Add display abstraction

In case we want to run this on something that isn't an ANSI terminal, we
have the option to implement it however we want.

Signed-off-by: Alek Ratzloff <alekratz@gmail.com>

agame/__main__.py

@@ -3,6 +3,8 @@ import importlib.util
 from pathlib import Path
 import sys
 from agame.color import colorize
+from agame.display import ANSIDisplay
+from agame.game import Game
 
 
 # Parse args
@@ -19,25 +21,36 @@ package = args.PACKAGE
 
 # Load game module
 game_module = importlib.import_module(package)
-game = game_module.game  # type: ignore
+database = game_module.database  # type: ignore
+start_room = game_module.start_room  # type: ignore
 
-# Run
-game.say("=" * 70)
-game.say("Type ((help)) for help, or ((quit)) to exit.")
-game.say("=" * 70)
-game.say()
+# Build the game state
+game = Game(
+    display=ANSIDisplay(),
+    database=database,
+    room=database.rooms["prelude"],
+)
 
-game.do_teleport_actions()
-while True:
-    try:
+try:
+    # Run
+    game.say("=" * 70)
+    game.say("Type ((help)) for help, or ((quit)) to exit.")
+    game.say("=" * 70)
     game.say()
-        line = input(colorize("{{>}} "))
+
+    game.do_teleport_actions()
+    while True:
+        game.say()
+        line = game.display.input()
         if line.lower() == "quit":
             break
         game.say()
         game.run_command(line)
-    except (KeyboardInterrupt, EOFError):
-        break
+except (KeyboardInterrupt, EOFError):
+    # no-op, these are expected events
+    pass
+finally:
+    game.display.finish()
 
 game.say()
 game.say("Bye.")

agame/action.py

@@ -13,6 +13,7 @@ __all__ = (
     "PrintAction",
     "PrintRoomAction",
     "PlayerInputAction",
+    "WaitForAckAction",
     "TeleportAction",
     "GetAction",
     "CheckInvItemsAction",
@@ -91,11 +92,10 @@ class PlayerInputAction(Action):
     Waits for a user to press a key, or press enter, or whatever.
     """
 
-    prompt: str = "Press enter to continue..."
     store_var_id: Optional[str] = None
 
     def act(self, game: "Game"):
-        line = input(self.prompt)
+        line = game.display.input()
         if self.store_var_id:
             assert (
                 self.store_var_id in game.vars
@@ -103,6 +103,18 @@ class PlayerInputAction(Action):
             game.vars[self.store_var_id] = line
 
 
+class WaitForAckAction(Action):
+    """
+    Waits for a player to press a single key, or press enter, to acknowledge and
+    continue processing.
+
+    This is basically "press any key to continue..." territory.
+    """
+
+    def act(self, game: "Game"):
+        game.display.wait_for_ack()
+
+
 @dataclasses.dataclass
 class TeleportAction(Action):
     """

agame/display/__init__.py

@@ -0,0 +1,18 @@
+import platform
+from .display import Display
+
+if platform.system() in ("Linux", "Darwin", "Unix"):
+    from .unix import *
+
+
+class BasicDisplay(Display):
+    """
+    A basic display that should be supported on all platforms. It just outputs
+    text with some color.
+    """
+
+    def line(self, line: str = ""):
+        print(line)
+
+    def input(self) -> str:
+        return input("> ")

agame/display/display.py

@@ -0,0 +1,32 @@
+import abc
+from typing import Optional
+
+
+class Display(metaclass=abc.ABCMeta):
+    """
+    Displays are an abstraction over printing things to the screen.
+
+    Use a specific implementation based on the kind of display you want to use.
+    """
+
+    @abc.abstractmethod
+    def line(self, line: str = ""):
+        "Print a single line to the display."
+
+    @abc.abstractmethod
+    def input(self) -> str:
+        "Get player input."
+
+    @abc.abstractmethod
+    def wait_for_ack(self, prompt: Optional[str] = None):
+        """
+        Wait for the user to press a key.
+
+        The behavior is up to the implementor. This could be something like
+        "press any key to continue", "press enter to continue", or "click OK to
+        continue". This method should block until input is acknowleged by the
+        user.
+        """
+
+    def finish(self):
+        "Final cleanup code for this display."

agame/display/unix.py

@@ -0,0 +1,88 @@
+import sys
+import termios
+from typing import Optional, TextIO
+from agame.color import colorize
+from .display import Display
+
+ESC = "\u001b"
+ANSI_MOVE_BOTTOM = f"{ESC}[999;0f"
+
+
+class ANSIDisplay(Display):
+    """
+    Display for a modern terminal.
+
+    This display attempts to keep the input at the bottom, and the output
+    scrolling up.
+
+    This utilizes `termios` and is therefore UNIX-only.
+    """
+
+    def __init__(
+        self,
+        input_prompt: str = colorize("{{>}} "),
+        stdin: TextIO = sys.stdin,
+        stdout: TextIO = sys.stdout,
+    ):
+        self.input_prompt = input_prompt
+        self.__stdin = stdin
+        self.__stdout = stdout
+        # Initial set-up:
+        # . Move the cursor to the bottom left part of the screen (this will set
+        #   the current line to a really high value and will move us to the
+        #   bottom of the screen)
+        self.stdout.write(ANSI_MOVE_BOTTOM)
+
+        # . Disable echo, set cbreak
+        fd = self.stdin.fileno()
+        self.__old_attrs = termios.tcgetattr(fd)
+        self.cbreak()
+
+        # . Clear
+        self.clear()
+
+    def line(self, line: str = ""):
+        self.stdout.write(line)
+        self.stdout.write("\n")
+
+    def input(self) -> str:
+        try:
+            self.nocbreak()
+            return input(self.input_prompt)
+        finally:
+            self.cbreak()
+
+    def wait_for_ack(self, prompt: Optional[str] = "Press any key to continue..."):
+        # Flush unread data
+        termios.tcflush(self.stdin.fileno(), termios.TCIFLUSH)
+        if prompt is not None:
+            self.line(prompt)
+        self.stdin.read(1)
+
+    def cbreak(self):
+        fd = self.stdin.fileno()
+        new = termios.tcgetattr(fd)
+        new[3] &= ~(termios.ECHO | termios.ICANON)
+        termios.tcsetattr(fd, termios.TCSADRAIN, new)
+
+    def nocbreak(self):
+        fd = self.stdin.fileno()
+        new = termios.tcgetattr(fd)
+        new[3] |= termios.ECHO | termios.ICANON
+        termios.tcsetattr(fd, termios.TCSADRAIN, new)
+
+    def finish(self):
+        # Clean up by restoring the old terminal state
+        fd = self.stdin.fileno()
+        termios.tcsetattr(fd, termios.TCSADRAIN, self.__old_attrs)
+
+    def clear(self):
+        self.stdout.write(f"{ESC}[2J")
+
+    @property
+    def stdin(self) -> TextIO:
+        return self.__stdin
+
+    @property
+    def stdout(self) -> TextIO:
+        return self.__stdout

agame/game.py

@@ -3,6 +3,7 @@ import textwrap
 from typing import Any, MutableMapping, List, Match, Optional, Sequence, Union
 from agame.action import Action
 from agame.color import colorize
+from agame.display import Display
 from agame.item import Item, ItemInst
 from agame.room import Room
 from agame.trigger import *
@@ -67,6 +68,8 @@ class Database:
 
 @dataclasses.dataclass
 class Game:
+    # Game display.
+    display: Display
     # Game room/items database
     database: Database
     # Current room.
@@ -138,13 +141,14 @@ class Game:
         "Format, colorize, wrap, and print the message."
         if lines:
             head = textwrap.fill(lines[0])
-            print(colorize(head))
+            # TODO - move colorize to Display
+            self.display.line(colorize(head))
             for line in lines[1:]:
                 message = textwrap.fill(line)
-                print()
-                print(colorize(message))
+                self.display.line()
+                self.display.line(colorize(message))
         else:
-            print()
+            self.display.line()
 
     @property
     def rooms(self):

examplegame/__init__.py

@@ -7,11 +7,8 @@ from agame.trigger import *
 # This is the *game* here
 database = Database()
 
+# This is the start room
+start_room = "prelude"
+
 from . import rooms
 from . import vars
-
-# Build the game state
-game = Game(
-    database=database,
-    room=database.rooms["prelude"],
-)

examplegame/rooms.py

@@ -59,7 +59,7 @@ database.add_room(
                 "This is one of those stories.",
                 LINEBREAK,
             ),
-            PlayerInputAction(),
+            WaitForAckAction(),
             PrintAction(
                 LINEBREAK,
                 #
@@ -75,7 +75,7 @@ database.add_room(
                 "No animals patrol the sky nor ground. Life has left this place.",
                 LINEBREAK,
             ),
-            PlayerInputAction(),
+            WaitForAckAction(),
             PrintAction(
                 LINEBREAK,
                 #
@@ -83,22 +83,25 @@ database.add_room(
                 #
                 LINEBREAK,
             ),
-            PlayerInputAction(),
-            SleepAction(1),
+            WaitForAckAction(),
+            PrintAction(LINEBREAK),
+            SleepAction(0.75),
             PrintAction("."),
-            SleepAction(1),
+            SleepAction(0.75),
             PrintAction(".."),
-            SleepAction(1),
+            SleepAction(0.75),
             PrintAction("..."),
-            SleepAction(1),
+            SleepAction(0.75),
             PrintAction("...."),
-            SleepAction(1),
+            SleepAction(0.75),
             PrintAction("....."),
-            SleepAction(1),
+            SleepAction(0.75),
             PrintAction("......"),
-            SleepAction(1),
+            SleepAction(0.75),
+            PrintAction(LINEBREAK),
             PrintAction("You awaken from a fitful sleep. Where are you again?"),
-            PlayerInputAction(),
+            WaitForAckAction(),
+            PrintAction(LINEBREAK),
             TeleportAction("cabin_inside"),
         ],
     )