require "forwardable" unless defined?(Forwardable)
require "singleton" unless defined?(Singleton)
require "inspec/input"
require "inspec/secrets"
require "inspec/exceptions"
require "inspec/plugin/v2"

module Inspec
  # The InputRegistry's responsibilities include:
  #   - maintaining a list of Input objects that are bound to profiles
  #   - assisting in the lookup and creation of Inputs
  class InputRegistry
    include Singleton
    extend Forwardable

    class Error < Inspec::Error; end

    class ProfileLookupError < Error
      attr_accessor :profile_name
    end

    class InputLookupError < Error
      attr_accessor :profile_name
      attr_accessor :input_name
    end

    attr_reader :inputs_by_profile, :profile_aliases, :plugins
    def_delegator :inputs_by_profile, :each
    def_delegator :inputs_by_profile, :[]
    def_delegator :inputs_by_profile, :key?, :profile_known?
    def_delegator :inputs_by_profile, :select
    def_delegator :profile_aliases, :key?, :profile_alias?

    attr_accessor :cache_inputs

    def initialize
      # Keyed on String profile_name => Hash of String input_name => Input object
      @inputs_by_profile = {}

      # this is a list of optional profile name overrides set in the inspec.yml
      @profile_aliases = {}

      # Upon creation, activate all input plugins
      activators = Inspec::Plugin::V2::Registry.instance.find_activators(plugin_type: :input)

      @plugins = activators.map do |activator|
        activator.activate!
        activator.implementation_class.new
      end

      # Activate caching for inputs by default
      @cache_inputs = true
    end

    #-------------------------------------------------------------#
    #                 Support for Profiles
    #-------------------------------------------------------------#

    def register_profile_alias(name, alias_name)
      @profile_aliases[name] = alias_name
    end

    # Returns an Hash, name => Input that have actually been mentioned
    def list_inputs_for_profile(profile)
      inputs_by_profile[profile] = {} unless profile_known?(profile)
      inputs_by_profile[profile]
    end

    # Returns an Array of input names. This includes input names
    # that plugins may be able to fetch, but have not actually been
    # mentioned in the control code.
    def list_potential_input_names_for_profile(profile_name)
      input_names_from_dsl = inputs_by_profile[profile_name].keys
      input_names_from_plugins = plugins.map { |plugin| plugin.list_inputs(profile_name) }
      (input_names_from_dsl + input_names_from_plugins).flatten.uniq
    end

    #-------------------------------------------------------------#
    #              Support for Individual Inputs
    #-------------------------------------------------------------#

    def find_or_register_input(input_name, profile_name, options = {})
      input_name = input_name.to_s
      profile_name = profile_name.to_s
      options[:event].value = Thor::CoreExt::HashWithIndifferentAccess.new(options[:event].value) if options[:event]&.value.is_a?(Hash)

      if profile_alias?(profile_name) && !profile_aliases[profile_name].nil?
        alias_name = profile_name
        profile_name = profile_aliases[profile_name]
        handle_late_arriving_alias(alias_name, profile_name) if profile_known?(alias_name)
      end

      # Find or create the input
      inputs_by_profile[profile_name] ||= {}
      if inputs_by_profile[profile_name].key?(input_name) && cache_inputs
        inputs_by_profile[profile_name][input_name].update(options)
      else
        inputs_by_profile[profile_name][input_name] = Inspec::Input.new(input_name, options)
        poll_plugins_for_update(profile_name, input_name)
      end

      inputs_by_profile[profile_name][input_name]
    end

    def poll_plugins_for_update(profile_name, input_name)
      plugins.each do |plugin|
        response = plugin.fetch(profile_name, input_name)
        evt = Inspec::Input::Event.new(
          action: :fetch,
          provider: plugin.class.plugin_name,
          priority: plugin.default_priority,
          hit: !response.nil?
        )
        evt.value = response unless response.nil?
        inputs_by_profile[profile_name][input_name].events << evt
      end
    end

    # It is possible for a wrapper profile to create an input in metadata,
    # referring to the child profile by an alias that has not yet been registered.
    # The registry will then store the inputs under the alias, as if the alias
    # were a true profile.
    # If that happens and the child profile also mentions the input, we will
    # need to move some things - all inputs should be stored under the true
    # profile name, and no inputs should be stored under the alias.
    def handle_late_arriving_alias(alias_name, profile_name)
      inputs_by_profile[profile_name] ||= {}
      inputs_by_profile[alias_name].each do |input_name, input_from_alias|
        # Move the inpuut, or if it exists, merge events
        existing = inputs_by_profile[profile_name][input_name]
        if existing
          existing.events.concat(input_from_alias.events)
        else
          inputs_by_profile[profile_name][input_name] = input_from_alias
        end
      end
      # Finally, delete the (now copied-out) entry for the alias
      inputs_by_profile.delete(alias_name)
    end
    #-------------------------------------------------------------#
    #               Support for Binding Inputs
    #-------------------------------------------------------------#

    # This method is called by the Profile as soon as it has
    # enough context to allow binding inputs to it.
    def bind_profile_inputs(profile_name, sources = {})
      inputs_by_profile[profile_name] ||= {}

      # In a more perfect world, we could let the core plugins choose
      # self-determine what to do; but as-is, the APIs that call this
      # are a bit over-constrained.
      bind_inputs_from_metadata(profile_name, sources[:profile_metadata])
      bind_inputs_from_input_files(profile_name, sources[:cli_input_files])
      bind_inputs_from_runner_api(profile_name, sources[:runner_api])
      bind_inputs_from_cli_args(profile_name, sources[:cli_input_arg])
    end

    private

    def bind_inputs_from_cli_args(profile_name, input_list)
      # TODO: move this into a core plugin

      return if input_list.nil?
      return if input_list.empty?

      # These arrive as an array of "name=value" strings
      # If the user used a comma, we'll see unfortunately see it as "name=value," pairs
      input_list.each do |pair|
        unless pair.include?("=")
          if pair.end_with?(".yaml")
            raise ArgumentError, "ERROR: --input is used for individual input values, as --input name=value. Use --input-file to load a YAML file."
          else
            raise ArgumentError, "ERROR: An '=' is required when using --input. Usage: --input input_name1=input_value1 input2=value2"
          end
        end
        pair = pair.match(/(.*?)=(.*)/)
        input_name, input_value = pair[1], pair[2]
        input_value = parse_cli_input_value(input_name, input_value)
        evt = Inspec::Input::Event.new(
          value: input_value,
          provider: :cli,
          priority: 50
        )
        find_or_register_input(input_name, profile_name, event: evt)
      end
    end

    # Remove trailing commas, resolve type.
    def parse_cli_input_value(input_name, given_value)
      value = given_value.chomp(",") # Trim trailing comma if any
      case value
      when /^true|false$/i
        value = !!(value =~ /true/i)
      when /^-?\d+$/
        value = value.to_i
      when /^-?\d+\.\d+$/
        value = value.to_f
      when /^(\[|\{).*(\]|\})$/
        # Look for complex values and try to parse them.
        require "yaml"
        begin
          value = YAML.load(value)
        rescue Psych::SyntaxError => yaml_error
          # It could be that we just tried to run JSON through the YAML parser.
          require "json" unless defined?(JSON)
          begin
            value = JSON.parse(value)
          rescue JSON::ParserError => json_error
            msg = "Unparseable value '#{value}' for --input #{input_name}.\n"
            msg += "When treated as YAML, error: #{yaml_error.message}\n"
            msg += "When treated as JSON, error: #{json_error.message}"
            Inspec::Log.warn msg
          end
        end
      end
      value
    end

    def bind_inputs_from_runner_api(profile_name, input_hash)
      # TODO: move this into a core plugin

      return if input_hash.nil?
      return if input_hash.empty?

      # These arrive as a bare hash - values are raw values, not options
      input_hash.each do |input_name, input_value|
        loc = Inspec::Input::Event.probe_stack # TODO: likely modify this to look for a kitchen.yml, if that is realistic
        evt = Inspec::Input::Event.new(
          value: input_value,
          provider: :runner_api, # TODO: suss out if audit cookbook or kitchen-inspec or something unknown
          priority: 40,
          file: loc.path,
          line: loc.lineno
        )
        find_or_register_input(input_name, profile_name, event: evt)
      end
    end

    def bind_inputs_from_input_files(profile_name, file_list)
      # TODO: move this into a core plugin

      return if file_list.nil?
      return if file_list.empty?

      file_list.each do |path|
        validate_inputs_file_readability!(path)

        # TODO: drop this SecretsBackend stuff, will be handled by plugin system
        data = Inspec::SecretsBackend.resolve(path)
        if data.nil?
          raise Inspec::Exceptions::SecretsBackendNotFound,
                "Cannot find parser for inputs file '#{path}'. " \
                "Check to make sure file has the appropriate extension."
        end

        next if data.inputs.nil?

        data.inputs.each do |input_name, input_value|
          evt = Inspec::Input::Event.new(
            value: input_value,
            provider: :cli_files,
            priority: 40,
            file: path
            # TODO: any way we could get a line number?
          )
          find_or_register_input(input_name, profile_name, event: evt)
        end
      end
    end

    def validate_inputs_file_readability!(path)
      unless File.exist?(path)
        raise Inspec::Exceptions::InputsFileDoesNotExist,
              "Cannot find input file '#{path}'. " \
              "Check to make sure file exists."
      end

      unless File.readable?(path)
        raise Inspec::Exceptions::InputsFileNotReadable,
              "Cannot read input file '#{path}'. " \
              "Check to make sure file is readable."
      end

      true
    end

    def bind_inputs_from_metadata(profile_name, profile_metadata_obj)
      # TODO: move this into a core plugin
      return if profile_metadata_obj.nil? # Metadata files are technically optional

      if profile_metadata_obj.params.key?(:inputs)
        raw_inputs = profile_metadata_obj.params[:inputs]
      elsif profile_metadata_obj.params.key?(:attributes)
        Inspec.deprecate(:attrs_rename_in_metadata, "Profile: '#{profile_name}'.")
        raw_inputs = profile_metadata_obj.params[:attributes]
      else
        return
      end

      unless raw_inputs.is_a?(Array)
        Inspec::Log.warn "Inputs must be defined as an Array in metadata files. Skipping definition from #{profile_name}."
        return
      end

      raw_inputs.each { |i| handle_raw_input_from_metadata(i, profile_name) }
    end

    def handle_raw_input_from_metadata(input_orig, profile_name)
      input_options = input_orig.dup
      input_name = input_options.delete(:name)
      input_options[:provider] = :profile_metadata
      input_options[:file] = File.join(profile_name, "inspec.yml")
      input_options[:priority] ||= 30
      evt = Inspec::Input.infer_event(input_options)

      # Profile metadata may set inputs in other profiles by naming them.
      if input_options[:profile]
        profile_name = input_options[:profile] || profile_name
        # Override priority to force this to win.  Allow user to set their own priority.
        evt.priority = input_orig[:priority] || 35
      end
      find_or_register_input(
        input_name,
        profile_name,
        type: input_options[:type],
        required: input_options[:required],
        sensitive: input_options[:sensitive],
        event: evt
      )
    end

    #-------------------------------------------------------------#
    #               Other Support
    #-------------------------------------------------------------#
    public

    # Used in testing
    def __reset
      @inputs_by_profile = {}
      @profile_aliases = {}
    end

    # These class methods are convenience methods so you don't always
    # have to call #instance when calling the registry
    %i{
      find_or_register_input
      register_profile_alias
      list_inputs_for_profile
      list_potential_input_names_for_profile
      bind_profile_inputs
    }.each do |meth|
      define_singleton_method(meth) do |*args|
        instance.send(meth, *args)
      end
    end
  end
end