[modules/battery] Re-enable battery module

Extend theme to be able to accept lists of values and cycle through
them. Use this to "animate" the charging symbol for the battery.

see #23

bumblebee/modules/battery.py

@@ -0,0 +1,54 @@
+# pylint: disable=C0111,R0903
+
+import os
+
+import bumblebee.input
+import bumblebee.output
+import bumblebee.engine
+
+class Module(bumblebee.engine.Module):
+    def __init__(self, engine, config):
+        super(Module, self).__init__(engine, config,
+            bumblebee.output.Widget(full_text=self.capacity)
+        )
+        battery = self.parameter("device", "BAT0")
+        self._path = "/sys/class/power_supply/{}".format(battery)
+        self._capacity = 100
+
+    def capacity(self):
+        return "{:02d}%".format(self._capacity)
+
+    def update(self, widgets):
+        widget = widgets[0]
+        self._ac = False
+        if not os.path.exists(self._path):
+            self._ac = True
+
+        with open(self._path + "/capacity") as f:
+            self._capacity = int(f.read())
+        self._capacity = self._capacity if self._capacity < 100 else 100
+
+    def state(self, widget):
+        state = []
+        if self._capacity < self.parameter("critical", 10):
+            state.append("critical")
+        elif self._capacity < self.parameter("warning", 20):
+            state.append("warning")
+
+        if self._ac:
+            state.append("AC")
+        else:
+            charge = ""
+            with open(self._path + "/status") as f:
+                charge = f.read().strip()
+            if charge == "Discharging":
+                state.append("discharging-{}".format(min([10, 25, 50, 80, 100] , key=lambda i:abs(i-self._capacity))))
+            else:
+                if self._capacity > 95:
+                    state.append("charged")
+                else:
+                    state.append("charging")
+
+        return state
+
+# vim: tabstop=8 expandtab shiftwidth=4 softtabstop=4

bumblebee/theme.py

@@ -132,6 +132,12 @@ class Theme(object):
         for theme in state_themes:
             value = theme.get(name, value)
 
+        if isinstance(value, list):
+            key = "{}-idx".format(name)
+            idx = widget.get(key, 0)
+            widget.set(key, (idx + 1) % len(value))
+            value = value[idx]
+
         return value
 
     # algorithm copied from