orbit/js/combat/EnemyShip.js

import Phaser from '../vendor/phaser.js';
import { config } from '../config/Config.js';
import { toColor } from '../utils/Color.js';
import { applyDamage, headingOf, orbitStep } from './Combat.js';

const FALLBACK_W = 76; // the procedural wedge (it faces east)
const FALLBACK_H = 46;

/**
 * A sandbox hostile (data/combat.json → enemy): an arcade-physics sprite
 * that keeps a standoff ring around the player, circles it (direction
 * alternates per craft), and lances when in range and roughly aimed.
 * The AI is deliberately dumb — the sandbox (js/combat/CombatScene.js)
 * is where it gets tuned before combat ships in the real game.
 *
 * Art: assets/images/ships-enemy.png — frameWidth×frameHeight frames,
 * `frame` picks which one (frame 0 = the red triple-boost fighter, art
 * facing north, filling its frame). The art's facing works exactly like
 * the player's (js/entities/Ship.js): a constant render offset
 * (this.artOffset) so heading math stays world-up = -π/2. If the sheet
 * isn't configured or didn't load, the built-in wedge is drawn instead
 * (it faces east, offset 0).
 *
 * Armor: { shields, hull } per js/combat/Combat.js (shields absorb
 * first). damage() applies a hit; the scene owns the FX + respawn.
 */
export class EnemyShip extends Phaser.Physics.Arcade.Sprite {
  static TEXTURE_KEY = '__enemy_ship';

  /** World angle (rad) for each direction the sheet art may face. */
  static FACING_ANGLE = {
    north: -Math.PI / 2,
    east: 0,
    south: Math.PI / 2,
    west: Math.PI,
  };

  /**
   * Ensure a texture exists under TEXTURE_KEY. The spritesheet (loaded
   * by CombatScene.preload / GameScene.preload) wins; otherwise the
   * built-in wedge — a blunt V-fin raider, clearly NOT the player dart.
   */
  static ensureTexture(scene) {
    if (scene.textures.exists(EnemyShip.TEXTURE_KEY)) return;

    const w = FALLBACK_W;
    const h = FALLBACK_H;
    const hull = toColor('#c8465c', 0xc8465c);
    const trim = toColor('#f0b7c2', 0xf0b7c2);
    const g = scene.make.graphics({ add: false });
    g.fillStyle(hull, 1);
    g.beginPath();
    g.moveTo(w - 4, h / 2); // nose (east)
    g.lineTo(10, 2);       // upper fin
    g.lineTo(22, h / 2);   // tail notch
    g.lineTo(10, h - 2);   // lower fin
    g.closePath();
    g.fillPath();
    g.fillStyle(trim, 1);
    g.fillCircle(Math.round(w - 20), h / 2, 4); // cockpit
    g.generateTexture(EnemyShip.TEXTURE_KEY, w, h);
    g.destroy();
  }

  /**
   * @param {object} scene the combat scene
   * @param {number} x spawn
   * @param {number} y spawn
   * @param {number} index the craft's slot in the pack (orbit direction alternates)
   */
  constructor(scene, x, y, index) {
    const hasSheet = scene.textures.exists(EnemyShip.TEXTURE_KEY);
    EnemyShip.ensureTexture(scene);
    super(scene, x, y, EnemyShip.TEXTURE_KEY, config.get('combat.enemy.frame', 0));

    scene.add.existing(this);
    scene.physics.add.existing(this);

    this.index = index ?? 0;
    this.orbitDir = this.index % 2 === 0 ? 1 : -1;
    this.orbitAngle = Math.random() * Math.PI * 2; // the scene re-anchors it on spawn

    // World size + render scale (the same contract as Ship: size × the
    // art's footprint = the hull's world length).
    this.size = Math.max(4, config.get('combat.enemy.size', 54));
    const frameWidth = hasSheet
      ? Math.max(1, config.get('combat.enemy.frameWidth', 128))
      : FALLBACK_W;
    this.setScale(this.size / frameWidth);
    const facing = EnemyShip.FACING_ANGLE[config.get('combat.enemy.artFacing', 'east')] ?? 0;
    this.artOffset = hasSheet ? -facing : 0;

    // A circle body (world px — data/combat.json → enemy.hitRadius):
    // the scene's collision pass uses it for rams + bullets.
    this.hitRadius = Math.max(4, config.get('combat.enemy.hitRadius', 20));
    const body = this.body;
    body.setCircle(this.hitRadius / this.scale); // texture-space radius (auto-scales)
    body.setAllowGravity(false);

    // Armor (js/combat/Combat.js rule: shields first, then hull).
    this.maxHull = Math.max(1, config.get('combat.enemy.hull', 60));
    this.maxShields = Math.max(0, config.get('combat.enemy.shields', 0));
    this.hull = this.maxHull;
    this.shields = this.maxShields;
    this.dead = false;

    // Chase feel (data/combat.json → enemy).
    this.speed = Math.max(0, config.get('combat.enemy.speed', 165));
    this.turn = Math.max(0.1, config.get('combat.enemy.turn', 3.2));
    this.orbitRadius = Math.max(40, config.get('combat.enemy.orbitRadius', 300));
    this.orbitSpeed = config.get('combat.enemy.orbitSpeed', 0.6);

    // Lance (data/combat.json → enemy.weapon).
    this.wpn = config.section('combat.enemy.weapon', {});
    this.nextFireAt = 0; // ms — the scene grants a short grace on spawn

    // The last player position (orbiting it while the player is down).
    this.lastPx = x;
    this.lastPy = y;
  }

  /** @returns {number} the render heading in world radians */
  heading() {
    return headingOf(this);
  }

  /** Rotate the render toward `angle` at the configured turn rate. */
  rotateToward(angle, dt) {
    let delta = Phaser.Math.Angle.Wrap(angle - this.rotation);
    const step = this.turn * dt;
    if (Math.abs(delta) <= step) this.rotation = angle;
    else this.rotation += Math.sign(delta) * step;
  }

  /**
   * Per-frame AI. Steers the standoff ring around the player, faces it
   * when close enough to aim, and asks to fire when lined up.
   *
   * @param {number} time game time (ms)
   * @param {number} delta frame delta (ms)
   * @param {object|null} player the player ship, or null when the player is down
   * @returns {boolean} true when this craft wants to fire THIS frame
   */
  update(time, delta, player) {
    if (this.dead) return false;
    const dt = Math.min(delta, 64) / 1000;

    const px = player ? player.x : this.lastPx;
    const py = player ? player.y : this.lastPy;
    if (player) {
      this.lastPx = px;
      this.lastPy = py;
    }

    // The standoff ring: circle the player at orbitRadius.
    const t = orbitStep(px, py, this.orbitAngle, this.orbitDir, this.orbitSpeed, dt, this.orbitRadius);
    this.orbitAngle = t.angle;

    const dx = t.x - this.x;
    const dy = t.y - this.y;
    const d = Math.hypot(dx, dy) || 1;
    const dist = Math.hypot(px - this.x, py - this.y);

    // Chase speed: full when far off the ring, half when crowding in.
    const sp = d > this.orbitRadius * 0.9 ? this.speed : this.speed * 0.55;

    // Exponential velocity approach (smooth turns, no overshoot).
    const k = 1 - Math.exp(-this.turn * dt);
    const body = this.body;
    if (body) {
      body.velocity.x += ((dx / d) * sp - body.velocity.x) * k;
      body.velocity.y += ((dy / d) * sp - body.velocity.y) * k;
    }

    // Face the player when close (aiming), else face the motion.
    const toPlayer = Math.atan2(py - this.y, px - this.x);
    const want = dist < this.orbitRadius * 1.5
      ? toPlayer
      : (body && body.velocity.length() > 4 ? Math.atan2(body.velocity.y, body.velocity.x) : toPlayer);
    this.rotateToward(want + this.artOffset, dt);

    // Lance? In range, roughly aimed, off cooldown — and only at a live player.
    const wpn = this.wpn ?? {};
    const range = Number(wpn.range) || 0;
    if (player && range > 0 && dist < range && time >= this.nextFireAt) {
      const lead = Math.abs(Phaser.Math.Angle.Wrap(toPlayer - this.heading()));
      if (lead < 0.6) {
        this.nextFireAt = time + (Number(wpn.cooldown) || 1.4) * 1000 * (0.85 + Math.random() * 0.4);
        return true;
      }
    }
    return false;
  }

  /**
   * Take a hit: shields first, then hull (js/combat/Combat.js).
   * @param {number} n damage
   * @returns {boolean} true when this shot killed the craft
   */
  damage(n) {
    if (this.dead) return false;
    const { dead } = applyDamage(this, n);
    if (dead) this.dead = true;
    return dead;
  }

  /** Bring the craft back to full (the scene re-positions + re-arms it). */
  revive() {
    this.hull = this.maxHull;
    this.shields = this.maxShields;
    this.dead = false;
    if (this.body) {
      this.body.velocity.x = 0;
      this.body.velocity.y = 0;
    }
  }
}