i3status: add battery block

1 files changed, 75 insertions, 0 deletions

diff --git a/pkg/i3status/battery.go b/pkg/i3status/battery.go
new file mode 100644
index 0000000..0b6979d
--- /dev/null
+++ b/pkg/i3status/battery.go
@@ -0,0 +1,75 @@
+/*******************************************************************************
+*
+* Copyright 2017 Stefan Majewsky <majewsky@gmx.net>
+*
+* This program is free software: you can redistribute it and/or modify it under
+* the terms of the GNU General Public License as published by the Free Software
+* Foundation, either version 3 of the License, or (at your option) any later
+* version.
+*
+* This program is distributed in the hope that it will be useful, but WITHOUT ANY
+* WARRANTY; without even the implied warranty of MERCHANTABILITY or FITNESS FOR
+* A PARTICULAR PURPOSE. See the GNU General Public License for more details.
+*
+* You should have received a copy of the GNU General Public License along with
+* this program. If not, see <http://www.gnu.org/licenses/>.
+*
+*******************************************************************************/
+
+package i3status
+
+import (
+	"fmt"
+	"io/ioutil"
+	"strconv"
+	"strings"
+)
+
+const (
+	batteryFullPath = "/sys/class/power_supply/BAT0/energy_full"
+	batteryNowPath  = "/sys/class/power_supply/BAT0/energy_now"
+	powerNowPath    = "/sys/class/power_supply/BAT0/power_now"
+)
+
+func getBatteryStatus() []Block {
+	//TODO: What's with /sys/class/power_supply/BAT0/uevent? Can this be used to
+	//remove all the polling overhead here?
+
+	energyFull, err := readNumberFromFile(batteryFullPath)
+	if err != nil {
+		return nil
+	}
+	energyNow, err := readNumberFromFile(batteryNowPath)
+	if err != nil {
+		return nil
+	}
+	powerNow, err := readNumberFromFile(powerNowPath)
+	if err != nil {
+		return nil
+	}
+
+	energyPerc := energyNow * 100 / energyFull
+	charging := powerNow == 0 //i.e. when we're not drawing power from the battery
+	color := "#AAAA00"
+	if charging {
+		color = "#00AA00"
+	} else if energyPerc < 10 {
+		color = "#AA0000"
+	}
+
+	return section(Block{
+		Name:     "battery",
+		Position: PositionBattery,
+		FullText: fmt.Sprintf("⚡ %d%%", energyPerc),
+		Urgent:   energyPerc < 10 && !charging,
+		Color:    color,
+	})
+}
+
+func readNumberFromFile(path string) (int64, error) {
+	buf, err := ioutil.ReadFile(path)
+	if err != nil {
+		return 0, err
+	}
+	return strconv.ParseInt(strings.TrimSpace(string(buf)), 0, 64)
+}