fix: loosen agent version checking

- warn instead of error when version mismatch
- check for major version only
- better version parsing

pkg/version.go

@@ -1,7 +1,117 @@
 package pkg
 
-var version = "unset"
+import (
+	"fmt"
+	"net/http"
+	"os"
+	"path/filepath"
+	"regexp"
+	"strconv"
+	"strings"
 
-func GetVersion() string {
-	return version
+	"github.com/yusing/go-proxy/internal/common"
+	"github.com/yusing/go-proxy/internal/logging"
+)
+
+func GetVersion() Version {
+	return currentVersion
+}
+
+func GetLastVersion() Version {
+	return lastVersion
+}
+
+func GetVersionHTTPHandler() http.HandlerFunc {
+	return func(w http.ResponseWriter, r *http.Request) {
+		w.Write([]byte(GetVersion().String()))
+	}
+}
+
+func init() {
+	currentVersion = ParseVersion(version)
+
+	// ignore errors
+	versionFile := filepath.Join(common.DataDir, "version")
+	var lastVersionStr string
+	f, err := os.OpenFile(versionFile, os.O_RDWR|os.O_CREATE, 0o644)
+	if err == nil {
+		_, err = fmt.Fscanf(f, "%s", &lastVersionStr)
+		lastVersion = ParseVersion(lastVersionStr)
+	}
+	if err != nil && !os.IsNotExist(err) {
+		logging.Warn().Err(err).Msg("failed to read version file")
+		return
+	}
+	if err := f.Truncate(0); err != nil {
+		logging.Warn().Err(err).Msg("failed to truncate version file")
+		return
+	}
+	_, err = f.WriteString(version)
+	if err != nil {
+		logging.Warn().Err(err).Msg("failed to save version file")
+		return
+	}
+}
+
+type Version struct{ Generation, Major, Minor int }
+
+func Ver(major, minor, patch int) Version {
+	return Version{major, minor, patch}
+}
+
+func (v Version) String() string {
+	return fmt.Sprintf("%d.%d.%d", v.Generation, v.Major, v.Minor)
+}
+
+func (v Version) MarshalText() ([]byte, error) {
+	return []byte(v.String()), nil
+}
+
+func (v Version) IsNewerMajorThan(other Version) bool {
+	if v.Generation != other.Generation {
+		return v.Generation > other.Generation
+	}
+	return v.Major > other.Major
+}
+
+func (v Version) IsEqual(other Version) bool {
+	return v.Generation == other.Generation && v.Major == other.Major && v.Minor == other.Minor
+}
+
+var (
+	version        = "unset"
+	currentVersion Version
+	lastVersion    Version
+)
+
+var versionRegex = regexp.MustCompile(`^v(\d+)\.(\d+)\.(\d+)(\-\w+)?$`)
+
+func ParseVersion(v string) (ver Version) {
+	if v == "" {
+		return
+	}
+
+	if !versionRegex.MatchString(v) { // likely feature branch (e.g. feat/some-feature)
+		return
+	}
+
+	v = strings.Split(v, "-")[0]
+	v = strings.TrimPrefix(v, "v")
+	parts := strings.Split(v, ".")
+	if len(parts) != 3 {
+		return
+	}
+	major, err := strconv.Atoi(parts[0])
+	if err != nil {
+		return
+	}
+	minor, err := strconv.Atoi(parts[1])
+	if err != nil {
+		return
+	}
+	patch, err := strconv.Atoi(parts[2])
+	if err != nil {
+		return
+	}
+	return Ver(major, minor, patch)
 }