# -*- encoding: utf-8 -*-
#
# Author:: Fletcher Nichol (<fnichol@nichol.ca>)
#
# Copyright (C) 2014, 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 "thor/util"

require "kitchen/lazy_hash"

module Kitchen

  # A mixin for providing configuration-related behavior such as default
  # config (static, computed, inherited), required config, local path
  # expansion, etc.
  #
  # @author Fletcher Nichol <fnichol@nichol.ca>
  module Configurable

    def self.included(base)
      base.extend(ClassMethods)
    end

    # @return [Kitchen::Instance] the associated instance
    attr_reader :instance

    # A lifecycle method that should be invoked when the object is about ready
    # to be used. A reference to an Instance is required as configuration
    # dependant data may be access through an Instance. This also acts as a
    # hook point where the object may wish to perform other last minute
    # checks, validations, or configuration expansions.
    #
    # @param instance [Instance] an associated instance
    # @return [self] itself, for use in chaining
    # @raise [ClientError] if instance parameter is nil
    def finalize_config!(instance)
      if instance.nil?
        raise ClientError, "Instance must be provided to #{self}"
      end

      @instance = instance
      expand_paths!
      validate_config!
      load_needed_dependencies!

      self
    end

    # Provides hash-like access to configuration keys.
    #
    # @param attr [Object] configuration key
    # @return [Object] value at configuration key
    def [](attr)
      config[attr]
    end

    # @return [TrueClass,FalseClass] true if `:shell_type` is `"bourne"` (or
    #   unset, for backwards compatability)
    def bourne_shell?
      ["bourne", nil].include?(instance.platform.shell_type)
    end

    # Find an appropriate path to a file or directory, based on graceful
    # fallback rules or returns nil if path cannot be determined.
    #
    # Given an instance with suite named `"server"`, a `test_base_path` of
    # `"/a/b"`, and a path segement of `"roles"` then following will be tried
    # in order (first match that exists wins):
    #
    # 1. /a/b/server/roles
    # 2. /a/b/roles
    # 3. $PWD/roles
    #
    # @param path [String] the base path segment to search for
    # @param opts [Hash] options
    # @option opts [Symbol] :type either `:file` or `:directory` (default)
    # @option opts [Symbol] :base_path a custom base path to search under,
    #   default uses value from `config[:test_base_path]`
    # @return [String] path to the existing file or directory, or nil if file
    #   or directory was not found
    # @raise [UserError] if `config[:test_base_path]` is used and is not set
    def calculate_path(path, opts = {})
      type = opts.fetch(:type, :directory)
      base = opts.fetch(:base_path) do
        config.fetch(:test_base_path) do |key|
          raise UserError, "#{key} is not found in #{self}"
        end
      end

      [
        File.join(base, instance.suite.name, path),
        File.join(base, path),
        File.join(Dir.pwd, path)
      ].find do |candidate|
        type == :directory ? File.directory?(candidate) : File.file?(candidate)
      end
    end

    # Returns an array of configuration keys.
    #
    # @return [Array] array of configuration keys
    def config_keys
      config.keys
    end

    # Returns a Hash of configuration and other useful diagnostic information.
    #
    # @return [Hash] a diagnostic hash
    def diagnose
      result = Hash.new
      config_keys.sort.each { |k| result[k] = config[k] }
      result
    end

    # Returns a Hash of configuration and other useful diagnostic information
    # associated with the plugin itself (such as loaded version, class name,
    # etc.).
    #
    # @return [Hash] a diagnostic hash
    def diagnose_plugin
      result = Hash.new
      result[:name] = name
      result.merge!(self.class.diagnose)
      result
    end

    # Returns the name of this plugin, suitable for display in a CLI.
    #
    # @return [String] name of this plugin
    def name
      self.class.name.split("::").last
    end

    # @return [TrueClass,FalseClass] true if `:shell_type` is `"powershell"`
    def powershell_shell?
      ["powershell"].include?(instance.platform.shell_type)
    end

    # Builds a file path based on the `:os_type` (`"windows"` or `"unix"`).
    #
    # @return [String] joined path for instance's os_type
    def remote_path_join(*parts)
      path = File.join(*parts)
      windows_os? ? path.gsub("/", "\\") : path.gsub("\\", "/")
    end

    # @return [TrueClass,FalseClass] true if `:os_type` is `"unix"` (or
    #   unset, for backwards compatibility)
    def unix_os?
      ["unix", nil].include?(instance.platform.os_type)
    end

    # Performs whatever tests that may be required to ensure that this plugin
    # will be able to function in the current environment. This may involve
    # checking for the presence of certain directories, software installed,
    # etc.
    #
    # @raise [UserError] if the plugin will not be able to perform or if a
    #   documented dependency is missing from the system
    def verify_dependencies
      # this method may be left unimplemented if that is applicable
    end

    # @return [TrueClass,FalseClass] true if `:os_type` is `"windows"`
    def windows_os?
      ["windows"].include?(instance.platform.os_type)
    end

    private

    # @return [LzayHash] a configuration hash
    # @api private
    attr_reader :config

    # Initializes an internal configuration hash. The hash may contain
    # callable blocks as values that are meant to be called lazily. This
    # method is intended to be included in an object's .initialize method.
    #
    # @param config [Hash] initial provided configuration
    # @api private
    def init_config(config)
      @config = LazyHash.new(config, self)
      self.class.defaults.each do |attr, value|
        @config[attr] = value unless @config.key?(attr)
      end
    end

    # Expands file paths for certain configuration values. A configuration
    # value is marked for file expansion with a expand_path_for declaration
    # in the included class.
    #
    # @api private
    def expand_paths!
      root_path = config[:kitchen_root] || Dir.pwd
      expanded_paths = LazyHash.new(self.class.expanded_paths, self).to_hash

      expanded_paths.each do |key, should_expand|
        next if !should_expand || config[key].nil? || config[key] == false

        config[key] = if config[key].is_a?(Array)
          config[key].map { |path| File.expand_path(path, root_path) }
        else
          File.expand_path(config[key], root_path)
        end
      end
    end

    # Loads any required third party Ruby libraries or runs any shell out
    # commands to prepare the plugin. This method will be called in the
    # context of the main thread of execution and so does not necessarily
    # have to be thread safe.
    #
    # **Note:** any subclasses overriding this method would be well advised
    # to call super when overriding this method, for example:
    #
    # @example overriding `#load_needed_dependencies!`
    #
    #   class MyProvisioner < Kitchen::Provisioner::Base
    #     def load_needed_dependencies!
    #       super
    #       # any further work
    #     end
    #   end
    #
    # @raise [ClientError] if any library loading fails or any of the
    #   dependency requirements cannot be satisfied
    # @api private
    def load_needed_dependencies!
      # this method may be left unimplemented if that is applicable
    end

    # @return [Logger] the instance's logger or Test Kitchen's common logger
    #   otherwise
    # @api private
    def logger
      instance ? instance.logger : Kitchen.logger
    end

    # @return [String] a powershell command to reload the `PATH` environment
    #   variable, only to be used to support old Omnibus Chef packages that
    #   require `PATH` to find the `ruby.exe` binary
    # @api private
    def reload_ps1_path
      [
        %{$env:PATH},
        %{[System.Environment]::GetEnvironmentVariable("PATH","Machine")\n\n}
      ].join(" = ")
    end

    # Builds a shell environment variable assignment string for the
    # required shell type.
    #
    # @param name [String] variable name
    # @param value [String] variable value
    # @return [String] shell variable assignment
    # @api private
    def shell_env_var(name, value)
      if powershell_shell?
        shell_var("env:#{name}", value)
      else
        "#{shell_var(name, value)}; export #{name}"
      end
    end

    # Builds a shell variable assignment string for the required shell type.
    #
    # @param name [String] variable name
    # @param value [String] variable value
    # @return [String] shell variable assignment
    # @api private
    def shell_var(name, value)
      if powershell_shell?
        %{$#{name} = "#{value}"}
      else
        %{#{name}="#{value}"}
      end
    end

    # Runs all validations set up for the included class. Each validation is
    # for a specific configuration attribute and has an associated callable
    # block. Each validation block is called with the attribute, its value,
    # and the included object for context.
    #
    # @api private
    def validate_config!
      self.class.validations.each do |attr, block|
        block.call(attr, config[attr], self)
      end
    end

    # Wraps a body of shell code with common context appropriate for the type
    # of shell.
    #
    # @param code [String] the shell code to be wrapped
    # @return [String] wrapped shell code
    # @api private
    def wrap_shell_code(code)
      return env_wrapped code if powershell_shell?
      Util.wrap_command((env_wrapped code))
    end

    def env_wrapped(code)
      (proxy_settings << code).join("\n")
    end

    def proxy_setting_keys
      [:http_proxy, :https_proxy, :ftp_proxy]
    end

    def resolve_proxy_settings_from_config
      proxy_setting_keys.each_with_object([]) do |protocol, set_env|
        if !config.key?(protocol) || config[protocol].nil?
          export_proxy(set_env, protocol)
        elsif proxy_config_setting_present?(protocol)
          set_env << shell_env_var("#{protocol.downcase}", config[protocol])
          set_env << shell_env_var("#{protocol.upcase}", config[protocol])
        end
      end
    end

    def proxy_settings
      env = resolve_proxy_settings_from_config

      # if http_proxy was set from environment variable or https_proxy was set
      # from environment variable, or ftp_proxy was set from environment
      # variable, include no_proxy environment variable, if set.
      if !proxy_from_config? && proxy_from_environment?
        env << shell_env_var("no_proxy", ENV["no_proxy"]) if ENV["no_proxy"]
        env << shell_env_var("NO_PROXY", ENV["NO_PROXY"]) if ENV["NO_PROXY"]
      end
      env
    end

    def proxy_from_config?
      proxy_setting_keys.any? do |protocol|
        !config[protocol].nil?
      end
    end

    def proxy_from_environment?
      proxy_setting_keys.any? do |protocol|
        !ENV["#{protocol.downcase}"].nil? || !ENV["#{protocol.upcase}"].nil?
      end
    end

    def proxy_config_setting_present?(protocol)
      config.key?(protocol) && !config[protocol].nil? && !config[protocol].empty?
    end

    # Helper method to export
    #
    # @param env [Array] the environment to modify
    # @param code [String] the type of proxy to export, one of 'http', 'https' or 'ftp'
    # @api private
    def export_proxy(env, type)
      env << shell_env_var("#{type}", ENV["#{type}"]) if ENV["#{type}"]
      env << shell_env_var("#{type.upcase}", ENV["#{type.upcase}"]) if
        ENV["#{type.upcase}"]
    end

    # Class methods which will be mixed in on inclusion of Configurable module.
    module ClassMethods

      # Sets the loaded version of this plugin, usually corresponding to the
      # RubyGems version of the plugin's library. If the plugin does not set
      # this value, then `nil` will be used and reported.
      #
      # @example setting a version used by RubyGems
      #
      #   require "kitchen/driver/vagrant_version"
      #
      #   module Kitchen
      #     module Driver
      #       class Vagrant < Kitchen::Driver::Base
      #
      #         plugin_version Kitchen::Driver::VAGRANT_VERSION
      #
      #       end
      #     end
      #   end
      #
      # @param version [String] a version string
      def plugin_version(version) # rubocop:disable Style/TrivialAccessors
        @plugin_version = version
      end

      # Returns a Hash of configuration and other useful diagnostic
      # information.
      #
      # @return [Hash] a diagnostic hash
      def diagnose
        {
          :class        => name,
          :version      => @plugin_version,
          :api_version  => @api_version
        }
      end

      # Sets a sane default value for a configuration attribute. These values
      # can be overridden by provided configuration or in a subclass with
      # another default_config declaration.
      #
      # @example a nil default value
      #
      #   default_config :i_am_nil
      #
      # @example a primitive default value
      #
      #   default_config :use_sudo, true
      #
      # @example a block to compute a default value
      #
      #   default_config :box_name do |subject|
      #     subject.instance.platform.name
      #   end
      #
      # @param attr [String] configuration attribute name
      # @param value [Object, nil] static default value for attribute
      # @yieldparam object [Object] a reference to the instantiated object
      # @yieldreturn [Object, nil] dynamically computed value for the attribute
      def default_config(attr, value = nil, &block)
        defaults[attr] = block_given? ? block : value
      end

      # Ensures that an attribute which is a path will be fully expanded at
      # the right time. This helps make the configuration unambiguous and much
      # easier to debug and diagnose.
      #
      # Note that the file path expansion is only intended for paths on the
      # local workstation invking the Test Kitchen code.
      #
      # @example the default usage
      #
      #   expand_path_for :data_path
      #
      # @example disabling path expansion with a falsey value
      #
      #   expand_path_for :relative_path, false
      #
      # @example using a block to determine whether or not to expand
      #
      #   expand_path_for :relative_or_not_path do |subject|
      #     subject.instance.name =~ /default/
      #   end
      #
      # @param attr [String] configuration attribute name
      # @param value [Object, nil] whether or not to exand the file path
      # @yieldparam object [Object] a reference to the instantiated object
      # @yieldreturn [Object, nil] dynamically compute whether or not to
      #   perform the file expansion
      def expand_path_for(attr, value = true, &block)
        expanded_paths[attr] = block_given? ? block : value
      end

      # Ensures that an attribute must have a non-nil, non-empty String value.
      # The default behavior will be to raise a user error and thereby halting
      # further configuration processing. Good use cases for require_config
      # might be cloud provider credential keys and other similar data.
      #
      # @example a value that must not be nil or an empty String
      #
      #   required_config :cloud_api_token
      #
      # @example using a block to use custom validation logic
      #
      #   required_config :email do |attr, value, subject|
      #     raise UserError, "Must be an email address" unless value =~ /@/
      #   end
      #
      # @param attr [String] configuration attribute name
      # @yieldparam attr [Symbol] the attribute name
      # @yieldparam value [Object] the current value of the attribute
      # @yieldparam object [Object] a reference to the instantiated object
      def required_config(attr, &block)
        if !block_given?
          klass = self
          block = lambda do |_, value, thing|
            if value.nil? || value.to_s.empty?
              attribute = "#{klass}#{thing.instance.to_str}#config[:#{attr}]"
              raise UserError, "#{attribute} cannot be blank"
            end
          end
        end
        validations[attr] = block
      end

      # @return [Hash] a hash of attribute keys and default values which has
      #   been merged with any superclass defaults
      # @api private
      def defaults
        @defaults ||= Hash.new.merge(super_defaults)
      end

      # @return [Hash] a hash of defaults from the included class' superclass
      #   if defined in the superclass, or an empty hash otherwise
      # @api private
      def super_defaults
        if superclass.respond_to?(:defaults)
          superclass.defaults
        else
          Hash.new
        end
      end

      # @return [Hash] a hash of attribute keys and truthy/falsey values to
      #   determine if said attribute needs to be fully file path expanded,
      #   which has been merged with any superclass expanded paths
      # @api private
      def expanded_paths
        @expanded_paths ||= Hash.new.merge(super_expanded_paths)
      end

      # @return [Hash] a hash of expanded paths from the included class'
      #   superclass if defined in the superclass, or an empty hash otherwise
      # @api private
      def super_expanded_paths
        if superclass.respond_to?(:expanded_paths)
          superclass.expanded_paths
        else
          Hash.new
        end
      end

      # @return [Hash] a hash of attribute keys and valudation callable blocks
      #   which has been merged with any superclass valudations
      # @api private
      def validations
        @validations ||= Hash.new.merge(super_validations)
      end

      # @return [Hash] a hash of validations from the included class'
      #   superclass if defined in the superclass, or an empty hash otherwise
      # @api private
      def super_validations
        if superclass.respond_to?(:validations)
          superclass.validations
        else
          Hash.new
        end
      end
    end
  end
end