%  main.erl
-module(main).
-compile([export_all]).
%

% w = 119
% b = 98
% . = 46

deletePawn(Pos, Board) ->
    {List1,End} = lists:split(Pos, Board),
    Start = lists:droplast(List1),
    Start++[46]++End.

movePawn(Src, Dest, Board) ->
    Pawn = lists:nth(Src, Board),
    TmpBoard = deletePawn(Src, Board),
    {List1,End} = lists:split(Dest, TmpBoard),
    Start = lists:droplast(List1),
    Start++[Pawn]++End.

righMoveWhite(Src, Dest, Board) ->
    Left = lists:nth(Src+7, Board),
    Right = lists:nth(Src+9, Board),
    LeftHit = lists:nth(Src+14, Board),
    RightHit = lists:nth(Src+18, Board),

    if  Src > Dest -> false;
        Src+7 == Dest;  Left == 46; (Dest div 8 - Src div 8) == 1 -> true;
        Src+9 == Dest;  Right == 46; (Dest div 8 - Src div 8) == 1 -> true;
        Src+14 == Dest; Left /= 46; LeftHit == 46; (Dest div 8 - Src div 8) == 2 -> true;
        Src+18 == Dest; Right /= 46; RightHit == 46; (Dest div 8 - Src div 8) == 2 -> true;
        true -> false
    end.

righMoveBlack(Src, Dest, Board) ->
    Left = lists:nth(Src-9, Board),
    Right = lists:nth(Src-7, Board),
    LeftHit = lists:nth(Src-18, Board),
    RightHit = lists:nth(Src-14, Board),

    if  Src > Dest -> false;
        Src-9 == Dest;  Left == 46; (Src div 8 - Dest div 8) == 1 -> true;
        Src-7 == Dest;  Right == 46; (Src div 8 - Dest div 8) == 1 -> true;
        Src-18 == Dest; Left /= 46; LeftHit == 46; (Src div 8 - Dest div 8) == 2 -> true;
        Src-14 == Dest; Right /= 46; RightHit == 46; (Src div 8 - Dest div 8) == 2 -> true;
        true -> false
    end.

moveWhite(Src, Dest, Board) ->
    RightMove = righMoveWhite(Src, Dest, Board),
    Diff = Dest div 8 - Src div 8,
    if  RightMove == true, Diff == 2 -> deletePawn(Dest, Board);
        RightMove == true -> movePawn(Src, Dest, Board)
    end.

moveBlack(Src, Dest, Board) ->
    RightMove = righMoveBlack(Src, Dest, Board),
    Diff = Src div 8 - Dest div 8,
    if  RightMove == true, Diff == 2 -> deletePawn(Dest, Board);
        RightMove == true -> movePawn(Src, Dest, Board)
    end.

endGame(Board) ->
    White = lists:member(119,Board),
    Black = lists:member(98,Board),
    if  White==true -> false;
        Black==true -> false;
        true -> true
    end.

game() ->
    BoardString = ".w.w.w.ww.w.w.w..w.w.w.w................b.b.b.b..b.b.b.bb.b.b.b.\n",
    io:format(BoardString).