Continually replace buffer contents with a command. A scrollable alternative to the linux `watch` command

watch.lua

local M = {}

local A = vim.api
M.buf = nil

-- Replace buffer's contents with a command and preserve the cursor
M.update = function(command)
  return function()
    -- Save current cursor position
    local saveCursor = A.nvim_win_get_cursor(0)

    -- Execute your command and capture its output
    local output = vim.fn.systemlist(command)

    -- Strip ANSI color codes from the output
    local strippedOutput = {}
    for _, line in ipairs(output) do
      local strippedLine = line:gsub("\27%[[%d;]*[mK]", "") -- Remove ANSI escape sequences
      table.insert(strippedOutput, strippedLine)
    end

    -- Clear the buffer and insert the stripped output
    A.nvim_buf_set_lines(M.buf, 0, -1, false, strippedOutput)

    -- Restore cursor position
    A.nvim_win_set_cursor(0, saveCursor)
  end
end

-- Continually replace buffer contents with command
M.start = function(command, refresh_rate)
  local uv = vim.loop or vim.uv

  -- Create a new buffer
  if not M.buf then
    M.buf = A.nvim_create_buf(false, true)
    -- Automatically delete buffer when no longer visible
    vim.api.nvim_set_option_value("bufhidden", "wipe", { buf = M.buf })
    -- A.nvim_command "split"
    A.nvim_win_set_buf(0, M.buf)
  end
  -- A.nvim_set_current_buf(buf)

  -- Set up a timer to run the function every 500ms
  M.watch_timer = uv.new_timer()
  M.watch_timer:start(refresh_rate, refresh_rate, vim.schedule_wrap(M.update(command)))

  local group = A.nvim_create_augroup("WatchCleanUp", { clear = true })

  -- Stop the timer when the buffer is unloaded or when quitting Neovim
  A.nvim_create_autocmd({ "BufUnload", "VimLeavePre" }, {
    group = group,
    buffer = M.buf,
    callback = M.stop,
  })
end

M.stop = function()
  M.buf = nil
  M.watch_timer:stop()
end

return M