "No examples were matched by #{filter.inspect}, running all"
      # reset the behaviour list to all example groups, and add back all examples
      @example_groups_to_run = @example_groups
      @example_groups.each { |b| b.examples_to_run.replace(b.examples) }
    else
      Rspec::Core.configuration.puts "Run filtered using #{filter.inspect}"          
    end
  else
    @example_groups_to_run = @example_groups
    @example_groups.each { |b| b.examples_to_run.replace(b.examples) }
  end      
  @example_groups_to_run
end

def exclusion_filter
  Rspec::Core.configuration.exclusion_filter
end

def filter
  Rspec::Core.configuration.filter
end

def filter_example_groups
  example_groups.inject([]) do |list_of_example_groups, example_group|
    examples = example_group.examples
    examples = apply_exclusion_filters(examples, exclusion_filter) if exclusion_filter
    examples = apply_inclusion_filters(examples, filter) if filter
    examples.uniq!
    example_group.examples_to_run.replace(examples)
    if examples.empty?
      list_of_example_groups << nil
    else
      list_of_example_groups << example_group
    end
  end.compact
end

def find(collection, type_of_filter=:positive, conditions={})
  negative = type_of_filter != :positive
  collection.select do |item|
    # negative conditions.any?, positive conditions.all? ?????
    result = conditions.all? do |filter_on, filter| 
      item.metadata.apply_condition(filter_on, filter)
    end
    negative ? !result : result
  end
end

def initialize
  @example_groups = []
end

def shared_example_groups
  @shared_example_groups ||= {}
end

def total_examples_to_run
  @total_examples_to_run ||= example_groups_to_run.inject(0) { |sum, b| sum += b.examples_to_run.size }
end