feat(tui): recognize sidescroll events (#19992)

Ref https://invisible-island.net/xterm/ctlseqs/ctlseqs.html#h3-Other-buttons
This works in xterm and kitty.
CSI < 66 ; x ; y M sequence is for ScrollWheelLeft.
CSI < 67 ; x ; y M sequence is for ScrollWheelRight.

2 files changed, 206 insertions, 2 deletions

diff --git a/src/nvim/tui/input.c b/src/nvim/tui/input.c
index 03cfb830e6..d269878f46 100644
--- a/src/nvim/tui/input.c
+++ b/src/nvim/tui/input.c
@@ -398,6 +398,14 @@ static void forward_mouse_event(TermInput *input, TermKeyKey *key)
     button = last_pressed_button;
   }
 
+  if (ev == TERMKEY_MOUSE_UNKNOWN && !(key->code.mouse[0] & 0x20)) {
+    int code = key->code.mouse[0] & ~0x3c;
+    if (code == 66 || code == 67) {
+      ev = TERMKEY_MOUSE_PRESS;
+      button = code - 60;
+    }
+  }
+
   if (button == 0 || (ev != TERMKEY_MOUSE_PRESS && ev != TERMKEY_MOUSE_DRAG
                       && ev != TERMKEY_MOUSE_RELEASE)) {
     return;
@@ -431,8 +439,11 @@ static void forward_mouse_event(TermInput *input, TermKeyKey *key)
     if (button == 4) {
       len += (size_t)snprintf(buf + len, sizeof(buf) - len, "ScrollWheelUp");
     } else if (button == 5) {
-      len += (size_t)snprintf(buf + len, sizeof(buf) - len,
-                              "ScrollWheelDown");
+      len += (size_t)snprintf(buf + len, sizeof(buf) - len, "ScrollWheelDown");
+    } else if (button == 6) {
+      len += (size_t)snprintf(buf + len, sizeof(buf) - len, "ScrollWheelLeft");
+    } else if (button == 7) {
+      len += (size_t)snprintf(buf + len, sizeof(buf) - len, "ScrollWheelRight");
     } else {
       len += (size_t)snprintf(buf + len, sizeof(buf) - len, "Mouse");
       last_pressed_button = button;
diff --git a/test/functional/terminal/tui_spec.lua b/test/functional/terminal/tui_spec.lua
index 99f69ef556..4f444316c3 100644
--- a/test/functional/terminal/tui_spec.lua
+++ b/test/functional/terminal/tui_spec.lua
@@ -297,6 +297,199 @@ describe('TUI', function()
     ]], attrs)
   end)
 
+  it('accepts mouse wheel events #19992', function()
+    child_session:request('nvim_command', [[
+      set number nostartofline nowrap mousescroll=hor:1,ver:1
+      call setline(1, repeat([join(range(10), '----')], 10))
+      vsplit
+    ]])
+    screen:expect([[
+      {11:  1 }{1:0}----1----2----3----4│{11:  1 }0----1----2----3----|
+      {11:  2 }0----1----2----3----4│{11:  2 }0----1----2----3----|
+      {11:  3 }0----1----2----3----4│{11:  3 }0----1----2----3----|
+      {11:  4 }0----1----2----3----4│{11:  4 }0----1----2----3----|
+      {5:[No Name] [+]             }{1:[No Name] [+]           }|
+                                                        |
+      {3:-- TERMINAL --}                                    |
+    ]])
+    -- <ScrollWheelDown> in active window
+    feed_data('\027[<65;8;1M')
+    screen:expect([[
+      {11:  2 }{1:0}----1----2----3----4│{11:  1 }0----1----2----3----|
+      {11:  3 }0----1----2----3----4│{11:  2 }0----1----2----3----|
+      {11:  4 }0----1----2----3----4│{11:  3 }0----1----2----3----|
+      {11:  5 }0----1----2----3----4│{11:  4 }0----1----2----3----|
+      {5:[No Name] [+]             }{1:[No Name] [+]           }|
+                                                        |
+      {3:-- TERMINAL --}                                    |
+    ]])
+    -- <ScrollWheelDown> in inactive window
+    feed_data('\027[<65;48;1M')
+    screen:expect([[
+      {11:  2 }{1:0}----1----2----3----4│{11:  2 }0----1----2----3----|
+      {11:  3 }0----1----2----3----4│{11:  3 }0----1----2----3----|
+      {11:  4 }0----1----2----3----4│{11:  4 }0----1----2----3----|
+      {11:  5 }0----1----2----3----4│{11:  5 }0----1----2----3----|
+      {5:[No Name] [+]             }{1:[No Name] [+]           }|
+                                                        |
+      {3:-- TERMINAL --}                                    |
+    ]])
+    -- <ScrollWheelRight> in active window
+    feed_data('\027[<67;8;1M')
+    screen:expect([[
+      {11:  2 }{1:-}---1----2----3----4-│{11:  2 }0----1----2----3----|
+      {11:  3 }----1----2----3----4-│{11:  3 }0----1----2----3----|
+      {11:  4 }----1----2----3----4-│{11:  4 }0----1----2----3----|
+      {11:  5 }----1----2----3----4-│{11:  5 }0----1----2----3----|
+      {5:[No Name] [+]             }{1:[No Name] [+]           }|
+                                                        |
+      {3:-- TERMINAL --}                                    |
+    ]])
+    -- <ScrollWheelRight> in inactive window
+    feed_data('\027[<67;48;1M')
+    screen:expect([[
+      {11:  2 }{1:-}---1----2----3----4-│{11:  2 }----1----2----3----4|
+      {11:  3 }----1----2----3----4-│{11:  3 }----1----2----3----4|
+      {11:  4 }----1----2----3----4-│{11:  4 }----1----2----3----4|
+      {11:  5 }----1----2----3----4-│{11:  5 }----1----2----3----4|
+      {5:[No Name] [+]             }{1:[No Name] [+]           }|
+                                                        |
+      {3:-- TERMINAL --}                                    |
+    ]])
+    -- <S-ScrollWheelDown> in active window
+    feed_data('\027[<69;8;1M')
+    screen:expect([[
+      {11:  5 }{1:-}---1----2----3----4-│{11:  2 }----1----2----3----4|
+      {11:  6 }----1----2----3----4-│{11:  3 }----1----2----3----4|
+      {11:  7 }----1----2----3----4-│{11:  4 }----1----2----3----4|
+      {11:  8 }----1----2----3----4-│{11:  5 }----1----2----3----4|
+      {5:[No Name] [+]             }{1:[No Name] [+]           }|
+                                                        |
+      {3:-- TERMINAL --}                                    |
+    ]])
+    -- <S-ScrollWheelDown> in inactive window
+    feed_data('\027[<69;48;1M')
+    screen:expect([[
+      {11:  5 }{1:-}---1----2----3----4-│{11:  5 }----1----2----3----4|
+      {11:  6 }----1----2----3----4-│{11:  6 }----1----2----3----4|
+      {11:  7 }----1----2----3----4-│{11:  7 }----1----2----3----4|
+      {11:  8 }----1----2----3----4-│{11:  8 }----1----2----3----4|
+      {5:[No Name] [+]             }{1:[No Name] [+]           }|
+                                                        |
+      {3:-- TERMINAL --}                                    |
+    ]])
+    -- <S-ScrollWheelRight> in active window
+    feed_data('\027[<71;8;1M')
+    screen:expect([[
+      {11:  5 }{1:-}---6----7----8----9 │{11:  5 }----1----2----3----4|
+      {11:  6 }----6----7----8----9 │{11:  6 }----1----2----3----4|
+      {11:  7 }----6----7----8----9 │{11:  7 }----1----2----3----4|
+      {11:  8 }----6----7----8----9 │{11:  8 }----1----2----3----4|
+      {5:[No Name] [+]             }{1:[No Name] [+]           }|
+                                                        |
+      {3:-- TERMINAL --}                                    |
+    ]])
+    -- <S-ScrollWheelRight> in inactive window
+    feed_data('\027[<71;48;1M')
+    screen:expect([[
+      {11:  5 }{1:-}---6----7----8----9 │{11:  5 }5----6----7----8----|
+      {11:  6 }----6----7----8----9 │{11:  6 }5----6----7----8----|
+      {11:  7 }----6----7----8----9 │{11:  7 }5----6----7----8----|
+      {11:  8 }----6----7----8----9 │{11:  8 }5----6----7----8----|
+      {5:[No Name] [+]             }{1:[No Name] [+]           }|
+                                                        |
+      {3:-- TERMINAL --}                                    |
+    ]])
+    -- <ScrollWheelUp> in active window
+    feed_data('\027[<64;8;1M')
+    screen:expect([[
+      {11:  4 }----6----7----8----9 │{11:  5 }5----6----7----8----|
+      {11:  5 }{1:-}---6----7----8----9 │{11:  6 }5----6----7----8----|
+      {11:  6 }----6----7----8----9 │{11:  7 }5----6----7----8----|
+      {11:  7 }----6----7----8----9 │{11:  8 }5----6----7----8----|
+      {5:[No Name] [+]             }{1:[No Name] [+]           }|
+                                                        |
+      {3:-- TERMINAL --}                                    |
+    ]])
+    -- <ScrollWheelUp> in inactive window
+    feed_data('\027[<64;48;1M')
+    screen:expect([[
+      {11:  4 }----6----7----8----9 │{11:  4 }5----6----7----8----|
+      {11:  5 }{1:-}---6----7----8----9 │{11:  5 }5----6----7----8----|
+      {11:  6 }----6----7----8----9 │{11:  6 }5----6----7----8----|
+      {11:  7 }----6----7----8----9 │{11:  7 }5----6----7----8----|
+      {5:[No Name] [+]             }{1:[No Name] [+]           }|
+                                                        |
+      {3:-- TERMINAL --}                                    |
+    ]])
+    -- <ScrollWheelLeft> in active window
+    feed_data('\027[<66;8;1M')
+    screen:expect([[
+      {11:  4 }5----6----7----8----9│{11:  4 }5----6----7----8----|
+      {11:  5 }5{1:-}---6----7----8----9│{11:  5 }5----6----7----8----|
+      {11:  6 }5----6----7----8----9│{11:  6 }5----6----7----8----|
+      {11:  7 }5----6----7----8----9│{11:  7 }5----6----7----8----|
+      {5:[No Name] [+]             }{1:[No Name] [+]           }|
+                                                        |
+      {3:-- TERMINAL --}                                    |
+    ]])
+    -- <ScrollWheelLeft> in inactive window
+    feed_data('\027[<66;48;1M')
+    screen:expect([[
+      {11:  4 }5----6----7----8----9│{11:  4 }-5----6----7----8---|
+      {11:  5 }5{1:-}---6----7----8----9│{11:  5 }-5----6----7----8---|
+      {11:  6 }5----6----7----8----9│{11:  6 }-5----6----7----8---|
+      {11:  7 }5----6----7----8----9│{11:  7 }-5----6----7----8---|
+      {5:[No Name] [+]             }{1:[No Name] [+]           }|
+                                                        |
+      {3:-- TERMINAL --}                                    |
+    ]])
+    -- <S-ScrollWheelUp> in active window
+    feed_data('\027[<68;8;1M')
+    screen:expect([[
+      {11:  1 }5----6----7----8----9│{11:  4 }-5----6----7----8---|
+      {11:  2 }5----6----7----8----9│{11:  5 }-5----6----7----8---|
+      {11:  3 }5----6----7----8----9│{11:  6 }-5----6----7----8---|
+      {11:  4 }5{1:-}---6----7----8----9│{11:  7 }-5----6----7----8---|
+      {5:[No Name] [+]             }{1:[No Name] [+]           }|
+                                                        |
+      {3:-- TERMINAL --}                                    |
+    ]])
+    -- <S-ScrollWheelUp> in inactive window
+    feed_data('\027[<68;48;1M')
+    screen:expect([[
+      {11:  1 }5----6----7----8----9│{11:  1 }-5----6----7----8---|
+      {11:  2 }5----6----7----8----9│{11:  2 }-5----6----7----8---|
+      {11:  3 }5----6----7----8----9│{11:  3 }-5----6----7----8---|
+      {11:  4 }5{1:-}---6----7----8----9│{11:  4 }-5----6----7----8---|
+      {5:[No Name] [+]             }{1:[No Name] [+]           }|
+                                                        |
+      {3:-- TERMINAL --}                                    |
+    ]])
+    -- <S-ScrollWheelLeft> in active window
+    feed_data('\027[<70;8;1M')
+    screen:expect([[
+      {11:  1 }0----1----2----3----4│{11:  1 }-5----6----7----8---|
+      {11:  2 }0----1----2----3----4│{11:  2 }-5----6----7----8---|
+      {11:  3 }0----1----2----3----4│{11:  3 }-5----6----7----8---|
+      {11:  4 }0----1----2----3----{1:4}│{11:  4 }-5----6----7----8---|
+      {5:[No Name] [+]             }{1:[No Name] [+]           }|
+                                                        |
+      {3:-- TERMINAL --}                                    |
+    ]])
+    -- <S-ScrollWheelLeft> in inactive window
+    feed_data('\027[<70;48;1M')
+    screen:expect([[
+      {11:  1 }0----1----2----3----4│{11:  1 }0----1----2----3----|
+      {11:  2 }0----1----2----3----4│{11:  2 }0----1----2----3----|
+      {11:  3 }0----1----2----3----4│{11:  3 }0----1----2----3----|
+      {11:  4 }0----1----2----3----{1:4}│{11:  4 }0----1----2----3----|
+      {5:[No Name] [+]             }{1:[No Name] [+]           }|
+                                                        |
+      {3:-- TERMINAL --}                                    |
+    ]])
+  end)
+
   it('accepts keypad keys from kitty keyboard protocol #19180', function()
     feed_data('i')
     feed_data(funcs.nr2char(57399)) -- KP_0