module InferredCrumpets
  class Builder
    attr_reader :view_context, :subject, :parents

    def self.build_inferred_crumbs!(view_context)
      subject = view_context.current_object rescue view_context.collection rescue nil
      return unless subject
      parents = [view_context.parent_object].compact rescue []
      build_all!(view_context, subject, parents)
    end

    def self.build_all!(view_context, subject, parents = [])
      new(view_context, subject, parents).build_all!
    end

    def self.build_single!(view_context, subject)
      new(view_context, subject).build_single!
    end

    def initialize(view_context, subject, parents = [])
      @view_context = view_context
      @subject      = subject
      @parents      = parents
    end

    def build_all!
      build_crumbs_for_parents!
      build_crumb_for_collection!
      build_crumb_for_action!
    end

    def build_single!
      build_crumb_for_subject!
    end

    private

    def build_crumbs_for_parents!
      parents.each do |parent|
        Builder.build_single!(view_context, parent)
      end
    end

    def build_crumb_for_collection!
      if subject.is_a?(ActiveRecord::Relation)
        view_context.crumbs.add_crumb subject_name.pluralize.titleize
      elsif subject.is_a?(ActiveRecord::Base)
        view_context.crumbs.add_crumb subject.class.table_name.titleize, url_for_collection
      end
    end

    def build_crumb_for_action!
      return unless subject.is_a?(ActiveRecord::Base)

      if %w(new create).include?(action)
        view_context.crumbs.add_crumb('New', wrapper_options: { class: 'active' })
        return
      end

      build_crumb_for_subject!
      if %w(edit update).include?(action)
        view_context.crumbs.add_crumb('Edit', wrapper_options: { class: 'active' })
      end
    end

    def build_crumb_for_subject!
      view_context.crumbs.add_crumb(subject_name, url_for_subject)
    end

    def url_for_subject
      return unless can_route?(:show, id: subject.id)
      view_context.url_for(shallow? ? subject : subject_with_parents)
    end

    def url_for_collection
      return view_context.objects_path if view_context.objects_path.present?
      return unless can_route?(:index)
      view_context.url_for(class_with_parents)
    end

    def subject_requires_transformation?
      subject.respond_to?(:becomes) && view_context.url_for((parents + [subject.class]).compact).blank?
    rescue NoMethodError
      true
    end

    def transformed_subject
      subject_requires_transformation? ? subject.becomes(subject.class.base_class) : subject
    end

    def shallow?
      view_context.url_for(subject)
    rescue NoMethodError
      false
    end

    def can_route?(action, params = {})
      view_context.url_for({
        action:     action,
        controller: subject.class.table_name,
      }.merge(params))
    rescue ActionController::RoutingError
      false
    end

    def action
      view_context.params[:action]
    end

    def subject_name
      subject.respond_to?(:name) && subject.name.present? ? subject.name : subject.to_s
    end

    def class_with_parents
      (parents + [transformed_subject.class]).compact
    end

    def subject_with_parents
      (parents + [transformed_subject]).compact
    end

    def inherited_resources?
      defined?(InheritedResources) && view_context.controller.responder == InheritedResources::Responder
    end
  end
end