#!/usr/bin/env julia

using DelimitedFiles

infile = size(ARGS, 1) > 0 ? ARGS[1] : "day5input.txt"
println("infile = ", infile)

# 0,9 -> 5,9
line_re = r"(\d+),(\d+) -> (\d+),(\d+)"

open(infile, "r") do io
    horiz = Vector[]
    vert  = Vector[]
    diag  = Vector[]
    max_x = 0
    max_y = 0

    for line in eachline(io)
        m = match(line_re, line)
        nums = [parse(Int, m[i])+1 for i in 1:4]
        max_x = max(max_x, nums[1], nums[3])
        max_y = max(max_y, nums[2], nums[4])
        if nums[1] == nums[3]
            if (nums[2] > nums[4])
                nums[2], nums[4] = nums[4], nums[2]
            end
            push!(vert, nums)
        elseif nums[2] == nums[4]
            if (nums[1] > nums[3])
                nums[1], nums[3] = nums[3], nums[1]
            end
            push!(horiz, nums)
        else
            push!(diag, nums)
        end
    end

    println("max ", max_x, ", ", max_y)
    println("horiz ", length(horiz))
    println("vert  ", length(vert))

    M = zeros(Int64, max_y, max_x)

    for hl in horiz
        M[hl[2], hl[1]:hl[3]] .+= 1
    end
    for vl in vert
        M[vl[2]:vl[4], vl[1]] .+= 1
    end

    if (length(M) < 1000)
        println("M")
        display(M)
        println()
    end

    ndanger = length(findall(M .> 1))
    println("dangerous coords ", ndanger)

    for d in diag
        if (d[1] > d[3])
            xrange = d[1]:-1:d[3]
        else
            xrange = d[1]:d[3]
        end
        if (d[2] > d[4])
            yrange = d[2]:-1:d[4]
        else
            yrange = d[2]:d[4]
        end
        idx = [CartesianIndex(c) for c in zip(yrange, xrange)]
        M[idx] .+= 1
    end

    if (length(M) < 1000)
        println("M")
        display(M)
        println()
    end

    ndanger2 = length(findall(M .> 1))
    println("dangerous coords (part 2) ", ndanger2)
end