feat: add GitVersion struct

pkg/commands/git_commands/version.go

@@ -0,0 +1,67 @@
+package git_commands
+
+import (
+	"errors"
+	"regexp"
+	"strconv"
+	"strings"
+
+	"github.com/jesseduffield/lazygit/pkg/commands/oscommands"
+)
+
+type GitVersion struct {
+	Major, Minor, Patch int
+	Additional          string
+}
+
+func GetGitVersion(osCommand *oscommands.OSCommand) (*GitVersion, error) {
+	versionStr, _, err := osCommand.Cmd.New("git --version").RunWithOutputs()
+	if err != nil {
+		return nil, err
+	}
+
+	version, err := ParseGitVersion(versionStr)
+	if err != nil {
+		return nil, err
+	}
+
+	return version, nil
+}
+
+func ParseGitVersion(versionStr string) (*GitVersion, error) {
+	// versionStr should be something like:
+	// git version 2.39.0
+	// git version 2.37.1 (Apple Git-137.1)
+	re := regexp.MustCompile(`[^\d]+(\d+)(\.\d+)?(\.\d+)?(.*)`)
+	matches := re.FindStringSubmatch(versionStr)
+
+	if len(matches) < 5 {
+		return nil, errors.New("unexpected git version format: " + versionStr)
+	}
+
+	v := &GitVersion{}
+	var err error
+
+	if v.Major, err = strconv.Atoi(matches[1]); err != nil {
+		return nil, err
+	}
+	if len(matches[2]) > 1 {
+		if v.Minor, err = strconv.Atoi(matches[2][1:]); err != nil {
+			return nil, err
+		}
+	}
+	if len(matches[3]) > 1 {
+		if v.Patch, err = strconv.Atoi(matches[3][1:]); err != nil {
+			return nil, err
+		}
+	}
+	v.Additional = strings.Trim(matches[4], " \r\n")
+
+	return v, nil
+}
+
+func (v *GitVersion) IsOlderThan(major, minor, patch int) bool {
+	actual := v.Major*1000*1000 + v.Minor*1000 + v.Patch
+	required := major*1000*1000 + minor*1000 + patch
+	return actual < required
+}