require "method_watcher/version"

module MethodWatcher
  class << self
    def init_method_watcher mod
      super_watch_methods = (mod.respond_to?(:superclass) && mod.superclass && mod.superclass.instance_variable_get("@_watch_methods")) || {}
      mod.instance_variable_set "@_watch_methods", super_watch_methods.merge({})
      mod.instance_variable_set "@_watch_method", false
    end

    def included mod
      MethodWatcher.init_method_watcher mod
      mod.singleton_class.class_eval do
        def watch_methods *methods
          if methods.empty?
            @_watch_method = true 
          else
            methods.each do |method|
              @_watch_methods[method.to_sym] = self
            end
          end
        end

        def unwatch_methods *methods
          if methods.empty?
            @_watch_method = false 
          else
            methods.each do |method|
              @_watch_methods.delete method.to_sym
            end
          end
        end

        def method_added method
          super
          if @_watch_methods.has_key?(method.to_sym)
            @_watch_methods[method].method_overriding method
          end

          watch_methods method if @_watch_method
        end

        def method_overriding method
          warn "method #{self}##{method} is overridden"
        end


        def inherited mod
          super
          MethodWatcher.init_method_watcher mod
        end
      end
    end
  end
end