Association = Struct.new(:klass, :name, :macro, :options)

Column = Struct.new(:name, :type, :limit) do
  # Returns +true+ if the column is either of type integer, float or decimal.
  def number?
    type == :integer || type == :float || type == :decimal
  end
end

Relation = Struct.new(:all) do
  def where(conditions = nil)
    self.class.new conditions ? all.first : all
  end

  def order(conditions = nil)
    self.class.new conditions ? all.last : all
  end

  alias_method :to_a, :all
end

Company = Struct.new(:id, :name) do
  extend ActiveModel::Naming
  include ActiveModel::Conversion

  class << self
    delegate :order, :where, to: :_relation
  end

  def self._relation
    Relation.new(all)
  end

  def self.all
    (1..3).map { |i| new(i, "#{name} #{i}") }
  end

  def persisted?
    true
  end
end

class Tag < Company; end

TagGroup = Struct.new(:id, :name, :tags)

class User
  extend ActiveModel::Naming
  include ActiveModel::Conversion

  attr_accessor :id, :name, :company, :company_id, :time_zone, :active, :age,
    :description, :created_at, :updated_at, :credit_limit, :password, :url,
    :delivery_time, :born_at, :special_company_id, :country, :tags, :tag_ids,
    :avatar, :home_picture, :email, :status, :residence_country, :phone_number,
    :post_count, :lock_version, :amount, :attempts, :action, :credit_card, :gender

  def initialize(options={})
    @new_record = false
    options.each do |key, value|
      send("#{key}=", value)
    end if options
  end

  def new_record!
    @new_record = true
  end

  def persisted?
    !@new_record
  end

  def company_attributes=(*)
  end

  def tags_attributes=(*)
  end

  def column_for_attribute(attribute)
    column_type, limit = case attribute.to_sym
      when :name, :status, :password then [:string, 100]
      when :description   then [:text, 200]
      when :age           then :integer
      when :credit_limit  then [:decimal, 15]
      when :active        then :boolean
      when :born_at       then :date
      when :delivery_time then :time
      when :created_at    then :datetime
      when :updated_at    then :timestamp
      when :lock_version  then :integer
      when :home_picture  then :string
      when :amount        then :integer
      when :attempts      then :integer
      when :action        then :string
      when :credit_card   then :string
    end
    Column.new(attribute, column_type, limit)
  end

  def self.human_attribute_name(attribute)
    case attribute
      when 'name'
        'Super User Name!'
      when 'description'
        'User Description!'
      when 'company'
        'Company Human Name!'
      else
        attribute.humanize
    end
  end

  def self.reflect_on_association(association)
    case association
      when :company
        Association.new(Company, association, :belongs_to, {})
      when :tags
        Association.new(Tag, association, :has_many, {})
      when :first_company
        Association.new(Company, association, :has_one, {})
      when :special_company
        Association.new(Company, association, :belongs_to, { conditions: { id: 1 } })
    end
  end

  def errors
    @errors ||= begin
      hash = Hash.new { |h,k| h[k] = [] }
      hash.merge!(
        name: ["can't be blank"],
        description: ["must be longer than 15 characters"],
        age: ["is not a number", "must be greater than 18"],
        company: ["company must be present"],
        company_id: ["must be valid"]
      )
    end
  end

  def self.readonly_attributes
    ["credit_card"]
  end
end

class ValidatingUser < User
  include ActiveModel::Validations
  validates :name, presence: true
  validates :company, presence: true
  validates :age, presence: true, if: Proc.new { |user| user.name }
  validates :amount, presence: true, unless: Proc.new { |user| user.age }

  validates :action,            presence: true, on: :create
  validates :credit_limit,      presence: true, on: :save
  validates :phone_number,      presence: true, on: :update

  validates_numericality_of :age,
    greater_than_or_equal_to: 18,
    less_than_or_equal_to: 99,
    only_integer: true
  validates_numericality_of :amount,
    greater_than: :min_amount,
    less_than: :max_amount,
    only_integer: true
  validates_numericality_of :attempts,
    greater_than_or_equal_to: :min_attempts,
    less_than_or_equal_to: :max_attempts,
    only_integer: true
  validates_length_of :name, maximum: 25
  validates_length_of :description, maximum: 50
  validates_length_of :action, maximum: 10, tokenizer: lambda { |str| str.scan(/\w+/) }
  validates_length_of :home_picture, is: 12

  def min_amount
    10
  end

  def max_amount
    100
  end

  def min_attempts
    1
  end

  def max_attempts
    100
  end
end

class OtherValidatingUser < User
  include ActiveModel::Validations
  validates_numericality_of :age,
    greater_than: 17,
    less_than: 100,
    only_integer: true
  validates_numericality_of :amount,
    greater_than: Proc.new { |user| user.age },
    less_than: Proc.new { |user| user.age + 100 },
    only_integer: true
  validates_numericality_of :attempts,
    greater_than_or_equal_to: Proc.new { |user| user.age },
    less_than_or_equal_to: Proc.new { |user| user.age + 100 },
    only_integer: true

  validates_format_of :country, with: /\w+/
  validates_format_of :name, with: Proc.new { /\w+/ }
  validates_format_of :description, without: /\d+/
end

class HashBackedAuthor < Hash
  extend ActiveModel::Naming
  include ActiveModel::Conversion

  def persisted?; false; end

  def name
    'hash backed author'
  end
end