require "active_support"
require "active_model"
require "chronic"

module BetterDatePicker
  module Model
    extend ActiveSupport::Concern

    included do
      extend ClassMethods
      class_attribute :better_date_fields
      class_attribute :better_date_defaults
    end

    module ClassMethods
      def better_time_picker(field, options = {})
        self.better_date_fields ||= []
        self.better_date_defaults ||= {}

        define_method "#{field}=" do |date_val|
          #we don't want to clobber the ivar if we're setting via the string
          unless setting_via_string?
            val_to_set = date_val.nil? ? nil : date_val.strftime(self.class.better_date_format)
            instance_variable_set("@#{field}_date", val_to_set)
          end

          #if the setter is not defined as a method, just set the ivar
          begin
            super(date_val)
          rescue NoMethodError => e
            instance_variable_set("@#{field}", date_val)
          end

        end

        define_method "#{field}_date" do
          string_val = instance_variable_get("@#{field}_date")
          if string_val.nil?
            if the_date = self.send(field)
              the_date.strftime(self.class.better_date_format)
            end
          else
            string_val
          end
        end

        define_method "#{field}_date=" do |stringified_date|
          setting_via_string do
            instance_variable_set("@#{field}_date", stringified_date)
            self.send("#{field}=", Chronic.parse(stringified_date))
          end
          stringified_date
        end

        self.better_date_fields << field
        self.better_date_defaults[field] = options[:default]
      end

      def better_date_format
       "%m/%d/%Y"
      end
    end

    protected
    def setting_via_string(&block)
      begin
        @setting_via_string = true
        block.call
      ensure
        @setting_via_string = false
      end
    end

    def setting_via_string?
      @setting_via_string
    end
  end
end