add battery widget (taken from https://github.com/coleifer/mastodon/b…

…lob/master/battery.go)

i3status/power.go

@@ -1,19 +1,26 @@
 package i3status
 
 import (
-	"bytes"
+	"errors"
 	"fmt"
-	"os/exec"
 	"strconv"
+	"strings"
 	"time"
 )
 
 const (
-	Charging    = "charging"
-	Discharging = "discharging"
-	Charged     = "charged"
+	BATTERY_DISCHARGING = iota
+	BATTERY_CHARGING
+	BATTERY_FULL
 )
 
+type BatteryInfo struct {
+	PercentRemaining float64
+	SecondsRemaining float64
+	Consumption      float64
+	status           int
+}
+
 type PowerWidget struct {
 	BaseWidget
 }
@@ -26,13 +33,25 @@ func NewPowerWidget() *PowerWidget {
 	return &w
 }
 
-func (w *PowerWidget) execCommand() string {
-	var out bytes.Buffer
-	cmd := exec.Command("acpi", "-b")
-	cmd.Stdout = &out
-	cmd.Run()
-	str, _ := out.ReadString('\n')
-	return str
+func (w *PowerWidget) getStatus() (string, string) {
+	bi, _ := readBatteryInfo(0)
+
+	bar := MakeBar(bi.PercentRemaining, 20)
+	remaining := HumanDuration(int64(bi.SecondsRemaining))
+	prefix := "BAT"
+	color := "#ffffff"
+	if bi.IsCharging() {
+		prefix = "CHR"
+	} else if bi.IsFull() {
+		prefix = "FULL"
+	} else {
+		if bi.PercentRemaining < 10 {
+			color = "#ff0000"
+		} else if bi.PercentRemaining < 30 {
+			color = "#ffff00"
+		}
+	}
+	return fmt.Sprintf("%s %s %s %0.1f%%", prefix, remaining, bar, bi.PercentRemaining), color
 }
 
 func (w *PowerWidget) basicLoop() {
@@ -41,8 +60,7 @@ func (w *PowerWidget) basicLoop() {
 	msg.Color = "#ffffff"
 	msg.Instance = strconv.Itoa(w.Instance)
 	for {
-		str := w.execCommand()
-		msg.FullText = fmt.Sprintf("%s", str)
+		msg.FullText, msg.Color = w.getStatus()
 		w.Output <- *msg
 		time.Sleep(5000 * time.Millisecond)
 	}
@@ -52,3 +70,81 @@ func (w *PowerWidget) Start() {
 	go w.basicLoop()
 	go w.readLoop()
 }
+
+// stolen from https://github.com/coleifer/mastodon/blob/master/battery.go
+func (batteryInfo *BatteryInfo) IsCharging() bool {
+	return batteryInfo.status == BATTERY_CHARGING
+}
+
+func (batteryInfo *BatteryInfo) IsFull() bool {
+	return batteryInfo.status == BATTERY_FULL
+}
+
+func readBatteryInfo(battery int) (*BatteryInfo, error) {
+	rawInfo := make(map[string]string)
+	batteryInfo := new(BatteryInfo)
+
+	path := fmt.Sprintf("/sys/class/power_supply/BAT%d/uevent", battery)
+	if !FileExists(path) {
+		return batteryInfo, errors.New("Battery not found")
+	}
+	callback := func(line string) bool {
+		data := strings.Split(string(line), "=")
+		rawInfo[data[0]] = data[1]
+		return true
+	}
+	ReadLines(path, callback)
+
+	var remaining, presentRate, voltage, fullDesign float64
+	var wattAsUnit bool
+	batteryInfo.status = BATTERY_DISCHARGING
+
+	if rawInfo["POWER_SUPPLY_STATUS"] == "Charging" {
+		batteryInfo.status = BATTERY_CHARGING
+	} else if rawInfo["POWER_SUPPLY_STATUS"] == "Full" {
+		batteryInfo.status = BATTERY_FULL
+	}
+
+	/* Convert to float shorthand */
+	pf := func(keys ...string) float64 {
+		for _, key := range keys {
+			if _, ok := rawInfo[key]; ok {
+				f, _ := strconv.ParseFloat(rawInfo[key], 64)
+				return f
+			}
+		}
+		return 0.
+	}
+
+	/* Read values from file */
+	remaining = pf("POWER_SUPPLY_ENERGY_NOW", "POWER_SUPPLY_CHARGE_NOW")
+	presentRate = pf("POWER_SUPPLY_CURRENT_NOW", "POWER_SUPPLY_POWER_NOW")
+	voltage = pf("POWER_SUPPLY_VOLTAGE_NOW")
+	fullDesign = pf("POWER_SUPPLY_CHARGE_FULL_DESIGN", "POWER_SUPPLY_ENERGY_FULL_DESIGN")
+	_, wattAsUnit = rawInfo["POWER_SUPPLY_ENERGY_NOW"]
+
+	if !wattAsUnit {
+		presentRate = (voltage / 1000.0) * (presentRate / 1000.0)
+		remaining = (voltage / 1000.0) * (remaining / 1000.0)
+		fullDesign = (voltage / 1000.0) * (fullDesign / 1000.0)
+	}
+
+	if fullDesign == 0 {
+		return batteryInfo, errors.New("Battery full design missing")
+	}
+
+	batteryInfo.PercentRemaining = (remaining / fullDesign) * 100
+
+	var remainingTime float64
+	if presentRate > 0 {
+		if batteryInfo.status == BATTERY_CHARGING {
+			remainingTime = (fullDesign - remaining) / presentRate
+		} else if batteryInfo.status == BATTERY_DISCHARGING {
+			remainingTime = remaining / presentRate
+		}
+		batteryInfo.SecondsRemaining = remainingTime * 3600
+	}
+	batteryInfo.Consumption = presentRate / 1000000.0
+
+	return batteryInfo, nil
+}

i3status/utils.go

@@ -0,0 +1,53 @@
+// this has been stolen form
+// https://github.com/coleifer/mastodon/blob/master/utils.go
+package i3status
+
+import (
+	"bufio"
+	"bytes"
+	"fmt"
+	"io"
+	"os"
+)
+
+func ReadLines(fileName string, callback func(string) bool) {
+	fin, err := os.Open(fileName)
+	if err != nil {
+		fmt.Fprintf(os.Stderr, "The file %s does not exist!\n", fileName)
+		return
+	}
+	defer fin.Close()
+
+	reader := bufio.NewReader(fin)
+	for line, _, err := reader.ReadLine(); err != io.EOF; line, _, err = reader.ReadLine() {
+		if !callback(string(line)) {
+			break
+		}
+	}
+}
+
+func FileExists(path string) bool {
+	_, err := os.Stat(path)
+	return err == nil
+}
+
+func MakeBar(percent float64, bar_size int) string {
+	var bar bytes.Buffer
+	cutoff := int(percent * .01 * float64(bar_size))
+	bar.WriteString("[")
+	for i := 0; i < bar_size; i += 1 {
+		if i <= cutoff {
+			bar.WriteString("#")
+		} else {
+			bar.WriteString(" ")
+		}
+	}
+	bar.WriteString("]")
+	return bar.String()
+}
+
+func HumanDuration(n int64) string {
+	hours := n / 3600
+	minutes := (n % 3600) / 60
+	return fmt.Sprintf("%d:%02d", hours, minutes)
+}

main.go

@@ -32,7 +32,7 @@ func main() {
 	b.Add(i3status.NewPowerWidget())
 	b.Add(i3status.NewOnOffWidget())
 	b.Add(i3status.NewI3statusWidget())
-	b.Add(i3status.NewEchoWidget())
+	//b.Add(i3status.NewEchoWidget())
 
 	for {
 		m := <-b.Output

test/power_test.go

@@ -30,7 +30,7 @@ func TestPowerWidgetHasMessage(t *testing.T) {
 			w.Start()
 			Convey("output message is available", func() {
 				msg := <-c
-				So(msg.FullText, ShouldContainSubstring, "Battery")
+				So(msg.FullText, ShouldContainSubstring, "BAT")
 			})
 		})
 	})