#
# Author:: Adam Jacob (<adam@opscode.com>)
# Author:: Tim Hinderliter (<tim@opscode.com>)
# Author:: Christopher Walters (<cw@opscode.com>)
# Author:: Daniel DeLeo (<dan@getchef.com>)
# Copyright:: Copyright 2008-2014 Chef Software, 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/log'
require 'chef/rest'
require 'chef/run_context'
require 'chef/config'
require 'chef/node'

class Chef
  module PolicyBuilder

    # Policyfile is an experimental policy builder implementation that gets run
    # list and cookbook version information from a single document.
    #
    # == WARNING
    # This implementation is experimental. It may be changed in incompatible
    # ways in minor or even patch releases, or even abandoned altogether. If
    # using this with other tools, you may be forced to upgrade those tools in
    # lockstep with chef-client because of incompatible behavior changes.
    #
    # == Unsupported Options:
    # * override_runlist:: This could potentially be integrated into the
    # policyfile, or replaced with a similar feature that has different
    # semantics.
    # * specific_recipes:: put more design thought into this use case.
    # * run_list in json_attribs:: would be ignored anyway, so it raises an error.
    # * chef-solo:: not currently supported. Need more design thought around
    # how this should work.
    class Policyfile

      class UnsupportedFeature < StandardError; end

      class PolicyfileError < StandardError; end

      RunListExpansionIsh = Struct.new(:recipes, :roles)

      attr_reader :events
      attr_reader :node
      attr_reader :node_name
      attr_reader :ohai_data
      attr_reader :json_attribs
      attr_reader :run_context

      def initialize(node_name, ohai_data, json_attribs, override_runlist, events)
        @node_name = node_name
        @ohai_data = ohai_data
        @json_attribs = json_attribs
        @events = events

        @node = nil

        Chef::Log.warn("Using experimental Policyfile feature")

        if Chef::Config[:solo]
          raise UnsupportedFeature, "Policyfile does not support chef-solo at this time."
        end

        if override_runlist
          raise UnsupportedFeature, "Policyfile does not support override run lists at this time"
        end

        if json_attribs && json_attribs.key?("run_list")
          raise UnsupportedFeature, "Policyfile does not support setting the run_list in json data at this time"
        end

        if Chef::Config[:environment] && !Chef::Config[:environment].chomp.empty?
          raise UnsupportedFeature, "Policyfile does not work with Chef Environments"
        end
      end

      ## API Compat ##
      # Methods related to unsupported features

      # Override run_list is not supported.
      def original_runlist
        nil
      end

      # Override run_list is not supported.
      def override_runlist
        nil
      end

      # Policyfile gives you the run_list already expanded, but users of this
      # class may expect to get a run_list expansion compatible object by
      # calling this method.
      #
      # === Returns
      # RunListExpansionIsh:: A RunListExpansion duck type
      def run_list_expansion
        run_list_expansion_ish
      end

      ## PolicyBuilder API ##

      # Loads the node state from the server.
      def load_node
        events.node_load_start(node_name, Chef::Config)
        Chef::Log.debug("Building node object for #{node_name}")

        @node = Chef::Node.find_or_create(node_name)
        validate_policyfile
        node
      rescue Exception => e
        events.node_load_failed(node_name, e, Chef::Config)
        raise
      end

      # Applies environment, external JSON attributes, and override run list to
      # the node, Then expands the run_list.
      #
      # === Returns
      # node<Chef::Node>:: The modified node object. node is modified in place.
      def build_node
        # consume_external_attrs may add items to the run_list. Save the
        # expanded run_list, which we will pass to the server later to
        # determine which versions of cookbooks to use.
        node.reset_defaults_and_overrides

        node.consume_external_attrs(ohai_data, json_attribs)

        expand_run_list
        apply_policyfile_attributes

        Chef::Log.info("Run List is [#{run_list}]")
        Chef::Log.info("Run List expands to [#{run_list_with_versions_for_display.join(', ')}]")


        events.node_load_completed(node, run_list_with_versions_for_display, Chef::Config)

        node
      rescue Exception => e
        events.node_load_failed(node_name, e, Chef::Config)
        raise
      end

      def setup_run_context(specific_recipes=nil)
        Chef::Cookbook::FileVendor.fetch_from_remote(http_api)
        sync_cookbooks
        cookbook_collection = Chef::CookbookCollection.new(cookbooks_to_sync)
        run_context = Chef::RunContext.new(node, cookbook_collection, events)

        run_context.load(run_list_expansion_ish)

        run_context
      end

      def expand_run_list
        node.run_list(run_list)
        node.automatic_attrs[:roles] = []
        node.automatic_attrs[:recipes] = run_list_expansion_ish.recipes
        run_list_expansion_ish
      end


      def sync_cookbooks
        Chef::Log.debug("Synchronizing cookbooks")
        synchronizer = Chef::CookbookSynchronizer.new(cookbooks_to_sync, events)
        synchronizer.sync_cookbooks

        # register the file cache path in the cookbook path so that CookbookLoader actually picks up the synced cookbooks
        Chef::Config[:cookbook_path] = File.join(Chef::Config[:file_cache_path], "cookbooks")

        cookbooks_to_sync
      end

      # Whether or not this is a temporary policy. Since PolicyBuilder doesn't
      # support override_runlist, this is always false.
      def temporary_policy?
        false
      end

      ## Internal Public API ##

      def run_list_with_versions_for_display
        run_list.map do |recipe_spec|
          cookbook, recipe = parse_recipe_spec(recipe_spec)
          lock_data = cookbook_lock_for(cookbook)
          display = "#{cookbook}::#{recipe}@#{lock_data["version"]} (#{lock_data["identifier"][0...7]})"
          display
        end
      end

      def run_list_expansion_ish
        recipes = run_list.map do |recipe_spec|
          cookbook, recipe = parse_recipe_spec(recipe_spec)
          "#{cookbook}::#{recipe}"
        end
        RunListExpansionIsh.new(recipes, [])
      end

      def apply_policyfile_attributes
        node.attributes.role_default = policy["default_attributes"]
        node.attributes.role_override = policy["override_attributes"]
      end

      def parse_recipe_spec(recipe_spec)
        rmatch = recipe_spec.match(/recipe\[([^:]+)::([^:]+)\]/)
        if rmatch.nil?
          raise PolicyfileError, "invalid recipe specification #{recipe_spec} in Policyfile from #{policyfile_location}"
        else
          [rmatch[1], rmatch[2]]
        end
      end

      def cookbook_lock_for(cookbook_name)
        cookbook_locks[cookbook_name]
      end

      def run_list
        policy["run_list"]
      end

      def policy
        @policy ||= http_api.get(policyfile_location)
      rescue Net::HTTPServerException => e
        raise ConfigurationError, "Error loading policyfile from `#{policyfile_location}': #{e.class} - #{e.message}"
      end

      def policyfile_location
        "data/policyfiles/#{deployment_group}"
      end

      # Do some mimimal validation of the policyfile we fetched from the
      # server. Compatibility mode relies on using data bags to store policy
      # files; therefore no real validation will be performed server-side and
      # we need to make additional checks to ensure the data will be formatted
      # correctly.
      def validate_policyfile
        errors = []
        unless run_list
          errors << "Policyfile is missing run_list element"
        end
        unless policy.key?("cookbook_locks")
          errors << "Policyfile is missing cookbook_locks element"
        end
        if run_list.kind_of?(Array)
          run_list_errors = run_list.select do |maybe_recipe_spec|
            validate_recipe_spec(maybe_recipe_spec)
          end
          errors += run_list_errors
        else
          errors << "Policyfile run_list is malformed, must be an array of `recipe[cb_name::recipe_name]` items: #{policy["run_list"]}"
        end

        unless errors.empty?
          raise PolicyfileError, "Policyfile fetched from #{policyfile_location} was invalid:\n#{errors.join("\n")}"
        end
      end

      def validate_recipe_spec(recipe_spec)
        parse_recipe_spec(recipe_spec)
        nil
      rescue PolicyfileError => e
        e.message
      end

      class ConfigurationError < StandardError; end

      def deployment_group
        Chef::Config[:deployment_group] or
          raise ConfigurationError, "Setting `deployment_group` is not configured."
      end

      # Builds a 'cookbook_hash' map of the form
      #   "COOKBOOK_NAME" => "IDENTIFIER"
      #
      # This can be passed to a Chef::CookbookSynchronizer object to
      # synchronize the cookbooks.
      #
      # TODO: Currently this makes N API calls to the server to get the
      # cookbook objects. With server support (bulk API or the like), this
      # should be reduced to a single call.
      def cookbooks_to_sync
        @cookbook_to_sync ||= begin
          events.cookbook_resolution_start(run_list_with_versions_for_display)

          cookbook_versions_by_name = cookbook_locks.inject({}) do |cb_map, (name, lock_data)|
            cb_map[name] = manifest_for(name, lock_data)
            cb_map
          end
          events.cookbook_resolution_complete(cookbook_versions_by_name)

          cookbook_versions_by_name
        end
      rescue Exception => e
        # TODO: wrap/munge exception to provide helpful error output
        events.cookbook_resolution_failed(run_list_with_versions_for_display, e)
        raise
      end

      # Fetches the CookbookVersion object for the given name and identifer
      # specified in the lock_data.
      # TODO: This only implements Chef 11 compatibility mode, which means that
      # cookbooks are fetched by the "dotted_decimal_identifier": a
      # representation of a SHA1 in the traditional x.y.z version format.
      def manifest_for(cookbook_name, lock_data)
        xyz_version = lock_data["dotted_decimal_identifier"]
        http_api.get("cookbooks/#{cookbook_name}/#{xyz_version}")
      rescue Exception => e
        message = "Error loading cookbook #{cookbook_name} at version #{xyz_version}: #{e.class} - #{e.message}"
        err = Chef::Exceptions::CookbookNotFound.new(message)
        err.set_backtrace(e.backtrace)
        raise err
      end

      def cookbook_locks
        policy["cookbook_locks"]
      end

      def http_api
        @api_service ||= Chef::REST.new(config[:chef_server_url])
      end

      def config
        Chef::Config
      end

    end
  end
end