1 files changed, 161 insertions, 0 deletions
diff --git a/snakegame/snake.py b/snakegame/snake.py
new file mode 100644
index 0000000..89e97da
--- /dev/null
+++ b/snakegame/snake.py
@@ -0,0 +1,161 @@
+#!/usr/bin/env python
+
+from __future__ import division
+
+import sys
+import time
+import string
+import random
+from colour import hash_colour
+from random import randint
+from collections import deque
+from copy import deepcopy
+import traceback
+
+from common import *
+
+class SnakeEngine(object):
+    def __init__(self, rows, columns, n_apples, wrap=False, results=False,
+                 *args, **kwargs):
+        super(SnakeEngine, self).__init__(*args, **kwargs)
+
+        self.wrap = wrap
+        self.bots = {}
+        self.results = None
+        if results:
+            self.results = open('results.csv', 'a+')
+
+        self.new_game(rows, columns, n_apples)
+
+    def get_random_position(self):
+        x = randint(0, self.columns - 1)
+        y = randint(0, self.rows - 1)
+        return (x, y)
+
+    def replace_random(self, old, new):
+        for i in xrange(self.rows * self.columns):
+            x, y = self.get_random_position()
+            if self.board[y][x] == old:
+                self.board[y][x] = new
+                return x, y
+
+    def new_game(self, rows, columns, n_apples):
+        self.game_ticks = 0
+        self.game_id = random.randint(0, sys.maxint)
+
+        self.letters = list(string.lowercase)
+        self.letters.reverse()
+
+        self.rows = rows
+        self.columns = columns
+
+        # make board
+        self.board = [[Squares.EMPTY for x in xrange(columns)] for y in xrange(rows)]
+        for i in xrange(n_apples):
+            x, y = self.get_random_position()
+            self.board[y][x] = Squares.APPLE
+
+    def add_bot(self, bot):
+        """
+        A bot is a callable object, with this method signature:
+            def bot_callable(
+                board=[[cell for cell in row] for row in board],
+                position=(snake_x, snake_y)
+                ):
+                return random.choice('RULD')
+        """
+        letter = self.letters.pop()
+
+        name = bot.__name__
+        colour = hash_colour(name)
+
+        position = self.replace_random(Squares.EMPTY, letter.upper())
+        if position is None:
+            raise KeyError, "Could not insert snake into the board."
+
+        self.bots[letter] = [bot, colour, deque([position])]
+        return letter
+
+    def remove_bot(self, letter):
+        letter = letter.lower()
+
+        time_score = self.game_ticks
+
+        for row in self.board:
+            for x, cell in enumerate(row):
+                if cell.lower() == letter:
+                    row[x] = Squares.EMPTY
+
+        bot = self.bots[letter]
+        del self.bots[letter]
+
+        if not self.results:
+            return
+
+        try:
+            name = bot[0].__name__
+        except AttributeError:
+            pass
+        else:
+            apple_score = len(bot[2])
+            self.results.write('%s,%s,%s,%s\n' % \
+                (self.game_id, name, apple_score, time_score))
+            self.results.flush()
+
+    def update_snakes(self, directions_id=id(directions)):
+        assert id(directions) == directions_id, \
+            "The common.directions dictionary has been modified since startup..."
+
+        self.game_ticks += 1
+
+        for letter, (bot, colour, path) in self.bots.items():
+            board = deepcopy(self.board)
+            try:
+                x, y = path[-1]
+                d = bot(board, (x, y))
+
+                # Sanity checking...
+                assert isinstance(d, basestring), \
+                    "Return value should be a string."
+                d = d.upper()
+                assert d in directions, "Return value should be 'U', 'D', 'L' or 'R'."
+
+                # Get new position.
+                dx, dy = directions[d]
+                nx = x + dx
+                ny = y + dy
+
+                if self.wrap:
+                    ny %= self.rows
+                    nx %= self.columns
+                else:
+                    if ny < 0 or ny >= self.rows or nx < 0 or nx >= self.columns:
+                        self.remove_bot(letter)
+                        continue
+
+                oldcell = self.board[ny][nx]
+                if oldcell in (Squares.EMPTY, Squares.APPLE):
+                    # Move snake forward.
+                    self.board[ny][nx] = letter.upper()
+                    path.append((nx, ny))
+
+                    # Make old head into body.
+                    self.board[y][x] = letter.lower()
+
+                    if oldcell == Squares.APPLE:
+                        # Add in an apple to compensate.
+                        self.replace_random(Squares.EMPTY, Squares.APPLE)
+                    else:
+                        # Remove last part of snake.
+                        ox, oy = path.popleft()
+                        self.board[oy][ox] = Squares.EMPTY
+                else:
+                    self.remove_bot(letter)
+
+            except:
+                print "Exception in bot %s (%s):" % (letter.upper(), bot)
+                print '-'*60
+                traceback.print_exc()
+                print '-'*60
+                self.remove_bot(letter)
+