const axios = require("axios");
const crypto = require("crypto");
const logger = require("../utils/logger");
const { defaults } = require("./config");

const DEFAULT_TIMEOUT = defaults.timeout;

function getBaseUrl(overrideUrl) {
  const baseUrl = overrideUrl || defaults.baseUrl;
  if (!baseUrl) {
    throw new Error("短信网关地址未配置: 请设置 CONFIG_SMS_BASE_URL 环境变量");
  }
  return baseUrl.endsWith("/") ? baseUrl : `${baseUrl}`;
}

function encodePayload(payload) {
  const json = JSON.stringify(payload);
  return Buffer.from(json, "utf8").toString("base64");
}

function tryDecodeResponse(data) {
  if (data === null || data === undefined) return data;
  if (typeof data !== "string") return data;
  const trimmed = data.trim();
  if (!trimmed) return "";
  try {
    const decoded = Buffer.from(trimmed, "base64").toString("utf8");
    const normalized = decoded.trim();
    if (!normalized) return decoded;
    if (normalized.startsWith("{") || normalized.startsWith("[")) {
      return JSON.parse(decoded);
    }
    return decoded;
  } catch (err) {
    return data;
  }
}

function buildMac(parts) {
  const raw = parts.join("");
  return crypto.createHash("md5").update(raw, "utf8").digest("hex");
}

async function post(pathname, payload, options = {}) {
  const baseUrl = getBaseUrl(options.baseUrl);
  const url = new URL(pathname, baseUrl).toString();
  const encodedPayload = encodePayload(payload);
  const timeout = options.timeout || DEFAULT_TIMEOUT;
  const headers = {
    "Content-Type": "application/json",
    ...(options.headers || {}),
  };

  const sanitizedPayload = {
    ecName: payload.ecName,
    apId: payload.apId,
    mobiles: payload.mobiles,
    templateId: payload.templateId,
    addSerial: payload.addSerial,
    contentBytes:
      typeof payload.content === "string"
        ? Buffer.byteLength(payload.content, "utf8")
        : undefined,
  };

  logger.info({ scope: "sms-request", url, payload: sanitizedPayload });

  try {
    const response = await axios.post(url, encodedPayload, {
      timeout,
      headers,
    });
    const decoded = tryDecodeResponse(response.data);
    logger.info({ scope: "sms-response", url, data: decoded });
    return decoded;
  } catch (error) {
    logger.error({
      scope: "sms-request-error",
      url,
      message: error.message,
    });
    throw error;
  }
}

module.exports = {
  post,
  buildMac,
  tryDecodeResponse,
};