%% to compile: erlc day3A.erl
%% to run: erl -noshell -s day3 solve
%%
-module(day4).

-export ([solve/0, solve/1, solve/2]).
-export ([read_boards/0]).

solve() ->
    solve(['1']),
    solve(['2']),
    init:stop().

solve(A) ->
    solve(A, read_boards()).

solve(['1'], D) ->
    io:format("The solution to ~p puzzle1 is: ~p~n", [?MODULE, solve(1, D)]);
solve(1, D) ->
    solution1(D);
solve(['2'], D) ->
    io:format("The solution to ~p puzzle2 is: ~p~n", [?MODULE, solve(2, D)]);
solve(2, D) ->
    solution2(D).

read_boards() ->
	{ok, IO} = file:open("boards.txt", 'read'),
	Data = read_boards(IO),
	file:close(IO),
        Data.

read_boards(IO) ->
	read_boards(IO, []).

read_boards('eof', Boards) ->
	Boards;
read_boards(IO, Boards) ->
	case read_board(IO) of
		'eof' -> Boards;
		Board -> read_boards(IO, Boards ++ [Board])
	end.

read_board(IO) ->
	read_line(IO, []).

read_line(IO, Board) ->
	case file:read_line(IO) of
		{ok, "\n"} -> make_board(Board);
		'eof' -> 'eof';
		{ok, Line} -> read_line(IO, [[ list_to_integer(X) || X <- string:tokens(Line, " \n")]|Board])
	end.

make_board(B) ->
	B ++ [lists:map(fun(X) -> lists:nth(Y,X) end, B) || Y <- lists:seq(1,5)].

solution1(Boards) ->
	Input = get_input(),
	Bingo = process(Boards, 1, Input),
	score(Bingo).

solution2(Boards) ->
	Input = get_input(),
	Bingo = process(Boards, length(Boards), Input),
	score(Bingo).

score({'bingo', Num, Board}) ->
	Fun = fun(L) -> lists:foldl(fun(X, Acc) -> X + Acc end, 0, L) end,
	Num * (Fun([Fun(X) || X <- Board]) / 2).

process(Boards, _Count, []) -> Boards;
process(Boards, Count, [H|T]) ->
	New_boards = process_boards(Boards, H, []),
	case is_bingo(New_boards) of
		{'bingo', Board} when Count ==  1 -> {'bingo', H, Board};
		{'bingo', _Board}  -> 
			New_boards2 = delete_bingo_boards(New_boards),
			process(New_boards2, Count - length(New_boards) + length(New_boards2), T);
		_Else -> process(New_boards, Count, T)
	end.


process_boards([], _Num, Acc) ->
	Acc;
process_boards([B|T], Num, Acc) ->
	process_boards(T, Num, [[lists:delete(Num, X) || X <- B]|Acc]).

is_bingo([]) -> 'false';
is_bingo([Board|Rest]) ->
	case is_line(Board) of
		'true' -> {'bingo', Board};
		'false' -> is_bingo(Rest)
	end.
is_line(Board) ->
	lists:any(fun(X) -> X == [] end, Board).

delete_bingo_boards(Boards) ->
	[Board || Board <- Boards, not is_line(Board)].

get_input() ->
	[83,69,34,46,30,23,19,75,22,37,89,78,32,39,11,44,95,43,26,48,84,53,94,88,18,40,62,35,27,42,15,2,91,20,4,64,99,71,54,97,52,36,28,7,74,45,70,86,98,1,61,50,68,6,77,8,57,47,51,72,65,3,49,24,79,13,17,92,41,80,63,67,82,90,55,0,10,93,38,21,59,73,33,31,9,76,5,66,16,58,85,87,12,29,25,14,96,56,60,81].