const axios = require("axios");
const baseModel = require("../../middleware/baseModel");
const config = require("../../config/config");
const logs = require("../../tool/logs_proxy");

const upstreamBaseUrl = config.upstream_api_url || "http://127.0.0.1:8888";

/** 写入日志用：序列化响应并截断，避免 TEXT 过大 */
const RESPONSE_BODY_MAX_LEN = 16000;

function serialize_response_for_log(data) {
  if (data === undefined || data === null) return "";
  let s;
  if (typeof data === "string") s = data;
  else {
    try {
      s = JSON.stringify(data);
    } catch (e) {
      s = String(data);
    }
  }
  if (s.length > RESPONSE_BODY_MAX_LEN) {
    return `${s.slice(0, RESPONSE_BODY_MAX_LEN)}…[truncated]`;
  }
  return s;
}

/**
 * 转发请求到上游并记录调用日志
 * @param {object} params
 * @param {string} params.api_path   - 接口路径，如 /user/GetProfile
 * @param {string} params.method     - HTTP 方法
 * @param {object} params.query      - query 参数（透传）
 * @param {object} params.body       - body 参数（透传）
 * @param {object} params.headers    - 需要透传的请求头
 * @param {object} params.auth_ctx   - 鉴权上下文（verifyRequest 返回的 context）
 * @returns {object} { status, data, headers }
 */
async function forwardRequest({ api_path, method, query, body, headers, auth_ctx = {} }) {
  const url = `${upstreamBaseUrl}${api_path}`;
  const start = Date.now();
  let status_code = 0;
  let resp_data = null;
  let resp_headers = {};

  try {
    const forwardHeaders = {};
    if (headers["content-type"]) forwardHeaders["content-type"] = headers["content-type"];
    if (headers["user-agent"]) forwardHeaders["user-agent"] = headers["user-agent"];

    const resp = await axios({
      method: method.toLowerCase(),
      url,
      params: query,
      data: body,
      headers: forwardHeaders,
      timeout: 30000,
      validateStatus: () => true,
    });

    status_code = resp.status;
    resp_data = resp.data;
    resp_headers = resp.headers;
  } catch (err) {
    status_code = 502;
    resp_data = { ok: false, error_code: "UPSTREAM_ERROR", message: err.message };
    logs.error(`[proxy] 转发失败 ${api_path}`, err.message);
  }

  const response_time = Date.now() - start;

  // 异步写调用日志，不阻塞响应
  writeCallLog({
    user_id: auth_ctx.user_id,
    token_id: auth_ctx.token_id,
    api_path,
    http_method: method.toUpperCase(),
    status_code,
    response_time,
    response_body: serialize_response_for_log(resp_data),
  }).catch((e) => logs.error("[proxy] 写调用日志失败", e.message));

  return { status: status_code, data: resp_data, headers: resp_headers };
}

/**
 * 写入 API 调用日志
 */
async function writeCallLog({
  user_id,
  token_id,
  api_path,
  http_method,
  status_code,
  response_time,
  response_body,
}) {
  try {
    const now = new Date();
    const call_date = `${now.getFullYear()}-${String(now.getMonth() + 1).padStart(2, "0")}-${String(now.getDate()).padStart(2, "0")}`;
    await baseModel.biz_api_call_log.create({
      user_id,
      token_id,
      api_path,
      http_method,
      status_code,
      response_time,
      response_body: response_body || null,
      call_date,
      created_at: now,
    });

  } catch (e) {
    logs.error("[proxy] 写调用日志失败", e.message);
  }
}

module.exports = { forwardRequest };