Feat: lots of things, preparing for live gig

src/state/undo.rs

@@ -0,0 +1,53 @@
+use crate::model::{Bank, Pattern};
+
+const MAX_UNDO: usize = 100;
+
+pub enum UndoScope {
+    Pattern {
+        bank: usize,
+        pattern: usize,
+        data: Pattern,
+    },
+    Bank {
+        bank: usize,
+        data: Bank,
+    },
+}
+
+pub struct UndoEntry {
+    pub scope: UndoScope,
+    pub cursor: (usize, usize, usize),
+}
+
+#[derive(Default)]
+pub struct UndoHistory {
+    pub(crate) undo_stack: Vec<UndoEntry>,
+    redo_stack: Vec<UndoEntry>,
+}
+
+impl UndoHistory {
+    pub fn push(&mut self, entry: UndoEntry) {
+        self.redo_stack.clear();
+        if self.undo_stack.len() >= MAX_UNDO {
+            self.undo_stack.remove(0);
+        }
+        self.undo_stack.push(entry);
+    }
+
+    pub fn pop_undo(&mut self) -> Option<UndoEntry> {
+        self.undo_stack.pop()
+    }
+
+    pub fn push_redo(&mut self, entry: UndoEntry) {
+        self.redo_stack.push(entry);
+    }
+
+    pub fn pop_redo(&mut self) -> Option<UndoEntry> {
+        self.redo_stack.pop()
+    }
+
+    pub fn clear(&mut self) {
+        self.undo_stack.clear();
+        self.redo_stack.clear();
+    }
+}