# Author:: Bryan McLellan <btm@loftninjas.org>
# Copyright:: Copyright (c) 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_relative "credentials"
autoload :Train, "train"
require_relative "../config"
require "chef-utils/dist" unless defined?(ChefUtils::Dist)

module ChefConfig
  module Mixin
    module TrainTransport
      include ChefConfig::Mixin::Credentials

      attr_accessor :logger

      def initialize(logger)
        @logger = logger
      end

      #
      # Returns a RFC099 credentials profile as a hash
      #
      def load_credentials(profile)
        # Tomlrb.load_file returns a hash with keys as strings
        credentials = parse_credentials_file
        if contains_split_fqdn?(credentials, profile)
          logger.warn("Credentials file #{credentials_file_path} contains target '#{profile}' as a Hash, expected a string.")
          logger.warn("Hostnames must be surrounded by single quotes, e.g. ['host.example.org']")
        end

        # host names must be specified in credentials file as ['foo.example.org'] with quotes
        if !credentials.nil? && !credentials[profile].nil?
          credentials[profile].transform_keys(&:to_sym) # return symbolized keys to match Train.options()
        else
          nil
        end
      end

      # Toml creates hashes when a key is separated by periods, e.g.
      # [host.example.org] => { host: { example: { org: {} } } }
      #
      # Returns true if the above example is true
      #
      # A hostname has to be specified as ['host.example.org']
      # This will be a common mistake so we should catch it
      #
      def contains_split_fqdn?(hash, fqdn)
        fqdn.split(".").reduce(hash) do |h, k|
          v = h[k]
          if Hash === v
            v
          else
            break false
          end
        end
      end

      # ChefConfig::Mixin::Credentials.credentials_file_path is designed around knife,
      # overriding it here.
      #
      # Credentials file preference:
      #
      # 1) target_mode.credentials_file
      # 2) /etc/chef/TARGET_MODE_HOST/credentials
      # 3) #credentials_file_path from parent ($HOME/.chef/credentials)
      #
      def credentials_file_path
        tm_config = config.target_mode
        profile = tm_config.host

        credentials_file =
          if tm_config.credentials_file && File.exist?(tm_config.credentials_file)
            tm_config.credentials_file
          elsif File.exist?(config.platform_specific_path("#{ChefConfig::Config.etc_chef_dir}/#{profile}/credentials"))
            config.platform_specific_path("#{ChefConfig::Config.etc_chef_dir}/#{profile}/credentials")
          else
            super
          end

        raise ArgumentError, "No credentials file found for target '#{profile}'" unless credentials_file
        raise ArgumentError, "Credentials file specified for target mode does not exist: '#{credentials_file}'" unless File.exist?(credentials_file)

        logger.debug("Loading credentials file '#{credentials_file}' for target '#{profile}'")

        credentials_file
      end

      def build_transport
        return nil unless config.target_mode?

        # TODO: Consider supporting parsing the protocol from a URI passed to `--target`
        #
        train_config = {}

        # Load the target_mode config context from config, and place any valid settings into the train configuration
        tm_config = config.target_mode
        protocol = tm_config.protocol
        train_config = tm_config.to_hash.select { |k| Train.options(protocol).key?(k) }
        logger.trace("Using target mode options from #{ChefUtils::Dist::Infra::PRODUCT} config file: #{train_config.keys.join(", ")}") if train_config

        # Load the credentials file, and place any valid settings into the train configuration
        credentials = load_credentials(tm_config.host)
        if credentials
          valid_settings = credentials.select { |k| Train.options(protocol).key?(k) }
          valid_settings[:enable_password] = credentials[:enable_password] if credentials.key?(:enable_password)
          train_config.merge!(valid_settings)
          logger.trace("Using target mode options from credentials file: #{valid_settings.keys.join(", ")}") if valid_settings
        end

        train_config[:logger] = logger

        # Train handles connection retries for us
        Train.create(protocol, train_config)
      rescue SocketError => e # likely a dns failure, not caught by train
        e.message.replace "Error connecting to #{train_config[:target]} - #{e.message}"
        raise e
      rescue Train::PluginLoadError
        logger.error("Invalid target mode protocol: #{protocol}")
        exit(1)
      end

      def config
        raise NotImplementedError
      end
    end
  end
end
