// 关卡设计辅助。GDD §8.2 的第 3–5 步：挑线索、验唯一、删到最少。
//
//   npm run design -- 1-7                 看这关：全部无线索路径、当前线索下的解
//   npm run design -- 1-7 --minimize      当前线索里哪些可以删掉仍唯一
//   npm run design -- 1-7 --suggest 2     以当前解为“作者解”，找 2 个线索（含 1）就唯一的方案
//   npm run design -- file.json           也可以直接指定一个临时关卡文件（单关 LevelDef 或整包）
import { existsSync, readFileSync, readdirSync } from 'node:fs';
import { dirname, join } from 'node:path';
import { fileURLToPath } from 'node:url';
import { Board } from '../src/board';
import { clueLabel, hasClue } from '../src/clue';
import { parsePack } from '../src/levels';
import { solve } from '../src/solver';
import type { CellDef, LevelDef } from '../src/types';
import { pathToIds, renderAscii } from './ascii';

const here = dirname(fileURLToPath(import.meta.url));
const args = process.argv.slice(2);
const target = args[0];
if (!target) {
  console.log('用法: npm run design -- <关卡id|json文件> [--minimize] [--suggest k] [--path a,b,c]');
  process.exit(1);
}

function findLevel(idOrFile: string): LevelDef {
  if (idOrFile.endsWith('.json') && existsSync(idOrFile)) {
    const raw = JSON.parse(readFileSync(idOrFile, 'utf8'));
    if (Array.isArray(raw.levels)) return parsePack(raw).levels[0];
    return raw as LevelDef;
  }
  const dir = join(here, '..', 'levels');
  for (const f of readdirSync(dir).filter((x) => x.endsWith('.json'))) {
    const pack = parsePack(JSON.parse(readFileSync(join(dir, f), 'utf8')));
    const lv = pack.levels.find((l) => l.id === idOrFile);
    if (lv) return lv;
  }
  throw new Error(`找不到关卡 ${idOrFile}`);
}

const level = findLevel(target);
const board = Board.fromLevel(level);
const clueCells = board.cells.filter((c) => c.clue !== null);

console.log(`\n${level.id}  N=${board.n}  线索: ${board.cells.filter(hasClue).map((c) => `${c.id}=${clueLabel(c)}`).join(' ') || '无'}`);
console.log(renderAscii(board));

const allPaths = solve(board, { ignoreClues: true, limit: 2000 });
console.log(`\n无线索哈密顿路径: ${allPaths.length >= 2000 ? '2000+' : allPaths.length}`);
const withClues = solve(board, { limit: 50 });
console.log(`当前线索下的解: ${withClues.length}${withClues.length >= 50 ? '+' : ''}`);
for (const p of withClues.slice(0, 8)) console.log('  ' + pathToIds(board, p));
if (withClues.length === 1) console.log(renderAscii(board, withClues[0]));

// 作者解：--path 指定，否则用当前唯一解
let author: number[] | null = null;
const pathArg = args.indexOf('--path');
if (pathArg !== -1) {
  author = args[pathArg + 1].split(',').map((id) => board.cellById(id.trim()).index);
} else if (withClues.length === 1) {
  author = withClues[0];
}

function countWithClues(clues: Map<number, number>, limit = 2): number {
  const defs: CellDef[] = level.cells.map(({ clue, ...c }, index) => ({
    ...c,
    ...(clues.has(index) ? { clue: clues.get(index)! } : {}),
  }));
  return solve(Board.fromCells(defs), { limit }).length;
}

if (args.includes('--minimize') && withClues.length === 1) {
  console.log('\n[minimize] 尝试删线索：');
  const current = new Map(clueCells.map((c) => [c.index, c.clue!]));
  const removable: string[] = [];
  for (const c of clueCells) {
    const trial = new Map(current);
    trial.delete(c.index);
    const n = countWithClues(trial);
    console.log(`  去掉 ${c.id}=${c.clue} → ${n === 1 ? '仍唯一 ✓' : n === 0 ? '无解' : '多解'}`);
    if (n === 1) removable.push(`${c.id}=${c.clue}`);
  }
  for (const c of board.cells.filter((cell) => cell.parity !== null)) {
    const defs = level.cells.map((d) => {
      const { parity, ...rest } = d;
      return d.id === c.id ? rest : d;
    });
    const n = solve(Board.fromCells(defs), { limit: 2 }).length;
    console.log(`  去掉 ${c.id}=${clueLabel(c)} → ${n === 1 ? '仍唯一 ✓' : '多解'}`);
    if (n === 1) removable.push(`${c.id}=${clueLabel(c)}`);
  }
  console.log(removable.length ? `  单独可删: ${removable.join(', ')}` : '  每个线索都必要');
}

const suggestArg = args.indexOf('--suggest');
if (suggestArg !== -1) {
  if (!author) {
    console.log('\n[suggest] 需要一条作者解：先让当前线索唯一，或用 --path 指定');
  } else {
    const k = Number(args[suggestArg + 1] ?? 2);
    const n = author.length;
    const keepStart = clueCells.some((c) => c.clue === 1);
    console.log(`\n[suggest] 作者解: ${pathToIds(board, author)}`);
    console.log(`  找 ${k} 个线索${keepStart ? '（含起点 1）' : ''} 使其唯一，按“少用端点、分布均匀”排序：`);
    const positions: number[] = [];
    for (let s = 1; s <= n; s++) if (board.cells[author[s - 1]].parity === null) positions.push(s);
    const results: { clues: number[]; score: number }[] = [];
    const combo: number[] = [];
    const startFixed = keepStart ? [1] : [];
    const pool = positions.filter((s) => !startFixed.includes(s));
    const need = k - startFixed.length;
    function rec(from: number): void {
      if (combo.length === need) {
        const steps = [...startFixed, ...combo];
        const clues = new Map(steps.map((s) => [author![s - 1], s]));
        if (countWithClues(clues) === 1) {
          // 端点扣分；线索之间间距越均匀越好
          const sorted = steps.slice().sort((a, b) => a - b);
          let score = 0;
          for (const s of sorted) if (s === 1 || s === n) score += 3;
          for (let i = 1; i < sorted.length; i++) score += Math.abs(sorted[i] - sorted[i - 1] - n / (sorted.length + 1)) * 0.2;
          results.push({ clues: steps, score });
        }
        return;
      }
      for (let i = from; i < pool.length; i++) {
        combo.push(pool[i]);
        rec(i + 1);
        combo.pop();
      }
    }
    rec(0);
    results.sort((a, b) => a.score - b.score);
    if (!results.length) console.log('  没有方案，试试 k+1');
    for (const r of results.slice(0, 12)) {
      const desc = r.clues
        .slice()
        .sort((a, b) => a - b)
        .map((s) => `${board.cells[author![s - 1]].id}=${s}`)
        .join('  ');
      console.log(`  ${desc}`);
    }
    if (results.length > 12) console.log(`  … 共 ${results.length} 个方案`);
  }
}