/**
 * m3.mjs — new-api M3 客户端(openai 协议 + function-calling)
 * owner：amodel-gen spike ｜ 消费方：gen.mjs(ReAct 循环每轮调 chat)
 *
 * 单一职责:发一轮 chat/completions(带 tools)→ 返 {message, usage, finishReason}。
 * 含超时 + 重试(429/5xx/IO 重试;4xx 不重试)。模型固定 MiniMax-M3(founder 定)。
 * 密钥(§9):优先 env NEWAPI_KEY,否则从 docs/内网凭据与端点.md(内网允许入仓)解析——doc 是单一事实源。
 */

'use strict';

import { readFileSync } from 'node:fs';
import { join } from 'node:path';
import { REPO_ROOT } from './tools.mjs';

const BASE = (process.env.NEWAPI_BASE_URL || 'http://100.64.0.8:3000').replace(/\/+$/, '');
const MODEL = process.env.AMGEN_MODEL || 'MiniMax-M3'; // founder:只用 M3
const sleep = (ms) => new Promise((r) => setTimeout(r, ms));

/** 取网关 token:env 优先,否则解析项目密钥文档(§9 单一事实源)。 */
function getKey() {
  if (process.env.NEWAPI_KEY) return process.env.NEWAPI_KEY;
  try {
    const doc = readFileSync(join(REPO_ROOT, 'docs/内网凭据与端点.md'), 'utf8');
    const m = doc.match(/NEWAPI_KEY[^\n]*?(sk-[A-Za-z0-9]+)/);
    if (m) return m[1];
  } catch { /* fall through */ }
  throw new Error('找不到 NEWAPI_KEY(请设 env 或确认 docs/内网凭据与端点.md 存在)');
}
const KEY = getKey();

/**
 * 发一轮带 tools 的 chat/completions。
 * @param {Array<object>} messages openai 消息数组(含 system/user/assistant/tool)
 * @param {Array<object>} tools    function-calling 工具定义
 * @param {{maxTokens?:number, temperature?:number, timeoutMs?:number}} [opt]
 * @returns {Promise<{message:object, usage:object, finishReason:string}>}
 */
export async function chat(messages, tools, opt = {}) {
  const { maxTokens = 16000, temperature = 0.3, timeoutMs = 180000 } = opt;
  const body = { model: MODEL, messages, tools, tool_choice: 'auto', max_tokens: maxTokens, temperature };
  let lastErr;
  for (let attempt = 0; attempt < 3; attempt++) {
    const ctrl = new AbortController();
    const timer = setTimeout(() => ctrl.abort(), timeoutMs);
    try {
      const r = await fetch(`${BASE}/v1/chat/completions`, {
        method: 'POST',
        headers: { Authorization: `Bearer ${KEY}`, 'Content-Type': 'application/json' },
        body: JSON.stringify(body),
        signal: ctrl.signal,
      });
      clearTimeout(timer);
      if (!r.ok) {
        const txt = await r.text().catch(() => '');
        // 4xx(除 429)= 请求本身错,不重试,直接抛
        if (r.status !== 429 && r.status < 500) throw new Error(`HTTP ${r.status}: ${txt.slice(0, 300)}`);
        lastErr = new Error(`HTTP ${r.status}: ${txt.slice(0, 200)}`);
        await sleep(1500 * (attempt + 1));
        continue;
      }
      const d = await r.json();
      const ch = d.choices && d.choices[0];
      if (!ch) throw new Error('响应无 choices: ' + JSON.stringify(d).slice(0, 300));
      return { message: ch.message, usage: d.usage || {}, finishReason: ch.finish_reason };
    } catch (e) {
      clearTimeout(timer);
      lastErr = e;
      await sleep(1500 * (attempt + 1)); // 超时/IO 重试
    }
  }
  throw lastErr || new Error('M3 chat 失败(重试耗尽)');
}

export { MODEL, BASE };