Add history based completion to the ask kitten

kittens/ask/main.py

@@ -3,15 +3,66 @@
 # License: GPL v3 Copyright: 2018, Kovid Goyal <kovid at kovidgoyal.net>
 
 import json
+import os
 import readline
 import sys
 from gettext import gettext as _
 
 from kitty.cli import parse_args
+from kitty.constants import cache_dir
 
 from ..tui.operations import alternate_screen, styled
 
 
+def get_history_items():
+    return list(map(readline.get_history_item, range(1, readline.get_current_history_length() + 1)))
+
+
+def sort_key(item):
+    return len(item), item.lower()
+
+
+class HistoryCompleter:
+
+    def __init__(self, name=None):
+        self.matches = []
+        self.history_path = None
+        if name:
+            ddir = os.path.join(cache_dir(), 'ask')
+            try:
+                os.makedirs(ddir)
+            except FileExistsError:
+                pass
+            self.history_path = os.path.join(ddir, name)
+
+    def complete(self, text, state):
+        response = None
+        if state == 0:
+            history_values = get_history_items()
+            if text:
+                self.matches = sorted(
+                        (h for h in history_values if h and h.startswith(text)), key=sort_key)
+            else:
+                self.matches = []
+        try:
+            response = self.matches[state]
+        except IndexError:
+            response = None
+        return response
+
+    def __enter__(self):
+        if self.history_path:
+            if os.path.exists(self.history_path):
+                readline.read_history_file(self.history_path)
+            readline.set_completer(self.complete)
+            readline.parse_and_bind('tab: complete')
+        return self
+
+    def __exit__(self, *a):
+        if self.history_path:
+            readline.write_history_file(self.history_path)
+
+
 def option_text():
     return '''\
 --type -t
@@ -23,24 +74,29 @@ Type of input. Defaults to asking for a line of text.
 --message -m
 The message to display to the user. If not specified a default
 message is shown.
+
+
+--name -n
+The name for this question. Used to store history of previous answers which can
+be used for completions and via the browse history readline bindings.
 '''
 
 
-def main(args=sys.argv):
+def real_main(args):
     msg = 'Ask the user for input'
     try:
         args, items = parse_args(args[1:], option_text, '', msg, 'kitty ask')
     except SystemExit as e:
         print(e.args[0], file=sys.stderr)
         input('Press enter to quit...')
-        return 1
+        raise SystemExit(1)
 
-    with alternate_screen():
+    readline.read_init_file()
+
+    with alternate_screen(), HistoryCompleter(args.name):
         if args.message:
             print(styled(args.message), bold=True)
 
-        readline.read_init_file()
-
         prompt = ': '
         if args.type == 'line':
             prompt = _('Enter line: ')
@@ -49,3 +105,13 @@ def main(args=sys.argv):
         except (KeyboardInterrupt, EOFError):
             return
     print('OK:', json.dumps(ans))
+
+
+def main(args=sys.argv):
+    try:
+        real_main(args)
+    except Exception:
+        import traceback
+        traceback.print_exc()
+        input('Press enter to quit...')
+        raise SystemExit(1)