module Paid
  class APIResource

    class << self
      # The default :id method is deprecated and isn't useful to us
      if method_defined?(:id)
        undef :id
      end
    end

    # The default :id method is deprecated and isn't useful to us
    if method_defined?(:id)
      undef :id
    end

    attr_reader :api_method
    attr_reader :json

    def initialize(json=nil, api_method=nil)
      refresh_from(json)
    end

    def refresh_from(json={}, api_method=nil)
      unless json.is_a?(Hash)
        json = { :id => json }
      end
      json = Util.symbolize_keys(json)

      # Clear or write over any old data
      clear_api_attributes
      @api_method = api_method
      @json = Util.sorta_deep_clone(json)

      # Use json (not the @json, the cloned copy)
      json.each do |k, v|
        if self.class.api_attribute_names.include?(k.to_sym)
          instance_variable_set("@#{k}", determine_api_attribute_value(k, v))
        end
      end
      self
    end

    def inspect
      id_string = (self.respond_to?(:id) && !self.id.nil?) ? " id=#{self.id}" : ""
      "#<#{self.class}:0x#{self.object_id.to_s(16)}#{id_string}> Attributes: " + JSON.pretty_generate(inspect_api_attributes)
    end

    def inspect_nested
      id_string = (self.respond_to?(:id) && !self.id.nil?) ? " id=#{self.id}" : ""
      "#<#{self.class}:0x#{self.object_id.to_s(16)}#{id_string}>"
    end

    def to_json(*args)
      JSON.generate(api_attributes)
    end

    def self.api_attribute_names
      @api_attributes.map(&:first)
    end

    def api_attributes
      ret = {}
      self.class.api_attribute_names.each do |attribute|
        ret[attribute] = self.send(attribute)
      end
      ret
    end

    def inspect_api_attributes
      ret = {}
      api_attributes.each do |k, v|
        if v.is_a?(APIResource)
          ret[k] = v.inspect_nested
        else
          ret[k] = v
        end
      end
      ret
    end

    # TODO(joncalhoun): Make this work for nested class construction.
    def changed_api_attributes
      ret = {}
      self.api_attributes.each do |name, value|
        if @json[name] != value
          ret[name] = value
        end
      end
      ret
    end

    def clear_api_attributes
      self.class.api_attribute_names.each do |name|
        instance_variable_set("@#{name}", nil)
      end
    end

    def self.determine_api_attribute_value(name, raw_value)
      if @api_attributes[name] && @api_attributes[name].has_key?(:constructor)
        klass = Util.constantize(@api_attributes[name][:constructor])
        if(klass.respond_to?(:construct))
          klass.construct(raw_value)
        else
          klass.new(raw_value)
        end
      else
        raw_value
      end
    end
    def determine_api_attribute_value(name, raw_value)
      self.class.determine_api_attribute_value(name, raw_value)
    end


    def self.api_subclasses
      return @api_subclasses ||= Set.new
    end

    def self.api_subclass_fetch(name)
      @api_subclasses_hash ||= {}
      if @api_subclasses_hash.has_key?(name)
        @api_subclasses_hash[name]
      end
    end

    def self.register_api_subclass(subclass, name=nil)
      @api_subclasses ||= Set.new
      @api_subclasses << subclass

      unless name.nil?
        @api_subclasses_hash ||= {}
        @api_subclasses_hash[name] = subclass
      end
    end

    @api_attributes = {}
  end
end