include("utils.jl")

function parse_input(filename)
    map(x->parse.(Int, x), split.(non_empty_lines(filename), ""))
end

function search(entry_risk)
    width, height = size(entry_risk)
    total_risk = fill(typemax(Int64), width, height)
    total_risk[1, 1] = 0

    to_visit = [(CartesianIndex(1,2), 0), (CartesianIndex(2,1), 0)]
    while length(to_visit) > 0
        rounds += 1
        coord, cost = popfirst!(to_visit)
        cost += entry_risk[coord]
        if cost < total_risk[coord]
            total_risk[coord] = cost
            if coord[1] > 1
                push!(to_visit, (CartesianIndex(coord[1] - 1, coord[2]), cost))
            end
            if coord[1] < width
                push!(to_visit, (CartesianIndex(coord[1] + 1, coord[2]), cost))
            end
            if coord[2] > 1
                push!(to_visit, (CartesianIndex(coord[1], coord[2] - 1), cost))
            end
            if coord[2] < height
                push!(to_visit, (CartesianIndex(coord[1], coord[2] + 1), cost))
            end
        end
    end
    total_risk[width, height]
end

function solution15_1()
    entry_risk = parse_input("15.data")
    width = length(entry_risk)
    height = length(entry_risk[1])
    entry_risk = transpose(reshape(reduce(vcat, entry_risk), height, width))
    search(entry_risk)
end

function solution15_2()
    entry_risk = parse_input("15.data")
    width = length(entry_risk)
    height = length(entry_risk[1])
    entry_risk = map(entry_risk) do line
        [line;
         map(x->mod((x-1)+1, 9)+1, line);
         map(x->mod((x-1)+2, 9)+1, line);
         map(x->mod((x-1)+3, 9)+1, line);
         map(x->mod((x-1)+4, 9)+1, line);
         ]
    end
    for _ in 1:(4*height)
        push!(entry_risk, map(x->mod((x-1)+1, 9)+1, entry_risk[length(entry_risk) - (height - 1)]))
    end
    entry_risk = transpose(reshape(reduce(vcat, entry_risk), height*5, width*5))
    search(entry_risk)
end

solution15_2()