(bash) robust way to get path to script

bash-test.sh

@@ -1,10 +1,15 @@
 #!/usr/bin/env bash
 
-if ! $(which navig &>/dev/null); then
-    echo "command not found"
-    return 1
+# NOTE: this is way simpler
+echo $(realpath "${BASH_SOURCE}")
+
+# NOTE: this is useless
+if [[ "${0}" == "${BASH_SOURCE}" ]]; then
+    root_dir="$(dirname "${0}")"
+    root_dir="$(realpath "${root_dir}")"
+else
+    root_dir="$(dirname "${0}")/$(dirname "${BASH_SOURCE}")"
+    root_dir="$(realpath "${root_dir}")"
 fi
 
-function bash_source_test_function {
-    echo "sourcing not interrupted"
-}
+echo ${root_dir}