amq-adapter-python/amqp/adapter/service_message_factory.py

import base64

from amqp.adapter.data_message_factory import DataMessageFactory
from amqp.adapter.logging_utils import logging_error, logging_info
from amqp.adapter.serializer import map_as_string, parse_map_string
from amqp.adapter.trace_info_adapter import TraceInfoAdapter
from amqp.model.model import ServiceMessage
from amqp.model.service_message_type import ServiceMessageType
from amqp.model.snowflake_id import SnowflakeId

RS = "|"
SPLIT_RS = r"\|"


INVALID_MESSAGE = ServiceMessage()  # default values mean invalid message


class ServiceMessageFactory:
    """
    build/serialize/deserialize CleverMicro Service Message class
    """

    def __init__(self, name: str):
        self.process_name = name

    def to_string(self, message: ServiceMessage) -> str:
        """
        Convert ServiceMessage to human-readable format
        :param message: ServiceMessage object
        :return: as string
        """
        if message is not None:
            return (
                f"ServiceMessage{{id={message.id.as_string()}|type={self.format_message_type(message)}|"
                f"recipient={message.recipient_name}|replyTo={message.reply_to}|"
                f"traceInfo={message.trace_info}|body={base64.b64encode(message.message.encode()).decode() if message.payload_type & 0x80 else message.message}}}"
            )
        return "null"

    def of(
        self, message_type: ServiceMessageType, payload: str, recipient_name: str
    ) -> ServiceMessage:
        """
        Builds ServiceMessage object from relevant values.
        :param message_type: enum Message type
        :param payload: Message content, stored as-is
        :param recipient_name: Recipient name (from the routing expression)
        :return: ServiceMessage  object
        """
        _id = DataMessageFactory.get_instance(1).generate_snowflake_id()
        return ServiceMessage(
            id=_id,
            payload_type=0,
            message_type=message_type,
            recipient_name=recipient_name,
            reply_to=self.process_name,
            trace_info=TraceInfoAdapter.create_produce_span(_id),
            message=payload,
        )

    def as_base64(
        self, message_type: ServiceMessageType, payload: str, recipient_name: str
    ) -> ServiceMessage:
        """
        Builds ServiceMessage object from relevant values, stores content Base64 encoded.
        :param message_type: enum Message type
        :param payload: Message content, stored as Base64 string
        :param recipient_name: Recipient name (from the routing expression)
        :return: ServiceMessage  object
        """
        _id = DataMessageFactory.get_instance(1).generate_snowflake_id()
        return ServiceMessage(
            id=_id,
            payload_type=0x80,
            message_type=message_type,
            recipient_name=recipient_name,
            reply_to=self.process_name,
            trace_info=TraceInfoAdapter.create_produce_span(_id.as_string()),
            message=payload,
        )

    def from_bytes(self, input_bytes: bytes) -> ServiceMessage:
        """
        Deserialize ServiceMessage from byte array serialized form.
        :param input_bytes: serialized ServiceMessage
        :return: ServiceMessage object represented by the input.
        """
        logging_info(f"ServiceMessage >>> [{input_bytes.decode()}]")
        input_str_array = input_bytes.decode().split(RS)
        try:
            i = 0
            _id = input_str_array[i]
            i += 1
            payload_type = int(input_str_array[i], 16)
            i += 1
            message_type = ServiceMessageType(payload_type + 1 & 0x7F)
            recipient_name = input_str_array[i] if i < len(input_str_array) else ""
            i += 1
            reply_to = input_str_array[i] if i < len(input_str_array) else ""
            i += 1
            trace_info = (
                parse_map_string(input_str_array[i]) if i < len(input_str_array) else {}
            )
            i += 1
            message = input_str_array[i] if i < len(input_str_array) else ""
            return ServiceMessage(
                id=SnowflakeId.from_hex(_id),
                payload_type=payload_type,
                message_type=message_type,
                recipient_name=recipient_name,
                reply_to=reply_to,
                trace_info=trace_info,
                message=(
                    base64.b64decode(message).decode()
                    if payload_type & 0x80
                    else message
                ),
            )
        except Exception as e:
            logging_error(
                "Unexpected ServiceMessage format. Expected 6 tokens separated by '|' in format: "
                "[ID(64bit number)|MessageType(8bit number)|RecipientName(String)|"
                "ReplyTo(String)|TraceInfo|Payload(String or Base64)], got: "
                "[%s], reported problem: %s",
                input_bytes.decode(),
                str(e),
            )
            return INVALID_MESSAGE

    def serialize(self, message: ServiceMessage) -> bytes:
        """
        Serialize ServiceMessage to byte array.
        :param message: ServiceMessage to serialize.
        :return: serialized object.
        """
        return (
            f"{message.id.as_string()}{RS}{self.format_message_type(message)}{RS}{message.recipient_name}{RS}"
            f"{message.reply_to}{RS}{map_as_string(message.trace_info)}{RS}"
            f"{base64.b64encode(message.message.encode()).decode() if message.payload_type != 0 else message.message}"
        ).encode("utf-8")

    def format_message_type(self, message: ServiceMessage) -> str:
        """
        Formats the Enum message type and decorates it with base64 flag at highest bit.
        For compatibility with 0-based enum ordinals in Java subtract 1 from ordinal value.
        :param message: Service message to send
        :return: formatted message type
        """
        num_type = (
            message.message_type.value
            if message.message_type
            else ServiceMessageType.UNKNOWN.value
        ) - 1
        fmt = (num_type & 0x7F) | (message.payload_type & 0x80)
        return f"{fmt:02X}"