#!/usr/bin/env node
/**
 * 会话上下文追踪器 (v5.0)
 *
 * 维护最近 10 次技能调用的滑动窗口,
 * 计算候选技能的上下文相关分数。
 *
 * 核心函数:
 *   recordSkillUsage(skillName) → 记录技能使用到滑动窗口
 *   computeContextScore(candidateSkill, composableIndex) → 上下文分数 (0~1.0)
 */

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

const detectClaudeRoot = () => require('./paths.config.js').PATHS.root;

const ROOT = detectClaudeRoot();
const STATE_FILE = path.join(ROOT, 'debug', 'context-state.json');

// v5.9: 多项目隔离 — 按 cwd 分离状态文件
let _isolator = null;
try { _isolator = require('./project-isolator.js'); } catch {}
function getStateFile(cwd) {
  if (_isolator && cwd) return _isolator.getIsolatedPath('context-state.json', cwd);
  return STATE_FILE;
}
const MAX_WINDOW = 10;
const DECAY_FACTOR = 0.70; // v5.9: 降低衰减因子 (0.85→0.70)，半衰期从 4.3 次降到 2.3 次
const ANTI_STICKY_THRESHOLD = 3; // 连续同技能超过此次数时降低同技能加成

/**
 * 加载上下文状态
 * @param {string} [cwd] - 工作目录 (v5.9 多项目隔离)
 * @returns {{ recentSkills: string[], updatedAt: string }}
 */
function loadState(cwd) {
  try {
    const file = getStateFile(cwd);
    if (fs.existsSync(file)) {
      return JSON.parse(fs.readFileSync(file, 'utf8'));
    }
  } catch {}
  return { recentSkills: [], updatedAt: new Date().toISOString() };
}

/**
 * 保存上下文状态
 * @param {Object} state
 * @param {string} [cwd] - 工作目录 (v5.9 多项目隔离)
 */
function saveState(state, cwd) {
  const file = getStateFile(cwd);
  const dir = path.dirname(file);
  if (!fs.existsSync(dir)) fs.mkdirSync(dir, { recursive: true });
  // P1-2: O_EXCL 文件锁 + 原子写入 (防并发竞态)
  const lockFile = file + '.lock';
  try {
    const lockFd = fs.openSync(lockFile, fs.constants.O_CREAT | fs.constants.O_EXCL | fs.constants.O_WRONLY);
    fs.writeSync(lockFd, String(process.pid));
    fs.closeSync(lockFd);
  } catch {
    try {
      const lockAge = Date.now() - fs.statSync(lockFile).mtimeMs;
      if (lockAge < 10000) return; // 未过期，跳过
      fs.unlinkSync(lockFile);
      const lockFd2 = fs.openSync(lockFile, fs.constants.O_CREAT | fs.constants.O_EXCL | fs.constants.O_WRONLY);
      fs.writeSync(lockFd2, String(process.pid));
      fs.closeSync(lockFd2);
    } catch { return; }
  }
  try {
    const tmpFile = file + '.tmp.' + process.pid;
    fs.writeFileSync(tmpFile, JSON.stringify(state, null, 2) + '\n');
    fs.renameSync(tmpFile, file);
  } finally {
    try { fs.unlinkSync(lockFile); } catch {}
  }
}

/**
 * 记录技能使用到滑动窗口
 * @param {string} skillName - 技能名称
 * @param {string} [cwd] - 工作目录 (v5.9 多项目隔离)
 */
function recordSkillUsage(skillName, cwd) {
  const state = loadState(cwd);
  state.recentSkills.push(skillName);
  // 保持窗口大小
  if (state.recentSkills.length > MAX_WINDOW) {
    state.recentSkills = state.recentSkills.slice(-MAX_WINDOW);
  }
  state.updatedAt = new Date().toISOString();
  saveState(state, cwd);
}

/**
 * 计算候选技能的上下文相关分数
 * @param {string} candidateSkill - 候选技能名
 * @param {Object} composableIndex - { skillName → { enhances, requires, conflicts } }
 * @param {Object} [preloadedState] - 预加载的状态 (避免重复 I/O，由调用方一次性加载)
 * @returns {number} 上下文分数 (0~1.0)
 */
function computeContextScore(candidateSkill, composableIndex, preloadedState) {
  const state = preloadedState || loadState();
  const recent = state.recentSkills;
  if (recent.length === 0) return 0;

  let score = 0;

  // v5.9: 计算最近连续同技能次数 (反粘滞检测)
  let consecutiveSame = 0;
  for (let j = recent.length - 1; j >= 0; j--) {
    if (recent[j] === candidateSkill) consecutiveSame++;
    else break;
  }

  for (let i = 0; i < recent.length; i++) {
    const recentSkill = recent[recent.length - 1 - i]; // 最新的在前
    const decay = Math.pow(DECAY_FACTOR, i);
    const comp = composableIndex[recentSkill] || {};

    // 同技能重复使用: 反粘滞 — 连续 >= 3 次时降低加成 (0.3→0.1)
    if (recentSkill === candidateSkill) {
      const sameBoost = consecutiveSame >= ANTI_STICKY_THRESHOLD ? 0.1 : 0.3;
      score += sameBoost * decay;
      continue;
    }

    // composable enhances 关系 +0.5
    if (comp.enhances && comp.enhances.includes(candidateSkill)) {
      score += 0.5 * decay;
    }

    // composable requires 关系 +0.4
    if (comp.requires && comp.requires.includes(candidateSkill)) {
      score += 0.4 * decay;
    }

    // 反向: 候选技能 enhances 最近使用的技能
    const candidateComp = composableIndex[candidateSkill] || {};
    if (candidateComp.enhances && candidateComp.enhances.includes(recentSkill)) {
      score += 0.3 * decay;
    }
  }

  // 上限 1.0
  // P2-2: sigmoid 归一化替代硬截断，保留高分区间区分度
    return score <= 0 ? 0 : Math.round((2.0 / (1.0 + Math.exp(-score)) - 1.0) * 100) / 100;
}

/**
 * 从 skills-index.json 构建 composable 索引
 * @param {Object} index - skills-index.json
 * @returns {Object} { skillName → composable }
 */
function buildComposableIndex(index) {
  const result = {};
  for (const skill of (index.skills || [])) {
    if (skill.composable) {
      result[skill.name] = skill.composable;
    }
  }
  return result;
}

// 模块导出
if (typeof module !== 'undefined') {
  module.exports = {
    loadState, saveState, recordSkillUsage,
    computeContextScore, buildComposableIndex,
    MAX_WINDOW, DECAY_FACTOR, ANTI_STICKY_THRESHOLD,
  };
}

// CLI 入口
if (require.main === module) {
  const state = loadState();
  console.log('=== 上下文状态 ===');
  console.log(`最近技能 (${state.recentSkills.length}/${MAX_WINDOW}):`);
  for (let i = 0; i < state.recentSkills.length; i++) {
    const decay = Math.pow(DECAY_FACTOR, state.recentSkills.length - 1 - i);
    console.log(`  ${i + 1}. ${state.recentSkills[i]} (decay: ${decay.toFixed(3)})`);
  }
  console.log(`更新时间: ${state.updatedAt}`);
}