feat: add an HTTP server to enable users to monitor status updates via status bars or other UI components.

progressbar.go

@@ -2,10 +2,13 @@ package progressbar
 
 import (
 	"bytes"
+	"encoding/json"
 	"errors"
 	"fmt"
 	"io"
+	"log"
 	"math"
+	"net/http"
 	"os"
 	"regexp"
 	"strings"
@@ -1009,6 +1012,31 @@ func (p *ProgressBar) State() State {
 	return s
 }
 
+// StartHTTPServer starts an HTTP server dedicated to serving progress bar updates. This allows you to
+// display the status in various UI elements, such as an OS status bar with an `xbar` extension.
+// It is recommended to run this function in a separate goroutine to avoid blocking the main thread.
+//
+// hostPort specifies the address and port to bind the server to, for example, "0.0.0.0:19999".
+func (p *ProgressBar) StartHTTPServer(hostPort string) {
+	// for advanced users, we can return the data as json
+	http.HandleFunc("/state", func(w http.ResponseWriter, r *http.Request) {
+		w.Header().Set("Content-Type", "text/json")
+		// since the state is a simple struct, we can just ignore the error
+		bs, _ := json.Marshal(p.State())
+		w.Write(bs)
+	})
+	// for others, we just return the description in a plain text format
+	http.HandleFunc("/desc", func(w http.ResponseWriter, r *http.Request) {
+		w.Header().Set("Content-Type", "text/plain")
+		fmt.Fprintf(w,
+			"%d/%d, %.2f%%, %s left",
+			p.State().CurrentNum, p.State().Max, p.State().CurrentPercent*100,
+			(time.Second * time.Duration(p.State().SecondsLeft)).String(),
+		)
+	})
+	log.Fatal(http.ListenAndServe(hostPort, nil))
+}
+
 // regex matching ansi escape codes
 var ansiRegex = regexp.MustCompile(`\x1b\[[0-9;]*[a-zA-Z]`)
 

progressbar_test.go

@@ -4,6 +4,7 @@ import (
 	"bytes"
 	"crypto/md5"
 	"encoding/hex"
+	"encoding/json"
 	"fmt"
 	"io"
 	"log"
@@ -1123,3 +1124,42 @@ func TestOptionShowTotalTrueIndeterminate(t *testing.T) {
 		t.Errorf("wrong string: %s", buf.String())
 	}
 }
+
+func TestStartHTTPServer(t *testing.T) {
+	bar := Default(10, "test")
+	bar.Add(1)
+
+	hostPort := "localhost:9696"
+	go bar.StartHTTPServer(hostPort)
+
+	// check plain text
+	resp, err := http.Get(fmt.Sprintf("http://%s/desc", hostPort))
+	if err != nil {
+		t.Error(err)
+	}
+	got, err := io.ReadAll(resp.Body)
+	if err != nil {
+		t.Error(err)
+	}
+	if string(got) != "1/10, 10.00%, 0s left" {
+		t.Errorf("wrong string: %s", string(got))
+	}
+
+	// check json
+	resp, err = http.Get(fmt.Sprintf("http://%s/state", hostPort))
+	if err != nil {
+		t.Error(err)
+	}
+	got, err = io.ReadAll(resp.Body)
+	if err != nil {
+		t.Error(err)
+	}
+	var result State
+	err = json.Unmarshal(got, &result)
+	if err != nil {
+		t.Error(err)
+	}
+	if result.Max != bar.State().Max || result.CurrentNum != bar.State().CurrentNum {
+		t.Errorf("wrong state: %v", result)
+	}
+}