module Rspec
  module Core
    class World

      attr_reader :example_groups

      def initialize
        @example_groups = []
      end

      def inclusion_filter
        Rspec.configuration.filter
      end

      def exclusion_filter
        Rspec.configuration.exclusion_filter
      end

      def shared_example_groups
        @shared_example_groups ||= {}
      end

      def example_groups_to_run
        @example_groups_to_run ||= begin
          if inclusion_filter || exclusion_filter
            if Rspec.configuration.run_all_when_everything_filtered? && filtered_example_groups.empty?
              Rspec.configuration.puts "No examples were matched by #{inclusion_filter.inspect}, running all"
              all_example_groups
            else
              Rspec.configuration.puts "Run filtered using #{inclusion_filter.inspect}"          
              filtered_example_groups
            end
          else
            all_example_groups
          end      
        end
      end

      def all_example_groups
        @example_groups.each { |g| g.examples_to_run.replace(g.examples) }
      end

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

      def filtered_example_groups
        @filtered_example_groups ||= example_groups.select do |example_group|
          examples = example_group.examples
          examples = apply_exclusion_filters(examples, exclusion_filter) if exclusion_filter
          examples = apply_inclusion_filters(examples, inclusion_filter) if inclusion_filter
          examples.uniq!
          example_group.examples_to_run.replace(examples)
          !examples.empty?
        end
      end

      def apply_inclusion_filters(examples, conditions={})
        examples.select &all_apply?(conditions)
      end

      alias_method :find, :apply_inclusion_filters

      def apply_exclusion_filters(examples, conditions={})
        examples.reject &all_apply?(conditions)
      end

      def preceding_example_or_group_line(filter_line) 
        declaration_line_numbers.inject(nil) do |highest_prior_declaration_line, line|
          line <= filter_line ? line : highest_prior_declaration_line
        end
      end
      
    private

      def all_apply?(conditions)
        lambda {|example| example.metadata.all_apply?(conditions)}
      end

      def declaration_line_numbers
        @line_numbers ||= example_groups.inject([]) do |lines, g|
          lines + g.declaration_line_numbers
        end
      end
      
    end
  end
end