#!/usr/bin/env node
/**
 * 跨 Hook 会话追踪 (Phase 3)
 *
 * 提供共享 traceId，使 3 个 hooks 的事件可以关联分析。
 * 所有消费者必须 try/catch 包裹，fail-open。
 */

const fs = require('fs');
const { safeAppendJsonl } = require('../hooks/lib/safe-append.js');
const path = require('path');

// ─── 路径解析 ────────────────────────────────────────
let debugDir;
try {
  const { PATHS } = require('./paths.config.js');
  debugDir = PATHS.debugDir;
} catch {
  debugDir = path.resolve(__dirname, '..', 'debug');
}

const SESSION_TRACE_FILE = path.join(debugDir, 'session-trace.json');
const SESSION_LOCK_FILE = path.join(debugDir, 'session-active.lock');

/**
 * 获取当前会话的 traceId（同 session 复用）
 * @returns {{ sessionId: string, traceId: string, startedAt: string, eventCount: number }}
 */
function getSessionTrace() {
  if (!fs.existsSync(debugDir)) fs.mkdirSync(debugDir, { recursive: true });

  // 读取当前 sessionId
  let sessionId = 'unknown';
  try {
    if (fs.existsSync(SESSION_LOCK_FILE)) {
      const lock = JSON.parse(fs.readFileSync(SESSION_LOCK_FILE, 'utf8'));
      sessionId = lock.sessionId || lock.id || 'unknown';
    }
  } catch {}

  // 读取或创建 trace 状态
  let trace = null;
  try {
    if (fs.existsSync(SESSION_TRACE_FILE)) {
      trace = JSON.parse(fs.readFileSync(SESSION_TRACE_FILE, 'utf8'));
    }
  } catch {}

  // 同 session 复用 traceId，否则创建新的
  if (trace && trace.sessionId === sessionId && sessionId !== 'unknown') {
    return trace;
  }

  // 新 trace
  const traceId = `t-${Date.now().toString(36)}-${Math.random().toString(36).slice(2, 8)}`;
  const newTrace = {
    sessionId,
    traceId,
    startedAt: new Date().toISOString(),
    eventCount: 0,
  };

  try {
    // W5: 原子写入 (temp+rename)
    var tmp = SESSION_TRACE_FILE + '.tmp.' + process.pid;
    fs.writeFileSync(tmp, JSON.stringify(newTrace, null, 2) + '\n');
    fs.renameSync(tmp, SESSION_TRACE_FILE);
  } catch {}

  return newTrace;
}

/**
 * 追加事件到日期分片的 trace 日志
 * @param {string} hookName - 来源 hook 名称
 * @param {string} eventType - 事件类型 (detection|block-warn|pass|outcome)
 * @param {Object} data - 附加数据
 */
function appendTraceEvent(hookName, eventType, data) {
  try {
    if (!fs.existsSync(debugDir)) fs.mkdirSync(debugDir, { recursive: true });

    const trace = getSessionTrace();
    const dateStr = new Date().toISOString().slice(0, 10);
    const logFile = path.join(debugDir, `trace-${dateStr}.jsonl`);

    const event = {
      ts: new Date().toISOString(),
      traceId: trace.traceId,
      sessionId: trace.sessionId,
      hook: hookName,
      event: eventType,
      data: data || {},
    };

    safeAppendJsonl(logFile, event);

    // 更新 eventCount (原子写入)
    trace.eventCount = (trace.eventCount || 0) + 1;
    try {
      var tmp2 = SESSION_TRACE_FILE + '.tmp.' + process.pid;
      fs.writeFileSync(tmp2, JSON.stringify(trace, null, 2) + '\n');
      fs.renameSync(tmp2, SESSION_TRACE_FILE);
    } catch {}
  } catch {}
}

// ─── 导出 ─────────────────────────────────────────────
if (typeof module !== 'undefined') {
  module.exports = { getSessionTrace, appendTraceEvent };
}