import { axisAlignedBoundingBox } from "../collision/aa.ts";
import { CircleLike } from "../collision/circular.ts";
import { Vector } from "../mod.ts";
import { Point } from "./vector.ts";

export class Polygon {
  points: Vector[];
  center: Vector;

  constructor(points: Point[]) {
    this.points = points.map((p) => new Vector(p));
    this.center = this.calcCenter();
  }

  draw(color?: string) {
    for (let i = 0; i < this.points.length; i++) {
      const p1 = this.points[i];
      const p2 = this.points.at(i - this.points.length + 1)!;
      doodler.line(p1.copy().add(this.center), p2.copy().add(this.center), {
        color,
      });
    }
  }

  calcCenter() {
    if (!this.points.length) return new Vector();
    const center = new Vector();

    for (const point of this.points) {
      center.add(point);
    }
    center.div(this.points.length);
    return center;
  }

  get circularHitbox(): CircleLike {
    let greatestDistance = 0;
    for (const p of this.points) {
      greatestDistance = Math.max(
        p.copy().add(this.center).dist(this.center),
        greatestDistance,
      );
    }

    return {
      center: this.center.copy(),
      radius: greatestDistance,
    };
  }

  _aabb?: axisAlignedBoundingBox;
  get AABB(): axisAlignedBoundingBox {
    if (!this._aabb) {
      this._aabb = this.recalculateAABB();
    }
    return this._aabb;
  }

  recalculateAABB(): axisAlignedBoundingBox {
    let smallestX, biggestX, smallestY, biggestY;
    smallestX =
      smallestY =
        Infinity;
    biggestX =
      biggestY =
        -Infinity;

    for (const p of this.points) {
      const temp = p.copy().add(this.center);
      smallestX = Math.min(temp.x, smallestX);
      biggestX = Math.max(temp.x, biggestX);
      smallestY = Math.min(temp.y, smallestY);
      biggestY = Math.max(temp.y, biggestY);
    }

    return {
      x: smallestX,
      y: smallestY,
      w: biggestX - smallestX,
      h: biggestY - smallestY,
    };
  }

  static createPolygon(sides = 3, radius = 100) {
    sides = Math.round(sides);
    if (sides < 3) {
      throw "You need at least 3 sides for a polygon";
    }

    const poly = new Polygon([]);
    // figure out the angles required
    const rotangle = (Math.PI * 2) / sides;
    let angle = 0;
    // loop through and generate each point
    for (let i = 0; i < sides; i++) {
      angle = (i * rotangle) + ((Math.PI - rotangle) * 0.5);
      const pt = new Vector(Math.cos(angle) * radius, Math.sin(angle) * radius);
      poly.points.push(pt);
    }
    poly.center = poly.calcCenter();
    return poly;
  }

  getEdges(): Vector[] {
    const edges: Vector[] = [];
    for (let i = 0; i < this.points.length; i++) {
      const nextIndex = (i + 1) % this.points.length;
      const edge = this.points[nextIndex].copy().add(this.center).sub(
        this.points[i].copy().add(this.center),
      );
      edges.push(edge);
    }
    return edges;
  }

  getNearestPoint(p: Vector) {
    let nearest = this.points[0];
    for (const point of this.points) {
      if (p.dist(point) < p.dist(nearest)) nearest = point;
    }
    return nearest;
  }
}