// メッセージ送信
async function sendLineworksMessage(botId, userId, messageText) {
    const accessToken = await getAccessToken();
    if (!accessToken) {
        console.log('アクセストークンの取得に失敗しました');
        throw new Error('アクセストークンの取得に失敗しました');
    }

    // userIdに@が含まれない場合はchannelIdとして扱う
    let apiUrl;
    if (userId.includes('@')) {
        apiUrl = `https://www.worksapis.com/v1.0/bots/${botId}/users/${userId}/messages`;
    } else {
        apiUrl = `https://www.worksapis.com/v1.0/bots/${botId}/channels/${userId}/messages`;
    }

    const body = {
        'content': {
            'type': 'text',
            'text': messageText
        }
    };

    const response = await fetch(apiUrl, {
        method: 'POST',
        headers: {
            'Content-Type': 'application/json;charset=UTF-8',
            'Authorization': `Bearer ${accessToken}`
        },
        body: JSON.stringify(body)
    });

    if (response.ok) {
        console.log('メッセージ送信成功');
        return { success: true, message: '送信成功' };
    } else {
        const errorText = await response.text();
        console.log('メッセージ送信失敗:', errorText);
        return { success: false, message: `送信失敗: ${errorText}` };
    }
}

// アクセストークン取得
async function getAccessToken() {
    const clientId = 'V58hNobcAqRcQPerySMz';
    const clientSecret = 'gJ84XQtigD';
    const serviceAccount = 'x94xh.serviceaccount@works-nextgroup2';
    const privateKey = fs.readFileSync('./modules/private_20250530180606.key', 'utf8');
    const apiUrl = 'https://auth.worksmobile.com/oauth2/v2.0/token';
    const now = Math.floor(Date.now() / 1000);

    // JWT生成
    const payload = {
        'iss': clientId,
        'sub': serviceAccount,
        'iat': now,
        'exp': now + 60 * 5,
        'aud': apiUrl
    };
    const assertion = jwt.sign(payload, privateKey, { 'algorithm': 'RS256' });

    const body = new URLSearchParams({
        'assertion': assertion,
        'grant_type': 'urn:ietf:params:oauth:grant-type:jwt-bearer',
        'client_id': clientId,
        'client_secret': clientSecret,
        'scope': 'bot'
    });

    const response = await fetch(apiUrl, {
        'method': 'POST',
        'headers': { 'Content-Type': 'application/x-www-form-urlencoded' },
        'body': body.toString()
    });

    if (response.ok) {
        const data = await response.json();
        console.log('アクセストークン取得成功');
        return data.access_token;
    } else {
        const errorText = await response.text();
        console.log('アクセストークン取得失敗:', errorText);
        return null;
    }
}