From b604ff30ecbed86d0d23409f7669a6f7f13a5af6 Mon Sep 17 00:00:00 2001
From: Eryn Wells <eryn@erynwells.me>
Date: Sun, 8 May 2022 23:38:48 -0700
Subject: [PATCH] Implement a basic AI for HostileMonster

This AI will walk randomly around the dungeon (pausing periodically) and
if the Hero comes into view, will b-line and attack
---
 roguebasin/ai.py | 100 ++++++++++++++++++++++++++++++++++++++++++++---
 1 file changed, 95 insertions(+), 5 deletions(-)

diff --git a/roguebasin/ai.py b/roguebasin/ai.py
index f758fb2..eb54f5c 100644
--- a/roguebasin/ai.py
+++ b/roguebasin/ai.py
@@ -1,22 +1,112 @@
 # Eryn Wells <eryn@erynwells.me>
 
-from typing import TYPE_CHECKING
+import logging
+from os import path
+import random
+from typing import TYPE_CHECKING, List, Optional
 
-from .actions import Action, WaitAction
+import numpy as np
+import tcod
+
+from .actions import Action, BumpAction, MeleeAction, WaitAction
 from .components import Component
+from .geometry import Direction, Point
 from .object import Entity
 
 if TYPE_CHECKING:
     from .engine import Engine
 
+LOG = logging.getLogger(__name__)
+
 class AI(Component):
     def __init__(self, entity: Entity) -> None:
         super().__init__()
         self.entity = entity
 
-    def act(self, engine: 'Engine') -> Action:
+    def act(self, engine: 'Engine') -> Optional[Action]:
+        '''Produce an action to perform'''
         raise NotImplementedError()
 
 class HostileEnemy(AI):
-    def act(self, engine: 'Engine') -> Action:
-        return WaitAction(self.entity)
\ No newline at end of file
+    def act(self, engine: 'Engine') -> Optional[Action]:
+        visible_tiles = tcod.map.compute_fov(
+            engine.map.tiles['transparent'],
+            pov=tuple(self.entity.position),
+            radius=self.entity.sight_radius)
+
+        hero_position = engine.hero.position
+        hero_is_visible = visible_tiles[hero_position.x, hero_position.y]
+
+        if hero_is_visible:
+            path_to_hero = self.get_path_to(hero_position, engine)
+            entity_position = self.entity.position
+
+            next_position = path_to_hero.pop(0) if len(path_to_hero) else hero_position
+            direction_to_next_position = entity_position.direction_to_adjacent_point(next_position)
+            LOG.info('Hero is visible to %s, bumping %s (%s)', self.entity, direction_to_next_position, next_position)
+
+            return BumpAction(self.entity, direction_to_next_position)
+        else:
+            move_or_wait_chance = random.random()
+            if move_or_wait_chance <= 0.7:
+                # Pick a random adjacent tile to move to
+                directions = list(Direction.all())
+                while len(directions) > 0:
+                    direction = random.choice(directions)
+                    directions.remove(direction)
+                    new_position = self.entity.position + direction
+                    overlaps_existing_entity = any(new_position == ent.position for ent in engine.entities)
+                    tile_is_walkable = engine.map.tile_is_walkable(new_position)
+                    if not overlaps_existing_entity and tile_is_walkable:
+                        LOG.info('Hero is NOT visible to %s, bumping %s randomly', self.entity, direction)
+                        action = BumpAction(self.entity, direction)
+                        break
+                else:
+                    # If this entity somehow can't move anywhere, just wait
+                    LOG.info("Hero is NOT visible to %s and it can't move anywhere, waiting", self.entity)
+                    action = WaitAction(self.entity)
+
+                return action
+            else:
+                return WaitAction(self.entity)
+
+    def get_path_to(self, point: Point, engine: 'Engine') -> List[Point]:
+        '''Compute a path to the given position.
+
+        Copied from the Roguelike tutorial. :)
+
+        Arguments
+        ---------
+        point : Point
+            The target point
+        engine : Engine
+            The game engine
+
+        Returns
+        -------
+        List[Point]
+            An array of Points representing a path from the Entity's position to the target point
+        '''
+        # Copy the walkable array
+        cost = np.array(engine.map.tiles['walkable'], dtype=np.int8)
+
+        for ent in engine.entities:
+            # Check that an entity blocks movement and the cost isn't zero (blocking)
+            position = ent.position
+            if ent.blocks_movement and cost[position.x, position.y]:
+                # Add to the cost of a blocked position. A lower number means more enemies will crowd behind each other
+                # in hallways. A higher number means enemies will take longer paths in order to surround the player.
+                cost[position.x, position.y] += 10
+
+        # Create a graph from the cost array and pass that graph to a new pathfinder.
+        graph = tcod.path.SimpleGraph(cost=cost, cardinal=2, diagonal=3)
+        pathfinder = tcod.path.Pathfinder(graph)
+
+        # Set the starting position
+        pathfinder.add_root(tuple(self.entity.position))
+
+        # Compute the path to the destination and remove the starting point.
+        path: List[List[int]] = pathfinder.path_to(tuple(point))[1:].tolist()
+
+        # Convert from List[List[int]] to List[Tuple[int, int]].
+        return [Point(index[0], index[1]) for index in path]
\ No newline at end of file