snapshot

htmlpopup.go

@@ -0,0 +1,119 @@
+package main
+
+import (
+	"context"
+	"fmt"
+	"io"
+	"log"
+	"net"
+	"net/http"
+	"os"
+	"os/exec"
+	"os/signal"
+	"runtime"
+	"strings"
+	"syscall"
+	"time"
+)
+
+// language=html
+const injectScript = `
+<script>
+	const sendShutdown = () => navigator.sendBeacon('/shutdown');
+
+	window.addEventListener('beforeunload', sendShutdown);
+	window.addEventListener('unload', sendShutdown);
+</script>
+`
+
+func main() {
+	if err := run(); err != nil {
+		log.Fatal(err)
+	}
+}
+
+func newHandler(html string, onShutdown func()) *http.ServeMux {
+	handler := http.NewServeMux()
+
+	handler.HandleFunc("POST /shutdown", func(w http.ResponseWriter, r *http.Request) {
+		onShutdown()
+	})
+
+	handler.HandleFunc("GET /", func(w http.ResponseWriter, r *http.Request) {
+		w.Header().Set("Content-Type", "text/html")
+		w.Write([]byte(html))
+	})
+
+	return handler
+}
+
+func run() error {
+	html, err := io.ReadAll(os.Stdin)
+	if err != nil {
+		return fmt.Errorf("failed to read HTML from stdin: %w", err)
+	}
+
+	htmlStr := string(html)
+	if strings.Contains(htmlStr, "</body>") {
+		htmlStr = strings.ReplaceAll(string(html), "</body>", injectScript+"</body>")
+	} else {
+		htmlStr += injectScript
+	}
+
+	listener, err := net.Listen("tcp", ":0")
+	if err != nil {
+		return fmt.Errorf("failed to create listener: %w", err)
+	}
+
+	ctx, cancel := signal.NotifyContext(context.Background(), os.Interrupt, syscall.SIGTERM)
+	defer cancel()
+
+	port := listener.Addr().(*net.TCPAddr).Port
+
+	server := &http.Server{Addr: listener.Addr().String()}
+	server.Handler = newHandler(htmlStr, func() {
+		cancel()
+	})
+
+	servedURL := fmt.Sprintf("http://localhost:%d", port)
+
+	go func() {
+		log.Printf("serving at %s", servedURL)
+		if err := server.Serve(listener); err != nil && err != http.ErrServerClosed {
+			log.Fatalf("failed to serve: %v", err)
+		}
+	}()
+
+	go func() {
+		// wait for server to start
+		time.Sleep(250 * time.Millisecond)
+		if err := openBrowser(servedURL); err != nil {
+			log.Fatalf("failed to open browser: %v", err)
+		}
+	}()
+
+	<-ctx.Done()
+
+	log.Printf("shutting down server")
+
+	if err := server.Shutdown(ctx); err != nil {
+		return fmt.Errorf("failed to shutdown server: %w", err)
+	}
+
+	return nil
+}
+
+func openBrowser(url string) error {
+	var cmd *exec.Cmd
+	switch runtime.GOOS {
+	case "darwin":
+		cmd = exec.Command("open", url)
+	case "linux":
+		cmd = exec.Command("xdg-open", url)
+	case "windows":
+		cmd = exec.Command("cmd", "/c", "start", url)
+	default:
+		return fmt.Errorf("invalid URL: %s", url)
+	}
+	return cmd.Run()
+}