include("utils.jl")

function parse_boards(lines)
    num_boards = div(length(lines),5)
    boards = Array{Array{Int}}(undef, num_boards)
    for i in 1:num_boards
        boards[i] = zeros(5, 5)
        for li in 1:5
            values = map(x->parse(Int, x), split(lines[(i - 1)*5+li]))
            boards[i][li,:] .= values
        end
    end
    boards
end

function parse_input(filename)
    lines = Iterators.Stateful(non_empty_lines(filename))
    numbers = map(x->parse(Int, x), split(popfirst!(lines), ","))
    boards = parse_boards(collect(lines))
    numbers, boards
end

function apply(number, boards)
    for board in boards
        for i in CartesianIndices((1:5, 1:5))
            if board[i] == number
                board[i] = -1
            end
        end
    end
end

function check(boards)
    for board in boards
        for i in 1:5
            if (reduce(+, board[i,:]) == -5) || (reduce(+, board[:,i]) == -5)
                return true, board
            end
        end
    end
    false, nothing
end

function solution4_1()
    numbers, boards = parse_input("4.data")
    for number in numbers
        apply(number, boards)
        winning, board = check(boards)
        if winning
            score = reduce(+, filter(>(0), board))
            return (score, number, score * number)
        end
    end
end

function remove_winning_boards(boards)
    last = nothing
    filtered = filter(boards) do board
        for i in 1:5
            if (reduce(+, board[i,:]) == -5) || (reduce(+, board[:,i]) == -5)
                last = board
                return false
            end
        end
        true
    end
    filtered, last
end


function solution4_2()
    numbers, boards = parse_input("4.data")
    for number in numbers
        apply(number, boards)
        boards, board = remove_winning_boards(boards)
        if length(boards) == 0
            score = reduce(+, filter(>(0), board))
            return (score, number, score * number)
        end
    end
end

solution4_2()