require 'set'

module EPUB
  module Publication
    class Package
      class Metadata
        include Inspector::PublicationModel

        DC_ELEMS = [:identifiers, :titles, :languages] +
                   [:contributors, :coverages, :creators, :dates, :descriptions, :formats, :publishers,
                    :relations, :rights, :sources, :subjects, :types]
        attr_accessor :package, :unique_identifier, :metas, :links,
                      *(DC_ELEMS.collect {|elem| "dc_#{elem}"})
        DC_ELEMS.each do |elem|
          alias_method elem, "dc_#{elem}"
          alias_method "#{elem}=", "dc_#{elem}="
        end

        def initialize
          (DC_ELEMS + [:metas, :links]).each do |elem|
            __send__ "#{elem}=", []
          end
        end

        def title
          return extended_title unless extended_title.empty?
          compositted = titles.select {|title| title.display_seq}.sort.join("\n")
          return compositted unless compositted.empty?
          return main_title unless main_title.empty?
          titles.sort.join("\n")
        end

        %w[main short collection edition extended].each do |type|
          define_method "#{type}_title" do
            titles.select {|title| title.title_type.to_s == type}.sort.join(' ')
          end
        end

        def subtitle
          titles.select {|title| title.title_type.to_s == 'subtitle'}.sort.join(' ')
        end

        def description
          descriptions.join(' ')
        end

        def date
          dates.first
        end

        def language
          languages.first
        end

        def to_h
          DC_ELEMS.inject({}) do |hsh, elem|
            hsh[elem] = __send__(elem)
            hsh
          end
        end

        def primary_metas
          metas.select {|meta| meta.primary_expression?}
        end

        module Refinee
          PROPERTIES = %w[alternate-script display-seq file-as group-position identifier-type meta-auth role title-type]

          attr_writer :refiners

          def refiners
            @refiners ||= Set.new
          end

          PROPERTIES.each do |voc|
            met = voc.gsub(/-/, '_')
            attr_writer met
            define_method met do
              refiners.find {|refiner| refiner.property == voc}
            end
          end
        end

        class DCMES
          include Refinee

          attr_accessor :content, :id, :lang, :dir

          def to_s
            content.to_s
          end
        end

        class Identifier < DCMES
          # @note This is ad-hoc
          # @todo Define and include OPF module for opf:scheme attribute
          # @todo Define generale way to handle with identifier-type refiners
          attr_accessor :scheme

          # @note This is ad-hoc
          # @todo Define and include OPF module for opf:scheme attribute
          # @todo Define generale way to handle with identifier-type refiners
          def isbn?
            refiners.any? {|refiner|
              refiner.property == 'identifier-type' and
              refiner.scheme == 'onix:codelist5' and
              %w[02 15].include? refiner.content
            } or
            scheme == 'ISBN' or
            content.to_s.downcase.start_with? 'urn:isbn'
          end
        end

        class Title < DCMES
          include Comparable

          def <=>(other)
            return 1 if other.display_seq.nil?
            return -1 if display_seq.nil?
            display_seq.to_s.to_i <=> other.display_seq.to_s.to_i
          end
        end

        class Meta
          include Refinee

          attr_accessor :property, :id, :scheme, :content
          attr_reader :refines

          def refines=(refinee)
            refinee.refiners << self
            @refines = refinee
          end

          def refines?
            ! refines.nil?
          end
          alias subexpression? refines?

          def primary_expression?
            ! subexpression?
          end

          def inspect
            ivs = instance_variables.map {|iv|
              [iv, instance_variable_get(iv).inspect].join('=')
            }.join(' ')
            '<#%s:%#0x %s>' % [self.class, __id__, ivs]
          end

          def to_s
            content.to_s
          end
        end

        class Link
          include Refinee

          attr_accessor :href, :rel, :id, :media_type
          attr_reader :refines

          def refines=(refinee)
            refinee.refiners << self
            @refines = refinee
          end
        end
      end
    end
  end
end