module Syspro
  class SysproObject

    # Re-initializes the object based on a hash of values (usually one that's
    # come back from an API call). Adds or removes value accessors as necessary
    # and updates the state of internal data.
    #
    # Protected on purpose! Please do not expose.
    #
    # ==== Options
    #
    # * +:values:+ Hash used to update accessors and values.
    # * +:opts:+ Options for SysproObject like an API key.
    # * +:partial:+ Indicates that the re-initialization should not attempt to
    #   remove accessors.
    def initialize_from(values, opts, partial = false)
      @opts = Util.normalize_opts(opts)

      # the `#send` is here so that we can keep this method private
      @original_values = self.class.send(:deep_copy, values)

      removed = partial ? Set.new : Set.new(@values.keys - values.keys)
      added = Set.new(values.keys - @values.keys)

      # Wipe old state before setting new.  This is useful for e.g. updating a
      # customer, where there is no persistent card parameter.  Mark those values
      # which don't persist as transient

      remove_accessors(removed)
      add_accessors(added, values)

      removed.each do |k|
        @values.delete(k)
        @transient_values.add(k)
        @unsaved_values.delete(k)
      end

      update_attributes(values, opts, dirty: false)
      values.each_key do |k|
        @transient_values.delete(k)
        @unsaved_values.delete(k)
      end

      self
    end

    def remove_accessors(keys)
      # not available in the #instance_eval below
      protected_fields = self.class.protected_fields

      metaclass.instance_eval do
        keys.each do |k|
          next if protected_fields.include?(k)
          next if @@permanent_attributes.include?(k)

          # Remove methods for the accessor's reader and writer.
          [k, :"#{k}=", :"#{k}?"].each do |method_name|
            remove_method(method_name) if method_defined?(method_name)
          end
        end
      end
    end

    def add_accessors(keys, values)
      # not available in the #instance_eval below
      protected_fields = self.class.protected_fields

      metaclass.instance_eval do
        keys.each do |k|
          next if protected_fields.include?(k)
          next if @@permanent_attributes.include?(k)

          if k == :method
            # Object#method is a built-in Ruby method that accepts a symbol
            # and returns the corresponding Method object. Because the API may
            # also use `method` as a field name, we check the arity of *args
            # to decide whether to act as a getter or call the parent method.
            define_method(k) { |*args| args.empty? ? @values[k] : super(*args) }
          else
            define_method(k) { @values[k] }
          end

          define_method(:"#{k}=") do |v|
            if v == ""
              raise ArgumentError, "You cannot set #{k} to an empty string. " \
                "We interpret empty strings as nil in requests. " \
                "You may set (object).#{k} = nil to delete the property."
            end
            @values[k] = Util.convert_to_stripe_object(v, @opts)
            dirty_value!(@values[k])
            @unsaved_values.add(k)
          end

          if [FalseClass, TrueClass].include?(values[k].class)
            define_method(:"#{k}?") { @values[k] }
          end
        end
      end
    end
  end
end