profiles: introduce DisplayNames

This is exactly the same as the DisplayName enum in Damus iOS. Due to
the various inconsistencies in `name` and `display_name` between
clients, we have to generalize DisplayName into two variants: one name
or two names.

If we have two names, we treat it in the standard way of display_name is
the real name, and `name` is the username.

If only one is set, then it is considered both the username and "real name".

Signed-off-by: William Casarin <jb55@jb55.com>

src/profile.rs

@@ -1,17 +1,39 @@
 use nostrdb::ProfileRecord;
 
-pub fn get_profile_name<'a>(record: &'a ProfileRecord) -> Option<&'a str> {
-    let profile = record.record().profile()?;
-    let display_name = profile.display_name();
-    let name = profile.name();
+pub enum DisplayName<'a> {
+    One(&'a str),
 
-    if display_name.is_some() && display_name.unwrap() != "" {
-        return display_name;
-    }
-
-    if name.is_some() && name.unwrap() != "" {
-        return name;
-    }
-
-    None
+    Both {
+        username: &'a str,
+        display_name: &'a str,
+    },
+}
+
+impl<'a> DisplayName<'a> {
+    pub fn username(&self) -> &'a str {
+        match self {
+            Self::One(n) => n,
+            Self::Both { username, .. } => username,
+        }
+    }
+}
+
+fn is_empty(s: &str) -> bool {
+    s.chars().all(|c| c.is_whitespace())
+}
+
+pub fn get_profile_name<'a>(record: &'a ProfileRecord) -> Option<DisplayName<'a>> {
+    let profile = record.record().profile()?;
+    let display_name = profile.display_name().filter(|n| !is_empty(n));
+    let name = profile.name().filter(|n| !is_empty(n));
+
+    match (display_name, name) {
+        (None, None) => None,
+        (Some(disp), None) => Some(DisplayName::One(disp)),
+        (None, Some(username)) => Some(DisplayName::One(username)),
+        (Some(display_name), Some(username)) => Some(DisplayName::Both {
+            display_name,
+            username,
+        }),
+    }
 }