require 'amsi/attribute_parser'
require_relative 'base/attribute_store'

module Amsi
  module Model
    # Base class for models, which are the return values from Requests
    class Base
      class << self
        attr_accessor :attribute_store
      end

      # Create a DSL to define the models attributes and their data types. This
      # bit of meta-programming will create a class method for each data type
      # to define the model's attributes of the type, e.g.
      #
      #   class LostAndFound < Base
      #     date_attr :found_date, :lost_date
      #   end
      #
      # When a new LostAndFound is initialized (from an AMSI response hash,
      # that may have the keys 'founddate' and 'lostdate'), it will create
      # attribute readers for #found_date and #lost_date that return Date
      # instances.
      #
      # Boolean attributes will have the existential '?', e.g.
      #
      #   class LostAndFound < Base
      #     boolean_attr :found
      #   end
      #
      # lost_and_found = LostAndFound.new('foundbit' => '1')
      # lost_and_found.found?
      # # => true
      %i[
        boolean date date_time decimal integer object string phone
      ].each do |data_type|
        define_singleton_method "#{data_type}_attrs" do |*attrs|
          self.attribute_store ||= AttributeStore.new(self)
          attribute_store.add(data_type, attrs).each do |attribute|
            define_method attribute.accessor_name do
              instance_variable_get("@#{attribute.name}")
            end
          end
        end
      end

      # Initialize a new model with the response hash from AMSI. Attribute
      # values are parsed into their configured data types.
      #
      # @param attrs [Hash<String, Object>] the response hash from AMSI.
      #   Attribute keys are case insensitive.
      def initialize(attrs = {})
        attrs.each do |attr, value|
          attribute = self.class.attribute_store.find(attr)
          next unless attribute
          parser = AttributeParser.new(value: value, type: attribute.type)
          instance_variable_set("@#{attribute.name}", parser.parse)
        end
      end
    end

    private_constant :Base
  end
end