module Rtml::Controller::State
  def find_or_build_state
    headers = request.headers
    if params[:terminal] && params[:terminal][:itid]
      itid = params[:terminal][:itid]
    elsif request.terminal?
      itid = headers['ITID'] || headers['HTTP_ITID'] || params['itid']
    else
      itid = headers['ITID'] || headers['HTTP_ITID'] || params['itid'] || 'web-browser'
    end
    
    @terminal_state = Rtml::State.find_by_itid(itid) || Rtml::State.new(:itid => itid,
                                                                        :model => params[:model])

    set_state_values
    verify_state unless request.post? || params.key?(:ignore_state) || !request.rtml?
  end

  def set_state_values
    state_variable_mapping.each do |tmlvar, state_attribute|
      if params[:terminal] && params[:terminal][state_attribute]
        value = params[:terminal][state_attribute]
      else
        code = "params['#{tmlvar.to_s.gsub(/\./, '\'][\'')}']"
        begin
          value = eval(code, binding, __FILE__, __LINE__)
        rescue NoMethodError
          value = nil
        end
      end
      state[state_attribute] = value if value
    end
  end

  def verify_state
    if @terminal_state.new_record?
      Rails.logger.debug "Terminal state for ITID #{@terminal_state[:itid]} needs to be created"
      render :rtml => 'get_state'
    elsif @terminal_state.updated_at < 1.day.ago
      Rails.logger.debug "Terminal state for ITID #{@terminal_state[:itid]} needs to be updated"
      render :rtml => 'get_state'
    end
  end

  def state
    @terminal_state
  end

  def save_state
    if @terminal_state.changed?
      @terminal_state.save # can fail silently
    end
    true
  end

  def state_variable_mapping
    self.class.state_variable_mapping
  end

  class << self
    def included(base)
      base.instance_eval do
        hide_action :find_or_build_state, :set_state_values, :verify_state, :save_state, :state, :state_variable_mapping
        before_filter :find_or_build_state
        after_filter :save_state
        helper_method :state

        def state_variable_mapping
          @state_variable_mapping ||= Rtml::State::VariableMapping.new
        end
      end
    end
  end
end