feat: bridge observed messages to postboxes
This commit is contained in:
@@ -0,0 +1,211 @@
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from __future__ import annotations
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import hashlib
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from email import policy
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from email.message import Message
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from email.parser import BytesParser
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from email.utils import getaddresses
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from sqlalchemy.orm import Session
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from govoplan_core.core.mail import (
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MailPostboxBridgeProvider,
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MailPostboxBridgeRequest,
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MailPostboxBridgeResult,
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)
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from govoplan_core.core.modules import ModuleContext
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from govoplan_core.core.postbox import (
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PostboxAttachmentRef,
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PostboxDeliveryRequest,
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PostboxParticipantRef,
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PostboxTargetRef,
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postbox_delivery_provider,
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)
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from govoplan_mail.backend.db.models import MailServerProfile
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from govoplan_mail.backend.runtime import configure_runtime, get_registry
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MAX_BRIDGE_MESSAGE_BYTES = 50 * 1024 * 1024
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MAX_POSTBOX_BODY_CHARS = 500_000
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class MailPostboxBridgeError(RuntimeError):
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pass
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class MailPostboxBridge(MailPostboxBridgeProvider):
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"""Translate immutable IMAP observations into native Postbox delivery."""
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def bridge_message(
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self,
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session: object,
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request: MailPostboxBridgeRequest,
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) -> MailPostboxBridgeResult:
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if not isinstance(session, Session):
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raise TypeError("Mail Postbox bridging requires a SQLAlchemy session.")
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if not isinstance(request.target, PostboxTargetRef):
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raise MailPostboxBridgeError("A typed Postbox target is required.")
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if len(request.raw_message) > MAX_BRIDGE_MESSAGE_BYTES:
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raise MailPostboxBridgeError("Mail message exceeds the Postbox bridge limit.")
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profile = session.get(MailServerProfile, request.profile_id)
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if profile is None or profile.tenant_id != request.tenant_id:
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raise MailPostboxBridgeError("Mail profile not found.")
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folder = request.folder.strip()
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uid = request.uid.strip()
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uidvalidity = request.uidvalidity.strip()
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if not folder or not uid or not uidvalidity:
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raise MailPostboxBridgeError(
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"Mail folder, UIDVALIDITY, and immutable UID are required."
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)
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try:
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message = BytesParser(policy=policy.default).parsebytes(request.raw_message)
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except Exception as exc:
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raise MailPostboxBridgeError("Mail message could not be parsed.") from exc
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provider = postbox_delivery_provider(get_registry())
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if provider is None:
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raise MailPostboxBridgeError("Postbox delivery is not available.")
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source_digest = hashlib.sha256(request.raw_message).hexdigest()
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source_key = hashlib.sha256(
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f"{request.tenant_id}\0{request.profile_id}\0{folder}\0{uidvalidity}\0{uid}".encode("utf-8")
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).hexdigest()
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result = provider.deliver(
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session,
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PostboxDeliveryRequest(
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tenant_id=request.tenant_id,
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target=request.target,
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producer_module="mail",
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producer_resource_type="imap_message",
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producer_resource_id=source_key,
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idempotency_key=f"mail-postbox:{source_key}:{source_digest}",
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subject=_header(message, "Subject") or "(No subject)",
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body_text=_plain_text_body(message),
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sender_label=_header(message, "From"),
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classification=request.classification,
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participants=_participants(message),
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attachments=_attachments(
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message,
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profile_id=request.profile_id,
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folder=folder,
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uidvalidity=uidvalidity,
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uid=uid,
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),
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metadata={
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**dict(request.metadata),
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"transport": "mail-imap",
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"mail_profile_id": request.profile_id,
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"mailbox_folder": folder,
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"mailbox_uidvalidity": uidvalidity,
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"mailbox_uid": uid,
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"rfc_message_id": _header(message, "Message-ID"),
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"raw_sha256": source_digest,
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},
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),
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)
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return MailPostboxBridgeResult(
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postbox_id=result.postbox_id,
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message_id=result.message_id,
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delivery_id=result.delivery_id,
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duplicate=result.duplicate,
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source_digest=source_digest,
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)
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def _header(message: Message, name: str) -> str | None:
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value = " ".join(str(message.get(name) or "").split())
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return value[:1000] or None
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def _plain_text_body(message: Message) -> str | None:
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candidates = message.walk() if message.is_multipart() else (message,)
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for part in candidates:
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if part.get_content_type() != "text/plain":
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continue
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if part.get_content_disposition() == "attachment":
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continue
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try:
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value = part.get_content()
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except Exception:
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payload = part.get_payload(decode=True) or b""
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value = payload.decode(part.get_content_charset() or "utf-8", errors="replace")
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if isinstance(value, bytes):
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value = value.decode(part.get_content_charset() or "utf-8", errors="replace")
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normalized = str(value).strip()
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if normalized:
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return normalized[:MAX_POSTBOX_BODY_CHARS]
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return None
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def _participants(message: Message) -> tuple[PostboxParticipantRef, ...]:
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result: list[PostboxParticipantRef] = []
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for kind, headers in (
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("sender", ("From",)),
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("to", ("To",)),
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("cc", ("Cc",)),
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("bcc", ("Bcc",)),
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):
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for name, address in getaddresses(
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[str(value) for header in headers for value in message.get_all(header, [])]
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):
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clean_address = address.strip()[:500]
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if not clean_address:
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continue
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result.append(
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PostboxParticipantRef(
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kind=kind,
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reference_type="external_email",
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label=name.strip()[:500] or None,
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address=clean_address,
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)
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)
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return tuple(result)
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def _attachments(
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message: Message,
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*,
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profile_id: str,
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folder: str,
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uidvalidity: str,
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uid: str,
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) -> tuple[PostboxAttachmentRef, ...]:
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result: list[PostboxAttachmentRef] = []
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for index, part in enumerate(message.walk()):
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filename = part.get_filename()
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if part.get_content_disposition() != "attachment" and not filename:
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continue
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payload = part.get_payload(decode=True) or b""
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digest = hashlib.sha256(payload).hexdigest()
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reference_id = hashlib.sha256(
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f"{profile_id}\0{folder}\0{uidvalidity}\0{uid}\0{index}\0{digest}".encode("utf-8")
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).hexdigest()
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result.append(
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PostboxAttachmentRef(
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reference_type="mail_attachment",
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reference_id=reference_id,
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name=str(filename or f"attachment-{index + 1}")[:1000],
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media_type=part.get_content_type(),
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size_bytes=len(payload),
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digest=digest,
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metadata={
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"mail_profile_id": profile_id,
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"mailbox_folder": folder,
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"mailbox_uidvalidity": uidvalidity,
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"mailbox_uid": uid,
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"mime_part_index": index,
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},
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)
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)
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return tuple(result)
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def create_postbox_bridge(context: ModuleContext) -> MailPostboxBridge:
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configure_runtime(registry=context.registry, settings=context.settings)
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return MailPostboxBridge()
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__all__ = [
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"MailPostboxBridge",
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"MailPostboxBridgeError",
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"create_postbox_bridge",
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]
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