% Row 1
wall([X,1]) :- X =\= 2.
% Row 2
wall([X,2]) :- X = 1; X = 4; X = 6.
% Row 3
wall([X,3]) :- X = 1; X = 2; X = 6.
% Row 4
wall([X,4]) :- X =\= 3,X =\= 5.
% Row 5
wall([X,5]) :- X = 1; X = 4; X = 6.
% Row 6
wall([X,6]) :- X =\= 2.
% Start / end
start([2,1]).
end([2,6]).

% Maze Size
mazeSize([6,6]).
badSpot([X,Y]) :- wall([X,Y]).
badSpot([X,Y]) :- X < 1; Y < 1.
badSpot([X,Y]) :- mazeSize([W, H]), (X > W; Y > H).

%up
move([CurrX, CurrY], [CurrX, NextY]) :- NextY is CurrY - 1.
%down
move([CurrX, CurrY], [NextX, NextY]) :- NextY is CurrY + 1, NextX = CurrX.
%left
move([CurrX, CurrY], [NextX, NextY]) :- NextY = CurrY, NextX is CurrX - 1.
%right
move([CurrX, CurrY], [NextX, NextY]) :- NextY = CurrY, NextX is CurrX + 1.

% move to the end of the maze
exitMaze([CurrX, CurrY], [NextX, NextY]) :- end([EndX, EndY]), 
       X is sqrt((EndX-CurrX)^2 + (EndY-CurrY)^2), 
       Y is sqrt((EndX-NextX)^2 + (EndY-NextY)^2), 
       X < Y.

% A solution of the maze from our current location is [] if our current location is the end.
solve2(OldLocation, _, Path) :- end(OldLocation), Path = [OldLocation].

solve2(OldLocation, BeenThere, Path):-
        move(OldLocation, NewLocation),
        exitMaze(NewLocation, NewLocation),
        \+badSpot(NewLocation),
        \+member(NewLocation, BeenThere),
        solve2(NewLocation,[NewLocation | BeenThere], RestPath),
        Path = [OldLocation | RestPath].
        
solve2(OldLocation, BeenThere, Path):-
        move(OldLocation, NewLocation),
        \+badSpot(NewLocation),
        \+member(NewLocation, BeenThere),
        solve2(NewLocation,[NewLocation | BeenThere], RestPath),
        Path = [OldLocation | RestPath].

solve2(Path) :- start(Start), solve2(Start,[Start], Path).



drawCell(Column, Row, _) :- wall([Column, Row]), write("X"), !.
drawCell(Column, Row, _) :- start([Column, Row]), write("S"), !.
drawCell(Column, Row, _) :- end([Column, Row]), write("E"), !.
drawCell(Column, Row, Path) :- member([Column, Row], Path), write("P"), !.
drawCell(_, _, _) :- write("O").

drawRow(Row, Path) :- drawCell(1, Row, Path), tab(1), drawCell(2, Row, Path), tab(1), 
        drawCell(3, Row, Path), tab(1), drawCell(4, Row, Path), tab(1), 
        drawCell(5, Row, Path), tab(1), drawCell(6, Row, Path), nl.
                
draw :- drawRow(1, []), drawRow(2, []), drawRow(3, []), drawRow(4, []), drawRow(5, []), 
        drawRow(6, []).
draw(Path) :- drawRow(1, Path), drawRow(2, Path), drawRow(3, Path), drawRow(4, Path),
        drawRow(5, Path), drawRow(6, Path).