@spec claim_draw(ExChess.Game.t()) :: ExChess.Game.t() | :error

Allows the active player to claim a draw in case of either:

• 50 move rule
• threefold repetition

Examples

50 move rule

iex> ExChess.start_game("knn5/8/8/8/8/8/8/KNN5 w - - 101 90") # 101 halfmoves
...> |> ExChess.claim_draw()
...> |> ExChess.Visualization.status()
"1/2-1/2"

Threefold repetition

iex> ExChess.start_game() # first occurence
...> |> ExChess.move("Nc3") |> ExChess.move("Nc6")
...> |> ExChess.move("Nb1") |> ExChess.move("Nb8") # second occurence
...> |> ExChess.move("Nc3") |> ExChess.move("Nc6")
...> |> ExChess.move("Nb1") |> ExChess.move("Nb8") # third occurence
...> |> ExChess.claim_draw()
...> |> ExChess.Visualization.status()
"1/2-1/2"

Draw unclaimable

iex> ExChess.start_game()
...> |> ExChess.claim_draw()
:error

Game already complete

iex> ExChess.start_game()
...> |> ExChess.resign()
...> |> ExChess.claim_draw()
:error

@spec list_legal_moves(ExChess.Game.t(), ExChess.Square.t()) :: [ExChess.Square.t()]

Lists all available target squares for the piece situated on from_square.

Examples

Getting legal moves for a piece

iex> ExChess.start_game()
...> |> ExChess.list_legal_moves(ExChess.Square.new(1, 1))
[%ExChess.Square{file: 1, rank: 2}, %ExChess.Square{file: 1, rank: 3}]

@spec move(ExChess.Game.t(), ExChess.Move.t() | ExChessCore.San.t()) ::
  ExChess.Game.t() | :error

Returns the updated ExChess.Game when the move is valid, and :error otherwise.

Examples

Making a move using SAN

iex> ExChess.start_game()
...> |> ExChess.move("Nf3")
...> |> ExChess.move("Nf6")
...> |> ExChess.Visualization.game()
"STATUS: * | FEN: rnbqkb1r/pppppppp/5n2/8/8/5N2/PPPPPPPP/RNBQKB1R w KQkq - 2 2"

Making a move using structs

iex> first_move = ExChess.Move.new(ExChess.Square.new(6, 0), ExChess.Square.new(5, 2))
...> second_move = ExChess.Move.new(ExChess.Square.new(6, 7), ExChess.Square.new(5, 5))
...> ExChess.start_game()
...> |> ExChess.move(first_move)
...> |> ExChess.move(second_move)
...> |> ExChess.Visualization.game()
"STATUS: * | FEN: rnbqkb1r/pppppppp/5n2/8/8/5N2/PPPPPPPP/RNBQKB1R w KQkq - 2 2"

Making an invalid move

iex> ExChess.start_game()
...> |> ExChess.move("a2b3")
:error

Game already complete

iex> ExChess.start_game()
...> |> ExChess.resign()
...> |> ExChess.move("h3")
:error

@spec resign(ExChess.Game.t()) :: ExChess.Game.t() | :error

Returns the update ExChess.Game with the current active color's side having resigned and the opponent is declared the winner.

If the game is already complete, this returns :error.

Examples

White resigns

iex> ExChess.start_game()
...> |> ExChess.resign()
...> |> ExChess.Visualization.status()
"0-1"

Black resigns

iex> ExChess.start_game()
...> |> ExChess.move("a3")
...> |> ExChess.resign()
...> |> ExChess.Visualization.status()
"1-0"

Game already complete

iex> ExChess.start_game()
...> |> ExChess.resign()
...> |> ExChess.resign()
:error

@spec start_game(ExChess.Fen.t() | nil) :: ExChess.Game.t()

Instantiates a new ExChess.Game. An optional fen string can be passed in to start the game at a particular position.

Examples

Starting a game

iex> ExChess.start_game()
...> |> ExChess.Visualization.game()
"STATUS: * | FEN: rnbqkbnr/pppppppp/8/8/8/8/PPPPPPPP/RNBQKBNR w KQkq - 0 1"

Starting a game using FEN

iex> ExChess.start_game("rnbqkb1r/pppppppp/5n2/8/8/5N2/PPPPPPPP/RNBQKB1R w KQkq - 2 2")
...> |> ExChess.Visualization.game()
"STATUS: * | FEN: rnbqkb1r/pppppppp/5n2/8/8/5N2/PPPPPPPP/RNBQKB1R w KQkq - 2 2"