with import ../../util.nix;

let
  # read input
  input = readFile ./input;
  pairs =
    let
      readRange = s: splitPair (a: b: [ (toInt a) (toInt b) ]) (splitString "-" s);
      readPair = a: b: [ (readRange a) (readRange b) ];
    in map
      (line: splitPair readPair (splitString "," line))
      (splitString "\n" input);

  # overlap functions
  partialOverlap = a1: a2: b1: b2:
    a1 <= b1 && b1 <= a2 || a1 <= b2 && b2 <= a2;
  completeOverlap = a1: a2: b1: b2:
    a1 <= b1 && a2 >= b2;

  # calc overlaps
  hasOverlap = overlapFunc: a: b:
    splitPair (splitPair overlapFunc a) b || splitPair (splitPair overlapFunc b) a;
  overlaps = overlapFunc: map boolToInt (map (splitPair (hasOverlap overlapFunc)) pairs);
in {
  part1 = sum (overlaps completeOverlap);
  part2 = sum (overlaps partialOverlap);
}