feat: add bar for traffic usage

bot.go

@@ -2,10 +2,12 @@ package main
 
 import (
 	"fmt"
+	"math"
 	"strings"
 	"time"
 
 	"github.com/go-errors/errors"
+	"github.com/samber/lo"
 	tele "gopkg.in/telebot.v3"
 
 	"git.gensokyo.cafe/kkyy/tgbot_misaka_5882f7/stats"
@@ -96,11 +98,12 @@ func handleTrafficCmd(c tele.Context) error {
 	// This month's traffic, if present
 	if len(monthlyTraffic) > 0 {
 		row := monthlyTraffic[len(monthlyTraffic)-1]
-
 		responseParts = append(
 			responseParts,
 			fmt.Sprintf("This month so far:` %s`", fmtTraffic(row)),
 		)
+		bar := fmt.Sprintf("\n```\n%s\n```", drawBarForTrafficRecord(row))
+		responseParts = append(responseParts, bar)
 	}
 
 	var respText string
@@ -114,12 +117,8 @@ func handleTrafficCmd(c tele.Context) error {
 }
 
 func fmtTraffic(r stats.VnstatTrafficRecord) string {
-	biggest := r.Rx
-	if r.Tx > biggest {
-		biggest = r.Tx
-	}
-
-	return fmt.Sprintf("%.2f GiB", float64(biggest)/1024/1024/1024)
+	effective := lo.Max([]uint64{r.Rx, r.Tx})
+	return fmt.Sprintf("%.2f GiB", float64(effective)/1024/1024/1024)
 }
 
 func handleUserInfoCmd(c tele.Context) error {
@@ -174,3 +173,27 @@ func handleChatInfoCmd(c tele.Context) error {
 	}
 	return c.Reply(strings.Join(replyText, "\n"), &tele.SendOptions{ParseMode: tele.ModeMarkdown})
 }
+
+func drawBar(progress float64, length int) string {
+	barChars := []rune("░▒▓█")
+
+	if length <= 0 {
+		return ""
+	}
+	step := 1 / float64(length)
+	buf := make([]rune, length)
+	for i := 0; i < length; i++ {
+		fill := (progress - float64(i)*step) / step
+		fill = math.Min(math.Max(fill, 0), 1)
+		idx := int(math.Round(fill * float64(len(barChars)-1)))
+		buf[i] = barChars[idx]
+	}
+	return string(buf)
+}
+
+func drawBarForTrafficRecord(r stats.VnstatTrafficRecord) string {
+	effective := lo.Max([]uint64{r.Rx, r.Tx})
+	max := config.MonthlyTrafficLimitGiB
+	ratio := float64(effective) / 1024 / 1024 / 1024 / float64(max)
+	return fmt.Sprintf("%s %2.0f%%", drawBar(ratio, 16), ratio*100)
+}