add ac plugin

contrib/README

@@ -18,6 +18,14 @@ could also depend on Lua libraries that are not distributed with the
 core Lua distribution. Ease of installation and use does not
 necessarily have to apply to contributed widgets.
 
+vicious.contrib.ac
+  - provide status about the power supply (AC)
+  - takes the AC device as an argument, i.e "AC" or "ACAD"
+  - the device is linked under /sys/class/power_supply/ and should
+    have a file called "online"
+  - if AC is connected, $1 returns "On", if not it returns "Off",
+    if AC doesn't exist, $1 is "N/A"
+
 vicious.contrib.batacpi
   -
 

contrib/ac.lua

@@ -0,0 +1,35 @@
+---------------------------------------------------
+-- Licensed under the GNU General Public License v2
+--  * (c) 2012, jinleileiking <jinleileiking@gmail.com>
+---------------------------------------------------
+
+-- {{{ Grab environment
+local tonumber = tonumber
+local setmetatable = setmetatable
+local string = { format = string.format }
+local helpers = require("vicious.helpers")
+local math = {
+    min = math.min,
+    floor = math.floor
+}
+-- }}}
+
+module("vicious.contrib.ac")
+
+-- {{{ AC widget type
+local function worker(format, warg)
+    local ac = helpers.pathtotable("/sys/class/power_supply/"..warg)
+
+    local state = ac.online
+    if state == nil then
+        return {"N/A"}
+    elseif state == "1\n" then
+        return {"On"}
+    else
+        return {"Off"}
+    end
+end
+-- }}}
+
+
+setmetatable(_M, { __call = function(_, ...) return worker(...) end })