Add middleware to strip ansi escape sequences

2 files changed, 88 insertions, 2 deletions

diff --git a/api/docker.go b/api/docker.go
index 248880e..0968a11 100644
--- a/api/docker.go
+++ b/api/docker.go
@@ -1,10 +1,12 @@
 package api
 
 import (
+	"bufio"
 	"context"
 	"fmt"
 	"io"
 	"log/slog"
+	"regexp"
 	"time"
 
 	"github.com/docker/docker/api/types/container"
@@ -13,6 +15,41 @@ import (
 
 const vttContainerId string = "foundry-foundry-1"
 
+// Strip ansi control characters from source
+//
+// The source reader is automatically closed when stripped reader is
+func StripAnsi(source io.ReadCloser) io.ReadCloser {
+
+	regex := regexp.MustCompile(`\x1b[[0-9;]*m`)
+	reader, writer := io.Pipe()
+
+	go func() {
+		bufReader := bufio.NewReader(source)
+		defer source.Close()
+		defer writer.Close()
+
+	cleanSource:
+		for {
+			line, err := bufReader.ReadBytes('\n')
+			switch {
+			case err == io.EOF:
+				if len(line) > 0 {
+					cleaned := regex.ReplaceAll(line, []byte(""))
+					writer.Write(cleaned)
+				}
+				break cleanSource
+			case err != nil:
+				panic(err)
+			default:
+				cleaned := regex.ReplaceAll(line, []byte(""))
+				writer.Write(cleaned)
+			}
+		}
+	}()
+
+	return reader
+}
+
 func stopVtt(ctx context.Context) error {
 	apiClient, err := client.NewClientWithOpts(client.FromEnv, client.WithAPIVersionNegotiation())
 	if err != nil {
@@ -42,7 +79,6 @@ func vttLogs(ctx context.Context, lines uint) (io.ReadCloser, error) {
 	opts := container.LogsOptions{
 		ShowStdout: true,
 		ShowStderr: true,
-		Timestamps: true,
 	}
 	if lines != 0 {
 		opts.Tail = fmt.Sprint(lines)
@@ -55,7 +91,7 @@ func vttLogs(ctx context.Context, lines uint) (io.ReadCloser, error) {
 		return nil, err
 	}
 
-	return r, nil
+	return StripAnsi(r), nil
 }
 
 func vttStatus(ctx context.Context) ServerStatus {
diff --git a/api/docker_test.go b/api/docker_test.go
new file mode 100644
index 0000000..acd92bc
--- /dev/null
+++ b/api/docker_test.go
@@ -0,0 +1,50 @@
+package api_test
+
+import (
+	"io"
+	"nonsense-time/api"
+	"strings"
+	"testing"
+)
+
+type stringReadCloser struct {
+	*strings.Reader
+}
+
+func newStringReadCloser(s string) stringReadCloser {
+	rc := stringReadCloser{}
+	rc.Reader = strings.NewReader(s)
+
+	return rc
+}
+
+func (stringReadCloser) Close() error {
+	return nil
+}
+
+func testAnsiStripper(t *testing.T, input string, expected string) {
+	reader := newStringReadCloser(input)
+	cleanReader := api.StripAnsi(reader)
+	defer cleanReader.Close()
+
+	buf := new(strings.Builder)
+	n, err := io.Copy(buf, cleanReader)
+	if err != nil {
+		t.Fatal("Error while copying cleaned text to output", err)
+	}
+
+	result := buf.String()
+
+	if n != int64(len(expected)) {
+		t.Errorf("Expected to write %d characters but wrote %d\n", 3, n)
+	}
+
+	if result != expected {
+		t.Errorf("Expected string `%s` but wrote `%s`", "abc", result)
+	}
+}
+
+func TestStripAnsiColors(t *testing.T) {
+	testAnsiStripper(t, "a\x1b[31mbc", "abc")
+    testAnsiStripper(t, "[\x1b[32minfo\x1b[39m]", "[info]")
+}