FIX: Default action with arguments does not consider built-in commands

Only $TODO_ACTIONS_DIR/$action, not even the $TODO_ACTIONS_DIR/$action/$action variant.
A totally different approach is needed: Instead of parsing off the first argument and treating that as the custom action, do a recursive invocation with the default action parsed as a command-line. A new isDefaultAction flag is needed so that we only do this when the default action actually applies (otherwise, strange invocations like todo.sh "add +project here" would also be possible). The condition for non-empty $TODOTXT_DEFAULT_ACTION avoids an endless loop.

tests/t0002-actions.sh

@@ -51,13 +51,28 @@ test_expect_success 'custom action (default action)' '
     test_cmp expect output && rm -rf .todo.actions.d
 '
 
+test_todo_session 'default built-in action with multiple arguments' <<EOF
+>>> TODOTXT_DEFAULT_ACTION='add +foo @bar baz' todo.sh
+1 +foo @bar baz
+TODO: 1 added.
+EOF
+
 test_todo_session 'default custom action with multiple arguments' <<EOF
 >>> mkdir -p .todo.actions.d && cp foo2 .todo.actions.d/
 
 >>> TODOTXT_DEFAULT_ACTION='foo2 foo bar baz' todo.sh
 TODO: foo-bar-baz
 EOF
 
+: > todo.txt
+export TODOTXT_DEFAULT_ACTION="add foo\\ bar \\\$HOSTNAME O\\'Really\\? \\\"quoted\\\""
+test_todo_session 'default built-in action with arguments that have special characters' <<EOF
+>>> todo.sh
+1 foo bar \$HOSTNAME O'Really? "quoted"
+TODO: 1 added.
+EOF
+
+: > todo.txt
 export TODOTXT_DEFAULT_ACTION="foo2 foo\\ bar \\\$HOSTNAME O\\'Really\\? \\\"quoted\\\""
 test_todo_session 'default custom action with arguments that have special characters' <<EOF
 >>> mkdir -p .todo.actions.d && cp foo2 .todo.actions.d/

todo.sh

@@ -727,7 +727,13 @@ if [ -n "$OVR_TODOTXT_FINAL_FILTER" ] ; then
   TODOTXT_FINAL_FILTER="$OVR_TODOTXT_FINAL_FILTER"
 fi
 
-ACTION=${1:-$TODOTXT_DEFAULT_ACTION}
+isDefaultAction=
+if [ -n "$1" ]; then
+    ACTION=$1
+else
+    ACTION=$TODOTXT_DEFAULT_ACTION
+    isDefaultAction=t
+fi
 
 [ -z "$ACTION" ]    && usage
 [ -d "$TODO_DIR" ]  || mkdir -p $TODO_DIR 2> /dev/null || dieWithHelp "$1" "Fatal Error: $TODO_DIR is not a directory"
@@ -982,15 +988,10 @@ elif [ -d "$TODO_ACTIONS_DIR" -a -x "$TODO_ACTIONS_DIR/$action" ]
 then
     "$TODO_ACTIONS_DIR/$action" "$@"
     exit $?
-else
-    ## Use eventually given parameters
-    eval "actionarray=($ACTION)"    # Note: Need to use original $ACTION to avoid that arguments are getting lowercased, too.
-    action=$( printf "%s\n" "${actionarray[0]}" | tr 'A-Z' 'a-z' )
-    if [ -d "$TODO_ACTIONS_DIR" -a -x "$TODO_ACTIONS_DIR/$action" ]
-    then
-      "$TODO_ACTIONS_DIR/$action" "${actionarray[@]}"
-      exit $?
-    fi
+elif [ "$isDefaultAction" ] && [ -n "$TODOTXT_DEFAULT_ACTION" ]; then
+    # Recursive invocation with the contents of the default action parsed as a
+    # command-line.
+    eval "exec \"\${BASH_SOURCE[0]}\" $TODOTXT_DEFAULT_ACTION"
 fi
 
 ## Only run if $action isn't found in .todo.actions.d