#
# Author:: Adam Jacob (<adam@opscode.com>)
# Author:: Christopher Walters (<cw@opscode.com>)
# Author:: Daniel DeLeo (<dan@opscode.com>)
# Copyright:: Copyright (c) 2008-2012 Opscode, Inc.
# License:: Apache License, Version 2.0
#
# Licensed under the Apache License, Version 2.0 (the "License");
# you may not use this file except in compliance with the License.
# You may obtain a copy of the License at
#
#     http://www.apache.org/licenses/LICENSE-2.0
#
# Unless required by applicable law or agreed to in writing, software
# distributed under the License is distributed on an "AS IS" BASIS,
# WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
# See the License for the specific language governing permissions and
# limitations under the License.
#

require 'chef/resource'
require 'chef/resource_resolver'
require 'chef/node'
require 'chef/log'
require 'chef/exceptions'
require 'chef/mixin/convert_to_class_name'
require 'chef/mixin/from_file'
require 'chef/mixin/params_validate' # for DelayedEvaluator

class Chef
  class Resource

    # == Chef::Resource::LWRPBase
    # Base class for LWRP resources. Adds DSL sugar on top of Chef::Resource,
    # so attributes, default action, etc. can be defined with pleasing syntax.
    class LWRPBase < Resource

      NULL_ARG = Object.new

      # Class methods
      class <<self

        include Chef::Mixin::ConvertToClassName
        include Chef::Mixin::FromFile

        attr_accessor :loaded_lwrps

        def build_from_file(cookbook_name, filename, run_context)
          if LWRPBase.loaded_lwrps[filename]
            Chef::Log.info("LWRP resource #{filename} from cookbook #{cookbook_name} has already been loaded!  Skipping the reload.")
            return loaded_lwrps[filename]
          end

          resource_name = filename_to_qualified_string(cookbook_name, filename)

          # We load the class first to give it a chance to set its own name
          resource_class = Class.new(self)
          resource_class.resource_name = resource_name
          resource_class.run_context = run_context
          resource_class.provides resource_name.to_sym
          resource_class.class_from_file(filename)

          # Respect resource_name set inside the LWRP
          resource_class.instance_eval do
            define_singleton_method(:to_s) do
              "LWRP resource #{resource_name} from cookbook #{cookbook_name}"
            end
            define_singleton_method(:inspect) { to_s }
          end

          Chef::Log.debug("Loaded contents of #{filename} into resource #{resource_name} (#{resource_class})")

          LWRPBase.loaded_lwrps[filename] = true

          Chef::Resource.register_deprecated_lwrp_class(resource_class, convert_to_class_name(resource_name))

          resource_class
        end

        def resource_name(arg = NULL_ARG)
          if arg.equal?(NULL_ARG)
            @resource_name
          else
            @resource_name = arg
          end
        end

        alias_method :resource_name=, :resource_name

        # Define an attribute on this resource, including optional validation
        # parameters.
        def attribute(attr_name, validation_opts={})
          define_method(attr_name) do |arg=nil|
            set_or_return(attr_name.to_sym, arg, validation_opts)
          end
        end

        # Sets the default action
        def default_action(action_name=NULL_ARG)
          unless action_name.equal?(NULL_ARG)
            @actions ||= []
            if action_name.is_a?(Array)
              action = action_name.map { |arg| arg.to_sym }
              @actions = actions | action
              @default_action = action
            else
              action = action_name.to_sym
              @actions.push(action) unless @actions.include?(action)
              @default_action = [action]
            end
          end

          @default_action ||= from_superclass(:default_action)
        end

        # Adds +action_names+ to the list of valid actions for this resource.
        def actions(*action_names)
          if action_names.empty?
            defined?(@actions) ? @actions : from_superclass(:actions, []).dup
          else
            # BC-compat way for checking if actions have already been defined
            if defined?(@actions)
              @actions.push(*action_names)
            else
              @actions = action_names
            end
          end
        end

        # @deprecated
        def valid_actions(*args)
          Chef::Log.warn("`valid_actions' is deprecated, please use actions `instead'!")
          actions(*args)
        end

        # Set the run context on the class. Used to provide access to the node
        # during class definition.
        attr_accessor :run_context

        def node
          run_context ? run_context.node : nil
        end

        def lazy(&block)
          DelayedEvaluator.new(&block)
        end

        protected

        def loaded_lwrps
          @loaded_lwrps ||= {}
        end

        private

        # Get the value from the superclass, if it responds, otherwise return
        # +nil+. Since class instance variables are **not** inherited upon
        # subclassing, this is a required check to ensure Chef pulls the
        # +default_action+ and other DSL-y methods when extending LWRP::Base.
        def from_superclass(m, default = nil)
          return default if superclass == Chef::Resource::LWRPBase
          superclass.respond_to?(m) ? superclass.send(m) : default
        end
      end

      private

      # Default initializer. Sets the default action and allowed actions.
      def initialize(name, run_context=nil)
        super(name, run_context)

        # Raise an exception if the resource_name was not defined
        if self.class.resource_name.nil?
          raise Chef::Exceptions::InvalidResourceSpecification,
            "You must specify `resource_name'!"
        end

        @resource_name = self.class.resource_name.to_sym
        @action = self.class.default_action
        allowed_actions.push(self.class.actions).flatten!
      end
    end
  end
end