Initial status for developed files on dagda

imap_utils.py

@@ -0,0 +1,96 @@
+"""Shared IMAP mailbox-name helpers."""
+
+import base64
+import re
+
+
+def to_mutf7(s: str) -> str:
+    """Encode a mailbox name as IMAP modified UTF-7."""
+    res = []
+    buf = []
+    for c in s:
+        if 0x20 <= ord(c) <= 0x7E and c != "&":
+            if buf:
+                b64 = (
+                    base64.b64encode("".join(buf).encode("utf-16-be"))
+                    .decode("ascii")
+                    .rstrip("=")
+                    .replace("/", ",")
+                )
+                res.append(f"&{b64}-")
+                buf.clear()
+            res.append(c)
+        elif c == "&":
+            if buf:
+                b64 = (
+                    base64.b64encode("".join(buf).encode("utf-16-be"))
+                    .decode("ascii")
+                    .rstrip("=")
+                    .replace("/", ",")
+                )
+                res.append(f"&{b64}-")
+                buf.clear()
+            res.append("&-")
+        else:
+            buf.append(c)
+    if buf:
+        b64 = (
+            base64.b64encode("".join(buf).encode("utf-16-be"))
+            .decode("ascii")
+            .rstrip("=")
+            .replace("/", ",")
+        )
+        res.append(f"&{b64}-")
+    return "".join(res)
+
+
+def from_mutf7(s: str) -> str:
+    """Decode an IMAP modified UTF-7 mailbox name."""
+    res = []
+    i = 0
+    while i < len(s):
+        if s[i] == "&":
+            j = s.index("-", i + 1)
+            if j == i + 1:
+                res.append("&")
+            else:
+                encoded = s[i + 1 : j].replace(",", "/")
+                pad = (4 - len(encoded) % 4) % 4
+                res.append(
+                    base64.b64decode(encoded + "=" * pad).decode("utf-16-be")
+                )
+            i = j + 1
+        else:
+            res.append(s[i])
+            i += 1
+    return "".join(res)
+
+
+def quote_mailbox(folder: str) -> str:
+    """Return an IMAP-safe quoted mailbox name."""
+    escaped = to_mutf7(folder).replace("\\", "\\\\").replace('"', r"\"")
+    return f'"{escaped}"'
+
+
+def parse_folder_name(raw: bytes) -> str | None:
+    """Extract and decode the mailbox name from an IMAP LIST response."""
+    decoded = raw.decode("ascii", errors="replace")
+    match = re.match(r'\(.*?\)\s+".*?"\s+(.*)', decoded)
+    if not match:
+        return None
+    name = match.group(1).strip().strip('"')
+    if not name:
+        return None
+    try:
+        return from_mutf7(name)
+    except Exception:
+        return name
+
+
+def list_folders(mail) -> list[str]:
+    """Return decoded folder names from an IMAP connection."""
+    status, raw_folders = mail.list()
+    if status != "OK" or not raw_folders:
+        return []
+    folders = [parse_folder_name(item) for item in raw_folders if item]
+    return sorted(folder for folder in folders if folder)