pass hook configuration through CLI arguments

hook.sh

@@ -1,8 +1,20 @@
 #!/bin/sh
-# Default standalone policy: append the hook invocation and its stdin to a log.
-# Integrations can supply another script with simplegit daemon -hook-script.
+# Default standalone policy. Optional CLI: --log=/path/to/hooks.log --
 
-log_file=${SIMPLEGIT_HOOK_LOG:-${SIMPLEGIT_REPO_ROOT%/repos}/hooks.log}
+log_file=
+while [ "$#" -gt 0 ]; do
+  case "$1" in
+    --log=*) log_file=${1#--log=}; shift ;;
+    --log) log_file=$2; shift 2 ;;
+    --) shift; break ;;
+    *) break ;;
+  esac
+done
+[ "$#" -ge 2 ] || exit 0
+if [ -z "$log_file" ]; then
+  repo_dir=$(pwd -P)
+  log_file=${repo_dir%/*/*}/hooks.log
+fi
 {
   printf '%s\t%s\t%s' "$(date -u +%Y-%m-%dT%H:%M:%SZ)" "$1" "$2"
   shift 2