ui/terminal: make terminal state redraw like any other state

Previously, ordinary redraws were missing from terminal mode. Instead,
there was an async callback that invoked update_screen() on terminal
data regardless of mode (as if :redraw! was invoked by a timer).

This created some issues:

- async changes to an unrelated ordinary buffer were not always redrawn in
  terminal mode
- screen cursor position was not properly updated in terminal mode (partial
  fix, will be properly fixed in a follow up PR)
- ad-hoc logic was needed for interaction with special states such as
  inccommand or horizontal wildmenu.

Instead redraw terminal mode just like any other state. This disables forced
redraws in cmdline mode, which were inconisent which async changes to
normal buffers (which are not redrawn in cmdline mode).

5 files changed, 54 insertions, 85 deletions

diff --git a/src/nvim/terminal.c b/src/nvim/terminal.c
index 79b0df842f..bdcade0d86 100644
--- a/src/nvim/terminal.c
+++ b/src/nvim/terminal.c
@@ -400,7 +400,6 @@ void terminal_enter(void)
   showmode();
   curwin->w_redr_status = true;  // For mode() in statusline. #8323
   ui_busy_start();
-  redraw(false);
 
   s->state.execute = terminal_execute;
   s->state.check = terminal_check;
@@ -416,8 +415,10 @@ void terminal_enter(void)
 
   // draw the unfocused cursor
   invalidate_terminal(s->term, s->term->cursor.row, s->term->cursor.row + 1);
+  if (curbuf->terminal == s->term && !s->close) {
+    terminal_check_cursor();
+  }
   unshowmode(true);
-  redraw(curbuf->handle != s->term->buf_handle);
   ui_busy_stop();
   if (s->close) {
     bool wipe = s->term->buf_handle != 0;
@@ -428,6 +429,20 @@ void terminal_enter(void)
   }
 }
 
+static void terminal_check_cursor(void)
+{
+  Terminal *term = curbuf->terminal;
+  curwin->w_wrow = term->cursor.row;
+  curwin->w_wcol = term->cursor.col + win_col_off(curwin);
+  curwin->w_cursor.lnum = MIN(curbuf->b_ml.ml_line_count,
+                              row_to_linenr(term, term->cursor.row));
+  // Nudge cursor when returning to normal-mode.
+  int off = is_focused(term) ? 0 : (curwin->w_p_rl ? 1 : -1);
+  curwin->w_cursor.col = MAX(0, term->cursor.col + win_col_off(curwin) + off);
+  curwin->w_cursor.coladd = 0;
+  mb_check_adjust_col(curwin);
+}
+
 // Function executed before each iteration of terminal mode.
 // Return:
 //   1 if the iteration should continue normally
@@ -438,6 +453,19 @@ static int terminal_check(VimState *state)
     stop_insert_mode = false;
     return 0;
   }
+
+  terminal_check_cursor();
+
+  if (must_redraw) {
+    update_screen(0);
+  }
+
+  if (need_maketitle) {  // Update title in terminal-mode. #7248
+    maketitle();
+  }
+
+  setcursor();
+  ui_flush();
   return 1;
 }
 
@@ -1151,11 +1179,7 @@ static void refresh_terminal(Terminal *term)
 static void refresh_timer_cb(TimeWatcher *watcher, void *data)
 {
   refresh_pending = false;
-  if (exiting  // Cannot redraw (requires event loop) during teardown/exit.
-      || (State & CMDPREVIEW)
-      // WM_LIST (^D) is not redrawn, unlike the normal wildmenu. So we must
-      // skip redraws to keep it visible.
-      || wild_menu_showing == WM_LIST) {
+  if (exiting) {  // Cannot redraw (requires event loop) during teardown/exit.
     return;
   }
   Terminal *term;
@@ -1165,12 +1189,8 @@ static void refresh_timer_cb(TimeWatcher *watcher, void *data)
   map_foreach(invalidated_terminals, term, stub, {
     refresh_terminal(term);
   });
-  bool any_visible = is_term_visible();
   pmap_clear(ptr_t)(invalidated_terminals);
   unblock_autocmds();
-  if (any_visible) {
-    redraw(true);
-  }
 }
 
 static void refresh_size(Terminal *term, buf_T *buf)
@@ -1284,61 +1304,6 @@ static void refresh_screen(Terminal *term, buf_T *buf)
   term->invalid_end = -1;
 }
 
-/// @return true if any invalidated terminal buffer is visible to the user
-static bool is_term_visible(void)
-{
-  FOR_ALL_WINDOWS_IN_TAB(wp, curtab) {
-    if (wp->w_buffer->terminal
-        && pmap_has(ptr_t)(invalidated_terminals, wp->w_buffer->terminal)) {
-      return true;
-    }
-  }
-  return false;
-}
-
-static void redraw(bool restore_cursor)
-{
-  Terminal *term = curbuf->terminal;
-  if (!term) {
-    restore_cursor = true;
-  }
-
-  int save_row = 0;
-  int save_col = 0;
-  if (restore_cursor) {
-    // save the current row/col to restore after updating screen when not
-    // focused
-    save_row = ui_current_row();
-    save_col = ui_current_col();
-  }
-  block_autocmds();
-
-  if (must_redraw) {
-    update_screen(0);
-  }
-
-  if (need_maketitle) {  // Update title in terminal-mode. #7248
-    maketitle();
-  }
-
-  if (restore_cursor) {
-    ui_cursor_goto(save_row, save_col);
-  } else if (term) {
-    curwin->w_wrow = term->cursor.row;
-    curwin->w_wcol = term->cursor.col + win_col_off(curwin);
-    curwin->w_cursor.lnum = MIN(curbuf->b_ml.ml_line_count,
-                                row_to_linenr(term, term->cursor.row));
-    // Nudge cursor when returning to normal-mode.
-    int off = is_focused(term) ? 0 : (curwin->w_p_rl ? 1 : -1);
-    curwin->w_cursor.col = MAX(0, term->cursor.col + win_col_off(curwin) + off);
-    curwin->w_cursor.coladd = 0;
-    mb_check_adjust_col(curwin);
-  }
-
-  unblock_autocmds();
-  ui_flush();
-}
-
 static void adjust_topline(Terminal *term, buf_T *buf, long added)
 {
   FOR_ALL_WINDOWS_IN_TAB(wp, curtab) {
diff --git a/test/functional/terminal/scrollback_spec.lua b/test/functional/terminal/scrollback_spec.lua
index 75bb89a1ab..544325e746 100644
--- a/test/functional/terminal/scrollback_spec.lua
+++ b/test/functional/terminal/scrollback_spec.lua
@@ -142,15 +142,15 @@ describe(':terminal scrollback', function()
     describe('and height decreased by 1', function()
       if helpers.pending_win32(pending) then return end
       local function will_hide_top_line()
-        feed([[<C-\><C-N>:]])  -- Go to cmdline-mode, so cursor is at bottom.
+        feed([[<C-\><C-N>]])
         screen:try_resize(screen._width - 2, screen._height - 1)
         screen:expect([[
           line2                       |
           line3                       |
           line4                       |
           rows: 5, cols: 28           |
-          {2: }                           |
-          :^                           |
+          {2:^ }                           |
+                                      |
         ]])
       end
 
@@ -166,11 +166,11 @@ describe(':terminal scrollback', function()
           screen:expect([[
             rows: 5, cols: 28         |
             rows: 3, cols: 26         |
-            {2: }                         |
-            :^                         |
+            {2:^ }                         |
+                                      |
           ]])
           eq(8, curbuf('line_count'))
-          feed([[<C-\><C-N>3k]])
+          feed([[3k]])
           screen:expect([[
             ^line4                     |
             rows: 5, cols: 28         |
diff --git a/test/functional/terminal/window_split_tab_spec.lua b/test/functional/terminal/window_split_tab_spec.lua
index c0ce656bb1..ad70b3d14f 100644
--- a/test/functional/terminal/window_split_tab_spec.lua
+++ b/test/functional/terminal/window_split_tab_spec.lua
@@ -69,7 +69,7 @@ describe(':terminal', function()
   end)
 
   it('forwards resize request to the program', function()
-    feed([[<C-\><C-N>G:]])  -- Go to cmdline-mode, so cursor is at bottom.
+    feed([[<C-\><C-N>G]])
     local w1, h1 = screen._width - 3, screen._height - 2
     local w2, h2 = w1 - 6, h1 - 3
 
@@ -92,16 +92,16 @@ describe(':terminal', function()
                                                      |
                                                      |
                                                      |
+      ^                                               |
                                                      |
-      :^                                              |
     ]])
     screen:try_resize(w2, h2)
     screen:expect([[
       tty ready                                |
       rows: 7, cols: 47                        |
       rows: 4, cols: 41                        |
-      {2: }                                        |
-      :^                                        |
+      {2:^ }                                        |
+                                               |
     ]])
   end)
 end)
diff --git a/test/functional/ui/searchhl_spec.lua b/test/functional/ui/searchhl_spec.lua
index a46670d8a2..65ae124353 100644
--- a/test/functional/ui/searchhl_spec.lua
+++ b/test/functional/ui/searchhl_spec.lua
@@ -163,12 +163,14 @@ describe('search highlighting', function()
     ]])
     feed('/foo')
     sleep(50)  -- Allow some terminal activity.
-    screen:expect([[
-        {3:foo} bar baz       {3:│}xxx                |
-        bar baz {2:foo}       {3:│}xxx                |
-        bar {2:foo} baz       {3:│}xxx                |
-                          {3:│}xxx                |
-      {1:~                   }{3:│}xxx                |
+    -- NB: in earlier versions terminal output was redrawn during cmdline mode.
+    -- For now just assert that the screens remain unchanged.
+    screen:expect([[
+        {3:foo} bar baz       {3:│}                   |
+        bar baz {2:foo}       {3:│}                   |
+        bar {2:foo} baz       {3:│}                   |
+                          {3:│}                   |
+      {1:~                   }{3:│}                   |
       {5:[No Name] [+]        }{3:term               }|
       /foo^                                    |
     ]], { [1] = {bold = true, foreground = Screen.colors.Blue1},
diff --git a/test/functional/ui/wildmode_spec.lua b/test/functional/ui/wildmode_spec.lua
index cf22bb0a6f..1c8854bb28 100644
--- a/test/functional/ui/wildmode_spec.lua
+++ b/test/functional/ui/wildmode_spec.lua
@@ -95,10 +95,12 @@ describe("'wildmenu'", function()
 
     feed([[<C-\><C-N>gg]])
     feed([[:sign <Tab>]])   -- Invoke wildmenu.
+    -- NB: in earlier versions terminal output was redrawn during cmdline mode.
+    -- For now just assert that the screen remains unchanged.
     expect_stay_unchanged{grid=[[
-      foo                      |
-      foo                      |
-      foo                      |
+                               |
+                               |
+                               |
       define  jump  list  >    |
       :sign define^             |
     ]]}