bang: add an option to provide a default handle

bang.py

@@ -72,7 +72,10 @@ def run_rofi(config, input_text="", title="bang", no_lines=False):
 
 def open_bang(config, handle, query):
     try:
-        bang = next(bang for bang in config["bangs"] if handle == bang["handle"])
+        bang = next(
+            bang for bang in config["bangs"]
+            if handle == bang["handle"]
+        )
     except StopIteration:
         print("Unknown handle.")
         return
@@ -85,10 +88,33 @@ def open_bang(config, handle, query):
 
 def main():
     ap = argparse.ArgumentParser()
-    ap.add_argument("-c", "--config", help="path to JSON config file")
-    ap.add_argument("-l", "--list", action="store_true", help="show available bangs")
-    ap.add_argument("-b", "--bang", nargs="+", help="launch with this bang already set")
-    ap.add_argument("-f", "--queries-file", help="file with one bang argument per line")
+    ap.add_argument(
+        "-c",
+        "--config",
+        help="path to JSON config file"
+    )
+    ap.add_argument(
+        "-l",
+        "--list",
+        action="store_true",
+        help="show available bangs"
+    )
+    ap.add_argument(
+        "-b",
+        "--bang",
+        nargs="+",
+        help="launch with this bang already set"
+    )
+    ap.add_argument(
+        "-f",
+        "--queries-file",
+        help="file with one bang argument per line"
+    )
+    ap.add_argument(
+        "-d",
+        "--default",
+        help="handle to use if the first word is not a known handle"
+    )
     args = ap.parse_args()
 
     config = load_config()
@@ -107,26 +133,36 @@ def main():
         except OSError:
             exit("Can't load queries file.")
 
-    # If a bang is specified on the command line, use it, optionally with its args.
+    handles = [
+        bang["handle"]
+        for bang in sorted(config["bangs"], key=lambda bang: bang["handle"])
+    ]
+
+    # If a bang is specified on the command line, use it,
+    # optionally with its args.
     if bang_args := args.bang:
         handle = bang_args[0]
         if bang_args[1:]:
             queries.append(" ".join(bang_args[1:]))
     # Else show a Rofi with the list of available bangs.
     else:
-        process_input = "\n".join(
-            i["handle"]
-            for i in sorted(config["bangs"], key=lambda bang: bang["handle"])
-        ) + "\n"
+        process_input = "\n".join(handles) + "\n"
         output = run_rofi(config, input_text=process_input)
         parts = output.split(maxsplit=1)
-        if len(parts) < 1:
+        if len(parts) == 0:
             exit("Bad Rofi output.")
+
         handle = parts[0]
-        if len(parts) > 1:
+        if handle not in handles and (default_handle := args.default):
+            handle = default_handle
+            if len(parts) == 1:
+                queries.append(parts[0])
+
+        if len(parts) == 2:
             queries.append(parts[1])
 
-    # If no queries were obtained during options parsing, show Rofi now to get a single query.
+    # If no queries were obtained during options parsing,
+    # show Rofi now to get a single query.
     if not queries:
         queries.append(run_rofi(config, title=handle, no_lines=True))