column: extract into_timeline logic into ColumnKind

I thought I needed this but maybe I don't. Anyways, it's a bit cleaner
this way.

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

src/column.rs

@@ -1,4 +1,6 @@
+use crate::{timeline::Timeline, Error};
 use enostr::Pubkey;
+use nostrdb::{Filter, Ndb, Transaction};
 use std::fmt::Display;
 
 #[derive(Clone, Debug)]
@@ -42,4 +44,50 @@ impl ColumnKind {
     pub fn contact_list(pk: PubkeySource) -> Self {
         ColumnKind::List(ListKind::Contact(pk))
     }
+
+    pub fn into_timeline(self, ndb: &Ndb, default_user: Option<&[u8; 32]>) -> Timeline {
+        match self {
+            ColumnKind::Universe => Timeline::new(ColumnKind::Universe, Some(vec![])),
+
+            ColumnKind::Generic => {
+                panic!("you can't convert a ColumnKind::Generic to a Timeline")
+            }
+
+            ColumnKind::List(ListKind::Contact(ref pk_src)) => {
+                let pk = match pk_src {
+                    PubkeySource::DeckAuthor => {
+                        if let Some(user_pk) = default_user {
+                            user_pk
+                        } else {
+                            // No user loaded, so we have to return an unloaded
+                            // contact list columns
+                            return Timeline::new(
+                                ColumnKind::contact_list(PubkeySource::DeckAuthor),
+                                None,
+                            );
+                        }
+                    }
+                    PubkeySource::Explicit(pk) => pk.bytes(),
+                };
+
+                let contact_filter = Filter::new().authors([pk]).kinds([3]).limit(1).build();
+                let txn = Transaction::new(ndb).expect("txn");
+                let results = ndb
+                    .query(&txn, vec![contact_filter], 1)
+                    .expect("contact query failed?");
+
+                if results.is_empty() {
+                    return Timeline::new(ColumnKind::contact_list(pk_src.to_owned()), None);
+                }
+
+                match Timeline::contact_list(&results[0].note) {
+                    Err(Error::EmptyContactList) => {
+                        Timeline::new(ColumnKind::contact_list(pk_src.to_owned()), None)
+                    }
+                    Err(e) => panic!("Unexpected error: {e}"),
+                    Ok(tl) => tl,
+                }
+            }
+        }
+    }
 }