feat: parse ConEmu OSC9;2 (#4447)

This PR implements support for the [ConEmu OSC9;2 escape
sequence](https://conemu.github.io/en/AnsiEscapeCodes.html#OSC_Operating_system_commands).

| Sequence | Description |
| - | - |
ESC ] 9 ; 2 ; ”txt“ ST | Show GUI MessageBox ( txt ) for any purposes.

src/terminal/osc.zig

@@ -158,6 +158,9 @@ pub const Command = union(enum) {
     /// End a hyperlink (OSC 8)
     hyperlink_end: void,
 
+    /// Show GUI message Box (OSC 9;2)
+    show_message_box: []const u8,
+
     /// Set progress state (OSC 9;4)
     progress: struct {
         state: ProgressState,
@@ -353,6 +356,7 @@ pub const Parser = struct {
         osc_9,
 
         // ConEmu specific substates
+        conemu_message_box,
         conemu_progress_prestate,
         conemu_progress_state,
         conemu_progress_prevalue,
@@ -777,6 +781,9 @@ pub const Parser = struct {
             },
 
             .osc_9 => switch (c) {
+                '2' => {
+                    self.state = .conemu_message_box;
+                },
                 '4' => {
                     self.state = .conemu_progress_prestate;
                 },
@@ -788,6 +795,17 @@ pub const Parser = struct {
                 else => self.showDesktopNotification(),
             },
 
+            .conemu_message_box => switch (c) {
+                ';' => {
+                    self.command = .{ .show_message_box = undefined };
+                    self.temp_state = .{ .str = &self.command.show_message_box };
+                    self.buf_start = self.buf_idx;
+                    self.complete = true;
+                    self.prepAllocableString();
+                },
+                else => self.state = .invalid,
+            },
+
             .conemu_progress_prestate => switch (c) {
                 ';' => {
                     self.command = .{ .progress = .{
@@ -1662,6 +1680,57 @@ test "OSC: show desktop notification with title" {
     try testing.expectEqualStrings(cmd.show_desktop_notification.body, "Body");
 }
 
+test "OSC: conemu message box" {
+    const testing = std.testing;
+
+    var p: Parser = .{};
+
+    const input = "9;2;hello world";
+    for (input) |ch| p.next(ch);
+
+    const cmd = p.end('\x1b').?;
+    try testing.expect(cmd == .show_message_box);
+    try testing.expectEqualStrings("hello world", cmd.show_message_box);
+}
+
+test "OSC: conemu message box invalid input" {
+    const testing = std.testing;
+
+    var p: Parser = .{};
+
+    const input = "9;2";
+    for (input) |ch| p.next(ch);
+
+    const cmd = p.end('\x1b');
+    try testing.expect(cmd == null);
+}
+
+test "OSC: conemu message box empty message" {
+    const testing = std.testing;
+
+    var p: Parser = .{};
+
+    const input = "9;2;";
+    for (input) |ch| p.next(ch);
+
+    const cmd = p.end('\x1b').?;
+    try testing.expect(cmd == .show_message_box);
+    try testing.expectEqualStrings("", cmd.show_message_box);
+}
+
+test "OSC: conemu message box spaces only message" {
+    const testing = std.testing;
+
+    var p: Parser = .{};
+
+    const input = "9;2;   ";
+    for (input) |ch| p.next(ch);
+
+    const cmd = p.end('\x1b').?;
+    try testing.expect(cmd == .show_message_box);
+    try testing.expectEqualStrings("   ", cmd.show_message_box);
+}
+
 test "OSC: OSC9 progress set" {
     const testing = std.testing;
 

src/terminal/stream.zig

@@ -1605,7 +1605,7 @@ pub fn Stream(comptime Handler: type) type {
                     } else log.warn("unimplemented OSC callback: {}", .{cmd});
                 },
 
-                .progress => {
+                .progress, .show_message_box => {
                     log.warn("unimplemented OSC callback: {}", .{cmd});
                 },
             }