import Phaser from '../vendor/phaser.js';
import { config } from '../config/Config.js';
import { toColor } from '../utils/Color.js';

/**
 * The player's ship: an arcade-physics sprite that flies to wherever you click.
 *
 * Art: the spritesheet in data/ship.json → `texture` (frameWidth×frameHeight
 * frames; `frame` picks which one — frame 0 is the starter ship). The art in
 * a frame faces `artFacing` ("north" | "east" | "south" | "west") and the
 * ship rotates about the frame center, so heading math is unchanged — only
 * a constant render offset (this.artOffset) is applied. If the sheet isn't
 * configured or didn't load, the built-in procedural dart is drawn instead
 * (it faces east, offset 0).
 *
 * All feel/balance numbers come from data/ship.json:
 *  - size (world px hull length) & scale (multiplier)
 *  - thrust, maxSpeed, drag      → how it accelerates and coasts
 *  - rotSpeed                    → how fast it turns toward its heading (rad/s)
 *  - brakeDistance               → where it starts easing off the throttle
 *  - arriveRadius / arriveSpeed  → when it considers itself "arrived"
 *
 * Base stats (data/ship.json → stats, exposed as this.stats) are the
 * ship's starting condition before any upgrades:
 *  - hullIntegrity  → the hull's max health (damage it can take)
 *  - shields        → damage absorbed in front of the hull
 *  - cargoHold      → goods capacity
 *  - mineralStorage → minerals capacity
 *  - miningSpeed    → multiplier on mining rate (1 = baseline)
 *
 * The hold (this.minerals / storageRoom / addMinerals): the minerals
 * hauled aboard — the mining beam loads it, capped at stats.mineralStorage.
 */
export class Ship extends Phaser.Physics.Arcade.Sprite {
  static TEXTURE_KEY = '__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. If the spritesheet was
   * loaded (GameScene.preload), it's already there and we do nothing.
   * Otherwise draw the built-in procedural dart — facing EAST (heading 0).
   */
  static ensureTexture(scene) {
    if (scene.textures.exists(Ship.TEXTURE_KEY)) return;

    const size = config.get('ship.size', 46);
    const W = size;
    const H = Math.round(size * 0.68);
    const hull = toColor(config.get('ship.color', '#dfe7ff'));
    const cockpit = toColor(config.get('ship.cockpitColor', '#41c7ff'));

    // A simple dart, pointing right (angle 0).
    const g = scene.make.graphics({ add: false });
    g.fillStyle(hull, 1);
    g.beginPath();
    g.moveTo(W - 4, H / 2); // nose
    g.lineTo(4, 3);         // top rear
    g.lineTo(12, H / 2);    // tail notch
    g.lineTo(4, H - 3);     // bottom rear
    g.closePath();
    g.fillPath();
    g.fillStyle(cockpit, 1);
    g.fillCircle(Math.round(W - W * 0.3), H / 2, Math.max(3, Math.round(W * 0.085)));
    g.generateTexture(Ship.TEXTURE_KEY, W, H);
    g.destroy();
  }

  constructor(scene, x, y) {
    // Is the spritesheet present (GameScene.preload queued it when
    // ship.texture is set)? The dart fallback faces EAST; the sheet art
    // faces ship.artFacing — the offset below reconciles the two.
    const hasSheet = scene.textures.exists(Ship.TEXTURE_KEY);
    Ship.ensureTexture(scene);
    super(scene, x, y, Ship.TEXTURE_KEY, config.get('ship.frame', 0));

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

    // Render offset: sprite rotation = heading + artOffset (0 for the dart).
    const facing = Ship.FACING_ANGLE[config.get('ship.artFacing', 'east')] ?? 0;
    this.artOffset = hasSheet ? -facing : 0;

    // Tuning (data/ship.json) -----------------------------------------
    this.thrust = config.get('ship.thrust', 900);             // px/s^2
    this.maxSpeed = config.get('ship.maxSpeed', 480);          // px/s
    this.drag = config.get('ship.drag', 2.4);                  // 1/s, exponential decay
    this.rotSpeed = config.get('ship.rotSpeed', 10);           // rad/s
    this.brakeDistance = config.get('ship.brakeDistance', 260); // px
    this.arriveRadius = config.get('ship.arriveRadius', 8);    // px
    this.arriveSpeed = config.get('ship.arriveSpeed', 50);     // px/s

    // Base stats (data/ship.json → stats) — the ship's starting
    // condition, before any upgrades. Combat, trading, and mining
    // systems will read these as capacities.
    this.stats = {
      hullIntegrity: config.get('ship.stats.hullIntegrity', 100),
      shields: config.get('ship.stats.shields', 0),
      cargoHold: config.get('ship.stats.cargoHold', 100),
      mineralStorage: config.get('ship.stats.mineralStorage', 250),
      miningSpeed: config.get('ship.stats.miningSpeed', 1),
    };

    // The hold: minerals aboard right now (0 … stats.mineralStorage).
    // The mining sequence (js/mining/Mining.js) loads it as the beam
    // strips the rock; the cap is the base stat above.
    this.minerals = 0;

    // World size = size × scale. Sheet frames are frameWidth px wide; the
    // dart is drawn at `size` px — the sprite scale maps either one onto
    // the same world size, so both look identical.
    const worldSize = config.get('ship.size', 46) * config.get('ship.scale', 1);
    const frameWidth = hasSheet
      ? Math.max(1, config.get('ship.frameWidth', 256))
      : Math.max(1, config.get('ship.size', 46));
    this.setScale(worldSize / frameWidth);

    // Collision radius (half the hull's width, at scale) — planets keep
    // the ship this far off their rims (see Planet.constrainShip).
    this.radius = worldSize / 2;

    this.target = null;

    // SHIP STATE — what the ship is doing right now. 'normal' is the
    // default: free to fly wherever the player sends it. 'mining' = the
    // arm's sequence owns the ship (js/mining/Mining.js drives it; the
    // beam + ore stream only live while the state holds). More states
    // will land here (docking, boarding, …). Any change OUT of a state —
    // another state, or the player MOVING the ship (setTarget, autopilot)
    // — is signalled via onStateChange, and the scene's handler tears
    // down whatever that state was doing (ends the mining sequence).
    this.state = 'normal'; // 'normal' | 'mining' (later: more)
    this.onStateChange = null; // (next, prev, reason) => void — the scene installs
  }

  /**
   * Change the ship's state ('normal' | 'mining' | …). A no-op when the
   * state is unchanged. On a real change, onStateChange fires — the scene
   * ends the mining sequence when the ship leaves 'mining', whichever
   * state (or movement) took it out.
   *
   * @returns {boolean} true when the state actually changed
   */
  setState(next, reason) {
    if (next === this.state) return false;
    const prev = this.state;
    this.state = next;
    if (typeof this.onStateChange === 'function') {
      try {
        this.onStateChange(next, prev, reason);
      } catch (err) {
        console.error('[ship] onStateChange handler failed', err);
      }
    }
    return true;
  }

  /** Room left in the hold (0 when full). */
  storageRoom() {
    return Math.max(0, this.stats.mineralStorage - this.minerals);
  }

  /**
   * Load up to `n` minerals into the hold (capped at
   * stats.mineralStorage). Returns the amount actually added — callers
   * see the excess as wasted when the hold was full.
   */
  addMinerals(n) {
    const take = Math.min(Math.max(0, Math.floor(n)), this.storageRoom());
    if (take > 0) this.minerals += take;
    return take;
  }

  /**
   * Set the hold directly (the SAVE/LOAD path — js/save/SaveData.js →
   * captureState writes it, GameScene.applyRestore restores it). Clamped
   * to [0, stats.mineralStorage] — a record can never overfill the hold.
   */
  setMinerals(n) {
    this.minerals = Math.max(0, Math.min(this.stats.mineralStorage, Math.round(Number(n) || 0)));
  }

  /** Set the destination to fly to (world coordinates). */
  setTarget(x, y) {
    this.target = { x, y };
    // Moving the ship ends whatever non-normal state it was in (mining,
    // and later states): the player's movement always wins, so any state
    // hands the ship back to 'normal' — the scene's onStateChange handler
    // finishes the teardown (retracts the beam, releases the arm).
    this.setState('normal', 'move');
  }

  /** Stop steering and brake immediately. */
  stop() {
    this.target = null;
    this.body.acceleration.set(0, 0);
    this.body.velocity.set(0, 0);
  }

  update(_time, delta) {
    const body = this.body;
    if (!body) return;
    const dt = Math.min(delta, 64) / 1000;

    if (this.target) {
      const dx = this.target.x - this.x;
      const dy = this.target.y - this.y;
      const dist = Math.hypot(dx, dy);
      const speed = body.velocity.length();

      // Arrived: close enough and slow enough → stop cleanly.
      if (dist <= this.arriveRadius && speed <= this.arriveSpeed) {
        this.target = null;
        // Clear acceleration too, so the physics step can't re-kick us.
        body.acceleration.set(0, 0);
        // Come to rest facing the direction we were traveling.
        if (speed > 1) {
          this.rotation = Phaser.Math.Angle.Wrap(
            Math.atan2(body.velocity.y, body.velocity.x) + this.artOffset,
          );
        }
        body.velocity.set(0, 0);
        return;
      }

      const nx = dx / dist;
      const ny = dy / dist;

      // Braking: with the throttle cut, drag carries the ship a further
      // speed / drag before it stops. While that still lands short of the
      // target, keep easing the throttle with distance; once we are too
      // fast to stop in time, cut the throttle and let drag bleed the
      // speed off, so we reach the target with little or no speed to spare.
      const canStopInTime = speed <= this.drag * dist;
      const throttle = canStopInTime
        ? Phaser.Math.Clamp(dist / this.brakeDistance, 0, 1)
        : 0;
      body.acceleration.set(nx * this.thrust * throttle, ny * this.thrust * throttle);

      // Gentle drag so we never coast forever.
      body.velocity.scale(Math.max(0, 1 - this.drag * dt));

      // Hard speed cap.
      const v = body.velocity.length();
      if (v > this.maxSpeed) {
        body.velocity.scale(this.maxSpeed / v);
      }

      // Heading: while the ship has speed it follows its actual direction
      // of motion (so it never flies "backwards" as it brakes); when it
      // (nearly) stands still it points at the target. Sprite rotation =
      // heading + artOffset (the sheet art may not face east).
      const wanted =
        (speed > 10
          ? Phaser.Math.Angle.Wrap(Math.atan2(body.velocity.y, body.velocity.x))
          : Phaser.Math.Angle.Wrap(Math.atan2(ny, nx))) + this.artOffset;
      const current = this.rotation;
      const step = Math.min(Math.abs(wanted - current), this.rotSpeed * dt);
      this.rotation = Phaser.Math.Angle.RotateTo(current, wanted, step);
    } else {
      body.acceleration.set(0, 0);
      // Inertial drift, decaying smoothly.
      if (body.velocity.length() > 0.5) {
        body.velocity.scale(Math.max(0, 1 - this.drag * dt));
      }
    }
  }
}