module Rake
  module Funnel
    module Support
      class Finder
        include Enumerable

        def initialize(search_pattern, task, message = nil)
          @search_pattern = search_pattern
          @task = task
          @message = message
        end

        def each
          block_given? || (return enum_for(__method__))
          all_or_default.each { |x| yield x }
        end

        def single_or_default
          first_sln
        end

        def single
          if first_sln.nil?
            raise Rake::Funnel::AmbiguousFileError.new(@message, @task.name, @search_pattern, candidates)
          end

          first_sln
        end

        def all_or_default
          candidates
        end

        def all
          if candidates.empty?
            raise Rake::Funnel::AmbiguousFileError.new(@message, @task.name, @search_pattern, candidates)
          end

          candidates
        end

        private

        def first_sln
          return candidates.first if candidates.one?

          nil
        end

        def candidates
          Dir[*@search_pattern.dup].select { |f| File.file?(f) }.uniq
        end
      end
    end
  end
end