feat(kanban): persist local reorder commands

req: local/001\nreq: local/002\nreq: local/003\nreq: local/004\nreq: sync/009

examples/kanban/src/lib.rs

@@ -1,25 +1,90 @@
 #[hemx::surface]
 pub mod ui {}
 
+#[cfg(feature = "client")]
+#[derive(Clone, Debug, Eq, PartialEq)]
+struct CardId(String);
+
+#[cfg(feature = "client")]
+struct ReorderCommand {
+    card: CardId,
+    input_kind: String,
+}
+
+#[cfg(feature = "client")]
+struct CardReordered {
+    card: CardId,
+    input_kind: String,
+}
+
+#[cfg(feature = "client")]
+struct BoardProjection {
+    first: CardId,
+}
+
+#[cfg(feature = "client")]
+struct ProjectedReorder {
+    card: CardId,
+    before: Option<CardId>,
+    input_kind: String,
+}
+
+#[cfg(feature = "client")]
+impl ReorderCommand {
+    fn from_client(event: hemx::wasm::ClientEvent) -> Self {
+        Self {
+            card: CardId(
+                event
+                    .value
+                    .filter(|card| !card.is_empty())
+                    .unwrap_or_else(|| "1".into()),
+            ),
+            input_kind: event.kind,
+        }
+    }
+
+    fn decide(self) -> CardReordered {
+        CardReordered {
+            card: self.card,
+            input_kind: self.input_kind,
+        }
+    }
+}
+
+#[cfg(feature = "client")]
+impl BoardProjection {
+    fn restore(state: hemx::wasm::ClientState) -> Self {
+        Self {
+            first: CardId(state.encoded.split('|').next().unwrap_or("1").to_owned()),
+        }
+    }
+
+    fn apply(self, event: CardReordered) -> ProjectedReorder {
+        let before = (event.card != self.first).then_some(self.first);
+        ProjectedReorder {
+            card: event.card,
+            before,
+            input_kind: event.input_kind,
+        }
+    }
+}
+
 #[cfg(feature = "client")]
 #[hemx::handler(client)]
 pub fn reorder_card(
     event: hemx::wasm::ClientEvent,
     state: hemx::wasm::ClientState,
 ) -> impl hemx::IntoEffect {
-    let card = event.value.unwrap_or_else(|| "1".to_owned());
-    let order = state.encoded.split('|').collect::<Vec<_>>();
-    let move_effect = if card == order.first().copied().unwrap_or("1") {
-        ui::client_board::client_cards.move_to_end(card.clone())
-    } else {
-        ui::client_board::client_cards.move_before(
-            card.clone(),
-            order.first().copied().unwrap_or("1").to_owned(),
-        )
+    let projected =
+        BoardProjection::restore(state).apply(ReorderCommand::from_client(event).decide());
+    let card = projected.card.0;
+    let move_effect = match projected.before {
+        Some(before) => ui::client_board::client_cards.move_before(card.clone(), before.0),
+        None => ui::client_board::client_cards.move_to_end(card.clone()),
     };
     vec![
         move_effect,
-        ui::client_board::client_notice.text(format!("Moved {card} with {}", event.kind)),
+        ui::client_board::client_notice.text(format!("Moved {card} with {}", projected.input_kind)),
     ]
 }