#!/usr/bin/env node
/**
 * Skill 加载器 - 从远程 Worker 拉取 prompt (含本地 LRU 缓存 + 离线降级)
 * 用法: node load-skill.js <skillName>
 *   由 stub SKILL.md 通过 Bash 调用, stdout 输出 prompt 给模型消费
 */
const fs = require("fs");
const path = require("path");
const os = require("os");
const https = require("https");
const crypto = require("crypto");

const API_BASE = process.env.BW_API_BASE || "https://bookworm-router.bookworm-api.workers.dev";
const CLAUDE_DIR = path.join(os.homedir(), ".claude");
const TOKEN_FILE = path.join(CLAUDE_DIR, ".bw-token");
const CACHE_DIR = path.join(CLAUDE_DIR, ".skill-cache");
const CACHE_TTL_MS = 24 * 60 * 60 * 1000;  // 24 小时

function die(msg, code = 1) { process.stderr.write(`[FAIL] ${msg}\n`); process.exit(code); }

const skillName = process.argv[2];
if (!skillName || !/^[a-z0-9-]{1,64}$/.test(skillName)) die("usage: load-skill <skill-name>");

function readToken() {
  if (!fs.existsSync(TOKEN_FILE)) die("未激活, 请先运行: node activate.js");
  const d = JSON.parse(fs.readFileSync(TOKEN_FILE, "utf8"));
  if (Date.now() > d.expires_at - 24 * 60 * 60 * 1000) {
    process.stderr.write(`[WARN] Token 即将过期, 请重新激活\n`);
  }
  if (Date.now() > d.expires_at) die("Token 已过期, 请重新激活");
  return d.token;
}

try { fs.mkdirSync(CACHE_DIR, { recursive: true, mode: 0o700 }); } catch {}
const cacheFile = path.join(CACHE_DIR, crypto.createHash("sha256").update(skillName).digest("hex").slice(0, 16));

// 先查缓存
function tryCache(fresh) {
  if (!fs.existsSync(cacheFile)) return null;
  const st = fs.statSync(cacheFile);
  if (fresh && Date.now() - st.mtimeMs > CACHE_TTL_MS) return null;
  return fs.readFileSync(cacheFile, "utf8");
}

const fresh = tryCache(true);
if (fresh) { process.stdout.write(fresh); process.exit(0); }

// 远程拉取
function fetch() {
  return new Promise((resolve, reject) => {
    const token = readToken();
    const req = https.request({
      hostname: new URL(API_BASE).hostname,
      port: 443,
      path: `/skill/${skillName}`,
      method: "POST",
      timeout: 15000,
      headers: { Authorization: `Bearer ${token}`, "Content-Type": "application/json", "Content-Length": 2 }
    }, (res) => {
      let buf = "";
      res.on("data", c => buf += c);
      res.on("end", () => {
        if (res.statusCode === 200) resolve(buf);
        else reject(new Error(`HTTP ${res.statusCode}: ${buf.slice(0, 150)}`));
      });
    });
    req.on("error", reject);
    req.on("timeout", () => { req.destroy(); reject(new Error("timeout")); });
    req.write("{}");
    req.end();
  });
}

fetch().then(prompt => {
  fs.writeFileSync(cacheFile, prompt, { mode: 0o600 });
  process.stdout.write(prompt);
}).catch(e => {
  // 离线降级: 用过期缓存
  const stale = tryCache(false);
  if (stale) {
    process.stderr.write(`[WARN] 离线模式, 使用 stale cache: ${e.message}\n`);
    process.stdout.write(stale);
  } else {
    die(`远程获取失败 + 无缓存: ${e.message}`);
  }
});