require 'error'

module MyApp
  
  # Define the that MyApp has an `Error`.
  # This makes it very easy to see if an exception came from your application what-so-ever.
  # 
  # This will define the `MyApp::Error` constant that is a `Class` that subclasses `::Error`.
  has_error
  
  # Define `Myapp::IntegerConversionError` class with a String (or anything responding to `to_s`).
  # 
  # This will add constant `IntegerConversionError` that subclasses `MyApp::Error`.
  has_error 'IntegerConversionError'
  
  # Define with a Symbol (or anything responding to `to_sym`).
  # If the given Object does not respond to `to_s`, it then checks to see if it responds to
  # `to_sym`. If it does, it simply converts the Object to a Symbol, then to a String using `to_s`.
  # When you pass the `message` option, it will be returned when you call `Error#to_s`.
  # 
  # Defines 'StringConversionError' that is a `Class` that subclasses `MyApp::Error`.
  has_error :string_conversion do |error|
    error.message { "`#@target` is not a String or does not respond to #to_s." }
  end
  
  # Define with a Hash (or anything responding to `to_h`).
  # Both the key and the value conform to the above rules.
  # 
  # Defines 'InvalidEmailError' that is a `Class` that subclasses `MyApp::StringConversionError`.
  has_error 'invalid_email' => StringConversionError do |e|
    e.message { "email is not a valid email address." }
  end
  
  # Advanced usage.
  has_error invalid_gender: 'String Conversion' do |e|
    e.message { "#{@target || 'gender'} must be either `male` or `female`." }
    e.unless { "#{@target || 'gender'} must be either `male` or `female`." }
  end
  
  class User
    def initialize(name, email, age, gender)
      # Raise error in a normal fashion.
      # The argument must be a `Hash`, subclass of `Hash`, or respond to `to_hash`, ot `to_h`.
      # 
      # All options passed to the `Hash` will be defined as instance variables on the instance of
      # the `Error` instance before the `message`, `if`, and `unless` `Proc`s are `instance_eval`'d
      # on the `Error` instance.
      raise StringConversionError, target: :name unless name.is_a?(String) || name.respond_to?(:string)
      
      raise InvalidEmailError, email: emai
      fail :invalid_gender, gender: gender
    end
  end
end