#!/usr/bin/env node
// patch-x04-handoff-stream-scan.js
// P1: scanToolOutputTiers() 全量 readFileSync transcript, 长会话 >100MB 会 OOM
// 修复: >20MB 跳过全量读取, 改用 readline 流式逐行扫描
'use strict';
const fs = require('fs');
const path = require('path');

const SENTINEL = '// [PATCH-X04-STREAM-SCAN]';
const target = path.join(__dirname, '..', '..', 'hooks', 'pre-compact-handoff.js');

if (!fs.existsSync(target)) {
  process.stdout.write('[SKIP] target not found\n');
  process.exit(0);
}

let contentRaw = fs.readFileSync(target, 'utf8');
const useCRLF = contentRaw.includes('\r\n');
let content = useCRLF ? contentRaw.replace(/\r\n/g, '\n') : contentRaw;

if (content.includes(SENTINEL)) {
  process.stdout.write('[SKIP] patch-x04 already applied\n');
  process.exit(0);
}

const bak = target + '.bak.x04';
if (!fs.existsSync(bak)) fs.writeFileSync(bak, contentRaw);

const OLD_FN = `// === TOOL_OUTPUT_TIER_V1 ===
// 扫描 transcript JSONL, 按工具类型分级保留大输出, 输出 TOP-10 摘要
function scanToolOutputTiers(transcriptPath) {
  if (!transcriptPath || !fs.existsSync(transcriptPath)) {
    return { applied: false, reason: 'no transcript_path' };
  }
  try {
    const raw = fs.readFileSync(transcriptPath, 'utf8');
    const lines = raw.split('\\n').filter(Boolean);
    const items = [];
    for (const line of lines) {
      let obj;
      try { obj = JSON.parse(line); } catch { continue; }
      // 只关注 tool_result 类型 (含工具调用响应)
      const content = obj?.message?.content || obj?.content;
      if (!Array.isArray(content)) continue;
      for (const part of content) {
        if (part?.type !== 'tool_result') continue;
        const text = typeof part.content === 'string'
          ? part.content
          : Array.isArray(part.content) ? part.content.map(c => c?.text || '').join('') : '';
        const size = Buffer.byteLength(text, 'utf8');
        if (size < 500) continue;
        // R2-INPUT-CAP-V2: 单条 tool_result > 5MB 截断, 防 tierize 正则扫描超时
        const MAX_ITEM_BYTES = 5 * 1024 * 1024;
        const safeText = size > MAX_ITEM_BYTES ? text.slice(0, MAX_ITEM_BYTES) : text;
        items.push({ size, text: safeText, tool_use_id: part.tool_use_id, capped: size > MAX_ITEM_BYTES });
      }
    }
    items.sort((a, b) => b.size - a.size);
    const top = items.slice(0, 10).map(it => tierize(it));
    const totalBytes = items.reduce((s, it) => s + it.size, 0);
    return {
      applied: true,
      total_tool_results_scanned: items.length,
      total_bytes: totalBytes,
      top_offenders: top
    };
  } catch (e) {
    return { applied: false, reason: 'scan_error: ' + (e.message || e) };
  }
}`;

const NEW_FN = `// === TOOL_OUTPUT_TIER_V1 === ${SENTINEL}
// 扫描 transcript JSONL, 按工具类型分级保留大输出, 输出 TOP-10 摘要
// X04: 流式逐行扫描, 避免大文件 OOM
function scanToolOutputTiers(transcriptPath) {
  if (!transcriptPath || !fs.existsSync(transcriptPath)) {
    return { applied: false, reason: 'no transcript_path' };
  }
  try {
    const stat = fs.statSync(transcriptPath);
    const MAX_FILE = 50 * 1024 * 1024; // 50MB 硬上限
    if (stat.size > MAX_FILE) {
      return { applied: false, reason: 'transcript_too_large: ' + (stat.size / 1024 / 1024).toFixed(1) + 'MB (limit 50MB)' };
    }

    const items = [];
    const MAX_ITEM_BYTES = 5 * 1024 * 1024;

    // 20MB 以下: 同步读取 (性能优先)
    // 20MB 以上: 逐行流式读取 (内存安全)
    const STREAM_THRESHOLD = 20 * 1024 * 1024;

    if (stat.size <= STREAM_THRESHOLD) {
      const raw = fs.readFileSync(transcriptPath, 'utf8');
      const lines = raw.split('\\n').filter(Boolean);
      for (const line of lines) {
        processLine(line, items, MAX_ITEM_BYTES);
      }
    } else {
      // 流式: 逐块读取, 按换行切割
      const fd = fs.openSync(transcriptPath, 'r');
      const CHUNK = 4 * 1024 * 1024; // 4MB 块
      const buf = Buffer.alloc(CHUNK);
      let remainder = '';
      let pos = 0;
      while (pos < stat.size) {
        const n = fs.readSync(fd, buf, 0, CHUNK, pos);
        if (n <= 0) break;
        const chunk = remainder + buf.toString('utf8', 0, n);
        const parts = chunk.split('\\n');
        remainder = parts.pop() || '';
        for (const line of parts) {
          if (!line) continue;
          processLine(line, items, MAX_ITEM_BYTES);
        }
        pos += n;
      }
      if (remainder) processLine(remainder, items, MAX_ITEM_BYTES);
      fs.closeSync(fd);
    }

    items.sort((a, b) => b.size - a.size);
    const top = items.slice(0, 10).map(it => tierize(it));
    const totalBytes = items.reduce((s, it) => s + it.size, 0);
    return {
      applied: true,
      total_tool_results_scanned: items.length,
      total_bytes: totalBytes,
      top_offenders: top,
      mode: stat.size > STREAM_THRESHOLD ? 'stream' : 'sync'
    };
  } catch (e) {
    return { applied: false, reason: 'scan_error: ' + (e.message || e) };
  }
}

function processLine(line, items, MAX_ITEM_BYTES) {
  let obj;
  try { obj = JSON.parse(line); } catch { return; }
  const content = obj?.message?.content || obj?.content;
  if (!Array.isArray(content)) return;
  for (const part of content) {
    if (part?.type !== 'tool_result') continue;
    const text = typeof part.content === 'string'
      ? part.content
      : Array.isArray(part.content) ? part.content.map(c => c?.text || '').join('') : '';
    const size = Buffer.byteLength(text, 'utf8');
    if (size < 500) return;
    const safeText = size > MAX_ITEM_BYTES ? text.slice(0, MAX_ITEM_BYTES) : text;
    items.push({ size, text: safeText, tool_use_id: part.tool_use_id, capped: size > MAX_ITEM_BYTES });
  }
}`;

if (!content.includes(OLD_FN)) {
  process.stdout.write('[ERROR] old function not found — file may have been modified by another patch\n');
  // 尝试检测 X03 已修改的版本 (handoff 变量名改 heartbeatPath)
  if (content.includes('const raw = fs.readFileSync(transcriptPath,')) {
    process.stdout.write('[HINT] readFileSync pattern found but surrounding context differs\n');
  }
  process.exit(1);
}

content = content.replace(OLD_FN, NEW_FN);
const finalContent = useCRLF ? content.replace(/\n/g, '\r\n') : content;
fs.writeFileSync(target, finalContent, 'utf8');

// 验证
const verify = fs.readFileSync(target, 'utf8');
const ok = verify.includes(SENTINEL) && verify.includes('processLine(') && verify.includes('STREAM_THRESHOLD');
process.stdout.write(ok ? '[DONE] patch-x04 applied: stream scan for large transcripts\n' : '[ERROR] verification failed\n');
process.exit(ok ? 0 : 1);