panel: add battery lemon

os/arch/.config/panel/lemons/battery

@@ -0,0 +1,22 @@
+#!/usr/bin/env dash
+
+# No guarantee that it will be called BAT0, but it suits my purposes.
+if ! command -v acpi >/dev/null
+then
+    >&2 echo "acpi is not installed, battery segment disabled"
+    exit
+fi
+if [ ! -d "/sys/class/power_supply/BAT0" ]
+then
+    >&2 echo "No battery! This must be a PC"
+    exit
+fi
+
+while :
+do
+    BAT=$(acpi --battery)
+    PERC=$(echo $BAT | cut -d, -f2)
+    echo -n "B${PERC#?}:"
+    echo "$BAT" | grep charging >/dev/null && echo "1" || echo "0"
+    sleep 15
+done

os/arch/.config/panel/panel

@@ -60,6 +60,22 @@ parse() {
         data="${line#?}"
         case $line in
             # Minimal icons
+            B*) perc="${data%\%:*}"
+                state="${data#*:}"
+                case "${perc}" in
+                    100|9[0-9]) icon="${ICON_BAT9}" ;;
+                    8[0-9]) icon="${ICON_BAT8}" ;;
+                    7[0-9]) icon="${ICON_BAT7}" ;;
+                    6[0-9]) icon="${ICON_BAT6}" ;;
+                    5[0-9]) icon="${ICON_BAT5}" ;;
+                    4[0-9]) icon="${ICON_BAT4}" ;;
+                    3[0-9]) icon="%{F$COLOR_3}${ICON_BAT3}%{F-}" ;;
+                    2[0-9]) icon="%{F$COLOR_3}${ICON_BAT2}%{F-}" ;;
+                    1[0-9]) icon="%{F$COLOR_1}${ICON_BAT1}%{F-}" ;;
+                    *) icon="%{F$COLOR_1}${ICON_BAT0}%{F-}" ;;
+                esac
+                [ "$state" = "1" ] && battery="${icon}${ICON_BATAC}" || battery="${icon} "
+                ;;
             U*) updates=" %{F${COLOR_DIM}}$ICON_UPD%{F-}"
                 if [ "$data" -gt 0 ]; then
                     updates=" %{F${COLOR_2}}$ICON_UPD$data%{F-}"
@@ -187,7 +203,7 @@ parse() {
         echo -e \
             "%{l}${wm}${song}" \
             "%{c}${xtitle}" \
-            "%{r}${mail}${updates}${vol}${wifi}${datetime} "
+            "%{r}${battery}${mail}${updates}${vol}${wifi}${datetime} "
     done
 }
 

os/arch/.config/panel/panel-config

@@ -68,3 +68,15 @@ ICON_SPEAKER=""
 # misc
 ICON_MAIL=""
 ICON_UPD=""
+# battery
+ICON_BAT0=""
+ICON_BAT1=""
+ICON_BAT2=""
+ICON_BAT3=""
+ICON_BAT4=""
+ICON_BAT5=""
+ICON_BAT6=""
+ICON_BAT7=""
+ICON_BAT8=""
+ICON_BAT9=""
+ICON_BATAC=""