Add moving pieces based on input SAN

src/lx_chess.cr

@@ -35,25 +35,23 @@ fen = LxChess::Fen.parse(options["fen_string"])
 game = LxChess::Game.new(board: fen.board)
 gb = LxChess::TermBoard.new(game.board)
 
-gb.draw
-puts
-
 loop do
+  gb.draw
+  puts
   print " > "
   input = gets
   if input
     notation = LxChess::Notation.new(input)
-    input = input.to_i16 if input =~ /^\d+$/
-    if move_set = game.moves(input)
-      puts move_set.moves.map { |m| game.board.cord(m) }
+    from, to = game.parse_san(notation)
+    if from && to
+      piece = game.board.move(from, to)
+      puts "#{notation.to_s}: #{game.board.cord(from)} => #{game.board.cord(to)}"
     end
-    # from, to = game.parse_san(notation)
-    # if from && to
-    #   puts "#{notation.to_s}: #{game.board.cord(from)} => #{game.board.cord(to)}"
-    # end
   end
 rescue e : LxChess::Notation::InvalidNotation
   puts e.message
+rescue e : LxChess::Game::SanError
+  puts e.message
 end
 
 # gb.flip!

src/lx_chess/board.cr

@@ -44,7 +44,7 @@ module LxChess
 
     # Set a piece an the board at a certain *index*
     def []=(index : Int, piece : Piece | Nil)
-      piece.index = index.to_i16
+      piece.index = index.to_i16 if piece
       @squares[index] = piece
     end
 
@@ -100,5 +100,11 @@ module LxChess
       rank, _ = index.divmod(@width)
       rank
     end
+
+    def move(from : (String | Int), to : (String | Int))
+      piece = self[from.to_i16]
+      self[from.to_i16] = nil
+      self[to.to_i16] = piece
+    end
   end
 end

src/lx_chess/game.cr

@@ -2,9 +2,12 @@ require "./player"
 require "./board"
 require "./notation"
 require "./move_set"
+require "./error"
 
 module LxChess
   class Game
+    class SanError < Error; end
+
     property turn : Int8, board : Board
 
     def initialize(@board : Board = Board.new, @players = [] of Player)
@@ -15,11 +18,16 @@ module LxChess
     def parse_san(notation : Notation)
       index = @board.index(notation.square)
       fen_symbol = notation.fen_symbol(@turn == 0 ? "w" : "b")
-      pieces = @board.select { |piece| piece && piece.fen_symbol == fen_symbol }
-      pieces = pieces.select { |piece| piece && moves(piece.index.as(Int16)).includes?(index) }
+      pieces = @board.select do |piece|
+        next if piece.nil?
+        next unless piece.fen_symbol == fen_symbol
+        if move_set = moves(piece.index.as(Int16))
+          move_set.moves.includes?(index)
+        end
+      end
 
-      raise "Ambiguous SAN" if pieces.size > 1
-      raise "Illegal move" if pieces.size == 0
+      raise SanError.new("Ambiguous SAN") if pieces.size > 1
+      raise SanError.new("Illegal move") if pieces.size == 0
       piece = pieces.first
 
       # from, to

src/lx_chess/notation.cr

@@ -65,6 +65,7 @@ module LxChess
 
       @from = nil
       @to = nil
+      validate
     end
 
     def initialize(
@@ -82,7 +83,10 @@ module LxChess
       @to = nil
     )
       @piece_abbr = "K" if @castles_q || @castles_k
+      validate
+    end
 
+    def validate
       raise InvalidMove.new("Cannot castle and promote") if castles? && promotion
       raise InvalidMove.new("Cannot capture while castling") if castles? && takes?
     end