# frozen_string_literal: true

require "active_support/core_ext/hash"

module ActiveJob
  # Raised when an exception is raised during job arguments deserialization.
  #
  # Wraps the original exception raised as +cause+.
  class DeserializationError < StandardError
    def initialize #:nodoc:
      super("Error while trying to deserialize arguments: #{$!.message}")
      set_backtrace $!.backtrace
    end
  end

  # Raised when an unsupported argument type is set as a job argument. We
  # currently support String, Integer, Float, NilClass, TrueClass, FalseClass,
  # BigDecimal, Symbol, Date, Time, DateTime, ActiveSupport::TimeWithZone,
  # ActiveSupport::Duration, Hash, ActiveSupport::HashWithIndifferentAccess,
  # Array or GlobalID::Identification instances, although this can be extended
  # by adding custom serializers.
  # Raised if you set the key for a Hash something else than a string or
  # a symbol. Also raised when trying to serialize an object which can't be
  # identified with a GlobalID - such as an unpersisted Active Record model.
  class SerializationError < ArgumentError; end

  module Arguments
    extend self
    # :nodoc:
    PERMITTED_TYPES = [ NilClass, String, Integer, Float, BigDecimal, TrueClass, FalseClass ]

    # Serializes a set of arguments. Intrinsic types that can safely be
    # serialized without mutation are returned as-is. Arrays/Hashes are
    # serialized element by element. All other types are serialized using
    # GlobalID.
    def serialize(arguments)
      arguments.map { |argument| serialize_argument(argument) }
    end

    # Deserializes a set of arguments. Intrinsic types that can safely be
    # deserialized without mutation are returned as-is. Arrays/Hashes are
    # deserialized element by element. All other types are deserialized using
    # GlobalID.
    def deserialize(arguments)
      arguments.map { |argument| deserialize_argument(argument) }
    rescue
      raise DeserializationError
    end

    private

      # :nodoc:
      GLOBALID_KEY = "_aj_globalid"
      # :nodoc:
      SYMBOL_KEYS_KEY = "_aj_symbol_keys"
      # :nodoc:
      WITH_INDIFFERENT_ACCESS_KEY = "_aj_hash_with_indifferent_access"
      # :nodoc:
      OBJECT_SERIALIZER_KEY = "_aj_serialized"

      # :nodoc:
      RESERVED_KEYS = [
        GLOBALID_KEY, GLOBALID_KEY.to_sym,
        SYMBOL_KEYS_KEY, SYMBOL_KEYS_KEY.to_sym,
        OBJECT_SERIALIZER_KEY, OBJECT_SERIALIZER_KEY.to_sym,
        WITH_INDIFFERENT_ACCESS_KEY, WITH_INDIFFERENT_ACCESS_KEY.to_sym,
      ]
      private_constant :RESERVED_KEYS, :GLOBALID_KEY, :SYMBOL_KEYS_KEY, :WITH_INDIFFERENT_ACCESS_KEY

      def serialize_argument(argument)
        case argument
        when *PERMITTED_TYPES
          argument
        when GlobalID::Identification
          convert_to_global_id_hash(argument)
        when Array
          argument.map { |arg| serialize_argument(arg) }
        when ActiveSupport::HashWithIndifferentAccess
          result = serialize_hash(argument)
          result[WITH_INDIFFERENT_ACCESS_KEY] = serialize_argument(true)
          result
        when Hash
          symbol_keys = argument.each_key.grep(Symbol).map(&:to_s)
          result = serialize_hash(argument)
          result[SYMBOL_KEYS_KEY] = symbol_keys
          result
        else
          Serializers.serialize(argument)
        end
      end

      def deserialize_argument(argument)
        case argument
        when String
          GlobalID::Locator.locate(argument) || argument
        when *PERMITTED_TYPES
          argument
        when Array
          argument.map { |arg| deserialize_argument(arg) }
        when Hash
          if serialized_global_id?(argument)
            deserialize_global_id argument
          elsif custom_serialized?(argument)
            Serializers.deserialize(argument)
          else
            deserialize_hash(argument)
          end
        else
          raise ArgumentError, "Can only deserialize primitive arguments: #{argument.inspect}"
        end
      end

      def serialized_global_id?(hash)
        hash.size == 1 && hash.include?(GLOBALID_KEY)
      end

      def deserialize_global_id(hash)
        GlobalID::Locator.locate hash[GLOBALID_KEY]
      end

      def custom_serialized?(hash)
        hash.key?(OBJECT_SERIALIZER_KEY)
      end

      def serialize_hash(argument)
        argument.each_with_object({}) do |(key, value), hash|
          hash[serialize_hash_key(key)] = serialize_argument(value)
        end
      end

      def deserialize_hash(serialized_hash)
        result = serialized_hash.transform_values { |v| deserialize_argument(v) }
        if result.delete(WITH_INDIFFERENT_ACCESS_KEY)
          result = result.with_indifferent_access
        elsif symbol_keys = result.delete(SYMBOL_KEYS_KEY)
          result = transform_symbol_keys(result, symbol_keys)
        end
        result
      end

      def serialize_hash_key(key)
        case key
        when *RESERVED_KEYS
          raise SerializationError.new("Can't serialize a Hash with reserved key #{key.inspect}")
        when String, Symbol
          key.to_s
        else
          raise SerializationError.new("Only string and symbol hash keys may be serialized as job arguments, but #{key.inspect} is a #{key.class}")
        end
      end

      def transform_symbol_keys(hash, symbol_keys)
        # NOTE: HashWithIndifferentAccess#transform_keys always
        # returns stringified keys with indifferent access
        # so we call #to_h here to ensure keys are symbolized.
        hash.to_h.transform_keys do |key|
          if symbol_keys.include?(key)
            key.to_sym
          else
            key
          end
        end
      end

      def convert_to_global_id_hash(argument)
        { GLOBALID_KEY => argument.to_global_id.to_s }
      rescue URI::GID::MissingModelIdError
        raise SerializationError, "Unable to serialize #{argument.class} " \
          "without an id. (Maybe you forgot to call save?)"
      end
  end
end