#!/usr/bin/env node
/**
 * C1 补丁 — 2026-04-16 audit-2026-04-16 遗留 CRITICAL
 *
 * 目标: scripts/fusion-weight-learner.js 两处 unlinkSync 改为原子 tmp+rename
 *  - 位置 A: resetOnDegeneracy 分支 (原 L331)
 *  - 位置 B: resetWeights() 函数 (原 L354)
 *
 * 修复原理:
 *   并发 readFileSync 与 unlinkSync 存在 TOCTOU 竞态，
 *   改为写 DEFAULT_WEIGHTS 到 tmp 再 rename 覆盖，
 *   读者永远看到合法 JSON (或旧值，不会 ENOENT)。
 *
 * 幂等: 若已打过补丁 (存在 atomicResetWeightsFile 函数名) 则跳过。
 */
'use strict';

const fs = require('fs');
const path = require('path');

const TARGET = path.join(__dirname, '..', 'fusion-weight-learner.js');
const SENTINEL = 'atomicResetWeightsFile';

function main() {
  if (!fs.existsSync(TARGET)) {
    console.error('[patch-c1] 目标文件不存在:', TARGET);
    process.exit(1);
  }
  const before = fs.readFileSync(TARGET, 'utf8');

  if (before.includes(SENTINEL)) {
    console.log('[patch-c1] 已打过补丁 (发现 ' + SENTINEL + ')，跳过');
    process.exit(0);
  }

  // ==== 注入 1: 在 _directWriteFallback 后追加 atomicResetWeightsFile 助手 ====
  const helperAnchor =
    'function _directWriteFallback(weightsFile, data) {\n' +
    '  try {\n' +
    '    if (!fs.existsSync(path.dirname(weightsFile))) {\n' +
    '      fs.mkdirSync(path.dirname(weightsFile), { recursive: true });\n' +
    '    }\n' +
    '    fs.writeFileSync(weightsFile, JSON.stringify(data, null, 2) + \'\\n\');\n' +
    '  } catch {}\n' +
    '}';

  const helperInjection =
    helperAnchor +
    '\n\n' +
    '/**\n' +
    ' * C1 原子重置助手 (patch-c1-atomic-reset, 2026-04-16)\n' +
    ' * 用 tmp+rename 覆盖为 DEFAULT_WEIGHTS，避免 unlinkSync 与并发 readFileSync 的 TOCTOU 竞态。\n' +
    ' * 读者永远看到合法 JSON (旧值或新的 DEFAULT)，不会 ENOENT。\n' +
    ' */\n' +
    'function atomicResetWeightsFile(weightsFile, reason) {\n' +
    '  try {\n' +
    '    if (!fs.existsSync(path.dirname(weightsFile))) {\n' +
    '      fs.mkdirSync(path.dirname(weightsFile), { recursive: true });\n' +
    '    }\n' +
    '    const payload = {\n' +
    '      weights: { ...DEFAULT_WEIGHTS },\n' +
    '      resetAt: new Date().toISOString(),\n' +
    '      resetReason: reason || \'manual\',\n' +
    '    };\n' +
    '    const _tmp = weightsFile + \'.tmp.\' + process.pid;\n' +
    '    fs.writeFileSync(_tmp, JSON.stringify(payload, null, 2) + \'\\n\');\n' +
    '    fs.renameSync(_tmp, weightsFile);\n' +
    '  } catch {}\n' +
    '}';

  if (!before.includes(helperAnchor)) {
    console.error('[patch-c1] 找不到 _directWriteFallback 锚点，源文件已变更');
    process.exit(2);
  }
  let after = before.replace(helperAnchor, helperInjection);

  // ==== 注入 2: 替换 resetOnDegeneracy 分支的 unlinkSync (原 L331) ====
  const degenPattern = /process\.stderr\.write\('\[fusion-weight\] 连续 ' \+ consecutiveHits \+ ' 周期退化命中，reset 到 DEFAULT_WEIGHTS\\n'\);\s*\n\s*if \(fs\.existsSync\(FUSION_WEIGHTS_FILE\)\) fs\.unlinkSync\(FUSION_WEIGHTS_FILE\);/;
  const degenReplacement =
    "process.stderr.write('[fusion-weight] 连续 ' + consecutiveHits + ' 周期退化命中，reset 到 DEFAULT_WEIGHTS\\n');\n" +
    '          atomicResetWeightsFile(FUSION_WEIGHTS_FILE, \'degen-consecutive-\' + consecutiveHits);';
  if (!degenPattern.test(after)) {
    console.error('[patch-c1] 找不到退化分支 unlinkSync 锚点');
    process.exit(3);
  }
  after = after.replace(degenPattern, degenReplacement);

  // ==== 注入 3: 替换 resetWeights() 的 unlinkSync (原 L354) ====
  const resetPattern = /function resetWeights\(\) \{\s*\n\s*if \(fs\.existsSync\(FUSION_WEIGHTS_FILE\)\) \{\s*\n\s*fs\.unlinkSync\(FUSION_WEIGHTS_FILE\);\s*\n\s*\}\s*\n\s*return \{ status: 'reset', weights: DEFAULT_WEIGHTS \};\s*\n\}/;
  const resetReplacement =
    'function resetWeights() {\n' +
    '  atomicResetWeightsFile(FUSION_WEIGHTS_FILE, \'manual-reset\');\n' +
    '  return { status: \'reset\', weights: DEFAULT_WEIGHTS };\n' +
    '}';
  if (!resetPattern.test(after)) {
    console.error('[patch-c1] 找不到 resetWeights() 锚点');
    process.exit(4);
  }
  after = after.replace(resetPattern, resetReplacement);

  // ==== 校验 ====
  if (after === before) {
    console.error('[patch-c1] 替换无效果，中止');
    process.exit(5);
  }
  const unlinkCount = (after.match(/fs\.unlinkSync\(FUSION_WEIGHTS_FILE\)/g) || []).length;
  if (unlinkCount !== 0) {
    console.error('[patch-c1] 仍有 ' + unlinkCount + ' 处 unlinkSync(FUSION_WEIGHTS_FILE) 未清理');
    process.exit(6);
  }

  // ==== 备份并原子写回 ====
  const backup = TARGET + '.bak.c1.' + Date.now();
  fs.writeFileSync(backup, before);
  const _tmp = TARGET + '.tmp.' + process.pid;
  fs.writeFileSync(_tmp, after);
  fs.renameSync(_tmp, TARGET);

  console.log('[patch-c1] ✓ 补丁应用成功');
  console.log('[patch-c1]   备份: ' + path.basename(backup));
  console.log('[patch-c1]   变更: 新增 atomicResetWeightsFile + 替换 2 处 unlinkSync');
}

try {
  main();
} catch (e) {
  console.error('[patch-c1] 异常:', e.message);
  process.exit(99);
}