algorithms/lib/toGetClosestPoint/toGetClosestPoint.ts

type Direction = "N" | "E" | "S" | "W" | "NW" | "NE" | "SW" | "SE";
export function toGetClosestPoint(
  x1: number,
  y1: number,
  x2: number,
  y2: number,
  sx: number,
  sy: number,
) {
  let direction: Direction = "N";

  const sectors: Record<Direction, number[]> = {
    NW: [x1, y2],
    N: [x1, y2],
    NE: [x2, y2],
    E: [x2, y2],
    SE: [x2, y1],
    S: [x1, y1],
    SW: [x1, y1],
    W: [x1, y2],
  };

  for (let key in sectors) {
    const [x, y] = sectors[key];

    if (sx <= x && sy >= y) {
      direction = "NW";
      break;
    }
    if (sx >= x && sy > y && sx <= x2) {
      direction = "N";
      break;
    }
    if (sx >= x && sy >= y) {
      direction = "NE";
      break;
    }

    if (sx >= x && sy <= y && sy >= y1) {
      direction = "E";
      break;
    }

    if (sx >= x && sy <= y && sx <= x2) {
      direction = "S";
      break;
    }

    if (sx >= x && sy <= y) {
      direction = "SE";
      break;
    }

    if (sy <= y && sx <= x) {
      direction = "SW";
      break;
    }

    if (sy <= y2 && sy >= y1 && sx <= x) {
      direction = "W";
      break;
    }
  }

  return direction;
}