// server/sim/units.js — Unit model (operators, tokens, enemies, devices) and stat aggregation (DESIGN §5.2).
//
// Aggregation (recomputed lazily whenever buffs change — `unit.markDirty()`):
//   ATK/DEF/maxHp = (base + Σflat) × (1 + Σpct) × Πmul
//   res           = clamp((base + Σflat) × Πmul, 0, 100)
//   aspd          = clamp(base + Σaspd, 20, 600)          (base is 100 for almost everyone; floor 20 = PRTS 数值范围)
//   interval      = bat × (1 + ΣbatPct) × 100 / aspd      (ΣbatPct floored at −0.9)
//   moveSpeed     = (base + ΣmoveFlat) × ΠmoveMul          (tiles/s = moveSpeed × MOVE_SCALE)
//   massLevel     = max(0, base + ΣmassFlat)                (重量: displacement, 浮空 halving; 失重 = massFlat −1)
// Changing maxHp keeps the HP ratio. The sim keeps floats; rounding happens only in snapshots.

import { aggregateMods } from './buffs.js';
import { flagsOf } from './snapshot.js';
import { ASPD_MIN, ASPD_MAX, ELEMENT_GAUGE_MAX, ELEMENT_GAUGE_MAX_LEADER } from './constants.js';
import { DIR_VEC, normDir } from './dir.js';

const clamp = (v, a, b) => (v < a ? a : v > b ? b : v);
const EMPTY = Object.freeze({});
/** Aggregates can overflow (huge stacked *Mul mods → Infinity) — fall back to `d` so no stat is ever non-finite. */
const fin = (v, d) => (Number.isFinite(v) ? v : d);

export class Unit {
  /**
   * @param {object} init
   */
  constructor(init) {
    // Heavy references are non-enumerable so assertion diffs / logs never walk the whole battle graph.
    for (const k of ['def', 'player', 'ownerUnit', 'kit', 'profile', 'skill', 'route', 'bossPool', 'blockedBy', 'blocking', 'carry', 'mem', 'trait']) {
      Object.defineProperty(this, k, { value: null, writable: true, enumerable: false, configurable: true });
    }
    this.id = init.id;
    this.side = init.side;            // 'ally' | 'enemy'
    this.kind = init.kind;            // 'op' | 'token' | 'enemy' | 'device'
    this.def = init.def;              // normalised def (chess / token / enemy / device)
    this.defId = init.defId ?? init.def?.id ?? 'unknown';
    this.name = init.name ?? init.def?.name ?? this.defId;
    this.ownerId = init.ownerId ?? null;  // playerId (enemies: field owner)
    this.uid = init.uid ?? null;          // match piece uid (ops/tokens from the board)
    this.ownerUnit = init.ownerUnit ?? null; // summoner (tokens)
    this.x = init.x ?? 0;
    this.y = init.y ?? 0;
    this.tileR = init.tileR ?? Math.round(this.y);
    this.tileC = init.tileC ?? Math.round(this.x);
    this.homeR = this.tileR;
    this.homeC = this.tileC;
    // knocked-out operators (Battle.isDown): [r, c] of the tile the body lies on and the unit comes back on — where it
    // fell, or its home (Battle._layBody); x / y / tileR / tileC keep where it fell
    this.body = null;
    // deploy direction (sim/dir.js; allies: from the board piece, default RIGHT); `facing` is its derived horizontal
    // sign (sprite flip only) — a legacy `init.facing` ±1 still maps to RIGHT / LEFT
    this.dir = normDir(init.dir ?? init.facing);
    this.base = {
      maxHp: 1, atk: 0, def: 0, res: 0, aspd: 100, bat: 1, blockCnt: 0, moveSpeed: 0, spRecovery: 1,
      tauntLevel: 0, massLevel: 0, hpRecoveryPerSec: 0, cost: 0, respawnTime: 0, rangeRadius: 0,
      ...(init.base || {}),
    };
    /** @type {object[]} */
    this.buffs = [];
    this._dirty = true;
    this._s = null;
    this.hp = this.base.maxHp;
    this.alive = true;
    this.deployed = false;
    this.removed = false;       // permanently gone (enemies, tokens, retreated-for-good)
    this.blocking = [];         // ops: enemies currently blocked
    this.blockedBy = null;      // enemies: blocker unit
    this.motion = init.motion ?? 'GROUND'; // enemies: 'WALK' | 'FLY'
    this.profile = null;        // resolved profession/attack profile
    this.skill = null;          // SkillRuntime
    this.kit = null;
    this.atkCd = 0;
    this.lastAttackAt = -Infinity;
    this.lastHitAt = -Infinity;
    this.deployedAt = -Infinity;
    this.deathAt = -Infinity;
    this.respawnAt = Infinity;
    this.deploySeq = 0;         // deployment counter; also the identity of one deployment (content: `seq === u.deploySeq`)
    this.aggroSeq = 0;          // 仇恨 order (the later the more attacked): = deploySeq, except summons of the initial deployment
    this.spawnSeq = 0;
    this.elem = { burn: 0, neural: 0, necrosis: 0, apoptosis: 0, erosion: 0 };
    this.burstPending = null;   // { [element]: true } while that element's burst resolves (damage.js burstLocked)
    this.tags = new Set(init.tags || []);
    this.mem = {};              // free scratch space for content (per unit)
    this.trait = {};            // profession runtime state
    this.stats = { dmg: 0, kills: 0, heal: 0, taken: 0, attacks: 0 };
    this.hidden = false;        // enemies inside a DISAPPEAR segment
    this.moving = false;        // enemies: walked this tick (drawn on the move clip; ai.js updateEnemy)
    this.form = null;           // the model's current form (content/enemies/helpers.js setForm, a 傀儡师's 替身 'doll' → snapshot.js unitInfo)
    this.anim = 0;
    this.persist = { redeployMul: 1, freeRedeploys: 0 };
    this.isBoss = false;
    this.bossPool = null;
  }

  markDirty() { this._dirty = true; }

  /** Horizontal sign of the direction (LEFT ⇒ −1, else +1): sprite flip only — geometry uses `dir` / `fwd`. */
  get facing() { return this.dir === 'LEFT' ? -1 : 1; }
  /** Legacy setter: ±1 ⇒ RIGHT / LEFT (prefer assigning `dir`). */
  set facing(v) { this.dir = normDir(v, this.dir); }
  /** Forward vector [dRow, dCol] (UP = +row). */
  get fwd() { return DIR_VEC[this.dir] ?? DIR_VEC.RIGHT; }

  /** Aggregated stats (lazy). */
  get s() {
    if (this._dirty) this._recalc();
    return this._s;
  }

  get maxHp() { return this.s.maxHp; }
  get atk() { return this.s.atk; }

  _recalc() {
    const prevMax = this._s ? this._s.maxHp : this.base.maxHp;
    const { add, mul, flags, shield, permRangeExtend } = aggregateMods(this.buffs);
    const a = (k) => add[k] ?? 0;
    const m = (k) => mul[k] ?? 1;
    const b = this.base;
    const bHp = fin(b.maxHp, 1) > 0 ? fin(b.maxHp, 1) : 1;
    const maxHp = Math.max(1, fin((bHp + a('hpFlat')) * Math.max(0, 1 + a('hpPct')) * m('hpMul'), bHp));
    const atk = Math.max(0, fin((b.atk + a('atkFlat')) * Math.max(0, 1 + a('atkPct')) * m('atkMul'), fin(b.atk, 0)));
    const def = Math.max(0, fin((b.def + a('defFlat')) * Math.max(0, 1 + a('defPct')) * m('defMul'), fin(b.def, 0)));
    const res = clamp(fin((b.res + a('resFlat')) * m('resMul'), fin(b.res, 0)), 0, 100);
    const aspd = clamp(fin(b.aspd + a('aspd'), 100), ASPD_MIN, ASPD_MAX);
    const bBat = fin(b.bat, 1) > 0 ? fin(b.bat, 1) : 1;
    const bat = fin(bBat * Math.max(0.1, 1 + a('batPct')), bBat);
    const s = {
      maxHp, atk, def, res, aspd, bat,
      interval: (bat * 100) / aspd,
      blockCnt: Math.max(0, fin(Math.round(b.blockCnt + a('blockCnt')), 0)),
      moveSpeed: Math.max(0, fin((b.moveSpeed + a('moveFlat')) * m('moveMul'), fin(b.moveSpeed, 0))),
      rangeExtend: Math.max(0, Math.round(a('rangeExtend'))),
      // 阻挡半径倍率 − 1 (PRTS 数值范围 BLOCK_RADIUS_SCALE "影响阻挡模式为飞行阻挡的单位的阻挡半径"): Battle._checkBlock
      blockRadiusScale: Math.max(0, fin(a('blockRadiusScale'), 0)),
      baseRangeExtend: Math.max(0, fin(Math.round(permRangeExtend), 0)),   // permanent part (initial range)
      massLevel: Math.max(0, fin(fin(b.massLevel, 0) + a('massFlat'), 0)),
      maxTargets: a('maxTargets'),
      // DESIGN §5.3 lists `taunt` as a buff flag (+aggro) as well as a numeric mod: the flag counts as +1 level
      taunt: (Number.isFinite(b.tauntLevel) ? b.tauntLevel : 0) + a('taunt') + (flags.taunt === true ? 1 : 0),
      dodgePhys: clamp(a('dodgePhys'), 0, 1),
      dodgeArts: clamp(a('dodgeArts'), 0, 1),
      defIgnoreFlat: a('defIgnoreFlat'),
      defIgnorePct: clamp(a('defIgnorePct'), 0, 1),
      resIgnoreFlat: a('resIgnoreFlat'),
      resIgnorePct: clamp(a('resIgnorePct'), 0, 1),
      dmgDealtMul: m('dmgDealtMul'),
      physDealtMul: m('physDealtMul'),
      artsDealtMul: m('artsDealtMul'),
      dmgTakenMul: m('dmgTakenMul'),
      physTakenMul: m('physTakenMul'),
      artsTakenMul: m('artsTakenMul'),
      trueTakenMul: m('trueTakenMul'),
      elemTakenMul: m('elemTakenMul'),           // 元素损伤倍率: element gauge fills (damage.js applyElement)
      elementalTakenMul: m('elementalTakenMul'), // 元素脆弱: 元素伤害 (the 'elemental' HP damage type)
      healingDealtMul: m('healingDealtMul'),
      healingTakenMul: m('healingTakenMul'),
      atkScaleMul: m('atkScaleMul'),
      spRecovery: Math.max(0, fin((b.spRecovery + a('spRecoveryFlat')) * m('spRecoveryMul'), 0)),
      spCostFlat: a('spCostFlat'),
      redeployMul: m('redeployMul'),
      hpRegen: fin(b.hpRecoveryPerSec + a('hpRegen') + a('hpRegenRatio') * maxHp, 0),
      shield,
      flags: flags || EMPTY,
    };
    s.flags.stun = !!(flags.stun || flags.freeze || flags.sleep || flags.levitate);
    this._s = s;
    this._dirty = false;
    if (this.alive && prevMax > 0 && Math.abs(prevMax - maxHp) > 1e-9) {
      this.hp = clamp(fin(this.hp * (maxHp / prevMax), maxHp), 0, maxHp);
    }
  }

  /** Current flags object (stun/freeze/sleep/…) */
  get flags() { return this.s.flags; }

  /** Can act at all this tick (not stunned/frozen/sleeping/levitated). */
  get canAct() { return this.alive && this.deployed && !this.hidden && !this.s.flags.stun; }

  hasFlag(k) { return !!this.s.flags[k]; }

  /**
   * Air unit (空中单位) for every targeting / ground-only rule: FLY movers, and enemies that hover (近地悬浮, buff flag
   * `float` — PRTS 术语释义 ba.float "算作空中单位"; they keep walking the ground path) or are levitated (浮空, gamedata_const
   * ba.levitate "变为空中单位"). A 缚地 enemy (status `groundbind`, ba.groundbind "目标变为地面单位") is a ground unit
   * meanwhile — unless a 浮空 lifts it again (浮空 lands on a 缚地 flyer: Battle.applyStatus). Movement and pathing read
   * `motion`, never this.
   */
  get isFlying() {
    if (this.side === 'enemy') {
      const f = this.s.flags;
      if (f.levitate) return true;
      if (f.groundbind) return false;
      return this.motion === 'FLY' || !!f.float;
    }
    return this.motion === 'FLY';
  }

  get hpRatio() { const mh = this.s.maxHp; return mh > 0 ? this.hp / mh : 0; }

  /** Snapshot status bitmask (UF bits: blocked, stunned, frozen, stealth, skill, shield, invuln, cold, sleep, flying). */
  get statusFlags() { return flagsOf(this); }
  /** Damage type of the unit's normal attack ('phys' | 'arts' | 'true' | 'heal' | 'none'). */
  get dmgType() { return (this.profile && this.profile.dmgType) || (this.def && this.def.dmgType) || 'phys'; }
  /** Displacement weight (= current massLevel incl. `massFlat` buffs). Enemies also carry `lpr` (LP cost) as a plain field. */
  get weight() { return this.s.massLevel; }

  get spMax() { return this.skill ? this.skill.spCost : 0; }
  get sp() { return this.skill ? this.skill.sp : 0; }

  isOp() { return this.kind === 'op'; }
  isEnemy() { return this.side === 'enemy'; }
  isAlly() { return this.side === 'ally'; }

  /** Element gauge capacity: 1000, leaders (enemy rank BOSS) 2000 (official "·我方" burst terms). */
  get gaugeMax() {
    return this.side === 'enemy' && (this.isBoss || (this.def && this.def.rank === 'BOSS')) ? ELEMENT_GAUGE_MAX_LEADER : ELEMENT_GAUGE_MAX;
  }

  /** Element gauge helper */
  elemRatio(el) { return (this.elem[el] ?? 0) / this.gaugeMax; }

  findBuff(key) {
    for (const b of this.buffs) if (b.key === key) return b;
    return null;
  }
  hasBuff(key) { return this.findBuff(key) !== null; }

  toString() { return `${this.kind}#${this.id}(${this.name})`; }

  /** Compact inspection (avoids dumping the whole battle graph in assertion messages / logs). */
  [Symbol.for('nodejs.util.inspect.custom')]() {
    return `Unit<${this.kind}#${this.id} ${this.defId} hp=${Math.round(this.hp)}${this.alive ? '' : ' dead'} @${this.x.toFixed(2)},${this.y.toFixed(2)}>`;
  }
}