# -*- encoding: utf-8 -*-
#
# Author:: Fletcher Nichol (<fnichol@nichol.ca>)
#
# Copyright (C) 2012, Fletcher Nichol
# Copyright (C) 2018, Chef Software
#
# 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/util"

module Kitchen
  module Plugin
    # Returns an instance of a plugin given a type, name, and config.
    #
    # @param type [Module] a Kitchen::<Module> of one of the plugin types
    #   (Driver, Provisioner, Transport, Verifier)
    # @param plugin [String] a plugin name, which will be constantized
    # @param config [Hash] a configuration hash to initialize the plugin
    # @return [Kitchen::<Module>::Base] a plugin instance
    # @raise [ClientError] if a plugin instance could not be created
    # @raise [UserError] if the plugin's dependencies could not be met
    def self.load(type, plugin, config)
      type_name = Kitchen::Util.snake_case(type.name.split("::").last)
      first_load = require("kitchen/#{type_name}/#{plugin}")

      str_const = Kitchen::Util.camel_case(plugin)
      klass = type.const_get(str_const)
      object = klass.new(config)
      object.verify_dependencies if first_load
      object
    rescue UserError
      raise
    rescue NameError => e
      raise ClientError, "Could not load the '#{plugin}' #{type_name}. Error: #{e.message}"
    rescue LoadError => e
      available_plugins = plugins_available(type_name)
      error_message = if available_plugins.include?(plugin)
                        e.message
                      else
                        " Did you mean: #{available_plugins.join(", ")} ?" \
                        " Please ensure that your #{type_name} is installed as a gem or included" \
                        " in your Gemfile if using Bundler."
                      end
      raise ClientError, "Could not load the '#{plugin}' #{type_name} from the load path." + error_message
    end

    # given a type of plugin, searches the Ruby load path for plugins of that
    # type based on the path+naming convention that plugin loading is based upon
    #
    # @param plugin_type [String] the name of a plugin type (e.g. driver,
    #   provisioner, transport, verifier)
    # @return [Array<String>] a collection of Ruby filenames that are probably
    #   plugins of the given type
    def self.plugins_available(plugin_type)
      $LOAD_PATH.map { |load_path| Dir[File.expand_path("kitchen/#{plugin_type}/*.rb", load_path)] }
        .reject(&:empty?)
        .flatten
        .uniq
        .select { |plugin_path| File.readlines(plugin_path).grep(/^\s*class \w* </).any? }
        .map { |plugin_path| File.basename(plugin_path).gsub(/\.rb$/, "") }
        .reject { |plugin_name| plugin_name == "base" }
        .sort
    end
  end
end