add support for plugins

Signed-off-by: Chmouel Boudjnah <[email protected]>

main.go

@@ -1,12 +1,15 @@
 package main
 
 import (
+	"fmt"
 	"os"
+	"syscall"
 
 	"github.com/openshift-pipelines/pipelines-as-code/pkg/cmd/tknpac"
 	"github.com/openshift-pipelines/pipelines-as-code/pkg/params"
 	"github.com/tektoncd/cli/pkg/cli"
 	"github.com/tektoncd/cli/pkg/cmd"
+	"github.com/tektoncd/cli/pkg/plugins"
 )
 
 const (
@@ -27,6 +30,24 @@ func main() {
 	pac.Long = pacLongDesc
 	tkn.AddCommand(pac)
 
+	args := os.Args[1:]
+	cmd, _, _ := tkn.Find(args)
+	if cmd != nil && cmd == tkn && len(args) > 0 {
+		exCmd, err := plugins.FindPlugin(os.Args[1])
+		// if we can't find command then execute the normal tkn command.
+		if err != nil {
+			goto CoreTkn
+		}
+
+		// if we have found the plugin then sysexec it by replacing current process.
+		if err := syscall.Exec(exCmd, append([]string{exCmd}, os.Args[2:]...), os.Environ()); err != nil {
+			fmt.Fprintf(os.Stderr, "Command finished with error: %v", err)
+			os.Exit(127)
+		}
+		return
+	}
+
+CoreTkn:
 	if err := tkn.Execute(); err != nil {
 		os.Exit(1)
 	}