module ActiveData
  module Model
    module Associations
      class Base
        attr_accessor :owner, :reflection
        delegate :macro, :collection?, to: :reflection

        def initialize owner, reflection
          @owner, @reflection = owner, reflection
          @evar_loaded = owner.persisted?
          reset
        end

        def reset
          @loaded = false
          @target = nil
        end

        def evar_loaded?
          !!@evar_loaded
        end

        def loaded?
          !!@loaded
        end

        def loaded!
          @evar_loaded = true
          @loaded = true
        end

        def target
          return @target if loaded?
          self.target = load_target
        end

        def reload
          reset
          target
        end

        def apply_changes!
          apply_changes or raise ActiveData::AssociationChangesNotApplied
        end

        def transaction &block
          data = Marshal.load(Marshal.dump(read_source))
          block.call
        rescue StandardError => e
          write_source data
          reload
          raise e
        end

        def inspect
          "#<#{reflection.macro.to_s.camelize} #{target.inspect.truncate(50, omission: collection? ? '...]' : '...')}>"
        end

      private

        def read_source
          reflection.read_source owner
        end

        def write_source value
          reflection.write_source owner, value
        end

        def target_for_inspect
          if value.length > 50
            "#{value[0..50]}...".inspect
          else
            value.inspect
          end
        end
      end
    end
  end
end