// Part of the Carbon Language project, under the Apache License v2.0 with LLVM
// Exceptions. See /LICENSE for license information.
// SPDX-License-Identifier: Apache-2.0 WITH LLVM-exception

// https://adventofcode.com/2024/day/14

library "day14_common";

import Core library "io";
import library "io_utils";

fn ReadXY(xy: (i32, i32)*) -> bool {
  return ReadInt(ref xy->0) and ConsumeChar(',') and ReadInt(ref xy->1);
}

fn SkipString(s: str) -> bool {
  return SkipNChars(s.Size() as i32);
}

fn Mod(a: i32, d: i32) -> i32 {
  let rem: i32 = a % d;
  return if rem < 0 then rem + d else rem;
}

class Robot {
  impl as Core.UnformedInit {}

  fn Read() -> Robot {
    returned var me: Robot;
    SkipString("p=");
    ReadXY(&me.p);
    SkipString(" v=");
    ReadXY(&me.v);
    SkipNewline();
    return var;
  }

  fn Pos[self: Self](t: i32) -> (i32, i32) {
    return (Mod((self.p.0 + self.v.0 * Mod(t, 101)), 101),
            Mod((self.p.1 + self.v.1 * Mod(t, 103)), 103));
  }

  impl as Core.Copy {
    fn Op[self: Self]() -> Self {
      return {.p = self.p, .v = self.v};
    }
  }

  var p: (i32, i32);
  var v: (i32, i32);
}