feat: :SosBufToggle command

This command allows for ignoring individual buffers so that they do not
get autosaved. Accepts an optional `{bufname}` argument to specify a
buffer other than the current one. Deleting a buffer (e.g. `:bdelete`)
resets its ignored status. Ignore status is stored at `b:sos_ignore`.

Also add dedicated API functions for this, as well as functions to
enable or disable the entire plugin. These are all found in the
`require('sos')` module.

Also do some refactoring/cleanup.

lua/sos/autocmds.lua

@@ -1,5 +1,4 @@
 local M = {}
-local commands = require 'sos.commands'
 local impl = require 'sos.impl'
 local api = vim.api
 local augroup = 'sos-autosaver'

lua/sos/commands.lua

@@ -1,11 +1,15 @@
+local errmsg = require('sos.util').errmsg
 local api = vim.api
-local extkeys = { action = true }
+local extkeys = { [1] = true }
 
 -- TODO: types
 
+---@class (exact) sos.Command: vim.api.keyset.user_command
+---@field [1] string|function
+
 local function Command(def)
   return setmetatable(def, {
-    __call = function(f, ...) return f.action(...) end,
+    __call = function(self, ...) return self[1](...) end,
   })
 end
 
@@ -19,13 +23,14 @@ local function filter_extkeys(tbl)
   return ret
 end
 
+---@param parent table<string, sos.Command>
 local function Commands(parent, ret)
   ret = ret or {}
 
   for k, v in pairs(parent) do
-    if type(v) == 'table' and v.action then
+    if type(v) == 'table' and v[1] then
       ret[k] = Command(v)
-      api.nvim_create_user_command(k, v.action, filter_extkeys(v))
+      api.nvim_create_user_command(k, v[1], filter_extkeys(v))
     else
       Commands(v, ret)
     end
@@ -34,23 +39,85 @@ local function Commands(parent, ret)
   return ret
 end
 
+-- local function assert_msg(cond, msg, ...)
+--   if not cond then
+--     api.nvim_notify(msg:format(...), vim.log.levels.ERROR, {})
+--     coroutine.yield(cond)
+--     error 'resumed dead coroutine'
+--   end
+--
+--   return cond
+-- end
+--
+-- local function ignore_error(f)
+--   return function(...)
+--     local ok, e = pcall(f)
+--     if not ok and e and e ~= '' then error(e) end
+--   end
+-- end
+--
+-- local function resolve_bufspec(bufspec) end
+
 return Commands {
   SosEnable = {
     desc = 'Enable sos autosaver',
-    action = function() require('sos').setup { enabled = true } end,
+    nargs = 0,
+    force = true,
+    function() require('sos').enable(true) end,
   },
 
   SosDisable = {
     desc = 'Disable sos autosaver',
-    action = function() require('sos').setup { enabled = false } end,
+    nargs = 0,
+    force = true,
+    function() require('sos').disable(true) end,
   },
 
   SosToggle = {
     desc = 'Toggle sos autosaver',
-    action = function()
-      require('sos').setup {
-        enabled = not require('sos.config').enabled,
-      }
+    nargs = 0,
+    force = true,
+    function()
+      if require('sos.config').enabled then
+        require('sos').disable(true)
+      else
+        require('sos').enable(true)
+      end
+    end,
+  },
+
+  SosBufToggle = {
+    desc = 'Toggle autosaver for buffer',
+    nargs = '?',
+    count = -1,
+    addr = 'buffers',
+    complete = 'buffer',
+    force = true,
+    function(info)
+      if #info.fargs > 1 then return errmsg 'only 1 argument is allowed' end
+      local buf
+
+      if info.range > 0 then
+        -- Here we either have range and int arg, or just range. No way to
+        -- decipher between the two. `count` is rightmost of the two on cmdline.
+        buf = info.count
+
+        if #info.fargs > 0 then
+          return errmsg 'only 1 arg or count is allowed, got both'
+        elseif info.range > 1 then
+          return errmsg 'only 1 arg or count is allowed, got range'
+        elseif buf < 1 or not api.nvim_buf_is_valid(buf) then
+          return errmsg('invalid buffer: ' .. buf)
+        end
+      else
+        local arg = info.fargs[1]
+
+        -- Use `[$]` for `$`, otherwise we'll get highest bufnr.
+        buf = vim.fn.bufnr(arg == '$' and '[$]' or arg or '')
+        if buf < 1 then errmsg 'argument matched none or multiple buffers' end
+      end
+
+      require('sos').toggle_buf(buf, true)
     end,
   },
 }

lua/sos/config.lua

@@ -1,12 +1,13 @@
----@class sos.Config                                                      # Plugin options passed to `setup()`.
----@field enabled boolean | nil                                           # Whether to enable or disable the plugin.
----@field timeout integer | nil                                           # Timeout in ms. Buffer changes debounce the timer.
----@field autowrite boolean | "all" | nil                                 # Set and manage Vim's 'autowrite' option.
----@field save_on_cmd "all" | "some" | table<string, true> | false | nil  # Save all buffers before executing a command on cmdline
----@field save_on_bufleave boolean | nil                                  # Save current buffer on `BufLeave` (see `:h BufLeave`)
----@field save_on_focuslost boolean | nil                                 # Save all bufs when Neovim loses focus or is suspended.
----@field should_observe_buf nil | fun(buf: integer): boolean             # Return true to observe/attach to buf.
----@field on_timer function                                               # The function to call when the timer fires.
+---@class sos.Config                                                 # Plugin options passed to `setup()`.
+---@field enabled? boolean                                           # Whether to enable or disable the plugin.
+---@field timeout? integer                                           # Timeout in ms. Buffer changes debounce the timer.
+---@field autowrite? boolean | "all"                                 # Set and manage Vim's 'autowrite' option.
+---@field save_on_cmd? "all" | "some" | table<string, true> | false  # Save all buffers before executing a command on cmdline
+---@field save_on_bufleave? boolean                                  # Save current buffer on `BufLeave` (see `:h BufLeave`)
+---@field save_on_focuslost? boolean                                 # Save all bufs when Neovim loses focus or is suspended.
+---@field should_observe_buf? fun(buf: integer): boolean             # Return true to observe/attach to buf.
+---@field on_timer? function                                         # The function to call when the timer fires.
+
 local defaults = {
   enabled = true,
   timeout = 20000,