#!/usr/bin/env node
/**
 * W1 补丁 — 2026-04-16 audit-2026-04-16 WARNING
 *
 * 问题: simulateSignals 中 context/project/workflow 三维梯度恒为 0，
 *      bm25/semantic 单向累积导致权重持续漂移 (当前 bm25=0.598, 距 DEFAULT 0.40 漂移 +0.198)。
 *      虽有 cooldown 防 reset 抖动，但根因未修，长期仍会趋近 MAX_WEIGHT 边界。
 *
 * 修复方案: 在两处梯度更新后追加 L2 权重衰减项 (正则化拉回 DEFAULT_WEIGHTS)。
 *   delta_new = LR * gradient + DECAY * (DEFAULT - current)
 *   当 current 远离 DEFAULT → 反向拉力加大
 *   当 current 等于 DEFAULT → 无影响
 *   稳态: 梯度力 = 衰减力 → spread 有界
 *
 * 常量: WEIGHT_DECAY = 0.02 (与 LEARNING_RATE 同量级)
 *       数学估算: 当前 bm25=0.598 → 每批衰减 0.02*(0.598-0.4)=0.004，
 *                 足以抵消 simulateSignals 给 bm25 的单向梯度 (~0.02 量级)
 *
 * 两处更新点:
 *   - L283  learnFusionWeights 主路径
 *   - L541  applyImplicitWeights 隐式反馈路径
 *
 * 幂等: sentinel = 'WEIGHT_DECAY'
 */
'use strict';

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

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

function main() {
  if (!fs.existsSync(TARGET)) {
    console.error('[patch-w1] 目标文件不存在');
    process.exit(1);
  }
  const before = fs.readFileSync(TARGET, 'utf8');

  if (before.includes(SENTINEL)) {
    console.log('[patch-w1] 已打过补丁 (发现 ' + SENTINEL + ')，跳过');
    process.exit(0);
  }

  // ==== 注入 1: 在 LEARNING_RATE 后追加 WEIGHT_DECAY 常量 ====
  const constAnchor = 'const LEARNING_RATE = 0.02;';
  const constInjection =
    'const LEARNING_RATE = 0.02;\n' +
    '// W1 修复 (patch-w1-weight-decay, 2026-04-16): L2 正则化强度\n' +
    '// 每批次将权重按比例拉回 DEFAULT_WEIGHTS，防止 simulateSignals 三维=0 导致的单向漂移\n' +
    'const WEIGHT_DECAY = 0.02;';
  if (!before.includes(constAnchor)) {
    console.error('[patch-w1] 找不到 LEARNING_RATE 常量锚点');
    process.exit(2);
  }
  let after = before.replace(constAnchor, constInjection);

  // ==== 注入 2: learnFusionWeights L283 梯度更新循环 ====
  const mainAnchor =
    '  // 梯度更新\n' +
    '  const newWeights = { ...weights };\n' +
    '  for (const key of Object.keys(newWeights)) {\n' +
    '    newWeights[key] += LEARNING_RATE * totalGradient[key];\n' +
    '  }';
  const mainReplacement =
    '  // 梯度更新 + W1 权重衰减 (L2 正则化拉回 DEFAULT_WEIGHTS)\n' +
    '  const newWeights = { ...weights };\n' +
    '  for (const key of Object.keys(newWeights)) {\n' +
    '    newWeights[key] += LEARNING_RATE * totalGradient[key];\n' +
    '    newWeights[key] += WEIGHT_DECAY * (DEFAULT_WEIGHTS[key] - newWeights[key]);\n' +
    '  }';
  if (!after.includes(mainAnchor)) {
    console.error('[patch-w1] 找不到 learnFusionWeights 梯度更新锚点');
    process.exit(3);
  }
  after = after.replace(mainAnchor, mainReplacement);

  // ==== 注入 3: applyImplicitWeights L541 梯度更新循环 ====
  const implicitAnchor =
    '    // 应用梯度更新（保守学习率，使用 LEARNING_RATE 的一半避免与 learnFusionWeights 叠加）\n' +
    '    const implicitLR = LEARNING_RATE * 0.5;\n' +
    '    const newWeights = { ...currentWeights };\n' +
    '    for (const key of Object.keys(newWeights)) {\n' +
    '      newWeights[key] += implicitLR * (totalGradient[key] || 0);\n' +
    '    }';
  const implicitReplacement =
    '    // 应用梯度更新（保守学习率，使用 LEARNING_RATE 的一半避免与 learnFusionWeights 叠加）\n' +
    '    // W1: 同步使用 WEIGHT_DECAY 的一半，与 implicitLR 成比例\n' +
    '    const implicitLR = LEARNING_RATE * 0.5;\n' +
    '    const implicitDecay = WEIGHT_DECAY * 0.5;\n' +
    '    const newWeights = { ...currentWeights };\n' +
    '    for (const key of Object.keys(newWeights)) {\n' +
    '      newWeights[key] += implicitLR * (totalGradient[key] || 0);\n' +
    '      newWeights[key] += implicitDecay * (DEFAULT_WEIGHTS[key] - newWeights[key]);\n' +
    '    }';
  if (!after.includes(implicitAnchor)) {
    console.error('[patch-w1] 找不到 applyImplicitWeights 梯度更新锚点');
    process.exit(4);
  }
  after = after.replace(implicitAnchor, implicitReplacement);

  // ==== 校验 ====
  if (after === before) {
    console.error('[patch-w1] 替换无效果');
    process.exit(5);
  }
  const decayCount = (after.match(/WEIGHT_DECAY/g) || []).length;
  if (decayCount < 4) {
    console.error('[patch-w1] WEIGHT_DECAY 引用数异常:', decayCount, '(期望 >= 4)');
    process.exit(6);
  }

  // ==== 备份并原子写回 ====
  const backup = TARGET + '.bak.w1.' + Date.now();
  fs.writeFileSync(backup, before);
  const _tmp = TARGET + '.tmp.' + process.pid;
  fs.writeFileSync(_tmp, after);
  fs.renameSync(_tmp, TARGET);

  console.log('[patch-w1] ✓ 补丁应用成功');
  console.log('[patch-w1]   备份: ' + path.basename(backup));
  console.log('[patch-w1]   变更: 新增 WEIGHT_DECAY=0.02 + 两处梯度循环加衰减项');
  console.log('[patch-w1]   WEIGHT_DECAY 引用数: ' + decayCount);
}

try {
  main();
} catch (e) {
  console.error('[patch-w1] 异常:', e.message);
  process.exit(99);
}