fix the backend validation logicv0.5.1

This might be a hack but I had to figure out how to work with the
following

- if no backend choice is given, assume bemenu
- if the user sets the TESSEN_BACKEND env var, use that
- if the user provides the `-b` flag at runtime, use that above all else

I've already assumed bemenu by default in the list of global variables.
However, figuring out how to prefer the command line flag over the env
var was a bit tricky I guess.

I changed the `validate_backend` function to always assign both backend
global variables as readonly and this function is always called if the
user provides a `-b` flag at runtime. If he doesn't though, I can safely
use the unset condition on the BACKEND_OPTS variable, instead of
BACKEND, since it has not been assigned anyways. If it can be unset, it
means it hasn't been made readonly, which means `-b` wasn't provided. We
can call the `validate_backend` function to do what we wanted.

1 files changed, 9 insertions, 4 deletions

diff --git a/tessen b/tessen
index fbc51da..26149d0 100755
--- a/tessen
+++ b/tessen
@@ -184,12 +184,15 @@ print_help() {
 validate_backend() {
   if [[ "$BACKEND" == "bemenu" ]]; then
     bmn_opt=("-i -l 10 -w --scrollbar=autohide -n")
-    readonly BEMENU_OPTS="${BEMENU_OPTS:-${bmn_opt[*]}}"
-    export BEMENU_OPTS
+    export BEMENU_OPTS="${BEMENU_OPTS:-${bmn_opt[*]}}"
+    readonly BACKEND="bemenu"
+    readonly BACKEND_OPTS=""
     unset -v bmn_opt
   elif [[ "$BACKEND" == "rofi" ]]; then
-    BACKEND=(rofi -dmenu)
+    readonly BACKEND="rofi"
+    readonly BACKEND_OPTS="-dmenu"
   else
+    printf '%s\n' "Please specify a backend: bemenu|rofi" >&2
     exit 1
   fi
 }
@@ -282,7 +285,9 @@ main() {
   done
   unset -v _opt
 
-  validate_backend
+  if unset -v BACKEND_OPTS 2> /dev/null; then
+    validate_backend
+  fi
   validate_clip_time
 
   readonly WTYPE