Determine and validate Git hook type

Since craft should only be referenced by a symlink like that:

    ln -s /usr/bin/craft myrepo/.git/hooks/post-receive

It is important to detect the hook type, in this case 'post-receive'.

This commit also validates that the determined hook type is supported.
Currently only the post-receive hook is supported.

1 files changed, 33 insertions, 0 deletions

diff --git a/main.go b/main.go
index 5ddc386..59f864f 100644
--- a/main.go
+++ b/main.go
@@ -8,9 +8,15 @@ import (
 	"io"
 	"log"
 	"os"
+	"strings"
 )
 
 func main() {
+	log.SetFlags(0)
+
+	log.Println("Starting craft")
+	log.Printf("Git hook type: %s\n", getHookType())
+
 	cwd, err := os.Getwd()
 	if err != nil {
 		log.Fatal(err)
@@ -22,6 +28,33 @@ func main() {
 	}
 }
 
+func getHookType() string {
+	args := len(os.Args)
+	if args != 1 {
+		log.Fatalf("Expected zero arguments but %d were given", args-1)
+	}
+	prefix := `hooks/`
+	path := os.Args[0]
+	hookType := strings.TrimPrefix(path, prefix)
+	if path == hookType {
+		log.Fatalf("Hook path '%s' has no '%s' prefix", path, prefix)
+	}
+	validateHookType(hookType)
+	return hookType
+}
+
+func validateHookType(hookType string) {
+	validTypes := [...]string{
+		`post-receive`,
+	}
+	for _, currentType := range validTypes {
+		if hookType == currentType {
+			return
+		}
+	}
+	log.Fatalf("Not supported Git hook type '%s'\n", hookType)
+}
+
 type update struct {
 	old, updated, ref string
 }