From f61b9ee0a7a9747a786964c746242e86b977568f Mon Sep 17 00:00:00 2001
From: Dan Ballard <dan@mindstab.net>
Date: Sun, 28 Aug 2011 16:39:17 -0700
Subject: [PATCH] finish move generator, add jump generator, add dup and all
 associated functions

---
 checkers.rb | 129 +++++++++++++++++++++++++++++++++++++++++++++++++++-
 1 file changed, 127 insertions(+), 2 deletions(-)

diff --git a/checkers.rb b/checkers.rb
index 4646cf7..955cb2d 100644
--- a/checkers.rb
+++ b/checkers.rb
@@ -1,5 +1,8 @@
 #!/usr/bin/ruby
 
+EMPTY = 0
+TEAM_1 = 1
+TEAM_2 = 2
 TEAM_1_MAN = ' w '
 TEAM_1_KING = ' W '
 TEAM_2_MAN = ' b '
@@ -10,6 +13,9 @@ BOARD_SIZE = 8
 class Board
 	def initialize()
 		@board = Array.new(BOARD_SIZE) {|i| Array.new(BOARD_SIZE, BOARD_EMPTY)}
+	end
+
+	def setup()
 		0.step(BOARD_SIZE) {|i|
 		       	peice = (i < 3 ? TEAM_1_MAN : TEAM_2_MAN)	
 			if [0,2,5,7].include? i
@@ -19,15 +25,23 @@ class Board
 			else
 				next
 			end
-			start.step(BOARD_SIZE,2) {|j|
+			start.step(BOARD_SIZE-1,2) {|j|
 				@board[i][j] = peice
 			}
 		}
 	end
 
+	def set(x, y, thing)
+		@board[y][x] = thing
+	end
+
+	def get(x, y)
+		@board[y][x]
+	end
+
 	def to_s()
 		str = '  '
-		0.step(BOARD_SIZE) {|i|
+		0.step(BOARD_SIZE-1) {|i|
 			str += ' ' + i.to_s + ' '
 		}
 		str += "\n"
@@ -43,7 +57,118 @@ class Board
 		return str
 	end
 
+	def piece_team(piece)
+		if piece == TEAM_1_MAN or piece == TEAM_1_KING
+			return TEAM_1
+		elsif piece == TEAM_2_MAN or piece == TEAM_2_KING
+			return TEAM_2
+		else
+			return EMPTY
+		end
+	end
+
+	def empty?(x, y)
+		return @board[y][x] == BOARD_EMPTY
+	end
+
+	def valid_coords(x, y)
+		return (x >= 0 and x < BOARD_SIZE and y >= 0 and y <= BOARD_SIZE)
+	end
+
+	def gen_moves(x, y, x_mod, y_mod)
+		moves = []
+		for xm in x_mod
+			new_x = x + xm
+			for ym in y_mod
+				new_y = y + ym
+				if valid_coords(new_x, new_y) and empty?(new_x, new_y)
+					moves += [[new_x, new_y]]
+				end
+			end
+		end
+		return moves
+	end
+
+	# function to chart path of jumps
+	# merging them together
+	# only returns full paths
+	#
+	# base case: no jumps avail, return path
+	# jumps avail: do all and merge and return
+	def gen_jumps(path, x, y, team, x_mod, y_mod)
+		jumps = []
+		for xm in x_mod
+			new_x = x + xm
+			for y in ymod
+				new_y = y + ym
+				if valid_coords(new_x, new_y) and piece?(new_x, new_y) and team != team(new_x, new_y)
+					final_x = new_x + xm
+					final_y = new_y + ym
+					if (valid_coords(final_x, final_y) and empty?(final_x, final_y))
+						jumps += gen_jumps(path + [[final_x, final_y]], final_x, final_y, x_mod, y_mod)
+					end
+				end
+			end
+		end
+
+		if jumps == []
+			return [path]
+		else
+			return jumps
+		end
+	end
+
+	def piece?(x, y)
+		return !emtpy(x, y)
+	end
+
+	def team(x, y)
+		if piece?(x, y)
+			if @board[y][x] == TEAM_1_MAN or @board[y][x] == TEAM_1_KING
+				return TEAM_1
+			else
+				return TEAM_2
+			end
+		end
+		return EMPTY
+	end
+
+	def man?(x, y)
+		return (@board[y][x] == TEAM_1_MAN or @board[y][x] == TEAM_2_MAN)
+	end
+	
+	def king?(x, y)
+		return (@board[y][x] == TEAM_1_KING or @board[y][x] == TEAM_2_KING)
+	end
+
+	def valid_moves(x, y, team)
+		moves = []
+		if piece_team(@board[y][x]) == team
+			direction = [1]
+			if king?(x, y)
+				direction = [-1, 1]
+			elsif team == TEAM_2 
+				direction = [-1]
+			end
+
+			moves = gen_moves(x, y, [-1,1], direction)
+			moves += gen_jumps([], x, y, team, [-1, 1], direction)
+		end
+		return moves
+	end
+
+	def dup() 
+		b = Board.new
+		for x in 0..(BOARD_SIZE-1)
+			for y in 0..(BOARD_SIZE-1)
+				b.set(x, y, get(x, y))
+			end
+		end
+		return b
+	end
+
 end
 
 b = Board.new()
+b.setup()
 puts b.to_s