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power.go (3103B)

      1 package power
      2 
      3 import (
      4 	"bufio"
      5 	"context"
      6 	"fmt"
      7 	"math"
      8 	"os"
      9 	"sort"
     10 	"strconv"
     11 	"strings"
     12 )
     13 
     14 type Config struct {
     15 	Path string `json:"path"`
     16 }
     17 
     18 // https://www.kernel.org/doc/html/latest/power/power_supply_class.html
     19 const Path = "/sys/class/power_supply"
     20 
     21 type Block struct {
     22 	path string
     23 }
     24 
     25 func New(path string) *Block {
     26 	return &Block{path: path}
     27 }
     28 
     29 func (b *Block) Name() string {
     30 	return "power"
     31 }
     32 
     33 func (b *Block) Render(ctx context.Context) (string, error) {
     34 	// Get the power supplies.
     35 	var supplies []string
     36 
     37 	files, err := os.ReadDir(b.path)
     38 	if err != nil {
     39 		return "", fmt.Errorf("failed to read dir %s: %v", b.path, err)
     40 	}
     41 	for _, f := range files {
     42 		name := f.Name()
     43 
     44 		if name == "AC" || strings.Contains(name, "BAT") {
     45 			supplies = append(supplies, f.Name())
     46 		}
     47 	}
     48 	sort.Slice(supplies, func(i, j int) bool {
     49 		return supplies[i] < supplies[j]
     50 	})
     51 
     52 	var sections = []string{}
     53 	for _, s := range supplies {
     54 		path := fmt.Sprintf("%s/%s/uevent", b.path, s)
     55 		f, err := os.Open(path)
     56 		if err != nil {
     57 			return "", fmt.Errorf(
     58 				"failed to open %s: %v", path, err,
     59 			)
     60 		}
     61 		defer f.Close()
     62 
     63 		switch {
     64 		case s == "AC":
     65 			sections = append(sections, outputAC(f))
     66 		case strings.Contains(s, "BAT"):
     67 			sections = append(sections, outputBAT(f))
     68 		}
     69 	}
     70 
     71 	var output strings.Builder
     72 	for i, s := range sections {
     73 		if i > 0 {
     74 			output.WriteRune(' ')
     75 			output.WriteRune(' ')
     76 		}
     77 		output.WriteString(s)
     78 	}
     79 
     80 	return output.String(), nil
     81 }
     82 
     83 func outputAC(f *os.File) string {
     84 	var scanner = bufio.NewScanner(f)
     85 	for scanner.Scan() {
     86 		k, v, found := strings.Cut(scanner.Text(), "=")
     87 		if !found {
     88 			continue
     89 		}
     90 		if k == "POWER_SUPPLY_ONLINE" {
     91 			online, err := strconv.ParseBool(v)
     92 			if err != nil {
     93 				break
     94 			}
     95 			if online {
     96 				return ""
     97 			} else {
     98 				return ""
     99 			}
    100 		}
    101 	}
    102 
    103 	return ""
    104 }
    105 
    106 func outputBAT(f *os.File) string {
    107 	// Compile the stats.
    108 	var (
    109 		stats   = map[string]string{}
    110 		scanner = bufio.NewScanner(f)
    111 	)
    112 	for scanner.Scan() {
    113 		k, v, found := strings.Cut(scanner.Text(), "=")
    114 		if !found {
    115 			continue
    116 		}
    117 		// Exit early if the battery is not present.
    118 		if k == "POWER_SUPPLY_PRESENT" && v == "0" {
    119 			return ""
    120 		}
    121 
    122 		stats[k] = v
    123 	}
    124 
    125 	// Assemble output.
    126 	var icon rune
    127 	switch stats["POWER_SUPPLY_STATUS"] {
    128 	case "Charging":
    129 		icon = ''
    130 	case "Discharging":
    131 		icon = ''
    132 	case "Full":
    133 		icon = ''
    134 	default:
    135 		icon = ''
    136 	}
    137 
    138 	// Get capacity.
    139 	var capacity string
    140 	if s, exists := stats["POWER_SUPPLY_CAPACITY"]; exists {
    141 		capacity = s + "%"
    142 	}
    143 
    144 	// Get remaining.
    145 	pn, _ := strconv.ParseFloat(stats["POWER_SUPPLY_POWER_NOW"], 64)
    146 	en, _ := strconv.ParseFloat(stats["POWER_SUPPLY_ENERGY_NOW"], 64)
    147 	if r := remaining(en, pn); r != "" {
    148 		return fmt.Sprintf("%c %s %s", icon, capacity, r)
    149 	}
    150 
    151 	return fmt.Sprintf("%c %s", icon, capacity)
    152 }
    153 
    154 func remaining(energy, power float64) string {
    155 	if energy == 0 || power == 0 {
    156 		return ""
    157 	}
    158 
    159 	// Calculate the remaining hours.
    160 	var hours = energy / power
    161 	if hours == 0 {
    162 		return ""
    163 	}
    164 
    165 	return fmt.Sprintf(
    166 		"%d:%02d",
    167 		int(hours),
    168 		int((hours-math.Floor(hours))*60),
    169 	)
    170 }