import { CFG } from './config.js';
import { clamp, random } from './util.js';
import { elementOf } from './elements.js';

let NEXT_ID = 1;

export class Particle {
  constructor(o = {}) {
    this.id = NEXT_ID++;
    this.x = o.x ?? 0;
    this.y = o.y ?? 0;
    this.vx = 0; this.vy = 0;
    this.charge = o.charge ?? 0;
    this.displayCharge = this.charge;

    // element drives colour / valence / radius / mass unless overridden
    this.el = o.el || null;
    const E = this.el ? elementOf(this.el) : null;
    this.col = E ? E.col : CFG.COL_NEU;
    this.noble = !!(E && E.noble);

    this.r = o.r ?? (E ? E.r : CFG.P_RADIUS);
    this.slots = o.slots ?? (E ? E.slots : 1);
    this.bonds = [];
    this.zoneTimer = 0;
    this.grace = 0;            // brief immunity after the player acts
    this.grabbedBy = null;     // 'L' | 'R' | null
    this.fixed = !!o.fixed;
    this.tag = o.tag ?? '';
    this.mass = o.mass ?? (E ? E.mass : 1);
    this.spin = random() * Math.PI * 2;
    this.flash = 0;
    // ideal angle between two bonds on this atom, radians. see elements.js
    this.bend = E && E.bend ? (E.bend * Math.PI) / 180 : 0;
  }

  get freeSlots() { return Math.max(0, this.slots - this.bonds.length); }
  get charged() { return this.charge !== 0; }

  setCharge(c) {
    c = clamp(c, -1, 1);
    if (c === this.charge) return false;
    this.charge = c;
    this.grace = CFG.ZONE_GRACE;
    this.zoneTimer = 0;
    this.flash = 1;
    return true;
  }

  addForce(fx, fy, dt) {
    if (this.fixed) return;
    this.vx += (fx / this.mass) * dt;
    this.vy += (fy / this.mass) * dt;
  }

  addImpulse(ix, iy) {
    if (this.fixed) return;
    this.vx += ix / this.mass;
    this.vy += iy / this.mass;
  }

  isBondedTo(p) { return this.bonds.includes(p); }
}

export function bond(a, b) {
  if (a === b || a.isBondedTo(b)) return false;
  a.bonds.push(b); b.bonds.push(a);
  return true;
}

export function unbond(a, b) {
  const i = a.bonds.indexOf(b); if (i >= 0) a.bonds.splice(i, 1);
  const j = b.bonds.indexOf(a); if (j >= 0) b.bonds.splice(j, 1);
}