/**
 * 飞书消息服务
 * 支持应用机器人（私聊/群聊）和自定义机器人（群聊 webhook）
 */

const crypto = require('crypto');
const config = require('../config/env');
const logger = require('../utils/logger');

let accessToken = null;
let tokenExpireAt = 0;

/**
 * 获取应用机器人的 access_token（用于私聊）
 */
async function getAccessToken() {
    const { appId, appSecret } = config.lark;

    if (!appId || !appSecret) {
        throw new Error('飞书应用未配置：请设置 LARK_APP_ID 和 LARK_APP_SECRET');
    }

    //如果 token 还有效，直接返回
    if (accessToken && Date.now() < tokenExpireAt - 60000) {
        return accessToken;
    }

    const res = await fetch('https://open.feishu.cn/open-apis/auth/v3/tenant_access_token/internal', {
        method: 'POST',
        headers: { 'Content-Type': 'application/json' },
        body: JSON.stringify({ app_id: appId, app_secret: appSecret })
    });

    const data = await res.json();

    if (data.code !== 0) {
        throw new Error(`获取飞书 access_token 失败: ${data.msg}`);
    }

    accessToken = data.tenant_access_token;
    tokenExpireAt = Date.now() + data.expire * 1000;

    logger.info('[Lark] Access token refreshed');
    return accessToken;
}

/**
 * 生成签名（用于自定义机器人 webhook）
 */
function genSign(timestamp, secret) {
    const stringToSign = `${timestamp}\n${secret}`;
    const hmac = crypto.createHmac('sha256', stringToSign);
    return hmac.digest('base64');
}

/**
 * 通过自定义机器人 webhook 发送消息（群聊）
 */
async function sendWebhook(webhookUrl, message, secret = null) {
    const body = { ...message };

    if (secret) {
        const timestamp = Math.floor(Date.now() / 1000).toString();
        body.timestamp = timestamp;
        body.sign = genSign(timestamp, secret);
    }

    const res = await fetch(webhookUrl, {
        method: 'POST',
        headers: { 'Content-Type': 'application/json' },
        body: JSON.stringify(body)
    });

    const data = await res.json();

    if (data.code !== 0) {
        throw new Error(`飞书 webhook 发送失败: ${data.msg || JSON.stringify(data)}`);
    }

    return data;
}

/**
 * 通过应用机器人 API 发送消息（私聊/群聊）
 * @param {string} receiveId - 接收者 ID（open_id/user_id/chat_id）
 * @param {string} receiveIdType - ID 类型：open_id | user_id | union_id | email | chat_id
 * @param {string} msgType - 消息类型：text | post | interactive
 * @param {object} content - 消息内容
 */
async function sendMessage(receiveId, receiveIdType, msgType, content) {
    const token = await getAccessToken();

    const res = await fetch(`https://open.feishu.cn/open-apis/im/v1/messages?receive_id_type=${receiveIdType}`, {
        method: 'POST',
        headers: {
            'Content-Type': 'application/json',
            'Authorization': `Bearer ${token}`
        },
        body: JSON.stringify({
            receive_id: receiveId,
            msg_type: msgType,
            content: typeof content === 'string' ? content : JSON.stringify(content)
        })
    });

    const data = await res.json();

    if (data.code !== 0) {
        throw new Error(`飞书消息发送失败: ${data.msg || JSON.stringify(data)}`);
    }

    return data;
}

/**
 * 发送文本消息（便捷方法）
 */
async function sendText(receiveId, receiveIdType, text, atUsers = []) {
    let finalText = text;

    //添加 @ 用户
    if (atUsers && atUsers.length > 0) {
        const atTags = atUsers.map(uid =>
            uid === 'all' ? '<at user_id="all">所有人</at>' : `<at user_id="${uid}"></at>`
        ).join(' ');
        finalText = `${atTags} ${text}`;
    }

    return sendMessage(receiveId, receiveIdType, 'text', { text: finalText });
}

/**
 * 发送富文本消息
 */
async function sendPost(receiveId, receiveIdType, title, content, atUsers = []) {
    const postContent = {
        zh_cn: {
            title,
            content: [[]]
        }
    };

    //添加 @ 用户
    if (atUsers && atUsers.length > 0) {
        atUsers.forEach(uid => {
            postContent.zh_cn.content[0].push({
                tag: 'at',
                user_id: uid
            });
        });
        postContent.zh_cn.content[0].push({ tag: 'text', text: ' ' });
    }

    //添加正文
    postContent.zh_cn.content[0].push({ tag: 'text', text: content });

    return sendMessage(receiveId, receiveIdType, 'post', { post: postContent });
}

/**
 * 发送 webhook 文本消息（便捷方法）
 */
async function sendWebhookText(webhookUrl, text, secret = null, atUsers = []) {
    let finalText = text;

    if (atUsers && atUsers.length > 0) {
        const atTags = atUsers.map(uid =>
            uid === 'all' ? '<at user_id="all">所有人</at>' : `<at user_id="${uid}"></at>`
        ).join(' ');
        finalText = `${atTags} ${text}`;
    }

    return sendWebhook(webhookUrl, {
        msg_type: 'text',
        content: { text: finalText }
    }, secret);
}

/**
 * 发送 webhook 富文本消息
 */
async function sendWebhookPost(webhookUrl, title, content, secret = null, atUsers = []) {
    const postContent = [[{ tag: 'text', text: content }]];

    if (atUsers && atUsers.length > 0) {
        const atElements = atUsers.map(uid => ({
            tag: 'at',
            user_id: uid
        }));
        postContent[0] = [...atElements, { tag: 'text', text: ' ' }, ...postContent[0]];
    }

    return sendWebhook(webhookUrl, {
        msg_type: 'post',
        content: {
            post: {
                zh_cn: { title, content: postContent }
            }
        }
    }, secret);
}

/**
 * 通过手机号或邮箱获取用户 open_id
 * @param {string} identifier - 手机号或邮箱
 * @returns {string} open_id
 */
async function getOpenIdByContact(identifier) {
    const token = await getAccessToken();

    const isEmail = identifier.includes('@');
    const payload = isEmail
        ? { emails: [identifier] }
        : { mobiles: [identifier] };

    const res = await fetch('https://open.feishu.cn/open-apis/contact/v3/users/batch_get_id?user_id_type=open_id', {
        method: 'POST',
        headers: {
            'Content-Type': 'application/json',
            'Authorization': `Bearer ${token}`
        },
        body: JSON.stringify(payload)
    });

    const data = await res.json();

    if (data.code !== 0) {
        throw new Error(`获取用户 open_id 失败: ${data.msg}`);
    }

    const userList = data.data?.user_list || [];
    if (userList.length === 0 || !userList[0].user_id) {
        throw new Error(`未找到用户: ${identifier}`);
    }

    return userList[0].user_id;
}

/**
 * 获取配置的默认 webhook URL
 */
function getDefaultWebhookUrl() {
    return config.lark.webhookUrl;
}

/**
 * 获取配置的默认 webhook secret
 */
function getDefaultWebhookSecret() {
    return config.lark.webhookSecret || null;
}

module.exports = {
    getAccessToken,
    genSign,
    sendWebhook,
    sendMessage,
    sendText,
    sendPost,
    sendWebhookText,
    sendWebhookPost,
    getOpenIdByContact,
    getDefaultWebhookUrl,
    getDefaultWebhookSecret
};