# This file is distributed under New Relic's license terms.
# See https://github.com/newrelic/newrelic-ruby-agent/blob/main/LICENSE for complete details.
# frozen_string_literal: true

require 'forwardable'
require 'new_relic/agent/configuration/mask_defaults'
require 'new_relic/agent/configuration/yaml_source'
require 'new_relic/agent/configuration/default_source'
require 'new_relic/agent/configuration/server_source'
require 'new_relic/agent/configuration/environment_source'
require 'new_relic/agent/configuration/high_security_source'
require 'new_relic/agent/configuration/security_policy_source'

module NewRelic
  module Agent
    module Configuration
      class Manager
        DEPENDENCY_DETECTION_VALUES = %i[prepend chain unsatisfied].freeze

        # Defining these explicitly saves object allocations that we incur
        # if we use Forwardable and def_delegators.
        def [](key)
          @cache[key]
        end

        def has_key?(key)
          @cache.has_key?(key)
        end

        def keys
          @cache.keys
        end

        def initialize
          reset_to_defaults
          @callbacks = Hash.new { |hash, key| hash[key] = [] }
          @lock = Mutex.new
        end

        def add_config_for_testing(source, level = 0)
          raise 'Invalid config type for testing' unless [Hash, DottedHash].include?(source.class)

          invoke_callbacks(:add, source)
          @configs_for_testing << [source.freeze, level]
          reset_cache
          log_config(:add, source)
        end

        def remove_config_type(sym)
          source = case sym
          when :security_policy then @security_policy_source
          when :high_security then @high_security_source
          when :environment then @environment_source
          when :server then @server_source
          when :manual then @manual_source
          when :yaml then @yaml_source
          when :default then @default_source
          end

          remove_config(source)
        end

        def remove_config(source)
          case source
          when SecurityPolicySource then @security_policy_source = nil
          when HighSecuritySource then @high_security_source = nil
          when EnvironmentSource then @environment_source = nil
          when ServerSource then @server_source = nil
          when ManualSource then @manual_source = nil
          when YamlSource then @yaml_source = nil
          when DefaultSource then @default_source = nil
          else
            @configs_for_testing.delete_if { |src, lvl| src == source }
          end

          reset_cache
          invoke_callbacks(:remove, source)
          log_config(:remove, source)
        end

        def replace_or_add_config(source)
          source.freeze
          was_finished = finished_configuring?

          invoke_callbacks(:add, source)

          case source
          when SecurityPolicySource then @security_policy_source = source
          when HighSecuritySource then @high_security_source = source
          when EnvironmentSource then @environment_source = source
          when ServerSource then @server_source = source
          when ManualSource then @manual_source = source
          when YamlSource then @yaml_source = source
          when DefaultSource then @default_source = source
          else
            NewRelic::Agent.logger.warn("Invalid config format; config will be ignored: #{source}")
          end

          reset_cache
          log_config(:add, source)

          notify_server_source_added if ServerSource === source
          notify_finished_configuring if !was_finished && finished_configuring?
        end

        def source(key)
          config_stack.each do |config|
            if config.respond_to?(key.to_sym) || config.has_key?(key.to_sym)
              return config
            end
          end
        end

        def fetch(key)
          config_stack.each do |config|
            next unless config

            accessor = key.to_sym

            if config.has_key?(accessor)
              begin
                return evaluate_and_apply_transformations(accessor, config[accessor])
              rescue
                next
              end
            end
          end

          nil
        end

        def evaluate_procs(value)
          if value.respond_to?(:call)
            instance_eval(&value)
          else
            value
          end
        end

        def evaluate_and_apply_transformations(key, value)
          evaluated = evaluate_procs(value)
          default = enforce_allowlist(key, evaluated)
          return default if default

          apply_transformations(key, evaluated)
        end

        def apply_transformations(key, value)
          if transform = transform_from_default(key)
            begin
              transform.call(value)
            rescue => e
              NewRelic::Agent.logger.error("Error applying transformation for #{key}, pre-transform value was: #{value}.", e)
              raise e
            end
          else
            value
          end
        end

        def enforce_allowlist(key, value)
          return unless allowlist = default_source.allowlist_for(key)
          return if allowlist.include?(value)

          default = default_source.default_for(key)
          NewRelic::Agent.logger.warn "Invalid value '#{value}' for #{key}, applying default value of '#{default}'"
          default
        end

        def transform_from_default(key)
          default_source.transform_for(key)
        end

        def default_source
          NewRelic::Agent::Configuration::DefaultSource
        end

        def register_callback(key, &proc)
          @callbacks[key] << proc
          yield(@cache[key])
        end

        def invoke_callbacks(direction, source)
          return unless source

          source.keys.each do |key|
            begin
              # we need to evaluate and apply transformations for the value to deal with procs as values
              # this is usually done by the fetch method when accessing config, however the callbacks bypass that
              evaluated_cache = evaluate_and_apply_transformations(key, @cache[key])
              evaluated_source = evaluate_and_apply_transformations(key, source[key])
            rescue
              next
            end

            if evaluated_cache != evaluated_source
              @callbacks[key].each do |proc|
                if direction == :add
                  proc.call(evaluated_source)
                else
                  proc.call(evaluated_cache)
                end
              end
            end
          end
        end

        # This event is intended to be fired every time the server source is
        # applied.  This happens after the agent's initial connect, and again
        # on every forced reconnect.
        def notify_server_source_added
          NewRelic::Agent.instance.events.notify(:server_source_configuration_added)
        end

        # This event is intended to be fired once during the entire lifespan of
        # an agent run, after the server source has been applied for the first
        # time.  This should indicate that all configuration has been applied,
        # and the main functions of the agent are safe to start.
        def notify_finished_configuring
          NewRelic::Agent.instance.events.notify(:initial_configuration_complete)
        end

        def finished_configuring?
          !@server_source.nil?
        end

        def flattened
          config_stack.reverse.inject({}) do |flat, layer|
            thawed_layer = layer.to_hash.dup
            thawed_layer.each do |k, v|
              begin
                thawed_layer[k] = instance_eval(&v) if v.respond_to?(:call)
              rescue => e
                NewRelic::Agent.logger.debug("#{e.class.name} : #{e.message} - when accessing config key #{k}")
                thawed_layer[k] = nil
              end
              thawed_layer.delete(:config)
            end
            flat.merge(thawed_layer.to_hash)
          end
        end

        def apply_mask(hash)
          MASK_DEFAULTS \
            .select { |_, proc| proc.call } \
            .each { |key, _| hash.delete(key) }
          hash
        end

        def to_collector_hash
          DottedHash.new(apply_mask(flattened)).to_hash.delete_if do |k, _v|
            default = DEFAULTS[k]
            if default
              default[:exclude_from_reported_settings]
            else
              # In our tests, we add totally bogus configs, because testing.
              # In those cases, there will be no default. So we'll just let
              # them through.
              false
            end
          end
        end

        MALFORMED_LABELS_WARNING = 'Skipping malformed labels configuration'
        PARSING_LABELS_FAILURE = 'Failure during parsing labels. Ignoring and carrying on with connect.'

        MAX_LABEL_COUNT = 64
        MAX_LABEL_LENGTH = 255

        def parsed_labels
          case NewRelic::Agent.config[:labels]
          when String
            parse_labels_from_string
          else
            parse_labels_from_dictionary
          end
        rescue => e
          NewRelic::Agent.logger.error(PARSING_LABELS_FAILURE, e)
          NewRelic::EMPTY_ARRAY
        end

        def parse_labels_from_string
          labels = NewRelic::Agent.config[:labels]
          label_pairs = break_label_string_into_pairs(labels)
          make_label_hash(label_pairs, labels)
        end

        def break_label_string_into_pairs(labels)
          stripped_labels = labels.strip.sub(/^;*/, '').sub(/;*$/, '')
          stripped_labels.split(';').map do |pair|
            pair.split(':').map(&:strip)
          end
        end

        def valid_label_pairs?(label_pairs)
          label_pairs.all? do |pair|
            pair.length == 2 &&
              valid_label_item?(pair.first) &&
              valid_label_item?(pair.last)
          end
        end

        def valid_label_item?(item)
          case item
          when String then !item.empty?
          when Numeric then true
          when true then true
          when false then true
          else false
          end
        end

        def make_label_hash(pairs, labels = nil)
          # This can accept a hash, so force it down to an array of pairs first
          pairs = Array(pairs)

          unless valid_label_pairs?(pairs)
            NewRelic::Agent.logger.warn("#{MALFORMED_LABELS_WARNING}: #{labels || pairs}")
            return NewRelic::EMPTY_ARRAY
          end

          pairs = limit_number_of_labels(pairs)
          pairs = remove_duplicates(pairs)
          pairs.map do |key, value|
            {
              'label_type' => truncate(key),
              'label_value' => truncate(value.to_s, key)
            }
          end
        end

        def truncate(text, key = nil)
          if text.length > MAX_LABEL_LENGTH
            if key
              msg = "The value for the label '#{key}' is longer than the allowed #{MAX_LABEL_LENGTH} and will be truncated. Value = '#{text}'"
            else
              msg = "Label name longer than the allowed #{MAX_LABEL_LENGTH} will be truncated. Name = '#{text}'"
            end
            NewRelic::Agent.logger.warn(msg)
            text[0..MAX_LABEL_LENGTH - 1]
          else
            text
          end
        end

        def limit_number_of_labels(pairs)
          if pairs.length > MAX_LABEL_COUNT
            NewRelic::Agent.logger.warn("Too many labels defined. Only taking first #{MAX_LABEL_COUNT}")
            pairs[0...64]
          else
            pairs
          end
        end

        # We only take the last value provided for a given label type key
        def remove_duplicates(pairs)
          grouped_by_type = pairs.group_by(&:first)
          grouped_by_type.values.map(&:last)
        end

        def parse_labels_from_dictionary
          make_label_hash(NewRelic::Agent.config[:labels])
        end

        # Generally only useful during initial construction and tests
        def reset_to_defaults
          @security_policy_source = nil
          @high_security_source = nil
          @environment_source = EnvironmentSource.new
          @server_source = nil
          @manual_source = nil
          @yaml_source = nil
          @default_source = DefaultSource.new

          @configs_for_testing = []

          reset_cache
        end

        # reset the configuration hash, but do not replace previously auto
        # determined dependency detection values with nil or 'auto'
        def reset_cache
          return new_cache unless defined?(@cache) && @cache

          @lock.synchronize do
            preserved = @cache.dup.select { |_k, v| DEPENDENCY_DETECTION_VALUES.include?(v) }
            new_cache
            preserved.each { |k, v| @cache[k] = v }
          end

          @cache
        end

        def new_cache
          @cache = Hash.new { |hash, key| hash[key] = self.fetch(key) }
        end

        def log_config(direction, source)
          # Just generating this log message (specifically calling `flattened`)
          # is expensive enough that we don't want to do it unless we're
          # actually going to be logging the message based on our current log
          # level, so use a `do` block.
          NewRelic::Agent.logger.debug do
            hash = flattened.delete_if { |k, _h| DEFAULTS.fetch(k, {}).fetch(:exclude_from_reported_settings, false) }
            "Updating config (#{direction}) from #{source.class}. Results: #{hash.inspect}"
          end
        end

        def delete_all_configs_for_testing
          @security_policy_source = nil
          @high_security_source = nil
          @environment_source = nil
          @server_source = nil
          @manual_source = nil
          @yaml_source = nil
          @default_source = nil
          @configs_for_testing = []
        end

        def num_configs_for_testing
          config_stack.size
        end

        def config_classes_for_testing
          config_stack.map(&:class)
        end

        private

        def config_stack
          stack = [@security_policy_source,
            @high_security_source,
            @environment_source,
            @server_source,
            @manual_source,
            @yaml_source,
            @default_source]

          stack.compact!

          @configs_for_testing.each do |config, at_start|
            if at_start
              stack.insert(0, config)
            else
              stack.push(config)
            end
          end

          stack
        end
      end
    end
  end
end