# -*- encoding: utf-8 -*-
#
# Author:: Fletcher Nichol (<fnichol@nichol.ca>)
#
# Copyright (C) 2013, Fletcher Nichol
#
# 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 "kitchen/errors"
require "kitchen/logging"
require "kitchen/shell_out"

module Kitchen

  module Provisioner

    module Chef

      # Chef cookbook resolver that uses Policyfiles to calculate dependencies.
      #
      # @author Fletcher Nichol <fnichol@nichol.ca>
      class Policyfile

        include Logging
        include ShellOut

        # Creates a new cookbook resolver.
        #
        # @param berksfile [String] path to a Berksfile
        # @param path [String] path in which to vendor the resulting
        #   cookbooks
        # @param logger [Kitchen::Logger] a logger to use for output, defaults
        #   to `Kitchen.logger`
        def initialize(policyfile, path, logger = Kitchen.logger)
          @policyfile = policyfile
          @path       = path
          @logger     = logger
        end

        # Loads the library code required to use the resolver.
        #
        # @param logger [Kitchen::Logger] a logger to use for output, defaults
        #   to `Kitchen.logger`
        def self.load!(logger = Kitchen.logger)
          detect_chef_command!(logger)
        end

        # Performs the cookbook resolution and vendors the resulting cookbooks
        # in the desired path.
        def resolve
          info("Exporting cookbook dependencies from Policyfile #{path}...")
          run_command("chef export #{policyfile} #{path} --force")
        end

        # Runs `chef install` to determine the correct cookbook set and
        # generate the policyfile lock.
        def compile
          info("Policy lock file doesn't exist, running `chef install` for "\
               "Policyfile #{policyfile}...")
          run_command("chef install #{policyfile}")
        end

        private

        # @return [String] path to a Berksfile
        # @api private
        attr_reader :policyfile

        # @return [String] path in which to vendor the resulting cookbooks
        # @api private
        attr_reader :path

        # @return [Kitchen::Logger] a logger to use for output
        # @api private
        attr_reader :logger

        # Ensure the `chef` command is in the path.
        #
        # @param logger [Kitchen::Logger] the logger to use
        # @raise [UserError] if the `chef` command is not in the PATH
        # @api private
        def self.detect_chef_command!(logger)
          unless ENV["PATH"].split(File::PATH_SEPARATOR).any? { |p|
            File.exist?(File.join(p, "chef"))
          }
            logger.fatal("The `chef` executable cannot be found in your " \
                         "PATH. Ensure you have installed ChefDK from " \
                         "https://downloads.chef.io and that your PATH " \
                         "setting includes the path to the `chef` comand.")
            raise UserError,
              "Could not find the chef executable in your PATH."
          end
        end
      end
    end
  end
end