#
# Author:: Doug MacEachern (<dougm@vmware.com>)
# Copyright:: Copyright 2010-2016, VMware, 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/provider"
require "chef/resource/env"

class Chef
  class Provider
    class Env < Chef::Provider
      attr_accessor :key_exists

      provides :env, os: "!windows"

      def whyrun_supported?
        false
      end

      def initialize(new_resource, run_context)
        super
        @key_exists = true
      end

      def load_current_resource
        @current_resource = Chef::Resource::Env.new(new_resource.name)
        current_resource.key_name(new_resource.key_name)

        if env_key_exists(new_resource.key_name)
          current_resource.value(env_value(new_resource.key_name))
        else
          @key_exists = false
          Chef::Log.debug("#{new_resource} key does not exist")
        end

        current_resource
      end

      def env_value(key_name)
        raise Chef::Exceptions::Env, "#{self} provider does not implement env_value!"
      end

      def env_key_exists(key_name)
        env_value(key_name) ? true : false
      end

      # Check to see if value needs any changes
      #
      # ==== Returns
      # <true>:: If a change is required
      # <false>:: If a change is not required
      def requires_modify_or_create?
        if new_resource.delim
          #e.g. check for existing value within PATH
          new_values.inject(0) do |index, val|
            next_index = current_values.find_index val
            return true if next_index.nil? || next_index < index
            next_index
          end
          false
        else
          new_resource.value != current_resource.value
        end
      end

      alias_method :compare_value, :requires_modify_or_create?

      def action_create
        if @key_exists
          if requires_modify_or_create?
            modify_env
            Chef::Log.info("#{new_resource} altered")
            new_resource.updated_by_last_action(true)
          end
        else
          create_env
          Chef::Log.info("#{new_resource} created")
          new_resource.updated_by_last_action(true)
        end
      end

      #e.g. delete a PATH element
      #
      # ==== Returns
      # <true>:: If we handled the element case and caller should not delete the key
      # <false>:: Caller should delete the key, either no :delim was specific or value was empty
      #           after we removed the element.
      def delete_element
        return false unless new_resource.delim #no delim: delete the key
        needs_delete = new_values.any? { |v| current_values.include?(v) }
        if !needs_delete
          Chef::Log.debug("#{new_resource} element '#{new_resource.value}' does not exist")
          return true #do not delete the key
        else
          new_value =
            current_values.select do |item|
              not new_values.include?(item)
            end.join(new_resource.delim)

          if new_value.empty?
            return false #nothing left here, delete the key
          else
            old_value = new_resource.value(new_value)
            create_env
            Chef::Log.debug("#{new_resource} deleted #{old_value} element")
            new_resource.updated_by_last_action(true)
            return true #we removed the element and updated; do not delete the key
          end
        end
      end

      def action_delete
        if @key_exists && !delete_element
          delete_env
          Chef::Log.info("#{new_resource} deleted")
          new_resource.updated_by_last_action(true)
        end
      end

      def action_modify
        if @key_exists
          if requires_modify_or_create?
            modify_env
            Chef::Log.info("#{new_resource} modified")
            new_resource.updated_by_last_action(true)
          end
        else
          raise Chef::Exceptions::Env, "Cannot modify #{new_resource} - key does not exist!"
        end
      end

      def create_env
        raise Chef::Exceptions::UnsupportedAction, "#{self} does not support :#{new_resource.action}"
      end

      def delete_env
        raise Chef::Exceptions::UnsupportedAction, "#{self} does not support :delete"
      end

      def modify_env
        if new_resource.delim
          new_resource.value((new_values + current_values).uniq.join(new_resource.delim))
        end
        create_env
      end

      # Returns the current values to split by delimiter
      def current_values
        @current_values ||= current_resource.value.split(new_resource.delim)
      end

      # Returns the new values to split by delimiter
      def new_values
        @new_values ||= new_resource.value.split(new_resource.delim)
      end
    end
  end
end