centralize movement logic/debounce mouse wheel on cursor tabs

src/tui.zig

@@ -308,6 +308,10 @@ pub const App = struct {
     classification_map: ?zfin.classification.ClassificationMap = null,
     account_map: ?zfin.analysis.AccountMap = null,
 
+    // Mouse wheel debounce for cursor-based tabs (portfolio, options).
+    // Terminals often send multiple wheel events per physical tick.
+    last_wheel_ns: i128 = 0,
+
     // Chart state (Kitty graphics)
     chart: ChartState = .{},
     vx_app: ?*vaxis.vxfw.App = null, // set during run(), for Kitty graphics access
@@ -346,29 +350,11 @@ pub const App = struct {
     fn handleMouse(self: *App, ctx: *vaxis.vxfw.EventContext, mouse: vaxis.Mouse) void {
         switch (mouse.button) {
             .wheel_up => {
-                if (self.active_tab == .portfolio) {
+                self.moveBy(-3, true);
-                    if (self.cursor > 0) self.cursor -= 1;
-                    self.ensureCursorVisible();
-                } else if (self.active_tab == .options) {
-                    if (self.options_cursor > 0) self.options_cursor -= 1;
-                    self.ensureOptionsCursorVisible();
-                } else {
-                    if (self.scroll_offset > 0) self.scroll_offset -= 3;
-                }
                 return ctx.consumeAndRedraw();
             },
             .wheel_down => {
-                if (self.active_tab == .portfolio) {
+                self.moveBy(3, true);
-                    if (self.portfolio_rows.items.len > 0 and self.cursor < self.portfolio_rows.items.len - 1)
-                        self.cursor += 1;
-                    self.ensureCursorVisible();
-                } else if (self.active_tab == .options) {
-                    if (self.options_rows.items.len > 0 and self.options_cursor < self.options_rows.items.len - 1)
-                        self.options_cursor += 1;
-                    self.ensureOptionsCursorVisible();
-                } else {
-                    self.scroll_offset += 3;
-                }
                 return ctx.consumeAndRedraw();
             },
             .left => {
@@ -577,30 +563,11 @@ pub const App = struct {
                 }
             },
             .select_next => {
-                if (self.active_tab == .portfolio) {
+                self.moveBy(1, false);
-                    if (self.portfolio_rows.items.len > 0 and self.cursor < self.portfolio_rows.items.len - 1)
-                        self.cursor += 1;
-                    self.ensureCursorVisible();
-                } else if (self.active_tab == .options) {
-                    if (self.options_rows.items.len > 0 and self.options_cursor < self.options_rows.items.len - 1)
-                        self.options_cursor += 1;
-                    self.ensureOptionsCursorVisible();
-                } else {
-                    self.scroll_offset += 1;
-                }
                 return ctx.consumeAndRedraw();
             },
             .select_prev => {
-                if (self.active_tab == .portfolio) {
+                self.moveBy(-1, false);
-                    if (self.cursor > 0) self.cursor -= 1;
-                    self.ensureCursorVisible();
-                } else if (self.active_tab == .options) {
-                    if (self.options_cursor > 0)
-                        self.options_cursor -= 1;
-                    self.ensureOptionsCursorVisible();
-                } else {
-                    if (self.scroll_offset > 0) self.scroll_offset -= 1;
-                }
                 return ctx.consumeAndRedraw();
             },
             .expand_collapse => {
@@ -737,6 +704,44 @@ pub const App = struct {
         }
     }
 
+    /// Move cursor/scroll. Positive = down, negative = up.
+    /// For portfolio and options tabs, moves the row cursor by 1.
+    /// For other tabs, adjusts scroll_offset by |n|.
+    /// When from_wheel is true, debounces on cursor tabs to absorb
+    /// duplicate events that terminals send per physical scroll tick.
+    fn moveBy(self: *App, n: isize, from_wheel: bool) void {
+        if (self.active_tab == .portfolio or self.active_tab == .options) {
+            if (from_wheel) {
+                const now = std.time.nanoTimestamp();
+                if (now - self.last_wheel_ns < 1 * std.time.ns_per_ms) return;
+                self.last_wheel_ns = now;
+            }
+            if (self.active_tab == .portfolio) {
+                stepCursor(&self.cursor, self.portfolio_rows.items.len, n);
+                self.ensureCursorVisible();
+            } else {
+                stepCursor(&self.options_cursor, self.options_rows.items.len, n);
+                self.ensureOptionsCursorVisible();
+            }
+        } else {
+            if (n > 0) {
+                self.scroll_offset += @intCast(n);
+            } else {
+                const abs: usize = @intCast(-n);
+                if (self.scroll_offset > abs) self.scroll_offset -= abs else self.scroll_offset = 0;
+            }
+        }
+    }
+
+    fn stepCursor(cursor: *usize, row_count: usize, direction: isize) void {
+        if (direction > 0) {
+            if (row_count > 0 and cursor.* < row_count - 1)
+                cursor.* += 1;
+        } else {
+            if (cursor.* > 0) cursor.* -= 1;
+        }
+    }
+
     fn ensureCursorVisible(self: *App) void {
         const cursor_row = self.cursor + self.portfolio_header_lines;
         if (cursor_row < self.scroll_offset) {