refactor(spell): migrate to Lua, drop netrw dependency

Problem:
Spell file downloads relied on Vimscript and netrw (:Nread). If netrw is
disabled, downloads fail.

Solution:
Port the logic to Lua as `nvim.spellfile` and wire it via a Lua plugin that
handles `SpellFileMissing`. Use `vim.net.request()` with a timeout for HTTP,
prompt via `vim.fn.input` and report via `vim.notify`.

Closes #7189

1 files changed, 278 insertions, 0 deletions

diff --git a/runtime/lua/nvim/spellfile.lua b/runtime/lua/nvim/spellfile.lua
new file mode 100644
index 0000000000..51c7a90f84
--- /dev/null
+++ b/runtime/lua/nvim/spellfile.lua
@@ -0,0 +1,278 @@
+local M = {}
+
+--- @class SpellfileConfig
+--- @field url string
+--- @field timeout_ms integer
+
+---@class SpellInfo
+---@field files string[]
+---@field key string
+---@field lang string
+---@field encoding string
+---@field dir string
+
+---@type SpellfileConfig
+M.config = {
+  url = 'https://ftp.nluug.nl/pub/vim/runtime/spell',
+  timeout_ms = 15000,
+}
+
+---@type table<string, boolean>
+M._done = {}
+
+---@return string[]
+local function rtp_list()
+  return vim.opt.rtp:get()
+end
+
+function M.isDone(key)
+  return M._done[key]
+end
+
+function M.setup(opts)
+  M._done = {}
+  M.config = vim.tbl_extend('force', M.config, opts or {})
+end
+
+local function notify(msg, level)
+  vim.notify(msg, level or vim.log.levels.INFO)
+end
+
+---@param lang string
+---@return string
+local function normalize_lang(lang)
+  local l = (lang or ''):lower():gsub('-', '_')
+  return (l:match('^[^,%s]+') or l)
+end
+
+local function writable_spell_dirs_from_rtp()
+  local dirs = {}
+  for _, dir in ipairs(rtp_list()) do
+    local spell = vim.fs.joinpath(vim.fn.fnamemodify(dir, ':p'), 'spell')
+    if vim.fn.isdirectory(spell) == 1 and vim.uv.fs_access(spell, 'W') then
+      table.insert(dirs, spell)
+    end
+  end
+  return dirs
+end
+
+local function default_spell_dir()
+  return vim.fs.joinpath(vim.fn.stdpath('data'), 'site', 'spell')
+end
+
+local function ensure_target_dir()
+  local dirs = writable_spell_dirs_from_rtp()
+  if #dirs > 0 then
+    return dirs[1]
+  end
+  local target = default_spell_dir()
+  if vim.fn.isdirectory(target) ~= 1 then
+    vim.fn.mkdir(target, 'p')
+    notify('Created ' .. target)
+  end
+  return target
+end
+
+local function file_ok(path)
+  local s = vim.uv.fs_stat(path)
+  return s and s.type == 'file' and (s.size or 0) > 0
+end
+
+local function reload_spell_silent()
+  vim.cmd('silent! setlocal spell!')
+  if vim.bo.spelllang and vim.bo.spelllang ~= '' then
+    vim.cmd('silent! setlocal spelllang=' .. vim.bo.spelllang)
+  end
+  vim.cmd('echo ""')
+end
+
+--- Blocking GET to file with timeout; treats status==0 as success if file exists.
+--- @return boolean ok, integer|nil status, string|nil err
+local function http_get_to_file_sync(url, outpath, timeout_ms)
+  local done, err, res = false, nil, nil
+  vim.net.request(url, { outpath = outpath }, function(e, r)
+    err, res, done = e, r, true
+  end)
+  vim.wait(timeout_ms or M.config.timeout_ms, function()
+    return done
+  end, 50, false)
+
+  local status = res and res.status or 0
+  local ok = (not err) and ((status >= 200 and status < 300) or (status == 0 and file_ok(outpath)))
+  return ok, (status ~= 0 and status or nil), err
+end
+
+---@return string[]
+function M.directory_choices()
+  local opts = {}
+  for _, dir in ipairs(rtp_list()) do
+    local spelldir = vim.fs.joinpath(vim.fn.fnamemodify(dir, ':p'), 'spell')
+    if vim.fn.isdirectory(spelldir) == 1 then
+      table.insert(opts, spelldir)
+    end
+  end
+  return opts
+end
+
+function M.choose_directory()
+  local dirs = writable_spell_dirs_from_rtp()
+  if #dirs == 0 then
+    return ensure_target_dir()
+  elseif #dirs == 1 then
+    return dirs[1]
+  end
+  local prompt ---@type string[]
+  prompt = {}
+  for i, d in
+    ipairs(dirs --[[@as string[] ]])
+  do
+    prompt[i] = string.format('%d: %s', i, d)
+  end
+  local choice = vim.fn.inputlist(prompt)
+  if choice < 1 or choice > #dirs then
+    return dirs[1]
+  end
+  return dirs[choice]
+end
+
+function M.parse(lang)
+  local code = normalize_lang(lang)
+  local enc = 'utf-8'
+  local dir = ensure_target_dir()
+
+  local missing = {}
+  local candidates = {
+    string.format('%s.%s.spl', code, enc),
+    string.format('%s.%s.sug', code, enc),
+  }
+  for _, fn in ipairs(candidates) do
+    if not file_ok(vim.fs.joinpath(dir, fn)) then
+      table.insert(missing, fn)
+    end
+  end
+
+  return {
+    files = missing,
+    key = code .. '.' .. enc,
+    lang = code,
+    encoding = enc,
+    dir = dir,
+  }
+end
+
+---@param info SpellInfo
+function M.download(info)
+  local dir = info.dir or ensure_target_dir()
+  if not dir then
+    notify('No (writable) spell directory found and could not create one.', vim.log.levels.ERROR)
+    return
+  end
+
+  local lang = info.lang
+  local enc = info.encoding
+
+  local spl_utf8 = string.format('%s.%s.spl', lang, enc)
+  local spl_ascii = string.format('%s.ascii.spl', lang)
+  local sug_name = string.format('%s.%s.sug', lang, enc)
+
+  local url_utf8 = M.config.url .. '/' .. spl_utf8
+  local out_utf8 = vim.fs.joinpath(dir, spl_utf8)
+  notify('Downloading ' .. spl_utf8 .. ' …')
+  local ok, st, err = http_get_to_file_sync(url_utf8, out_utf8, M.config.timeout_ms)
+  if not ok then
+    notify(
+      ('Could not get %s (status %s): trying %s …'):format(
+        spl_utf8,
+        tostring(st or 'nil'),
+        spl_ascii
+      )
+    )
+    local url_ascii = M.config.url .. '/' .. spl_ascii
+    local out_ascii = vim.fs.joinpath(dir, spl_ascii)
+    local ok2, st2, err2 = http_get_to_file_sync(url_ascii, out_ascii, M.config.timeout_ms)
+    if not ok2 then
+      notify(
+        ('No spell file available for %s (utf8:%s ascii:%s) — %s'):format(
+          lang,
+          tostring(st or err or 'fail'),
+          tostring(st2 or err2 or 'fail'),
+          url_utf8
+        ),
+        vim.log.levels.WARN
+      )
+      vim.schedule(function()
+        vim.cmd('echo ""')
+      end)
+      M._done[info.key] = true
+      return
+    end
+    notify('Saved ' .. spl_ascii .. ' to ' .. out_ascii)
+  else
+    notify('Saved ' .. spl_utf8 .. ' to ' .. out_utf8)
+  end
+
+  reload_spell_silent()
+
+  if not file_ok(vim.fs.joinpath(dir, sug_name)) then
+    local url_sug = M.config.url .. '/' .. sug_name
+    local out_sug = vim.fs.joinpath(dir, sug_name)
+    notify('Downloading ' .. sug_name .. ' …')
+    local ok3, st3, err3 = http_get_to_file_sync(url_sug, out_sug, M.config.timeout_ms)
+    if ok3 then
+      notify('Saved ' .. sug_name .. ' to ' .. out_sug)
+    else
+      local is404 = (st3 == 404) or (tostring(err3 or ''):match('%f[%d]404%f[%D]') ~= nil)
+      if is404 then
+        notify('Suggestion file not available: ' .. sug_name, vim.log.levels.DEBUG)
+      else
+        notify(
+          ('Failed to download %s (status %s): %s'):format(
+            sug_name,
+            tostring(st3 or 'nil'),
+            tostring(err3 or '')
+          ),
+          vim.log.levels.INFO
+        )
+      end
+      vim.schedule(function()
+        vim.cmd('echo ""')
+      end)
+    end
+  end
+
+  M._done[info.key] = true
+end
+
+function M.load_file(lang)
+  local info = M.parse(lang)
+  if #info.files == 0 then
+    return
+  end
+  if M._done[info.key] then
+    notify('Already attempted spell load for ' .. lang, vim.log.levels.DEBUG)
+    return
+  end
+
+  local answer = vim.fn.input(
+    string.format('No spell file found for %s (%s). Download? [y/N] ', info.lang, info.encoding)
+  )
+  if (answer or ''):lower() ~= 'y' then
+    return
+  end
+
+  M.download(info)
+end
+
+function M.exists(filename)
+  local stat = (vim.uv or vim.loop).fs_stat
+  for _, dir in ipairs(M.directory_choices()) do
+    local p = vim.fs.joinpath(dir, filename)
+    local s = stat(p)
+    if s and s.type == 'file' then
+      return true
+    end
+  end
+  return false
+end
+
+return M