/**
 * rigging.js — prep-phase rig selection and hardware economy.  [Lane B]
 *
 * The money half of the sail. Ports the prototype's economy verbatim ($80
 * budget, $5/$15/$30 hardware, $15 spare) and adds the state machine around it:
 * which anchors are rigged, what hangs at each corner, how tight, how many
 * spares in the bag.
 *
 * Kept three-free and DOM-free like sail.js so it is testable headless. The
 * picking/DOM layer is deliberately NOT here yet — it needs Lane A's camera and
 * anchor markers, which do not exist at time of writing; see createRiggingUI at
 * the bottom for the seam it will plug into.
 */

import { HARDWARE, START_BUDGET, SPARE_COST } from './contracts.js';
import { orderRing, TENSION_MIN, TENSION_MAX } from './sail.js';

export { START_BUDGET, SPARE_COST };
export const MAX_CORNERS = 4;
export const DEFAULT_TENSION = 1.0;

const clamp = (v, lo, hi) => (v < lo ? lo : v > hi ? hi : v);

const OK = { ok: true };
const fail = (reason) => ({ ok: false, reason });

export class RiggingSession {
  /**
   * @param {object} opts
   * @param {Array}  opts.anchors  world.anchors — [{id, pos, type, sway?}]
   * @param {number} opts.budget   starting cash
   */
  constructor({ anchors = [], budget = START_BUDGET } = {}) {
    this.anchors = anchors;
    this.budget = budget;
    this.tension = DEFAULT_TENSION;
    this.spares = 0;
    /** @type {{anchorId: string, hw: object}[]} — ring-ordered once 4 are rigged */
    this.picks = [];
  }

  get spent() { return START_BUDGET - this.budget; }
  get canStart() { return this.picks.length === MAX_CORNERS; }
  isRigged(anchorId) { return this.picks.some((p) => p.anchorId === anchorId); }
  pickOf(anchorId) { return this.picks.find((p) => p.anchorId === anchorId) || null; }

  /** Charge (or refund, when amount is negative) against the budget. */
  _spend(amount) {
    if (this.budget - amount < 0) return false;
    this.budget -= amount;
    return true;
  }

  /** Rig a corner at an anchor, starting on the cheapest hardware (prototype). */
  rig(anchorId) {
    const a = this.anchors.find((x) => x.id === anchorId);
    if (!a) return fail('no such anchor');
    if (this.isRigged(anchorId)) return fail('already rigged');
    if (this.picks.length >= MAX_CORNERS) return fail('a sail has four corners');
    if (!this._spend(HARDWARE[0].cost)) return fail('not enough budget');
    this.picks.push({ anchorId, hw: HARDWARE[0] });
    this._reorder();
    return OK;
  }

  /**
   * Unrig a corner and refund its hardware. Not in the prototype (which had no
   * way back from a misclick) but it is a pure refund, so it costs the economy
   * nothing and saves the player a restart.
   */
  unrig(anchorId) {
    const i = this.picks.findIndex((p) => p.anchorId === anchorId);
    if (i < 0) return fail('not rigged');
    this.budget += this.picks[i].hw.cost;
    this.picks.splice(i, 1);
    return OK;
  }

  /** Cycle a corner's hardware to the next tier, paying (or refunding) the difference. */
  cycleHardware(anchorId) {
    const p = this.pickOf(anchorId);
    if (!p) return fail('not rigged');
    const next = HARDWARE[(HARDWARE.indexOf(p.hw) + 1) % HARDWARE.length];
    if (!this._spend(next.cost - p.hw.cost)) return fail('not enough budget');
    p.hw = next;
    return OK;
  }

  setHardware(anchorId, hw) {
    const p = this.pickOf(anchorId);
    if (!p) return fail('not rigged');
    if (!HARDWARE.includes(hw)) return fail('unknown hardware');
    if (!this._spend(hw.cost - p.hw.cost)) return fail('not enough budget');
    p.hw = hw;
    return OK;
  }

  /** 0.6 loose (soaks gusts, flogs) .. 1.4 drum tight (no flap, shock-loads). */
  setTension(v) {
    this.tension = clamp(v, TENSION_MIN, TENSION_MAX);
    return this.tension;
  }

  /** Spares are what Lane D's hold-E re-rig consumes mid-storm. */
  setSpares(n) {
    n = Math.max(0, Math.floor(n));
    const delta = (n - this.spares) * SPARE_COST;
    if (!this._spend(delta)) return fail('not enough budget');
    this.spares = n;
    return OK;
  }

  /**
   * Ring-order the picks by angle around their ground-plane centroid, so corner
   * i of the cloth grid always maps to a neighbouring anchor. Without it,
   * picking anchors in a silly order knots the sail through itself.
   */
  _reorder() {
    if (this.picks.length < MAX_CORNERS) return;
    const byId = new Map(this.picks.map((p) => [p.anchorId, p]));
    const ring = orderRing(this.picks.map((p) => this.anchors.find((a) => a.id === p.anchorId)));
    this.picks = ring.map((a) => byId.get(a.id));
  }

  /** Hand the finished rig to the sim. Mirrors contracts.js sailRig.attach(). */
  commit(rig) {
    if (!this.canStart) throw new Error(`sail needs ${MAX_CORNERS} corners, have ${this.picks.length}`);
    return rig.attach(this.picks.map((p) => p.anchorId), this.picks.map((p) => p.hw), this.tension);
  }

  /** Everything the HUD needs to draw the prep panel, in one read. */
  get summary() {
    return {
      budget: this.budget,
      spent: this.spent,
      tension: this.tension,
      spares: this.spares,
      canStart: this.canStart,
      corners: this.picks.map((p) => ({ anchorId: p.anchorId, hw: p.hw.name, rating: p.hw.rating, cost: p.hw.cost })),
      weakest: this.picks.length
        ? this.picks.reduce((w, p) => (p.hw.rating < w.hw.rating ? p : w)).anchorId
        : null,
    };
  }
}

/**
 * Prep-phase picking UI.
 *
 * Deliberately unimplemented: it needs Lane A's camera, renderer canvas and
 * anchor markers to raycast against, none of which exist yet. RiggingSession
 * above holds all the rules and is fully tested, so this stays a thin
 * click-to-session adapter once M0 lands. See THREADS.md.
 */
export async function createRiggingUI() {
  throw new Error('rigging UI lands once Lane A has a camera and anchor markers — see THREADS.md');
}