// AI 전투 밸런스 시뮬레이터 — 오프라인 몬테카를로.
// ⚠️ 전투 규칙은 tools/deck/gen-slaydeck.mjs 의 Lua(SlayDeckController)와 동기화 유지할 것.
//    (데이터는 data/*.json 공유, 규칙 로직은 JS로 중복 재현)
import { readFileSync } from 'node:fs';

export const PLAYER_HP = 80; // 데이터 미포함 placeholder (codeblock과 일치)
export const ENERGY = 3;
export const HAND_SIZE = 5;
export const MAX_TURNS = 100;

export function mulberry32(seed) {
  let a = seed >>> 0;
  return function () {
    a |= 0; a = (a + 0x6D2B79F5) | 0;
    let t = Math.imul(a ^ (a >>> 15), 1 | a);
    t = (t + Math.imul(t ^ (t >>> 7), 61 | t)) ^ t;
    return ((t ^ (t >>> 14)) >>> 0) / 4294967296;
  };
}

export function shuffle(arr, rng) {
  const a = arr.slice();
  for (let i = a.length - 1; i > 0; i--) {
    const j = Math.floor(rng() * (i + 1));
    [a[i], a[j]] = [a[j], a[i]];
  }
  return a;
}

// 방어 우선 차감 후 hp 적용 → { hp, block }
export function applyDamage(hp, block, amount) {
  let dmg = amount;
  if (block > 0) {
    const absorbed = Math.min(block, dmg);
    block -= absorbed;
    dmg -= absorbed;
  }
  hp -= dmg;
  if (hp < 0) hp = 0;
  return { hp, block };
}

export function loadData() {
  const cardsData = JSON.parse(readFileSync('data/cards.json', 'utf8'));
  const enemiesData = JSON.parse(readFileSync('data/enemies.json', 'utf8'));
  const ids = enemiesData.simEncounter || [enemiesData.activeEnemy];
  const monsters = ids.map((id) => {
    const e = enemiesData.enemies[id];
    if (!e) throw new Error(`simEncounter 적 없음: ${id}`);
    return { name: e.name, maxHp: e.maxHp, intents: e.intents };
  });
  return { cards: cardsData.cards, starterDeck: cardsData.starterDeck, monsters };
}

// 주의: 인게임은 플레이어가 카드를 직접 선택한다. 이 chooseAction은 밸런스 추정용 자동 플레이 휴리스틱일 뿐
// 이며, Lua에 대응 AI가 없다(동기화 대상은 데미지/방어/의도/승패 규칙이지 플레이어 선택이 아님).
// 손패에서 낼 카드 인덱스(-1=종료). 공격 우선, 없으면 스킬.
export function chooseAction(hand, cards, energy) {
  const entries = hand.map((id, i) => ({ id, i })).filter((x) => cards[x.id].cost <= energy);
  const attacks = entries.filter((x) => cards[x.id].kind === 'Attack');
  const skills = entries.filter((x) => cards[x.id].kind === 'Skill');
  const dmgEff = (x) => (cards[x.id].damage || 0) / cards[x.id].cost;
  const blkEff = (x) => (cards[x.id].block || 0) / cards[x.id].cost;
  const bestBy = (list, fn) => list.slice().sort((a, b) => fn(b) - fn(a))[0];
  if (attacks.length) return bestBy(attacks, dmgEff).i;
  if (skills.length) return bestBy(skills, blkEff).i;
  return -1;
}

// 공격 타겟 선택: 이번 타격으로 처치 가능한 최소 유효체력, 없으면 유효체력 최소.
export function chooseTarget(aliveMonsters, plannedDamage) {
  const eff = (m) => m.hp + m.block;
  const killable = aliveMonsters.filter((m) => eff(m) <= plannedDamage);
  const pool = killable.length ? killable : aliveMonsters;
  return pool.slice().sort((a, b) => eff(a) - eff(b) || pool.indexOf(a) - pool.indexOf(b))[0];
}

function bump(s, cost, dmg, blk) {
  s = s || { plays: 0, energy: 0, damage: 0, block: 0 };
  s.plays++; s.energy += cost; s.damage += dmg; s.block += blk;
  return s;
}

// 단일 전투 시뮬. stats(선택): {cardId: {plays,energy,damage,block}} 누적.
// 반환: { win, turns, playerHpRemaining, draw? }
export function simulateCombat(data, rng, stats) {
  const { cards, starterDeck, monsters } = data;
  if (monsters.length === 0) return { win: true, turns: 0, playerHpRemaining: PLAYER_HP };
  let drawPile = shuffle(starterDeck, rng);
  let discard = [];
  let hand = [];
  let pHp = PLAYER_HP, pBlock = 0;
  const mob = monsters.map((m) => ({
    name: m.name, hp: m.maxHp, maxHp: m.maxHp, block: 0,
    intents: m.intents, intentIdx: 0, alive: true,
  }));
  let turns = 0;

  function draw(n) {
    for (let k = 0; k < n; k++) {
      if (drawPile.length === 0) { drawPile = shuffle(discard, rng); discard = []; }
      if (drawPile.length === 0) break;
      hand.push(drawPile.pop());
    }
  }
  const aliveList = () => mob.filter((m) => m.alive);

  while (turns < MAX_TURNS) {
    turns++;
    let energy = ENERGY; pBlock = 0; hand = []; draw(HAND_SIZE);
    while (true) {
      const alive = aliveList();
      if (alive.length === 0) break;
      const idx = chooseAction(hand, cards, energy);
      if (idx < 0) break;
      const id = hand[idx], c = cards[id];
      energy -= c.cost;
      if (c.kind === 'Attack') {
        const target = chooseTarget(alive, c.damage || 0);
        const r = applyDamage(target.hp, target.block, c.damage || 0);
        target.hp = r.hp; target.block = r.block;
        if (target.hp <= 0) target.alive = false;
        if (stats) stats[id] = bump(stats[id], c.cost, c.damage || 0, 0);
      } else {
        pBlock += c.block || 0;
        if (stats) stats[id] = bump(stats[id], c.cost, 0, c.block || 0);
      }
      hand.splice(idx, 1); discard.push(id);
      if (aliveList().length === 0) return { win: true, turns, playerHpRemaining: pHp };
    }
    discard.push(...hand); hand = [];
    for (const m of mob) {
      if (!m.alive) continue;
      m.block = 0; // 매 턴 초기화 (이전 턴 블록 미이월)
      const it = m.intents[m.intentIdx];
      if (it) {
        if (it.kind === 'Attack') { const r = applyDamage(pHp, pBlock, it.value); pHp = r.hp; pBlock = r.block; }
        else if (it.kind === 'Defend') { m.block += it.value; }
      }
      m.intentIdx = (m.intentIdx + 1) % m.intents.length;
      if (pHp <= 0) return { win: false, turns, playerHpRemaining: 0 };
    }
  }
  return { win: false, turns, playerHpRemaining: pHp, draw: true };
}

function mean(a) { return a.length ? a.reduce((s, x) => s + x, 0) / a.length : 0; }
function median(a) {
  if (!a.length) return 0;
  const s = a.slice().sort((x, y) => x - y), m = Math.floor(s.length / 2);
  return s.length % 2 ? s[m] : (s[m - 1] + s[m]) / 2;
}

export function runBatch(N, seed) {
  const data = loadData();
  const rng = mulberry32(seed);
  const cardStats = {};
  let wins = 0, draws = 0;
  const turnsArr = [], hpArr = [];
  for (let i = 0; i < N; i++) {
    const r = simulateCombat(data, rng, cardStats);
    if (r.draw) draws++;
    if (r.win) { wins++; hpArr.push(r.playerHpRemaining); }
    turnsArr.push(r.turns);
  }
  return {
    N, wins, draws, losses: N - wins - draws,
    winRate: wins / N,
    avgTurns: mean(turnsArr), medianTurns: median(turnsArr),
    avgHpOnWin: mean(hpArr),
    cardStats, cards: data.cards, monsters: data.monsters, seed,
  };
}

export function formatReport(r) {
  const L = [];
  L.push(`=== 밸런스 시뮬레이션 (인카운터: ${r.monsters.map((m) => `${m.name}(${m.maxHp})`).join(', ')}) ===`);
  L.push(`시뮬 ${r.N}회 (seed=${r.seed})`);
  L.push(`승률: ${(r.winRate * 100).toFixed(1)}%  (승 ${r.wins} / 패 ${r.losses}${r.draws ? ` / 무 ${r.draws}` : ''})`);
  L.push(`평균 턴: ${r.avgTurns.toFixed(2)}  중앙값 턴: ${r.medianTurns}`);
  L.push(`승리 시 평균 잔여 HP: ${r.avgHpOnWin.toFixed(1)} / ${PLAYER_HP}`);
  if (r.draws) L.push(`⚠️ 무승부 ${r.draws}건 (턴 상한 ${MAX_TURNS} 초과)`);
  L.push('');
  L.push('카드별:');
  const rows = Object.entries(r.cardStats).map(([id, s]) => {
    const kind = r.cards[id].kind;
    const eff = kind === 'Attack' ? s.damage / s.energy : s.block / s.energy;
    return { id, name: r.cards[id].name, kind, plays: s.plays, eff };
  });
  for (const kind of ['Attack', 'Skill']) {
    const kr = rows.filter((x) => x.kind === kind);
    if (!kr.length) continue;
    const med = median(kr.map((x) => x.eff));
    const unit = kind === 'Attack' ? '뎀/E' : '블록/E';
    for (const x of kr) {
      const op = med > 0 && x.eff >= med * 1.5 ? '  ⚠️ OP 의심' : '';
      L.push(`  ${x.name}(${x.id}): 사용 ${x.plays}, 효율 ${x.eff.toFixed(2)} ${unit}${op}`);
    }
  }
  const sorted = rows.slice().sort((a, b) => b.plays - a.plays);
  if (sorted.length) L.push(`최다 사용: ${sorted[0].name} / 최소 사용: ${sorted[sorted.length - 1].name}`);
  return L.join('\n');
}

function main() {
  const args = process.argv.slice(2);
  let N = 2000, seed = 1;
  for (let i = 0; i < args.length; i++) {
    if (args[i] === '--seed') seed = parseInt(args[++i], 10);
    else if (/^\d+$/.test(args[i])) N = parseInt(args[i], 10);
  }
  console.log(formatReport(runBatch(N, seed)));
}

if (process.argv[1] && process.argv[1].endsWith('sim-balance.mjs')) main();