Vim function: toggle ".only" on the current jest test

ToggleJestOnlyGlobal.vim

" This function adds ".only" to the nearest "it(..." block above the cursor, or
" removes ".only" if that is already present. If a "describe..." block is
" nearer above the cursor than any "it..." block, ".only" is toggled on it.

function! ToggleJestOnlyGlobal()
  let cursor_position = getpos('.')
  let current_line = getline('.')

  " Search backwards from the current line for the nearest occurrence of it( or describe(
  let match_pos_it = search('\v(it|it\.only)\(', 'bcnW')
  let match_pos_describe = search('\v(describe|describe\.only)\(', 'bcnW')

  " If no match was found in backward search, reset cursor position and echo a message
  if match_pos_it == 0 && match_pos_describe == 0
    call setpos('.', cursor_position)
    echo "No 'it' or 'describe' block found."
    return
  endif

  " Determine the nearest block to toggle .only
  let nearest_match_pos = match_pos_it == 0 ? match_pos_describe : (match_pos_describe == 0 ? match_pos_it : (match_pos_it > match_pos_describe ? match_pos_it : match_pos_describe))
  let target_line = getline(nearest_match_pos)
  let statement = target_line =~ '^\s*it\(\.only\)\?' ? 'it' : (target_line =~ '^\s*describe\(\.only\)\?' ? 'describe' : '')

  if statement == ''
    call setpos('.', cursor_position)
    echo "No toggleable 'it' or 'describe' block found."
    return
  endif

  " Perform the toggle on the identified line
  if target_line =~ '\<'. statement . '\.only'
    let modified_line = substitute(target_line, '\<'. statement . '\.only', statement, '')
  else
    let modified_line = substitute(target_line, '\<'. statement . '\>', statement . '.only', '')
  endif

  " Update the line with the modified content
  call setline(nearest_match_pos, modified_line)

  " Reset the cursor to its original position
  call setpos('.', cursor_position)
endfunction

nnoremap <leader>jo :call ToggleJestOnlyGlobal()<CR>