require 'active_model/forbidden_attributes_protection'

module ActiveRecord
  module AttributeAssignment
    extend ActiveSupport::Concern
    include ActiveModel::AttributeAssignment

    # Alias for ActiveModel::AttributeAssignment#assign_attributes. See ActiveModel::AttributeAssignment.
    def attributes=(attributes)
      assign_attributes(attributes)
    end

    private

    def _assign_attributes(attributes) # :nodoc:
      multi_parameter_attributes  = {}
      nested_parameter_attributes = {}

      attributes.each do |k, v|
        if k.include?("(")
          multi_parameter_attributes[k] = attributes.delete(k)
        elsif v.is_a?(Hash)
          nested_parameter_attributes[k] = attributes.delete(k)
        end
      end
      super(attributes)

      assign_nested_parameter_attributes(nested_parameter_attributes) unless nested_parameter_attributes.empty?
      assign_multiparameter_attributes(multi_parameter_attributes) unless multi_parameter_attributes.empty?
    end

    # Assign any deferred nested attributes after the base attributes have been set.
    def assign_nested_parameter_attributes(pairs)
      pairs.each { |k, v| _assign_attribute(k, v) }
    end

    # Instantiates objects for all attribute classes that needs more than one constructor parameter. This is done
    # by calling new on the column type or aggregation type (through composed_of) object with these parameters.
    # So having the pairs written_on(1) = "2004", written_on(2) = "6", written_on(3) = "24", will instantiate
    # written_on (a date type) with Date.new("2004", "6", "24"). You can also specify a typecast character in the
    # parentheses to have the parameters typecasted before they're used in the constructor. Use i for Fixnum and
    # f for Float. If all the values for a given attribute are empty, the attribute will be set to +nil+.
    def assign_multiparameter_attributes(pairs)
      execute_callstack_for_multiparameter_attributes(
        extract_callstack_for_multiparameter_attributes(pairs)
      )
    end

    def execute_callstack_for_multiparameter_attributes(callstack)
      errors = []
      callstack.each do |name, values_with_empty_parameters|
        begin
          if values_with_empty_parameters.each_value.all?(&:nil?)
            values = nil
          else
            values = values_with_empty_parameters
          end
          send("#{name}=", values)
        rescue => ex
          errors << AttributeAssignmentError.new("error on assignment #{values_with_empty_parameters.values.inspect} to #{name} (#{ex.message})", ex, name)
        end
      end
      unless errors.empty?
        error_descriptions = errors.map(&:message).join(",")
        raise MultiparameterAssignmentErrors.new(errors), "#{errors.size} error(s) on assignment of multiparameter attributes [#{error_descriptions}]"
      end
    end

    def extract_callstack_for_multiparameter_attributes(pairs)
      attributes = {}

      pairs.each do |(multiparameter_name, value)|
        attribute_name = multiparameter_name.split("(").first
        attributes[attribute_name] ||= {}

        parameter_value = value.empty? ? nil : type_cast_attribute_value(multiparameter_name, value)
        attributes[attribute_name][find_parameter_position(multiparameter_name)] ||= parameter_value
      end

      attributes
    end

    def type_cast_attribute_value(multiparameter_name, value)
      multiparameter_name =~ /\([0-9]*([if])\)/ ? value.send("to_" + $1) : value
    end

    def find_parameter_position(multiparameter_name)
      multiparameter_name.scan(/\(([0-9]*).*\)/).first.first.to_i
    end
  end
end