3 files changed, 73 insertions, 0 deletions
diff --git a/pkg/atexit/atexit.go b/pkg/atexit/atexit.go
new file mode 100644
index 0000000..a349649
--- /dev/null
+++ b/pkg/atexit/atexit.go
@@ -0,0 +1,13 @@
+package atexit
+
+var hooks = []func(){}
+
+func Register(f func()) {
+	hooks = append(hooks, f)
+}
+
+func Exec() {
+	for i := len(hooks) - 1; i >= 0; i-- {
+		hooks[i]()
+	}
+}
diff --git a/pkg/try/try.go b/pkg/try/try.go
new file mode 100644
index 0000000..2576dcd
--- /dev/null
+++ b/pkg/try/try.go
@@ -0,0 +1,19 @@
+package try
+
+import (
+	"log"
+
+	"git.thomasvoss.com/euro-cash.eu/pkg/atexit"
+)
+
+func Try(e error) {
+	if e != nil {
+		atexit.Exec()
+		log.Fatalln(e)
+	}
+}
+
+func Try2[T any](x T, e error) T {
+	Try(e)
+	return x
+}
diff --git a/pkg/watch/watch.go b/pkg/watch/watch.go
new file mode 100644
index 0000000..f409dac
--- /dev/null
+++ b/pkg/watch/watch.go
@@ -0,0 +1,41 @@
+package watch
+
+import (
+	"errors"
+	"io/fs"
+	"log"
+	"os"
+	"time"
+
+	. "git.thomasvoss.com/euro-cash.eu/pkg/try"
+)
+
+func File(path string, f func()) {
+	impl(path, os.Stat, f)
+}
+
+func FileFS(dir fs.FS, path string, f func()) {
+	impl(path, func(path string) (os.FileInfo, error) {
+		return fs.Stat(dir, path)
+	}, f)
+}
+
+func impl(path string, statfn func(string) (os.FileInfo, error), f func()) {
+	ostat := Try2(statfn(path))
+
+	for {
+		nstat, err := statfn(path)
+		switch {
+		case errors.Is(err, os.ErrNotExist):
+			return
+		case err != nil:
+			log.Println(err)
+		}
+
+		if nstat.ModTime() != ostat.ModTime() {
+			f()
+			ostat = nstat
+		}
+		time.Sleep(1 * time.Second)
+	}
+}