import { _decorator, Component, Node, Prefab, instantiate, Vec3 } from "cc";
const { ccclass, property } = _decorator;

@ccclass("TrajectoryPreview")
export class TrajectoryPreview extends Component {
  @property(Prefab)
  pointPrefab: Prefab = null!;

  @property
  maxPoints: number = 20;

  @property
  timeStep: number = 0.1;

  @property
  gravity: Vec3 = new Vec3(0, -9.8, 0);

  private points: Node[] = [];

  onLoad() {
    for (let i = 0; i < this.maxPoints; i++) {
      const p = instantiate(this.pointPrefab);
      p.active = false;
      this.node.addChild(p); // 确保挂在场景下的空节点
      this.points.push(p);
    }
  }

  showTrajectory(
    startPos: Vec3,
    forward: Vec3,
    power: number,
    sideForce: number
  ) {
    const velocity = forward.multiplyScalar(power);
    velocity.x += sideForce;

    const ballRadius = 0.01; // ⚽ 球半径
    const groundY = 0; // 🟩 地面高度

    for (let i = 0; i < this.maxPoints; i++) {
      const t = i * this.timeStep;

      const pos = new Vec3(
        startPos.x + velocity.x * t,
        startPos.y + velocity.y * t + 0.5 * this.gravity.y * t * t,
        startPos.z + velocity.z * t
      );

      // ⭐ 限制最低不低于地面
      if (pos.y < groundY + ballRadius * 0.5) {
        pos.y = groundY + ballRadius * 0.5;
      }

      this.points[i].setWorldPosition(pos);
      this.points[i].active = true;
    }
  }

  hideTrajectory() {
    this.points.forEach((p) => (p.active = false));
  }
}