module Ddr
  module Auth
    class Ability

      include Hydra::PolicyAwareAbility

      self.ability_logic.insert(self.ability_logic.index(:custom_permissions), :action_aliases, :collection_permissions,
            :discover_permissions, :events_permissions, :attachment_permissions, :children_permissions, :upload_permissions)

      def action_aliases
        # read aliases
        alias_action :attachments, :collection_info, :components, :event, :events, :items, :targets, to: :read
        # edit/update aliases
        alias_action :permissions, :default_permissions, to: :update
      end

      def collection_permissions
        can :create, Collection if current_user.member_of?(Ddr::Auth.collection_creators_group)
      end

      def read_permissions
        super
        can :read, ActiveFedora::Datastream do |ds|
          can? :read, ds.pid
        end
      end

      def edit_permissions
        super
        can [:edit, :update, :destroy], ActiveFedora::Datastream do |action, ds|
          can? action, ds.pid
        end
      end

      def events_permissions
        can :read, Ddr::Events::Event do |e|
          can? :read, e.pid
        end
      end
            
      def download_permissions
        can :download, ActiveFedora::Base do |obj|
          if obj.is_a? Component
            can?(:edit, obj) || (can?(:read, obj) && current_user.has_role?(obj, :downloader))
          else
            can? :read, obj
          end
        end
        can :download, SolrDocument do |doc|
          if doc.active_fedora_model == "Component"
            can?(:edit, doc) || (can?(:read, doc) && current_user.has_role?(doc, :downloader))
          else
            can? :read, doc
          end
        end
        can :download, ActiveFedora::Datastream do |ds|
          if ds.dsid == Ddr::Datastreams::CONTENT and ds.digital_object.original_class == Component
            can?(:edit, ds.pid) || (can?(:read, ds.pid) && current_user.has_role?(solr_doc(ds.pid), :downloader))
          else
            can? :read, ds.pid
          end
        end
      end

      def upload_permissions
        can :upload, Ddr::Models::HasContent do |obj|
          can?(:edit, obj)
        end
      end

      def children_permissions
        can :add_children, Ddr::Models::HasChildren do |obj|
          can?(:edit, obj)
        end
      end

      # Mimics Hydra::Ability#read_permissions
      def discover_permissions
        can :discover, String do |pid|
          test_discover(pid)
        end

        can :discover, ActiveFedora::Base do |obj|
          test_discover(obj.pid)
        end 
        
        can :discover, SolrDocument do |obj|
          cache.put(obj.id, obj)
          test_discover(obj.id)
        end 
      end

      def attachment_permissions
        can :add_attachment, Ddr::Models::HasAttachments do |obj|
          can?(:edit, obj)
        end
      end

      # Mimics Hydra::Ability#test_read + Hydra::PolicyAwareAbility#test_read in one method
      def test_discover(pid)
        Rails.logger.debug("[CANCAN] Checking discover permissions for user: #{current_user.user_key} with groups: #{user_groups.inspect}")
        group_intersection = user_groups & discover_groups(pid)
        result = !group_intersection.empty? || discover_persons(pid).include?(current_user.user_key)
        result || test_discover_from_policy(pid)
      end 

      # Mimics Hydra::PolicyAwareAbility#test_read_from_policy
      def test_discover_from_policy(object_pid)
        policy_pid = policy_pid_for(object_pid)
        if policy_pid.nil?
          return false
        else
          Rails.logger.debug("[CANCAN] -policy- Does the POLICY #{policy_pid} provide DISCOVER permissions for #{current_user.user_key}?")
          group_intersection = user_groups & discover_groups_from_policy(policy_pid)
          result = !group_intersection.empty? || discover_persons_from_policy(policy_pid).include?(current_user.user_key)
          Rails.logger.debug("[CANCAN] -policy- decision: #{result}")
          result
        end
      end 

      # Mimics Hydra::Ability#read_groups
      def discover_groups(pid)
        doc = permissions_doc(pid)
        return [] if doc.nil?
        dg = edit_groups(pid) | read_groups(pid) | (doc[self.class.discover_group_field] || [])
        Rails.logger.debug("[CANCAN] discover_groups: #{dg.inspect}")
        return dg
      end

      # Mimics Hydra::PolicyAwareAbility#read_groups_from_policy
      def discover_groups_from_policy(policy_pid)
        policy_permissions = policy_permissions_doc(policy_pid)
        discover_group_field = Hydra.config[:permissions][:inheritable][:discover][:group]
        dg = edit_groups_from_policy(policy_pid) | read_groups_from_policy(policy_pid) | ((policy_permissions == nil || policy_permissions.fetch(discover_group_field, nil) == nil) ? [] : policy_permissions.fetch(discover_group_field, nil))
        Rails.logger.debug("[CANCAN] -policy- discover_groups: #{dg.inspect}")
        return dg
      end

      # Mimics Hydra::Ability#read_persons
      def discover_persons(pid)
        doc = permissions_doc(pid)
        return [] if doc.nil?
        dp = edit_users(pid) | read_users(pid) | (doc[self.class.discover_person_field] || [])
        Rails.logger.debug("[CANCAN] discover_persons: #{dp.inspect}")
        return dp
      end

      def discover_persons_from_policy(policy_pid)
        policy_permissions = policy_permissions_doc(policy_pid)
        discover_individual_field = Hydra.config[:permissions][:inheritable][:discover][:individual]
        dp = edit_persons_from_policy(policy_pid) | read_persons_from_policy(policy_pid) | ((policy_permissions == nil || policy_permissions.fetch(discover_individual_field, nil) == nil) ? [] : policy_permissions.fetch(discover_individual_field, nil))
        Rails.logger.debug("[CANCAN] -policy- discover_persons: #{dp.inspect}")
        return dp
      end

      def self.discover_person_field 
        Hydra.config[:permissions][:discover][:individual]
      end

      def self.discover_group_field
        Hydra.config[:permissions][:discover][:group]
      end

      private

      def authenticated_user?
        current_user.persisted?
      end

      def solr_doc(pid)
        SolrDocument.new(ActiveFedora::SolrService.query("id:\"#{pid}\"", rows: 1).first)
      end

    end
  end
end