Initial commit

src/imap/automap.rs

@@ -0,0 +1,236 @@
+/*
+ * SPDX-FileCopyrightText: 2020 Stalwart Labs LLC <[email protected]>
+ *
+ * SPDX-License-Identifier: Apache-2.0 OR MIT
+ */
+
+pub fn role_from_special_use(attributes: &[String]) -> Option<&'static str> {
+    for attr in attributes {
+        match attr.to_ascii_lowercase().as_str() {
+            "\\all" => return Some("all"),
+            "\\archive" => return Some("archive"),
+            "\\drafts" => return Some("drafts"),
+            "\\flagged" => return Some("flagged"),
+            "\\important" => return Some("important"),
+            "\\junk" => return Some("junk"),
+            "\\sent" => return Some("sent"),
+            "\\trash" => return Some("trash"),
+            _ => {}
+        }
+    }
+    None
+}
+
+pub fn role_for_folder(
+    folder_name: &str,
+    attributes: &[String],
+    namespace_prefix: &str,
+    automap_enabled: bool,
+) -> Option<&'static str> {
+    if folder_name.eq_ignore_ascii_case("INBOX") {
+        return Some("inbox");
+    }
+    if let Some(r) = role_from_special_use(attributes) {
+        return Some(r);
+    }
+    if !automap_enabled {
+        return None;
+    }
+    let stripped = strip_prefix_case_insensitive(folder_name, namespace_prefix);
+    let leaf = leaf_component(stripped);
+    role_from_name(stripped, leaf)
+}
+
+fn role_from_name(full: &str, leaf: &str) -> Option<&'static str> {
+    for (role, patterns) in ROLE_PATTERNS {
+        for p in *patterns {
+            if leaf.eq_ignore_ascii_case(p) || full.eq_ignore_ascii_case(p) {
+                return Some(role);
+            }
+        }
+    }
+    None
+}
+
+fn strip_prefix_case_insensitive<'a>(name: &'a str, prefix: &str) -> &'a str {
+    if prefix.is_empty() {
+        return name;
+    }
+    if name.len() < prefix.len() {
+        return name;
+    }
+    if name[..prefix.len()].eq_ignore_ascii_case(prefix) {
+        &name[prefix.len()..]
+    } else {
+        name
+    }
+}
+
+fn leaf_component(name: &str) -> &str {
+    if let Some(idx) = name.rfind(['/', '.']) {
+        &name[idx + 1..]
+    } else {
+        name
+    }
+}
+
+const ROLE_PATTERNS: &[(&str, &[&str])] = &[
+    (
+        "sent",
+        &[
+            "Sent",
+            "Sent Mail",
+            "Sent Items",
+            "Sent Messages",
+            "Sent-Mail",
+            "[Gmail]/Sent Mail",
+            "[Gmail]/Sent",
+        ],
+    ),
+    (
+        "drafts",
+        &["Drafts", "Draft", "Brouillons", "[Gmail]/Drafts"],
+    ),
+    (
+        "trash",
+        &[
+            "Trash",
+            "Deleted",
+            "Deleted Items",
+            "Deleted Messages",
+            "[Gmail]/Trash",
+            "[Gmail]/Bin",
+        ],
+    ),
+    (
+        "junk",
+        &["Junk", "Spam", "Junk E-mail", "Junk Email", "[Gmail]/Spam"],
+    ),
+    ("all", &["[Gmail]/All Mail"]),
+    ("archive", &["Archive", "Archives"]),
+];
+
+#[cfg(test)]
+mod tests {
+    use super::*;
+
+    fn attrs(s: &[&str]) -> Vec<String> {
+        s.iter().map(|x| (*x).to_owned()).collect()
+    }
+
+    #[test]
+    fn inbox_always_maps_to_inbox() {
+        assert_eq!(role_for_folder("INBOX", &[], "", true), Some("inbox"));
+        assert_eq!(role_for_folder("inbox", &[], "", true), Some("inbox"));
+        assert_eq!(role_for_folder("Inbox", &[], "", false), Some("inbox"));
+    }
+
+    #[test]
+    fn special_use_drives_role() {
+        let r = role_for_folder("Whatever", &attrs(&["\\Sent"]), "", false);
+        assert_eq!(r, Some("sent"));
+        let r = role_for_folder("Anywhere", &attrs(&["\\Drafts"]), "", true);
+        assert_eq!(r, Some("drafts"));
+    }
+
+    #[test]
+    fn special_use_table_covers_all_iana_roles() {
+        for (attr, expected) in [
+            ("\\All", "all"),
+            ("\\Archive", "archive"),
+            ("\\Drafts", "drafts"),
+            ("\\Flagged", "flagged"),
+            ("\\Important", "important"),
+            ("\\Junk", "junk"),
+            ("\\Sent", "sent"),
+            ("\\Trash", "trash"),
+        ] {
+            let r = role_from_special_use(&attrs(&[attr]));
+            assert_eq!(r, Some(expected), "for {attr}");
+        }
+    }
+
+    #[test]
+    fn special_use_attrs_unrelated_to_roles_yield_none() {
+        for s in [
+            "\\Subscribed",
+            "\\HasChildren",
+            "\\HasNoChildren",
+            "\\Marked",
+            "\\Unmarked",
+            "\\Noselect",
+            "\\Noinferiors",
+            "\\Remote",
+        ] {
+            assert_eq!(role_from_special_use(&attrs(&[s])), None);
+        }
+    }
+
+    #[test]
+    fn name_heuristic_when_no_special_use() {
+        assert_eq!(role_for_folder("Sent", &[], "", true), Some("sent"));
+        assert_eq!(role_for_folder("Sent Items", &[], "", true), Some("sent"));
+        assert_eq!(role_for_folder("Drafts", &[], "", true), Some("drafts"));
+        assert_eq!(role_for_folder("Trash", &[], "", true), Some("trash"));
+        assert_eq!(
+            role_for_folder("Deleted Items", &[], "", true),
+            Some("trash")
+        );
+        assert_eq!(role_for_folder("Junk", &[], "", true), Some("junk"));
+        assert_eq!(role_for_folder("Spam", &[], "", true), Some("junk"));
+        assert_eq!(role_for_folder("Archive", &[], "", true), Some("archive"));
+        assert_eq!(
+            role_for_folder("[Gmail]/All Mail", &[], "", true),
+            Some("all")
+        );
+        assert_eq!(role_for_folder("Archives", &[], "", true), Some("archive"));
+    }
+
+    #[test]
+    fn name_heuristic_disabled_when_automap_off() {
+        assert_eq!(role_for_folder("Sent", &[], "", false), None);
+        assert_eq!(role_for_folder("Trash", &[], "", false), None);
+    }
+
+    #[test]
+    fn namespace_prefix_stripped_before_name_match() {
+        assert_eq!(
+            role_for_folder("INBOX.Sent", &[], "INBOX.", true),
+            Some("sent")
+        );
+        assert_eq!(
+            role_for_folder("INBOX.Drafts", &[], "INBOX.", true),
+            Some("drafts")
+        );
+    }
+
+    #[test]
+    fn unknown_folder_yields_none() {
+        assert_eq!(role_for_folder("My Custom Folder", &[], "", true), None);
+        assert_eq!(role_for_folder("Projects/Alpha", &[], "", true), None);
+    }
+
+    #[test]
+    fn case_insensitive_name_match() {
+        assert_eq!(role_for_folder("sent", &[], "", true), Some("sent"));
+        assert_eq!(role_for_folder("DRAFTS", &[], "", true), Some("drafts"));
+    }
+
+    #[test]
+    fn all_special_use_wins_over_heuristic_archive() {
+        let r = role_for_folder("[Gmail]/All Mail", &attrs(&["\\All"]), "", true);
+        assert_eq!(r, Some("all"));
+    }
+
+    #[test]
+    fn gmail_all_mail_no_attribute_is_all_not_archive() {
+        let r = role_for_folder("[Gmail]/All Mail", &[], "", true);
+        assert_eq!(r, Some("all"));
+    }
+
+    #[test]
+    fn plain_archive_name_resolves_to_archive() {
+        assert_eq!(role_for_folder("Archive", &[], "", true), Some("archive"));
+        assert_eq!(role_for_folder("Archives", &[], "", true), Some("archive"));
+    }
+}