Add git-version helper command

docs/build-scripts.md

@@ -465,4 +465,21 @@ Examples:
 
 ```bash
 install-library ./${name}/build/libadldap.so
+```
+
+### git-version
+
+`git-version` returns a version number based on the git revision of a repository.
+
+If an argument is provided, it will be used as the path to the repo. Otherwise, the current directory will be used.
+
+The version number will be the amount of revisions, a dot, and the short hash of the current revision. For example: `118.e4b8348`.
+
+The AUR's convention includes an `r` at the beginning of the version number. This is ommitted because some distros expect the version number to start with a digit.
+
+Examples:
+
+```bash
+git-version
+git-version "$srcdir/itd"
 ```

helpers.go

@@ -10,6 +10,8 @@ import (
 	"strings"
 	"unsafe"
 
+	"github.com/go-git/go-git/v5"
+	"github.com/go-git/go-git/v5/plumbing/object"
 	"go.arsenm.dev/lure/internal/shutils"
 	"golang.org/x/exp/slices"
 	"mvdan.cc/sh/v3/interp"
@@ -30,6 +32,7 @@ var helpers = shutils.ExecFuncs{
 	"install-manual":       installManualCmd,
 	"install-completion":   installCompletionCmd,
 	"install-library":      installLibraryCmd,
+	"git-version":          gitVersionCmd,
 }
 
 func installHelperCmd(prefix string, perms os.FileMode) shutils.ExecFunc {
@@ -189,6 +192,40 @@ func getLibPrefix(hc interp.HandlerContext) string {
 	return out
 }
 
+func gitVersionCmd(hc interp.HandlerContext, cmd string, args []string) error {
+	path := hc.Dir
+	if len(args) > 0 {
+		path = resolvePath(hc, args[0])
+	}
+
+	r, err := git.PlainOpen(path)
+	if err != nil {
+		return fmt.Errorf("git-version: %w", err)
+	}
+
+	revNum := 0
+	commits, err := r.Log(&git.LogOptions{})
+	if err != nil {
+		return fmt.Errorf("git-version: %w", err)
+	}
+
+	commits.ForEach(func(*object.Commit) error {
+		revNum++
+		return nil
+	})
+
+	HEAD, err := r.Head()
+	if err != nil {
+		return fmt.Errorf("git-version: %w", err)
+	}
+
+	hash := HEAD.Hash().String()
+
+	fmt.Fprintf(hc.Stdout, "%d.%s", revNum, hash[:7])
+
+	return nil
+}
+
 func helperInstall(from, to string, perms os.FileMode) error {
 	err := os.MkdirAll(filepath.Dir(to), 0o755)
 	if err != nil {