const WECOM_API_ORIGIN = "https://qyapi.weixin.qq.com";
const DEFAULT_DUE_DAYS = 3;

export type WecomBindings = {
  WECOM_CORP_ID?: string;
  WECOM_AGENT_ID?: string;
  WECOM_SECRET?: string;
  WECOM_ROBOT_WEBHOOK?: string;
  WECOM_NOTIFY_DUE_DAYS?: string;
};

export type WecomConfig = {
  corpId: string;
  agentId: string;
  secret: string;
  robotWebhook: string;
  dueDays: number;
};

type FetchLike = typeof fetch;

type WecomEnvelope = {
  errcode?: number;
  errmsg?: string;
  access_token?: string;
  expires_in?: number;
  invaliduser?: string;
  follow_user?: Array<{ userid: string }>;
  external_userid?: string[];
  external_contact?: {
    external_userid?: string;
    name?: string;
    avatar?: string;
    corp_fullname?: string;
  };
  next_cursor?: string;
  group_chat_list?: Array<{ chat_id?: string; status?: number }>;
  group_chat?: {
    name?: string;
    owner?: string;
    member_count?: number;
  };
  fail_list?: string[];
  msgid?: string;
};

export type WecomExternalContact = {
  externalUserId: string;
  name: string;
  avatar: string;
  corpName: string;
  ownerUserId: string;
};

type CachedAccessToken = {
  corpId: string;
  secret: string;
  token: string;
  expiresAt: number;
};

let cachedAccessToken: CachedAccessToken | null = null;

export class WecomClientError extends Error {
  status: number;

  constructor(message: string, status = 502) {
    super(message);
    this.name = "WecomClientError";
    this.status = status;
  }
}

function bindingValue(value: unknown) {
  return String(value ?? "").trim();
}

function safeMessage(value: unknown) {
  return String(value ?? "").trim().slice(0, 240);
}

export function resolveWecomConfig(bindings: WecomBindings): WecomConfig {
  return {
    corpId: bindingValue(bindings.WECOM_CORP_ID),
    agentId: bindingValue(bindings.WECOM_AGENT_ID),
    secret: bindingValue(bindings.WECOM_SECRET),
    robotWebhook: bindingValue(bindings.WECOM_ROBOT_WEBHOOK),
    dueDays: parseDueDays(bindings.WECOM_NOTIFY_DUE_DAYS),
  };
}

function parseDueDays(value: string | undefined) {
  const parsed = Number(bindingValue(value));
  if (!Number.isFinite(parsed) || parsed < 1) return DEFAULT_DUE_DAYS;
  return Math.min(30, Math.floor(parsed));
}

function hasAppCredentials(config: WecomConfig) {
  return Boolean(config.corpId && config.agentId && config.secret);
}

async function readEnvelope(
  response: Response,
  fallbackMessage: string,
): Promise<WecomEnvelope> {
  const text = await response.text();
  try {
    return JSON.parse(text) as WecomEnvelope;
  } catch {
    throw new WecomClientError(
      `${fallbackMessage}（企业微信返回了非 JSON 响应）`,
      502,
    );
  }
}

function ensureOk(
  payload: WecomEnvelope,
  fallbackMessage: string,
) {
  const code = Number(payload.errcode ?? 0);
  if (code === 0) return;
  const message = safeMessage(payload.errmsg) || fallbackMessage;
  if (code === 40014 || code === 42001) {
    throw new WecomClientError(`企业微信 access_token 无效：${message}`, 401);
  }
  throw new WecomClientError(`${fallbackMessage}（${message}）`, 502);
}

async function fetchAccessToken(
  config: WecomConfig,
  fetchImpl: FetchLike,
) {
  if (
    cachedAccessToken?.corpId === config.corpId &&
    cachedAccessToken?.secret === config.secret &&
    cachedAccessToken.expiresAt > Date.now() + 60_000
  ) {
    return cachedAccessToken.token;
  }
  const url = new URL(`${WECOM_API_ORIGIN}/cgi-bin/gettoken`);
  url.searchParams.set("corpid", config.corpId);
  url.searchParams.set("corpsecret", config.secret);
  const response = await fetchImpl(url.toString(), {
    method: "GET",
    signal: AbortSignal.timeout(12_000),
  });
  const payload = await readEnvelope(response, "获取企业微信 access_token 失败");
  if (!response.ok) {
    throw new WecomClientError(
      `获取企业微信 access_token 失败（HTTP ${response.status}）`,
      502,
    );
  }
  ensureOk(payload, "获取企业微信 access_token 失败");
  const token = bindingValue(payload.access_token);
  if (!token) {
    throw new WecomClientError("企业微信未返回有效 access_token", 502);
  }
  cachedAccessToken = {
    corpId: config.corpId,
    secret: config.secret,
    token,
    expiresAt:
      Date.now() + Math.max(300, Number(payload.expires_in) || 7_200) * 1_000,
  };
  return token;
}

export async function sendWecomRobotMessage(
  content: string,
  config: WecomConfig,
  fetchImpl: FetchLike = fetch,
): Promise<void> {
  if (!config.robotWebhook) {
    console.warn("[KOC LOOP] wecom robot webhook not configured, skipping");
    return;
  }
  const response = await fetchImpl(config.robotWebhook, {
    method: "POST",
    headers: { "Content-Type": "application/json; charset=utf-8" },
    body: JSON.stringify({
      msgtype: "text",
      text: { content },
    }),
    signal: AbortSignal.timeout(10_000),
  });
  const payload = await readEnvelope(response, "企业微信群机器人推送失败");
  if (!response.ok) {
    throw new WecomClientError(
      `企业微信群机器人推送失败（HTTP ${response.status}）`,
      502,
    );
  }
  ensureOk(payload, "企业微信群机器人推送失败");
}

export async function sendWecomAppMessage(
  externalUserIds: string[],
  content: string,
  config: WecomConfig,
  fetchImpl: FetchLike = fetch,
): Promise<{ sent: number; failed: number; skipped: boolean }> {
  const normalized = externalUserIds
    .map((id) => bindingValue(id))
    .filter((id) => id.length > 0);
  if (normalized.length === 0) {
    return { sent: 0, failed: 0, skipped: true };
  }
  if (!hasAppCredentials(config)) {
    return { sent: 0, failed: 0, skipped: true };
  }
  const token = await fetchAccessToken(config, fetchImpl);
  const url = `${WECOM_API_ORIGIN}/cgi-bin/message/send?access_token=${encodeURIComponent(token)}`;
  const response = await fetchImpl(url, {
    method: "POST",
    headers: { "Content-Type": "application/json; charset=utf-8" },
    body: JSON.stringify({
      touser: normalized.join("|"),
      msgtype: "text",
      agentid: Number(config.agentId),
      text: { content },
    }),
    signal: AbortSignal.timeout(12_000),
  });
  const payload = await readEnvelope(response, "企业微信应用消息推送失败");
  if (!response.ok) {
    throw new WecomClientError(
      `企业微信应用消息推送失败（HTTP ${response.status}）`,
      502,
    );
  }
  ensureOk(payload, "企业微信应用消息推送失败");
  const invalid = bindingValue(payload.invaliduser).split("|").filter(Boolean);
  return {
    sent: Math.max(0, normalized.length - invalid.length),
    failed: invalid.length,
    skipped: false,
  };
}

export function clearWecomAccessTokenCacheForTests() {
  cachedAccessToken = null;
}

export type WecomGroupChat = {
  chatId: string;
  name: string;
  ownerUserId: string;
  memberCount: number;
  status: number;
};

export async function listCustomerGroupChats(
  config: WecomConfig,
  fetchImpl: FetchLike = fetch,
): Promise<WecomGroupChat[]> {
  if (!hasAppCredentials(config)) return [];
  const token = await fetchAccessToken(config, fetchImpl);

  const chatIds: Array<{ chatId: string; status: number }> = [];
  let cursor = "";
  do {
    const listUrl = `${WECOM_API_ORIGIN}/cgi-bin/externalcontact/groupchat/list?access_token=${encodeURIComponent(token)}`;
    const listResp = await fetchImpl(listUrl, {
      method: "POST",
      headers: { "Content-Type": "application/json; charset=utf-8" },
      body: JSON.stringify({ limit: 100, cursor }),
      signal: AbortSignal.timeout(12_000),
    });
    const listPayload = await readEnvelope(listResp, "获取企业微信客户群列表失败");
    if (!listResp.ok) {
      throw new WecomClientError(
        `获取企业微信客户群列表失败（HTTP ${listResp.status}）`,
        502,
      );
    }
    ensureOk(listPayload, "获取企业微信客户群列表失败");
    for (const chat of listPayload.group_chat_list ?? []) {
      const chatId = bindingValue(chat.chat_id);
      if (chatId) chatIds.push({ chatId, status: Number(chat.status ?? 0) });
    }
    cursor = bindingValue(listPayload.next_cursor);
  } while (cursor);

  const groups: WecomGroupChat[] = [];
  for (const { chatId, status } of chatIds) {
    if (status !== 0) continue;
    const getUrl = `${WECOM_API_ORIGIN}/cgi-bin/externalcontact/groupchat/get?access_token=${encodeURIComponent(token)}`;
    const getResp = await fetchImpl(getUrl, {
      method: "POST",
      headers: { "Content-Type": "application/json; charset=utf-8" },
      body: JSON.stringify({ chat_id: chatId }),
      signal: AbortSignal.timeout(12_000),
    });
    const getPayload = await readEnvelope(getResp, "获取企业微信客户群详情失败");
    if (!getResp.ok) continue;
    if (Number(getPayload.errcode ?? 0) !== 0) continue;
    const detail = getPayload.group_chat;
    groups.push({
      chatId,
      name: bindingValue(detail?.name),
      ownerUserId: bindingValue(detail?.owner),
      memberCount: Number(detail?.member_count ?? 0),
      status,
    });
  }
  return groups;
}

export type WecomGroupMsgLink = {
  title: string;
  desc?: string;
  url: string;
  picurl?: string;
};

export async function createGroupMsgTemplate(
  config: WecomConfig,
  params: {
    sender: string;
    chatIdList: string[];
    text?: string;
    link?: WecomGroupMsgLink;
  },
  fetchImpl: FetchLike = fetch,
): Promise<{ msgid: string; failList: string[] }> {
  if (!hasAppCredentials(config)) {
    throw new WecomClientError(
      "企业微信自建应用未配置（WECOM_CORP_ID / WECOM_AGENT_ID / WECOM_SECRET）",
      400,
    );
  }
  const chatIdList = params.chatIdList.map(bindingValue).filter(Boolean);
  if (chatIdList.length === 0) {
    throw new WecomClientError("客户群列表为空", 400);
  }
  const sender = bindingValue(params.sender);
  if (!sender) {
    throw new WecomClientError("发送成员（群主 userid）不能为空", 400);
  }
  const text = String(params.text ?? "").trim();
  const link = params.link;
  if (!text && !link) {
    throw new WecomClientError("文本与图文附件不能同时为空", 400);
  }

  const token = await fetchAccessToken(config, fetchImpl);
  const url = `${WECOM_API_ORIGIN}/cgi-bin/externalcontact/add_msg_template?access_token=${encodeURIComponent(token)}`;
  const response = await fetchImpl(url, {
    method: "POST",
    headers: { "Content-Type": "application/json; charset=utf-8" },
    body: JSON.stringify({
      chat_type: "group",
      chat_id_list: chatIdList,
      sender,
      ...(text ? { text: { content: text } } : {}),
      ...(link
        ? {
            attachments: [
              {
                msgtype: "link",
                link: {
                  title: link.title,
                  desc: link.desc ?? "",
                  url: link.url,
                  picurl: link.picurl ?? "",
                },
              },
            ],
          }
        : {}),
    }),
    signal: AbortSignal.timeout(12_000),
  });
  const payload = await readEnvelope(response, "创建企业群发失败");
  if (!response.ok) {
    throw new WecomClientError(
      `创建企业群发失败（HTTP ${response.status}）`,
      502,
    );
  }
  ensureOk(payload, "创建企业群发失败");
  return {
    msgid: bindingValue(payload.msgid),
    failList: (payload.fail_list ?? []).filter(Boolean),
  };
}

export async function listExternalContacts(
  config: WecomConfig,
  fetchImpl: FetchLike = fetch,
): Promise<WecomExternalContact[]> {
  if (!hasAppCredentials(config)) return [];
  const token = await fetchAccessToken(config, fetchImpl);

  const followUrl = `${WECOM_API_ORIGIN}/cgi-bin/externalcontact/get_follow_user_list?access_token=${encodeURIComponent(token)}`;
  const followResp = await fetchImpl(followUrl, {
    method: "GET",
    signal: AbortSignal.timeout(12_000),
  });
  const followPayload = await readEnvelope(
    followResp,
    "获取企业微信跟进人列表失败",
  );
  if (!followResp.ok) {
    throw new WecomClientError(
      `获取企业微信跟进人列表失败（HTTP ${followResp.status}）`,
      502,
    );
  }
  ensureOk(followPayload, "获取企业微信跟进人列表失败");
  const ownerUserIds = (followPayload.follow_user ?? [])
    .map((user) => bindingValue(user.userid))
    .filter(Boolean);

  const ownerToExternalIds: Array<{ externalUserId: string; ownerUserId: string }> = [];
  for (const ownerUserId of ownerUserIds) {
    const listUrl = `${WECOM_API_ORIGIN}/cgi-bin/externalcontact/list?access_token=${encodeURIComponent(token)}&userid=${encodeURIComponent(ownerUserId)}`;
    const listResp = await fetchImpl(listUrl, {
      method: "GET",
      signal: AbortSignal.timeout(12_000),
    });
    const listPayload = await readEnvelope(
      listResp,
      "获取企业微信外部联系人列表失败",
    );
    if (!listResp.ok) continue;
    if (Number(listPayload.errcode ?? 0) !== 0) continue;
    const externalIds = (listPayload.external_userid ?? []).filter(Boolean);
    for (const externalUserId of externalIds) {
      ownerToExternalIds.push({ externalUserId, ownerUserId });
    }
  }

  const contacts: WecomExternalContact[] = [];
  for (const { externalUserId, ownerUserId } of ownerToExternalIds) {
    const getUrl = `${WECOM_API_ORIGIN}/cgi-bin/externalcontact/get?access_token=${encodeURIComponent(token)}&external_userid=${encodeURIComponent(externalUserId)}`;
    const getResp = await fetchImpl(getUrl, {
      method: "GET",
      signal: AbortSignal.timeout(12_000),
    });
    const getPayload = await readEnvelope(
      getResp,
      "获取企业微信外部联系人详情失败",
    );
    if (!getResp.ok) continue;
    if (Number(getPayload.errcode ?? 0) !== 0) continue;
    const info = getPayload.external_contact;
    if (!info) continue;
    contacts.push({
      externalUserId,
      name: bindingValue(info.name),
      avatar: bindingValue(info.avatar),
      corpName: bindingValue(info.corp_fullname) || bindingValue(info.name),
      ownerUserId,
    });
  }
  return contacts;
}