Generate items and display on map, implement exception handling

actions.py

@@ -3,10 +3,11 @@ from __future__ import annotations
 from typing import overload, Optional, Tuple, TYPE_CHECKING
 
 import color
+import exceptions
 
 if TYPE_CHECKING:
     from engine import Engine
-    from entity import Actor, Entity
+    from entity import Actor, Entity, Item
 
 
 class Action:
@@ -31,6 +32,29 @@ class Action:
         """
 
 
+class ItemAction(Action):
+    def __init__(
+            self,
+            entity: Actor,
+            item: Item,
+            target_xy: Optional[Tuple[int, int]] = None
+    ):
+        super().__init__(entity)
+        self.item = item
+        if not target_xy:
+            target_xy = entity.x, entity.y
+        self.target_xy = target_xy
+
+    @property
+    def target_actor(self) -> Optional[Actor]:
+        """Return the actor at this action's destination."""
+        return self.engine.game_map.get_actor_at_location(*self.target_xy)
+
+    def perform(self) -> None:
+        """Invoke the item's ability, this action will be given to provide context."""
+        self.item.consumable.activate(self)
+
+
 class EscapeAction(Action):
     def perform(self) -> None:
         raise SystemExit()
@@ -68,7 +92,7 @@ class MeleeAction(ActionWithDirection):
     def perform(self) -> None:
         target = self.target_actor
         if not target:
-            return  # No entity to attack.
+            raise exceptions.Impossible("Nothing to attack.")
 
         damage = self.entity.fighter.power - target.fighter.defense
 
@@ -96,11 +120,14 @@ class MovementAction(ActionWithDirection):
         dest_x, dest_y = self.dest_xy
 
         if not self.engine.game_map.in_bounds(dest_x, dest_y):
-            return  # Destination is out of bounds
+            # Destination is out of bounds
+            raise exceptions.Impossible("That way is blocked.")
         if not self.engine.game_map.tiles["walkable"][dest_x, dest_y]:
-            return  # Destination is blocked by a tile.
+            # Destination is blocked by a tile.
+            raise exceptions.Impossible("That way is blocked.")
         if self.engine.game_map.get_blocking_entity_at_location(dest_x, dest_y):
-            return  # Destination is blocked by an entity.
+            # Destination is blocked by an entity.
+            raise exceptions.Impossible("That way is blocked.")
 
         self.entity.move(self.dx, self.dy)
 

color.py

@@ -7,7 +7,12 @@ enemy_atk = (0xFF, 0xC0, 0xC0)
 player_die = (0xFF, 0x30, 0x30)
 enemy_die = (0xFF, 0xA0, 0x30)
 
+invalid = (0xFF, 0xFF, 0x00)
+impossible = (0x80, 0x80, 0x80)
+error = (0xFF, 0x40, 0x40)
+
 welcome_text = (0x20, 0xA0, 0xFF)
+health_recovered = (0x0, 0xFF, 0x0)
 
 bar_text = white
 bar_filled = (0x0, 0x60, 0x0)

components/consumable.py

@@ -0,0 +1,43 @@
+from __future__ import annotations
+
+from typing import Optional, TYPE_CHECKING
+
+import actions
+import color
+from components.base_component import BaseComponent
+from exceptions import Impossible
+
+if TYPE_CHECKING:
+    from entity import Actor, Item
+
+
+class Consumable(BaseComponent):
+    parent: Item
+
+    def get_action(self, consumer: Actor) -> Optional[actions.Action]:
+        """Try to return the action for this item."""
+        return actions.ItemAction(consumer, self.parent)
+
+    def activate(self, action: actions.ItemAction) -> None:
+        """Invoke this item's ability.
+
+        `action` is the context for this activation.
+        """
+        raise NotImplementedError()
+
+
+class HealingConsumable(Consumable):
+    def __init__(self, amount: int):
+        self.amount = amount
+
+    def activate(self, action: actions.ItemAction) -> None:
+        consumer = action.entity
+        amount_recovered = consumer.fighter.heal(self.amount)
+
+        if amount_recovered > 0:
+            self.engine.message_log.add_message(
+                f"You consume the {self.parent.name}, and recover {amount_recovered} HP!",
+                color.health_recovered
+            )
+        else:
+            raise Impossible(f"Your health is already full.")

components/fighter.py

@@ -47,3 +47,21 @@ class Fighter(BaseComponent):
         self.parent.render_order = RenderOrder.CORPSE
 
         self.engine.message_log.add_message(death_message, death_message_color)
+
+    def heal(self, amount: int) -> int:
+        if self.hp == self.max_hp:
+            return 0
+
+        new_hp_value = self.hp + amount
+
+        if new_hp_value > self.max_hp:
+            new_hp_value = self.max_hp
+
+        amount_recovered = new_hp_value - self.hp
+
+        self.hp = new_hp_value
+
+        return amount_recovered
+
+    def take_damage(self, amount: int) -> None:
+        self.hp -= amount

engine.py

@@ -6,6 +6,7 @@ from tcod.context import Context
 from tcod.console import Console
 from tcod.map import compute_fov
 
+import exceptions
 from input_handlers import MainGameEventHandler
 from message_log import MessageLog
 from render_functions import render_bar, render_names_at_mouse_location
@@ -27,7 +28,10 @@ class Engine:
     def handle_enemy_turns(self) -> None:
         for entity in set(self.game_map.actors) - {self.player}:
             if entity.ai:
+                try:
                     entity.ai.perform()
+                except exceptions.Impossible:
+                    pass  # Ignore impossible action exceptions from AI.
 
     def update_fov(self) -> None:
         """Recompute the visible area based on the player's point of view."""

entity.py

@@ -7,6 +7,7 @@ from render_order import RenderOrder
 
 if TYPE_CHECKING:
     from components.ai import BaseAI
+    from components.consumable import Consumable
     from components.fighter import Fighter
     from game_map import GameMap
 
@@ -105,3 +106,28 @@ class Actor(Entity):
     def is_alive(self) -> bool:
         """Returns True as long as this actor can perform actions."""
         return bool(self.ai)
+
+
+class Item(Entity):
+    def __init__(
+            self,
+            *,
+            x: int = 0,
+            y: int = 0,
+            char: str = "?",
+            color: Tuple[int, int, int] = (255, 255, 255),
+            name: str = "<Unamed>",
+            consumable: Consumable,
+    ):
+        super().__init__(
+            x=x,
+            y=y,
+            char=char,
+            color=color,
+            name=name,
+            blocks_movement=False,
+            render_order=RenderOrder.ITEM,
+        )
+
+        self.consumable = consumable
+        self.consumable.parent = self

entity_factories.py

@@ -1,6 +1,7 @@
 from components.ai import HostileEnemy
+from components.consumable import HealingConsumable
 from components.fighter import Fighter
-from entity import Actor
+from entity import Actor, Item
 
 player = Actor(
     char="@",
@@ -24,3 +25,10 @@ troll = Actor(
     ai_cls=HostileEnemy,
     fighter=Fighter(hp=16, defense=1, power=4)
 )
+
+health_potion = Item(
+    char="!",
+    color=(127, 0, 255),
+    name="Health Potion",
+    consumable=HealingConsumable(amount=4)
+)

exceptions.py

@@ -0,0 +1,5 @@
+class Impossible(Exception):
+    """Exception raised when an action is impossible to be performed.
+
+    The reason is given as the exception message.
+    """

input_handlers.py

@@ -4,7 +4,14 @@ from typing import overload, Optional, TYPE_CHECKING
 
 import tcod.event
 
-from actions import Action, BumpAction, EscapeAction, WaitAction
+from actions import (
+    Action,
+    BumpAction,
+    EscapeAction,
+    WaitAction
+)
+import color
+import exceptions
 
 if TYPE_CHECKING:
     from engine import Engine
@@ -52,10 +59,28 @@ class EventHandler(tcod.event.EventDispatch[Action]):
     def __init__(self, engine: Engine):
         self.engine = engine
 
-    def handle_events(self, context: tcod.context.Context) -> None:
-        for event in tcod.event.wait():
-            context.convert_event(event)
-            self.dispatch(event)
+    def handle_events(self, event: tcod.event.Event) -> None:
+        self.handle_action(self.dispatch(event))
+
+    def handle_action(self, action: Optional[Action]) -> bool:
+        """Handle actions returned from event methods.
+
+        Returns True if the action will advance a turn.
+        """
+        if action is None:
+            return False
+
+        try:
+            action.perform()
+        except exceptions.Impossible as exc:
+            self.engine.message_log.add_message(exc.args[0], color.impossible)
+            return False  # Skip enemy turn on exceptions.
+
+        self.engine.handle_enemy_turns()
+
+        self.engine.update_fov()
+
+        return True
 
     def ev_mousemotion(self, event: tcod.event.MouseMotion) -> None:
         if self.engine.game_map.in_bounds(event.tile.x, event.tile.y):
@@ -69,20 +94,6 @@ class EventHandler(tcod.event.EventDispatch[Action]):
 
 
 class MainGameEventHandler(EventHandler):
-    def handle_events(self, context: tcod.context.Context) -> None:
-        for event in tcod.event.wait():
-            context.convert_event(event)
-
-            action = self.dispatch(event)
-
-            if action is None:
-                continue
-
-            action.perform()
-
-            self.engine.handle_enemy_turns()
-            self.engine.update_fov()
-
     def ev_keydown(self, event: tcod.event.KeyDown) -> Optional[Action]:
         action: Optional[Action] = None
 
@@ -106,25 +117,9 @@ class MainGameEventHandler(EventHandler):
 
 
 class GameOverEventHandler(EventHandler):
-    def handle_events(self, context: tcod.context.Context) -> None:
-        for event in tcod.event.wait():
-            action = self.dispatch(event)
-
-            if action is None:
-                continue
-
-            action.perform()
-
-    def ev_keydown(self, event: tcod.event.KeyDown) -> Optional[Action]:
-        action: Optional[Action] = None
-
-        key = event.sym
-
-        if key == tcod.event.K_ESCAPE:
-            action = EscapeAction(self.engine.player)
-
-        # No valid key was pressed
-        return action
+    def ev_keydown(self, event: tcod.event.KeyDown) -> None:
+        if event.sym == tcod.event.K_ESCAPE:
+            raise SystemExit()
 
 
 CURSOR_Y_KEYS = {

main.py

@@ -1,5 +1,6 @@
 #!/usr/bin/env python3
 import copy
+import traceback
 
 import tcod
 
@@ -21,6 +22,7 @@ def main() -> None:
     max_rooms = 30
 
     max_monsters_per_room = 2
+    max_items_per_room = 2
 
     tileset = tcod.tileset.load_tilesheet(
         "dejavu10x10_gs_tc.png",
@@ -40,6 +42,7 @@ def main() -> None:
         map_width,
         map_height,
         max_monsters_per_room,
+        max_items_per_room,
         engine,
     )
     engine.update_fov()
@@ -62,7 +65,14 @@ def main() -> None:
             engine.event_handler.on_render(console=root_console)
             context.present(root_console)
 
-            engine.event_handler.handle_events(context)
+            try:
+                for event in tcod.event.wait():
+                    context.convert_event(event)
+                    engine.event_handler.handle_events(event)
+            except Exception:  # Handle exceptions in game.
+                traceback.print_exc()  # Print error to stderr.
+                # Then print the error to the message log.
+                engine.message_log.add_message(traceback.format_exc(), color.error)
 
 
 if __name__ == "__main__":

procgen.py

@@ -46,8 +46,10 @@ def place_entities(
         room: RectangularRoom,
         dungeon: GameMap,
         maximum_monsters: int,
+        maximum_items: int,
 ) -> None:
     number_of_monsters = random.randint(0, maximum_monsters)
+    number_of_items = random.randint(0, maximum_items)
 
     for i in range(number_of_monsters):
         x = random.randint(room.x1 + 1, room.x2 - 1)
@@ -59,6 +61,13 @@ def place_entities(
             else:
                 entity_factories.troll.spawn(dungeon, x, y)
 
+    for i in range(number_of_items):
+        x = random.randint(room.x1 + 1, room.x2 - 1)
+        y = random.randint(room.y1 + 1, room.y2 - 1)
+
+        if not any(entity.x == x and entity.y == y for entity in dungeon.entities):
+            entity_factories.health_potion.spawn(dungeon, x, y)
+
 
 def tunnel_between(start: Tuple[int, int], end: Tuple[int, int]) -> Iterator[Tuple[int, int]]:
     """Return an L-shaped tunnel between these two points."""
@@ -86,6 +95,7 @@ def generate_dungeon(
         map_width: int,
         map_height: int,
         max_monsters_per_room: int,
+        max_items_per_room: int,
         engine: Engine,
 ) -> GameMap:
     """Generate a new dungeon map."""
@@ -120,7 +130,7 @@ def generate_dungeon(
             for x, y in tunnel_between(rooms[-1].center, new_room.center):
                 dungeon.tiles[x, y] = tile_types.floor
 
-        place_entities(new_room, dungeon, max_monsters_per_room)
+        place_entities(new_room, dungeon, max_monsters_per_room, max_items_per_room)
 
         # Finally, append the new room to the list.
         rooms.append(new_room)