aoc-2019/10/main.pony

use "collections"
use "files"
use "itertools"

primitive Math
  fun gcd(x: ISize, y: ISize): ISize =>
    var a = x
    var b = y
    var d: USize = 0
    while ((a % 2) == 0) and ((b % 2) == 0) do
      a = a / 2
      b = b / 2
      d = d + 1
    end
    while a != b do
      if (a % 2) == 0 then a = a / 2
      elseif (b % 2) == 0 then b = b / 2
      elseif a > b then a = (a - b) / 2
      else b = (b - a) / 2
      end
    end
    if d > 0 then
      a * (2 << (d-1)).isize()
    else
      a
    end

// A basic two-dimensional point class
class val Point is Hashable
  let x: ISize
  let y: ISize

  new val create(_x: ISize, _y: ISize) =>
    x = _x
    y = _y

  // because we want to use this as a key in a hashmap
  fun hash(): USize =>
    // hey this is probably bad, huh?
    (x.hash() + y.hash()).usize()

  fun eq(other: Point): Bool =>
    (x == other.x) and (y == other.y)

  fun ne(other: Point): Bool => not eq(other)

  fun sub(other: Point): Point =>
    Point(x - other.x, y - other.y)

  fun simplify(): Point =>
    let d = Math.gcd(x, y)
    Point(x/d, y/d)

actor Asteroid
  let _loc: Point
  let _field: AsteroidField tag
  let _io: IO tag
  let _visible: Map[Point, Point] = Map[Point, Point]()

  new create(p: Point, field: AsteroidField tag, io: IO tag) =>
    _loc = p
    _field = field
    _io = io

  be print() =>
    _io.print("Asteroid(" + _loc.x.string() + ", " + _loc.y.string() + ")")

  be find_visible(loc: Point, other: Asteroid) =>
    None

actor AsteroidField
  var _io: IO
  var _locs: Set[Point] = Set[Point]()

  new create(io: IO) =>
    _io = io

  be register(p: Point) =>
    _locs.set(p)

  be print() =>
    _io.print("whoo")

actor IO
  let _env: Env
  new create(env: Env) =>
    _env = env

  be print(str: String) =>
    _env.out.print(str)

actor Main
  new create(env: Env) =>
    let io = IO(env)
    let field = AsteroidField(io)
    build_field(env, io, field)
    field.print()

  fun build_field(env: Env, io: IO, field: AsteroidField): (Array[Asteroid] | None) =>
    let caps = recover val FileCaps.>set(FileRead).>set(FileStat) end
    let target_file = try env.args(1)? else "input.txt" end
    try
      var asteroids: Array[Asteroid] = Array[Asteroid]()
      with
        file = OpenFile(FilePath(env.root as AmbientAuth, target_file, caps)?) as File
      do
        for (y, line) in Iter[String](file.lines()).enum() do
          for (x, char) in Iter[U8](line.values()).enum() do
            if char == '#' then
              let p = Point(x.isize(), y.isize())
              field.register(p)
              asteroids.push(Asteroid(p, field, io))
            end
          end
        end
      end
      for a in asteroids.values() do
        a.print()
      end
      asteroids
    else
      env.err.print("Couldn't read file `" + target_file + "`")
      env.exitcode(99)
    end