1 files changed, 88 insertions, 0 deletions
diff --git a/mu4web/maildir.py b/mu4web/maildir.py
new file mode 100644
index 0000000..831f23d
--- /dev/null
+++ b/mu4web/maildir.py
@@ -0,0 +1,88 @@
+from dataclasses import dataclass
+import os.path
+
+from html_render import HTML
+from util import find
+
+from urllib.parse import urlencode
+
+from typing import (
+    Union
+)
+
+try:
+    from natsort import natsorted
+except ModuleNotFoundError:
+    natsorted = sorted
+
+@dataclass
+class MaildirEntry:
+    """A single maildir, used by find_maildirs."""
+    name: str
+
+
+@dataclass
+class MaildirGroup:
+    """A group of maildir, which isn't a maildir in itself."""
+    name: str
+    children: list[Union[MaildirEntry, 'MaildirGroup']]
+
+
+def _build_tree(items: list[list[str]]) -> MaildirGroup:
+    groups: dict[str, list[list[str]]] = {}
+    direct: list[MaildirEntry] = []
+    for key, *rest in items:
+        if rest:
+            groups.setdefault(key, []).append(rest)
+        else:
+            direct.append(MaildirEntry(key))
+
+    node = MaildirGroup('root', [])
+    for key, values in groups.items():
+        next = _build_tree(values)
+        next.name = key
+        node.children.append(next)
+    node.children.extend(direct)
+    return node
+
+
+
+def find_maildirs(basedir) -> MaildirGroup:
+    """
+    Find all maildirs located under basedir.
+
+    A maildir is defined as any directory which contains a `cur`
+    directory.
+
+    Returns a MaildirGroup of the root, whose children will be all the
+    maildirs under basedir. Note that if a directory is both a maildir
+    and a group of maildirs then it will have two separate entries.
+    """
+    basedir = basedir.rstrip('/')
+    files = find(basedir, type='d', name='cur')
+    # + 1 removes leading slash
+    # - 4 removes '/cur'
+    dirs = [entry[len(basedir)+1:-4].decode('UTF-8').split(os.path.sep)
+            for entry in files]
+
+    return _build_tree(dirs)
+
+
+def serialize_maildir(maildir: MaildirGroup, path: list[str] = []) -> HTML:
+    """Build a (recursive) list from a maildir node."""
+    entries: list[HTML] = []
+    for node in natsorted(maildir.children, key=lambda n: n.name):
+        if isinstance(node, MaildirEntry):
+            parts = '/'.join(path + [node.name])
+            url = 'search?' + urlencode({'q': f'maildir:"/{parts}"'})
+            entry = ('li', ('a', {'href': url},
+                            node.name or ('i', 'root')))
+        else:
+            entry = ('li',
+                     ('details',
+                      ('summary', node.name),
+                       serialize_maildir(node, path + [node.name])))
+        entries.append(entry)
+
+    return ('ul', *entries)
+