import * as THREE from "three";
import { BasePart } from "./BasePart.js";

export class LerpedBasePart extends BasePart { // Extends BasePart to add smooth interpolation for networked parts
  constructor() {
    super();
    this.ClassName = "LerpedBasePart"; // 👈 Roblox-style ClassName
    this._lastReplicatedState = null;
    this._nextReplicatedState = null;
  }

  // Called when replication data arrives from the server
  OnReplicated() {
    // Keep old state to interpolate from
    this._lastReplicatedState = this._nextReplicatedState;

    // Store new replication state
    this._nextReplicatedState = {
      pos: this.Position.clone(),
      quat: new THREE.Quaternion().setFromEuler(this.Orientation),
      time: performance.now(),
    };

    // Apply anchored state from server
    this._applyAnchoredState?.();
    this.updateSizes(); // In case Size changed
  }

  // Smooth visual updates
  updateVisual(dt) {
    // Don’t lerp anchored parts — they don’t move
    if (this.Anchored) {
      this.mesh.position.copy(this.Position);
      this.mesh.quaternion.setFromEuler(this.Orientation);
      return;
    }

    if (this._nextReplicatedState && this._lastReplicatedState) {
      // Interpolate between last and next states
      const now = performance.now();
      const t = Math.min(
        (now - this._lastReplicatedState.time) / 100, // ~10Hz replication → 100ms
        1
      );

      this.mesh.position.lerpVectors(
        this._lastReplicatedState.pos,
        this._nextReplicatedState.pos,
        t
      );
      this.mesh.quaternion.slerpQuaternions(
        this._lastReplicatedState.quat,
        this._nextReplicatedState.quat,
        t
      );
    } else {
      // Fallback to default behavior
      this.mesh.position.copy(this.body.position);
      this.mesh.quaternion.copy(this.body.quaternion);
      console.warn("LerpedBasePart: No replication data yet, using physics state.");
    }
  }
}