require_relative 'tagged_with_query'
require_relative 'tag_list_type'

module ActsAsTaggableOn::Taggable
  module Core

    def self.included(base)
      base.extend ActsAsTaggableOn::Taggable::Core::ClassMethods

      base.class_eval do
        attr_writer :custom_contexts
        after_save :save_tags
      end

      base.initialize_acts_as_taggable_on_core
    end

    module ClassMethods
      def initialize_acts_as_taggable_on_core
        include taggable_mixin
        tag_types.map(&:to_s).each do |tags_type|
          tag_type = tags_type.to_s.singularize
          context_taggings = "#{tag_type}_taggings".to_sym
          context_tags = tags_type.to_sym
          taggings_order = (preserve_tag_order? ? "#{ActsAsTaggableOn::Tagging.table_name}.id" : [])

          class_eval do
            # when preserving tag order, include order option so that for a 'tags' context
            # the associations tag_taggings & tags are always returned in created order
            has_many context_taggings, -> { includes(:tag).order(taggings_order).where(context: tags_type) },
                     as: :taggable,
                     class_name: 'ActsAsTaggableOn::Tagging',
                     dependent: :destroy,
                     after_add: :dirtify_tag_list,
                     after_remove: :dirtify_tag_list

            has_many context_tags, -> { order(taggings_order) },
                     class_name: 'ActsAsTaggableOn::Tag',
                     through: context_taggings,
                     source: :tag

            attribute "#{tags_type.singularize}_list".to_sym, ActsAsTaggableOn::Taggable::TagListType.new
          end

          taggable_mixin.class_eval <<-RUBY, __FILE__, __LINE__ + 1
            def #{tag_type}_list
              tag_list_on('#{tags_type}')
            end

            def #{tag_type}_list=(new_tags)
              parsed_new_list = ActsAsTaggableOn.default_parser.new(new_tags).parse

              if self.class.preserve_tag_order? || (parsed_new_list.sort != #{tag_type}_list.sort)
                if ActsAsTaggableOn::Utils.legacy_activerecord?
                  set_attribute_was("#{tag_type}_list", #{tag_type}_list)
                else
                  unless #{tag_type}_list_changed?
                    @attributes["#{tag_type}_list"] = ActiveModel::Attribute.from_user("#{tag_type}_list", #{tag_type}_list, ActsAsTaggableOn::Taggable::TagListType.new)
                  end
                end
                write_attribute("#{tag_type}_list", parsed_new_list)
              end

              set_tag_list_on('#{tags_type}', new_tags)
            end

            def all_#{tags_type}_list
              all_tags_list_on('#{tags_type}')
            end

            private
            def dirtify_tag_list(tagging)
              attribute_will_change! tagging.context.singularize+"_list"
            end
          RUBY
        end
      end

      def taggable_on(preserve_tag_order, *tag_types)
        super(preserve_tag_order, *tag_types)
        initialize_acts_as_taggable_on_core
      end

      # all column names are necessary for PostgreSQL group clause
      def grouped_column_names_for(object)
        object.column_names.map { |column| "#{object.table_name}.#{column}" }.join(', ')
      end

      ##
      # Return a scope of objects that are tagged with the specified tags.
      #
      # @param tags The tags that we want to query for
      # @param [Hash] options A hash of options to alter you query:
      #                       * <tt>:exclude</tt> - if set to true, return objects that are *NOT* tagged with the specified tags
      #                       * <tt>:any</tt> - if set to true, return objects that are tagged with *ANY* of the specified tags
      #                       * <tt>:order_by_matching_tag_count</tt> - if set to true and used with :any, sort by objects matching the most tags, descending
      #                       * <tt>:match_all</tt> - if set to true, return objects that are *ONLY* tagged with the specified tags
      #                       * <tt>:owned_by</tt> - return objects that are *ONLY* owned by the owner
      #                       * <tt>:start_at</tt> - Restrict the tags to those created after a certain time
      #                       * <tt>:end_at</tt> - Restrict the tags to those created before a certain time
      #
      # Example:
      #   User.tagged_with(["awesome", "cool"])                     # Users that are tagged with awesome and cool
      #   User.tagged_with(["awesome", "cool"], :exclude => true)   # Users that are not tagged with awesome or cool
      #   User.tagged_with(["awesome", "cool"], :any => true)       # Users that are tagged with awesome or cool
      #   User.tagged_with(["awesome", "cool"], :any => true, :order_by_matching_tag_count => true)  # Sort by users who match the most tags, descending
      #   User.tagged_with(["awesome", "cool"], :match_all => true) # Users that are tagged with just awesome and cool
      #   User.tagged_with(["awesome", "cool"], :owned_by => foo ) # Users that are tagged with just awesome and cool by 'foo'
      #   User.tagged_with(["awesome", "cool"], :owned_by => foo, :start_at => Date.today ) # Users that are tagged with just awesome, cool by 'foo' and starting today
      def tagged_with(tags, options = {})
        tag_list = ActsAsTaggableOn.default_parser.new(tags).parse
        options = options.dup

        return none if tag_list.empty?

        ::ActsAsTaggableOn::Taggable::TaggedWithQuery.build(self, ActsAsTaggableOn::Tag, ActsAsTaggableOn::Tagging, tag_list, options)
      end

      def is_taggable?
        true
      end

      def taggable_mixin
        @taggable_mixin ||= Module.new
      end
    end

    # all column names are necessary for PostgreSQL group clause
    def grouped_column_names_for(object)
      self.class.grouped_column_names_for(object)
    end

    def custom_contexts
      @custom_contexts ||= taggings.map(&:context).uniq
    end

    def is_taggable?
      self.class.is_taggable?
    end

    def add_custom_context(value)
      custom_contexts << value.to_s unless custom_contexts.include?(value.to_s) or self.class.tag_types.map(&:to_s).include?(value.to_s)
    end

    def cached_tag_list_on(context)
      self["cached_#{context.to_s.singularize}_list"]
    end

    def tag_list_cache_set_on(context)
      variable_name = "@#{context.to_s.singularize}_list"
      instance_variable_defined?(variable_name) && instance_variable_get(variable_name)
    end

    def tag_list_cache_on(context)
      variable_name = "@#{context.to_s.singularize}_list"
      if instance_variable_get(variable_name)
        instance_variable_get(variable_name)
      elsif cached_tag_list_on(context) && ensure_included_cache_methods! && self.class.caching_tag_list_on?(context)
        instance_variable_set(variable_name, ActsAsTaggableOn.default_parser.new(cached_tag_list_on(context)).parse)
      else
        instance_variable_set(variable_name, ActsAsTaggableOn::TagList.new(tags_on(context).map(&:name)))
      end
    end

    def tag_list_on(context)
      add_custom_context(context)
      tag_list_cache_on(context)
    end

    def all_tags_list_on(context)
      variable_name = "@all_#{context.to_s.singularize}_list"
      return instance_variable_get(variable_name) if instance_variable_defined?(variable_name) && instance_variable_get(variable_name)

      instance_variable_set(variable_name, ActsAsTaggableOn::TagList.new(all_tags_on(context).map(&:name)).freeze)
    end

    ##
    # Returns all tags of a given context
    def all_tags_on(context)
      tagging_table_name = ActsAsTaggableOn::Tagging.table_name

      opts = ["#{tagging_table_name}.context = ?", context.to_s]
      scope = base_tags.where(opts)

      if ActsAsTaggableOn::Utils.using_postgresql?
        group_columns = grouped_column_names_for(ActsAsTaggableOn::Tag)
        scope.order(Arel.sql("max(#{tagging_table_name}.created_at)")).group(group_columns)
      else
        scope.group("#{ActsAsTaggableOn::Tag.table_name}.#{ActsAsTaggableOn::Tag.primary_key}")
      end.to_a
    end

    ##
    # Returns all tags that are not owned of a given context
    def tags_on(context)
      scope = base_tags.where(["#{ActsAsTaggableOn::Tagging.table_name}.context = ? AND #{ActsAsTaggableOn::Tagging.table_name}.tagger_id IS NULL", context.to_s])
      # when preserving tag order, return tags in created order
      # if we added the order to the association this would always apply
      scope = scope.order("#{ActsAsTaggableOn::Tagging.table_name}.id") if self.class.preserve_tag_order?
      scope
    end

    def set_tag_list_on(context, new_list)
      add_custom_context(context)

      variable_name = "@#{context.to_s.singularize}_list"

      parsed_new_list = ActsAsTaggableOn.default_parser.new(new_list).parse

      instance_variable_set(variable_name, parsed_new_list)
    end

    def tagging_contexts
      self.class.tag_types.map(&:to_s) + custom_contexts
    end

    def reload(*args)
      self.class.tag_types.each do |context|
        instance_variable_set("@#{context.to_s.singularize}_list", nil)
        instance_variable_set("@all_#{context.to_s.singularize}_list", nil)
      end

      super(*args)
    end

    ##
    # Find existing tags or create non-existing tags
    def load_tags(tag_list)
      ActsAsTaggableOn::Tag.find_or_create_all_with_like_by_name(tag_list)
    end

    def save_tags
      tagging_contexts.each do |context|
        next unless tag_list_cache_set_on(context)
        # List of currently assigned tag names
        tag_list = tag_list_cache_on(context).uniq

        # Find existing tags or create non-existing tags:
        tags = find_or_create_tags_from_list_with_context(tag_list, context)

        # Tag objects for currently assigned tags
        current_tags = tags_on(context)

        # Tag maintenance based on whether preserving the created order of tags
        if self.class.preserve_tag_order?
          old_tags, new_tags = current_tags - tags, tags - current_tags

          shared_tags = current_tags & tags

          if shared_tags.any? && tags[0...shared_tags.size] != shared_tags
            index = shared_tags.each_with_index { |_, i| break i unless shared_tags[i] == tags[i] }

            # Update arrays of tag objects
            old_tags |= current_tags[index...current_tags.size]
            new_tags |= current_tags[index...current_tags.size] & shared_tags

            # Order the array of tag objects to match the tag list
            new_tags = tags.map do |t|
              new_tags.find { |n| n.name.downcase == t.name.downcase }
            end.compact
          end
        else
          # Delete discarded tags and create new tags
          old_tags = current_tags - tags
          new_tags = tags - current_tags
        end

        # Destroy old taggings:
        if old_tags.present?
          taggings.not_owned.by_context(context).where(tag_id: old_tags).destroy_all
        end

        # Create new taggings:
        new_tags.each do |tag|
          taggings.create!(tag_id: tag.id, context: context.to_s, taggable: self)
        end
      end

      true
    end

    private

    def ensure_included_cache_methods!
      self.class.columns
    end

    # Filters the tag lists from the attribute names.
    def attributes_for_update(attribute_names)
      tag_lists = tag_types.map {|tags_type| "#{tags_type.to_s.singularize}_list"}
      super.delete_if {|attr| tag_lists.include? attr }
    end

    # Filters the tag lists from the attribute names.
    def attributes_for_create(attribute_names)
      tag_lists = tag_types.map {|tags_type| "#{tags_type.to_s.singularize}_list"}
      super.delete_if {|attr| tag_lists.include? attr }
    end

    ##
    # Override this hook if you wish to subclass {ActsAsTaggableOn::Tag} --
    # context is provided so that you may conditionally use a Tag subclass
    # only for some contexts.
    #
    # @example Custom Tag class for one context
    #   class Company < ActiveRecord::Base
    #     acts_as_taggable_on :markets, :locations
    #
    #     def find_or_create_tags_from_list_with_context(tag_list, context)
    #       if context.to_sym == :markets
    #         MarketTag.find_or_create_all_with_like_by_name(tag_list)
    #       else
    #         super
    #       end
    #     end
    #
    # @param [Array<String>] tag_list Tags to find or create
    # @param [Symbol] context The tag context for the tag_list
    def find_or_create_tags_from_list_with_context(tag_list, _context)
      load_tags(tag_list)
    end
  end
end

