tidy: move ColumnKind to its own file

timeline file is starting to get messy

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

src/column.rs

@@ -0,0 +1,45 @@
+use enostr::Pubkey;
+use std::fmt::Display;
+
+#[derive(Clone, Debug)]
+pub enum PubkeySource {
+    Explicit(Pubkey),
+    DeckAuthor,
+}
+
+#[derive(Debug)]
+pub enum ListKind {
+    Contact(PubkeySource),
+}
+
+///
+/// What kind of column is it?
+///   - Follow List
+///   - Notifications
+///   - DM
+///   - filter
+///   - ... etc
+#[derive(Debug)]
+pub enum ColumnKind {
+    List(ListKind),
+    Universe,
+
+    /// Generic filter
+    Generic,
+}
+
+impl Display for ColumnKind {
+    fn fmt(&self, f: &mut std::fmt::Formatter<'_>) -> std::fmt::Result {
+        match self {
+            ColumnKind::List(ListKind::Contact(_src)) => f.write_str("Contacts"),
+            ColumnKind::Generic => f.write_str("Timeline"),
+            ColumnKind::Universe => f.write_str("Universe"),
+        }
+    }
+}
+
+impl ColumnKind {
+    pub fn contact_list(pk: PubkeySource) -> Self {
+        ColumnKind::List(ListKind::Contact(pk))
+    }
+}