#!/usr/bin/env node
/**
 * project-context-injector.js · R3 · 2026-04-26
 *
 * UserPromptSubmit Hook · 项目级稳定上下文自动注入
 *
 * 触发条件 (全部满足):
 *   1. cwd 是项目根 (含 .git/package.json/pyproject.toml/go.mod/Cargo.toml/CLAUDE.md 之一)
 *   2. <cwd>/.bookworm-context.md 文件存在
 *   3. 本会话尚未为该项目注入过 (per-session-per-project 去重)
 *
 * 注入内容: .bookworm-context.md 头 100 行 (可被文件首行 `<!-- max-lines: N -->` 覆盖)
 *
 * 行为约束:
 *   - 始终 exit 0 (fail-open, 不阻断 prompt)
 *   - 失败/无文件时无输出
 *   - 单次 IO ≤ 50KB, 超大文件被截断
 *   - 去重缓存路径: ~/.claude/session-state/project-context-injected.json
 */
'use strict';

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

const CLAUDE_ROOT = require('./lib/root.js');
const readStdin = require('./lib/read-stdin.js');

const STATE_DIR = path.join(CLAUDE_ROOT, 'session-state');
const CACHE_PATH = path.join(STATE_DIR, 'project-context-injected.json');
const CONTEXT_FILENAME = '.bookworm-context.md';
const MAX_BYTES = 50 * 1024;
const DEFAULT_MAX_LINES = 100;

const ROOT_MARKERS = ['.git', 'package.json', 'pyproject.toml', 'go.mod', 'Cargo.toml', 'CLAUDE.md'];

function isProjectRoot(dir) {
  for (const m of ROOT_MARKERS) {
    if (fs.existsSync(path.join(dir, m))) return true;
  }
  return false;
}

function loadCache() {
  try {
    if (!fs.existsSync(CACHE_PATH)) return {};
    const raw = fs.readFileSync(CACHE_PATH, 'utf8');
    return JSON.parse(raw) || {};
  } catch {
    return {};
  }
}

function saveCache(cache) {
  try {
    if (!fs.existsSync(STATE_DIR)) fs.mkdirSync(STATE_DIR, { recursive: true });
    const tmp = CACHE_PATH + '.tmp.' + process.pid;
    fs.writeFileSync(tmp, JSON.stringify(cache, null, 2), 'utf8');
    fs.renameSync(tmp, CACHE_PATH);
  } catch {}
}

function pruneStaleCache(cache) {
  const now = Date.now();
  const TTL = 7 * 24 * 3600 * 1000;
  for (const k of Object.keys(cache)) {
    if (!cache[k] || !cache[k].ts || now - cache[k].ts > TTL) delete cache[k];
  }
  return cache;
}

(async () => {
  try {
    let hookData = {};
    try { hookData = await readStdin(); } catch {}

    const cwd = hookData.cwd || process.cwd();
    if (!cwd || !isProjectRoot(cwd)) {
      process.exit(0);
    }

    const ctxPath = path.join(cwd, CONTEXT_FILENAME);
    if (!fs.existsSync(ctxPath)) {
      process.exit(0);
    }

    // R3-FALLBACK-V2: 无 session_id 直接放弃, 防 'unknown-session' 跨会话缓存污染
    if (!hookData.session_id) process.exit(0);
    const sessionId = hookData.session_id;
    const cacheKey = sessionId + '::' + cwd;
    const cache = pruneStaleCache(loadCache());
    if (cache[cacheKey]) {
      process.exit(0);
    }

    let raw = fs.readFileSync(ctxPath, 'utf8');
    if (Buffer.byteLength(raw, 'utf8') > MAX_BYTES) {
      raw = raw.slice(0, MAX_BYTES);
    }

    let maxLines = DEFAULT_MAX_LINES;
    const m = raw.match(/^<!--\s*max-lines:\s*(\d+)\s*-->/);
    if (m) maxLines = Math.min(parseInt(m[1], 10) || DEFAULT_MAX_LINES, 500);

    const lines = raw.split(/\r?\n/);
    const truncated = lines.length > maxLines;
    const body = lines.slice(0, maxLines).join('\n');
    const tail = truncated
      ? '\n\n... [项目上下文截断, 完整内容见 ' + CONTEXT_FILENAME + ' (' + lines.length + ' 行)]'
      : '';

    const additionalContext = '[PROJECT_CONTEXT · ' + path.basename(cwd) + ']\n' +
      '源文件: ' + ctxPath + '\n' +
      '─────────────────────────────────────\n' +
      body + tail;

    cache[cacheKey] = { ts: Date.now(), ctxPath: ctxPath, lines: lines.length };
    saveCache(cache);

    process.stdout.write(JSON.stringify({
      continue: true,
      suppressOutput: true,
      hookSpecificOutput: {
        hookEventName: 'UserPromptSubmit',
        additionalContext: additionalContext
      }
    }));
    process.exit(0);
  } catch {
    process.exit(0);
  }
})();