human handoffs

backend/app/services/reply_recipients.py

@@ -0,0 +1,49 @@
+from app.schemas import MailAddress
+
+
+def _addresses(items: list[dict] | list[MailAddress] | None) -> list[str]:
+    if not items:
+        return []
+    values: list[str] = []
+    for item in items:
+        if isinstance(item, dict):
+            address = item.get("address", "")
+        else:
+            address = item.address
+        if address:
+            values.append(address.lower())
+    return values
+
+
+def reply_recipients(
+    *,
+    message: dict,
+    viewer_email: str,
+    reply_all: bool = False,
+) -> tuple[list[str], list[str]]:
+    viewer = viewer_email.lower()
+    own_addresses = {viewer}
+
+    reply_to = _addresses(message.get("reply_to"))
+    sender = _addresses([message.get("sender", {})])
+    to = _addresses(message.get("to") or message.get("recipients"))
+    cc = _addresses(message.get("cc"))
+
+    primary = reply_to or sender
+    primary = [address for address in primary if address not in own_addresses]
+
+    if not reply_all:
+        return primary, []
+
+    recipients = []
+    for address in [*primary, *to, *cc]:
+        if address in own_addresses or address in recipients:
+            continue
+        recipients.append(address)
+
+    if not recipients and primary:
+        recipients = primary
+
+    to_out = recipients[:1] if recipients else []
+    cc_out = recipients[1:] if len(recipients) > 1 else []
+    return to_out, cc_out