From d8d491741b1d01f67879dddc8e642b04a211afa2 Mon Sep 17 00:00:00 2001
From: Johannes Altmanninger <aclopte@gmail.com>
Date: Sun, 10 Mar 2024 10:16:35 +0100
Subject: [PATCH] edit_command_buffer: preserve external editor's cursor
 position

Unless the editor changed to a different file for some reason.

Note that the Kakoune integration uses -always to export the cursor even if
the user temporarily suppressed hooks - possibly a "fish_indent" hook.
---
 CHANGELOG.rst                            |  3 +-
 share/functions/edit_command_buffer.fish | 42 ++++++++++++++++++++++--
 2 files changed, 42 insertions(+), 3 deletions(-)

diff --git a/CHANGELOG.rst b/CHANGELOG.rst
index 61c6c7352..e7ec373c0 100644
--- a/CHANGELOG.rst
+++ b/CHANGELOG.rst
@@ -51,7 +51,8 @@ Interactive improvements
 - Command-specific tab completions may now offer results whose first character is a period. For example, it is now possible to tab-complete ``git add`` for files with leading periods. The default file completions hide these files, unless the token itself has a leading period (:issue:`3707`).
 - The :kbd:`Control-R` history search now uses glob syntax (:issue:`10131`).
 - When the cursor is on a command that resolves to a script, :kbd:`Alt-O` will now open that script in your editor.
-- :kbd:`Alt-E` now passes the cursor position to the external editor also if the editor aliases a supported editor (via ``complete --wraps``).
+- After using :kbd:`Alt-E` to edit the commandline in an external editor, the editor's cursor position will be copied over to fish. This is currently supported for Vim and Kakoune.
+- When deciding how to pass the cursor position to and from the external editor, :kbd:`Alt-E` now resolves aliases. For example use ``complete --wraps my-vim vim`` to synchronize cursors when `EDITOR=my-vim`.
 - Option completion now uses fuzzy subsequence filtering as well. This means that ``--fb`` may be completed to ``--foobar`` if there is no better match.
 - ASCII control characters are now rendered using symbols from Unicode's Control Pictures block.
 
diff --git a/share/functions/edit_command_buffer.fish b/share/functions/edit_command_buffer.fish
index 6c6f60358..6e382b361 100644
--- a/share/functions/edit_command_buffer.fish
+++ b/share/functions/edit_command_buffer.fish
@@ -38,12 +38,34 @@ function edit_command_buffer --description 'Edit the command buffer in an extern
         set -a wrapped_commands $tmp[1]
     end
     set -l found false
+    set -l cursor_from_editor
     for editor_command in $editor_basename $wrapped_commands
         switch $editor_command
             case vi vim nvim
-                set -a editor +$line +"norm! $col|" $f
-            case emacs emacsclient gedit kak
+                if test $editor_command = vi && not set -l vi_version "$(vi --version 2>/dev/null)"
+                    if printf %s $vi_version | grep -q BusyBox
+                        break
+                    end
+                    set -a editor +{$line} $f
+                    set found true
+                    break
+                end
+                set cursor_from_editor (mktemp)
+                set -a editor +$line "+norm! $col|" $f \
+                    '+autocmd VimLeave * ++once call writefile(
+                        [printf("%s %s %s", shellescape(bufname()), line("."), col("."))],
+                        "'$cursor_from_editor'"
+                     )'
+            case emacs emacsclient gedit
                 set -a editor +$line:$col $f
+            case kak
+                set cursor_from_editor (mktemp)
+                set -a editor +$line:$col $f -e "
+                        hook -always -once global ClientClose %val{client} %{
+                            echo -to-file $cursor_from_editor -quoting shell \
+                                %val{buffile} %val{cursor_line} %val{cursor_column}
+                        }
+                    "
             case nano
                 set -a editor +$line,$col $f
             case joe ee
@@ -80,6 +102,22 @@ function edit_command_buffer --description 'Edit the command buffer in an extern
         echo (_ "Ignoring the output of your editor since its exit status was non-zero")
         echo (_ "or the file was empty")
     end
+    if set -q cursor_from_editor[1]
+        eval set -l pos "$(cat $cursor_from_editor)"
+        if set -q pos[1] && test $pos[1] = $f
+            set -l line $pos[2]
+            set -l column $pos[3]
+            commandline -C 0
+            for _line in (seq $line)[2..]
+                commandline -f down-line
+            end
+            commandline -f beginning-of-line
+            for _column in (seq $column)[2..]
+                commandline -f forward-single-char
+            end
+        end
+        command rm $cursor_from_editor
+    end
     command rm $f
     # We've probably opened something that messed with the screen.
     # A repaint seems in order.