require File.join(File.dirname(__FILE__), 'event')
require File.join(File.dirname(__FILE__), 'state')
require File.join(File.dirname(__FILE__), 'persistence')

module AASM
  class InvalidTransition < Exception
  end
  
  def self.included(base) #:nodoc:
    base.extend AASM::ClassMethods
    AASM::Persistence.set_persistence(base)
  end

  module ClassMethods
    def aasm_initial_state(set_state=nil)
      if set_state
        aasm_initial_state = set_state
      else
        @aasm_initial_state
      end
    end
    
    def aasm_initial_state=(state)
      @aasm_initial_state = state
    end
    
    def aasm_state(name, options={})
      aasm_states << name unless aasm_states.include?(name)
      self.aasm_initial_state = name unless self.aasm_initial_state

      define_method("#{name.to_s}?") do
        aasm_current_state == name
      end
    end
    
    def aasm_event(name, &block)
      unless aasm_events.has_key?(name)
        aasm_events[name] = AASM::SupportingClasses::Event.new(name, &block)
      end

      define_method("#{name.to_s}!") do
        new_state = self.class.aasm_events[name].fire(self)
        unless new_state.nil?
          self.aasm_current_state = new_state
          true
        else
          false
        end
      end
    end

    def aasm_states
      @aasm_states ||= []
    end

    def aasm_events
      @aasm_events ||= {}
    end
  end

  # Instance methods
  def aasm_current_state
    return @aasm_current_state if @aasm_current_state

    if self.respond_to?(:aasm_read_state) || self.private_methods.include?('aasm_read_state')
      @aasm_current_state = aasm_read_state
    end
    return @aasm_current_state if @aasm_current_state
    self.class.aasm_initial_state
  end

  private
  def aasm_current_state=(state)
    @aasm_current_state = state
    if self.respond_to?(:aasm_write_state) || self.private_methods.include?('aasm_write_state')
      aasm_write_state(state)
    end
  end
end