Neovim ncbackup

ncbackup.lua

--[[

WORKED with NVchad, not with LazyVim, however - neovim's undo is making this obsolete

Description: Numbered Central Backup
Created by:  Martin Krischik (2006)
Adapted by:  Ondrej Brablc (2011 for vim, 2024 for neovim)
Customize:
 vim.g.ncbackup_directory   name of backup directory central to edited file by default ~/.local/state/nvim/ncbackups
 vim.g.ncbackup_purge       count of backups to hold - purge older once.  0 switches the feature off
--]]

vim.opt.backup = true  -- Enable backup file creation
vim.opt.writebackup = true  -- Keep a backup file while writing

local ncbackup = {}
ncbackup.directory = vim.g.ncbackup_directory or (vim.fn.stdpath('data') .. "/ncbackup")
ncbackup.purge = vim.g.ncbackup_purge or 10

local function make_backup_dir(path)
  if vim.fn.isdirectory(path) == 0 then
    vim.fn.mkdir(path, "p", "0770")
  end
end

local function get_version(filename)
  return tonumber(filename:match(";(.*)"))
end

local function version_compare(left, right)
  local left_ver = get_version(left)
  local right_ver = get_version(right)
  if left_ver == right_ver then
    return 0
  elseif left_ver > right_ver then
    return 1
  else
    return -1
  end
end

local function set_backup(doc_path, doc_name)
  local backup_path = vim.fn.expand(ncbackup.directory) .. '/' .. doc_path:gsub("[:\\]", "/")
  make_backup_dir(backup_path)
  vim.opt.backupdir:prepend(vim.fn.fnameescape(backup_path))

  local existing_backups = {}
  local glob_results = vim.fn.globpath(backup_path, doc_name .. ";*")
  if glob_results ~= "" then
    existing_backups = vim.split(glob_results, "\n")
    table.sort(existing_backups, version_compare)
  end

  if #existing_backups == 0 then
    vim.opt.backupext = ";1"
  else
    local latest_version = get_version(existing_backups[#existing_backups])
    vim.opt.backupext = ";" .. tostring(latest_version + 1)

    if ncbackup.purge > 0 and #existing_backups > ncbackup.purge then
      for i = 1, #existing_backups - ncbackup.purge do
        vim.fn.delete(existing_backups[i])
      end
    end
  end
end

make_backup_dir(vim.fn.expand(ncbackup.directory))
vim.api.nvim_create_autocmd("BufWritePre", {
  pattern = "*",
  callback = function(args)
    set_backup(vim.fn.expand("<afile>:p:h"), vim.fn.expand("<afile>:p:t"))
  end
}