import {
  decryptWecomCallback,
  verifyWecomCallbackSignature,
  wecomSignaturesMatch,
  WecomCallbackCryptoError,
} from "../../../lib/wecom-callback-crypto";
import {
  extractWecomEncryptField,
  handleWecomCallbackEvent,
  parseWecomCallbackXml,
} from "../../../lib/wecom-callback-events";
import { isEnabled, getRuntimeEnv } from "../../../lib/runtime-env";

type CallbackConfig = {
  token: string;
  encodingAesKey: string;
  corpId: string;
};

function resolveCallbackConfig(): CallbackConfig | null {
  const env = getRuntimeEnv();
  if (!isEnabled(env.WECOM_CALLBACK_ENABLED, false)) return null;
  const token = String(env.WECOM_CALLBACK_TOKEN ?? "").trim();
  const encodingAesKey = String(
    env.WECOM_CALLBACK_ENCODING_AES_KEY ?? "",
  ).trim();
  if (!token || !encodingAesKey) return null;
  return {
    token,
    encodingAesKey,
    corpId: String(env.WECOM_CORP_ID ?? "").trim(),
  };
}

function readCallbackQuery(request: Request) {
  const url = new URL(request.url);
  return {
    msgSignature: url.searchParams.get("msg_signature") ?? "",
    timestamp: url.searchParams.get("timestamp") ?? "",
    nonce: url.searchParams.get("nonce") ?? "",
    echostr: url.searchParams.get("echostr") ?? "",
  };
}

export async function GET(request: Request) {
  const config = resolveCallbackConfig();
  if (!config) {
    return new Response("企业微信回调未启用", { status: 403 });
  }
  const { msgSignature, timestamp, nonce, echostr } =
    readCallbackQuery(request);
  if (!msgSignature || !timestamp || !nonce || !echostr) {
    return new Response("缺少回调校验参数", { status: 400 });
  }
  const expected = verifyWecomCallbackSignature(
    config.token,
    timestamp,
    nonce,
    echostr,
  );
  if (!wecomSignaturesMatch(expected, msgSignature)) {
    return new Response("签名校验失败", { status: 403 });
  }
  try {
    const { message } = decryptWecomCallback(echostr, config.encodingAesKey);
    return new Response(message, {
      status: 200,
      headers: { "Content-Type": "text/plain; charset=utf-8" },
    });
  } catch (error) {
    if (error instanceof WecomCallbackCryptoError) {
      console.warn("[KOC LOOP] wecom callback echostr decrypt failed", error);
      return new Response(error.message, { status: 400 });
    }
    throw error;
  }
}

export async function POST(request: Request) {
  const config = resolveCallbackConfig();
  if (!config) {
    return new Response("企业微信回调未启用", { status: 403 });
  }
  const { msgSignature, timestamp, nonce } = readCallbackQuery(request);
  try {
    const body = await request.text();
    const encrypt = extractWecomEncryptField(body);
    if (!encrypt) {
      return new Response("回调报文缺少 Encrypt 字段", { status: 400 });
    }
    if (!msgSignature || !timestamp || !nonce) {
      return new Response("缺少回调校验参数", { status: 400 });
    }
    const expected = verifyWecomCallbackSignature(
      config.token,
      timestamp,
      nonce,
      encrypt,
    );
    if (!wecomSignaturesMatch(expected, msgSignature)) {
      return new Response("签名校验失败", { status: 403 });
    }
    const { message, receiveId } = decryptWecomCallback(
      encrypt,
      config.encodingAesKey,
    );
    if (config.corpId && receiveId !== config.corpId) {
      console.warn(
        "[KOC LOOP] wecom callback receiveid mismatch",
        { expected: config.corpId },
      );
      return new Response("receiveid 校验失败", { status: 403 });
    }
    const fields = parseWecomCallbackXml(message);
    handleWecomCallbackEvent(fields);
    return new Response("", { status: 200 });
  } catch (error) {
    if (error instanceof WecomCallbackCryptoError) {
      console.warn("[KOC LOOP] wecom callback decrypt failed", error);
      return new Response(error.message, { status: 400 });
    }
    console.error("[KOC LOOP] wecom callback failed", error);
    return new Response("", { status: 200 });
  }
}