From b2cb003d8235bb4e00f58b9ec93eb8432c0f60f7 Mon Sep 17 00:00:00 2001
From: Danylo Kondratiev <danylo@posteo.ie>
Date: Thu, 22 Jan 2026 23:33:09 +0200
Subject: [PATCH] feat: add toggle_case

---
 src/buffer/unicode.zig | 18 ++++++++++++++++++
 src/tui/editor.zig     | 24 ++++++++++++++++++++++++
 2 files changed, 42 insertions(+)

diff --git a/src/buffer/unicode.zig b/src/buffer/unicode.zig
index eca8f5e8..fd13e91d 100644
--- a/src/buffer/unicode.zig
+++ b/src/buffer/unicode.zig
@@ -201,6 +201,24 @@ pub fn switch_case(allocator: std.mem.Allocator, text: []const u8) TransformErro
         to_upper(allocator, text);
 }
 
+pub fn toggle_case(allocator: std.mem.Allocator, text: []const u8) TransformError![]u8 {
+    var result: std.Io.Writer.Allocating = .init(allocator);
+    defer result.deinit();
+    const writer = &result.writer;
+    const view: Utf8View = .initUnchecked(text);
+    var it = view.iterator();
+    while (it.nextCodepoint()) |cp| {
+        const cp_ = if (uucode.get(.is_lowercase, cp))
+            uucode.get(.simple_uppercase_mapping, cp) orelse cp
+        else
+            uucode.get(.simple_lowercase_mapping, cp) orelse cp;
+        var utf8_buf: [6]u8 = undefined;
+        const size = try utf8Encode(cp_, &utf8_buf);
+        try writer.writeAll(utf8_buf[0..size]);
+    }
+    return result.toOwnedSlice();
+}
+
 pub fn is_lowercase(text: []const u8) bool {
     return utf8_predicate_all(.is_lowercase, text);
 }
diff --git a/src/tui/editor.zig b/src/tui/editor.zig
index 620f2390..a4456dad 100644
--- a/src/tui/editor.zig
+++ b/src/tui/editor.zig
@@ -7347,6 +7347,30 @@ pub const Editor = struct {
     }
     pub const switch_case_meta: Meta = .{ .description = "Switch the case of selection or character at cursor" };
 
+    fn toggle_case_cursel(self: *Self, root_: Buffer.Root, cursel: *CurSel, allocator: Allocator) error{Stop}!Buffer.Root {
+        var root = root_;
+        const saved = cursel.*;
+        const sel = try self.get_selection_or_select_word(root, cursel);
+        var sfa = std.heap.stackFallback(4096, self.allocator);
+        const sfa_allocator = sfa.get();
+        const cut_text = copy_selection(root, sel.*, sfa_allocator, self.metrics) catch return error.Stop;
+        defer sfa_allocator.free(cut_text);
+        const transformed = Buffer.unicode.toggle_case(sfa_allocator, cut_text) catch return error.Stop;
+        defer sfa_allocator.free(transformed);
+        root = try self.delete_selection(root, cursel, allocator);
+        root = self.insert(root, cursel, transformed, allocator) catch return error.Stop;
+        cursel.* = saved;
+        return root;
+    }
+
+    pub fn toggle_case(self: *Self, _: Context) Result {
+        const b = try self.buf_for_update();
+        const root = try self.with_cursels_mut_once(b.root, toggle_case_cursel, b.allocator);
+        try self.update_buf(root);
+        self.clamp();
+    }
+    pub const toggle_case_meta: Meta = .{ .description = "Toggle the case of each character in selection or character at cursor" };
+
     pub fn forced_mark_clean(self: *Self, _: Context) Result {
         if (self.buffer) |b| {
             b.mark_clean();