From 63df6b0b52d5f7b3e2885009c6fdf5f29288e227 Mon Sep 17 00:00:00 2001
From: Wanja <wanja.chresta@gmail.com>
Date: Fri, 23 Mar 2012 01:35:02 +0100
Subject: [PATCH] First (untested) version of tafl.js

---
 assets/www/tafl.js | 201 +++++++++++++++++++++++++++++++++++++++++++++
 1 file changed, 201 insertions(+)
 create mode 100644 assets/www/tafl.js

diff --git a/assets/www/tafl.js b/assets/www/tafl.js
new file mode 100644
index 0000000..07fa8cb
--- /dev/null
+++ b/assets/www/tafl.js
@@ -0,0 +1,201 @@
+/*
+ * This is the JS Tafl Game lib and part of Androtafl.
+ */
+
+(function () {
+	'use strict';
+	
+	Array.prototype.has = function(obj) {
+	    var i = this.length;
+	    while (i--) {
+	        if (this[i] === obj) {
+	            return true;
+	        }
+	    }
+	    return false;
+	};
+	
+	function TaflState() {
+		this.board = [''];
+		this.N = 0;
+		this.to_move = 'w';
+		this.legal_moves_cache = null;
+		this.winner = null;
+		
+		this.loadBoard = function(board) {
+			this.board = board;
+			this.N = board.length;
+			if (board[0].length !== this.N) throw "BoardNotSquare";
+		};
+		
+		this.clone = function() {
+			var i, t = new TaflState();
+						
+			for (i = 0; i < this.N; ++i) {
+				t.board[i] = this.board[i];
+			}
+			
+			t.N = this.N;
+			t.to_move = this.to_move;
+			t.legal_moves_cache = this.legal_moves_cache;
+			t.winner = this.winner;
+		}
+	}
+	
+	var Tafl = {
+		legal_moves: function(s) {
+			if (s.legal_moves_cache) return s.legal_moves_cache;
+			
+			var i,j,k, N=s.N, moves=[], legal_fields;
+			
+			
+			for (i=0; i<N; ++i) {
+				for (j=0; j<N; ++j) {
+					if (! this.is_moving_color(s, [i,j])) continue;
+					
+					legal_fields = ['.'];
+					if (s.board[i][j] === 'K') legal_fields.push(','); // Only king can step on throne
+					
+					for (k=i+1; k<N; ++k) {
+						if (legal_fields.has(s.board[k][j])) {
+							moves.push([ [i,j], [k,j] ]);
+						} else break;
+					}
+					
+					for (k=1; k<i+1; ++k) {
+						if (legal_fields.has(s.board[i-k][j])) {
+							moves.push([ [i,j], [i-k,j] ]);
+						} else break;
+					}
+					
+					for (k=j+1; k<N; ++k) {
+						if (legal_fields.has(s.board[i][k])) {
+							moves.push([ [i,j], [i,k] ]);
+						} else break;
+					}
+					
+					for (k=1; k<j+1; ++k) {
+						if (legal_fields.has(s.board[i][j-k])) {
+							moves.push([ [i,j], [i,j-k] ]);
+						} else break;
+					}
+				}
+			}
+			
+			s.legal_moves_cache = moves;
+			return moves;
+		},
+		
+		make_move: function(s, move) {
+			if (! ( this.legal_moves(s).has(move) )) throw "IllegalMove";
+			
+			var i=move[0][0],j=move[0][1],k=move[1][0],l=move[1][1],c, empty='.', t;
+			
+			
+			if (s.board[k][l] === 'k') empty = ','; // King was on throne
+			
+			s.board[k][l] = s.board[i][j];
+			s.board[i][j] = empty;
+			
+			c = this.get_catches(s, [k,l]);
+			for ( t=0; t < c.length; ++t ) {
+				s[c[t][0]][c[t][1]] = '.';
+			}
+			
+			if (s.to_move === 'W') s.to_move = 'B';
+			else				   s.to_move = 'W';
+			
+			s.legal_moves_cache = null;
+		},
+	
+		get_catches: function(s, last_move) {
+			var catches = [], k=last_move[0], l=last_move[1], directions, 
+			    d, di, dj, king_pos, i,j, king_capturers;
+			
+			directions = [[1,0],[-1,0],[0,1],[0,-1]];
+			
+			for (d=0; d < directions.length; ++d) {
+				di = directions[d][0]; dj = directions[d][1];
+				
+				if (!this.is_moving_color(s, [k+di, j+dj]) &&
+					 this.is_moving_color(s, [k+2*di, j+2*dj]) &&
+					 s.board[k][l].toUpperCase() !== 'K') {
+					catches.push([k+di, l+dj]);
+				}
+			}
+			
+			// Check if king is captured separately
+			king_pos = this.find_king(s);
+			i = king_pos[0]; j=king_pos[1];
+			
+			king_capturers = ['W',',']; // Kings can be captured by white stones
+										// or the throne
+			if (i > 0 && j > 0 && i < s.N-1 && j < s.N-1) { // King is in not on
+															// an edge
+				if (king_capturers.has(s.board[i][j-1]) && king_capturers.has(s.board[i][j+1]) &&
+					king_capturers.has(s.board[i-1][j]) && king_capturers.has(s.board[i+1][j])) {
+					catches.push([i,j]);
+				}
+			}
+				
+			
+			return catches;
+		},
+		
+		is_moving_color: function(s, move) {
+			var i=move[0], j=move[1];
+			
+			if (s.to_move === s.board[i][j]) return true;
+			// K and k are both kings
+			if (s.to_move === 'B' && s.board[i][j].toUpperCase() === 'K') return true;	
+			
+			return false;
+		},
+		
+		find_king: function(s) {
+			for (i=0; i<s.N; ++i){
+				j = s.board[i].find('K'); // Kind is in the field?
+				if (! j > 0) s.board[i].find('k'); // King is on throne?
+				if (j >= 0)  return [i,j];
+			}
+			
+			return null;
+		}
+		
+		terminal_test: function(s) {
+			var i, j, king_found = false, corners;
+			
+			// find position of king and check if he's on an edge
+			for (i=0; i<s.N; ++i){
+				j = s.board[i].find('K'); // Kind is in the field?
+				if (! j > 0) s.board[i].find('k'); // King is on throne?
+				
+				if (j >= 0) { // Found king
+					
+					// King is at an edge
+					if (i === 0 || i === s.N-1 || j === 0 || j === s.N-1) {
+						s.winner = 'B';
+						return true;
+					}
+					
+					kind_found = true;
+					break;
+				}
+			}
+			
+			if (! king_found) {
+				s.winner = 'W';
+				return true; // King was captured
+			}
+			
+			// Are there any legal moves? If not, player loses
+			if (this.legal_moves(s).length == 0) {
+				if (s.to_move === 'W') s.winner = 'B';
+				else				   s.winner = 'W';
+				return true;
+			}
+			
+			return false; // no one won, yet
+		}
+	};
+})();