const axios = require('axios');

async function getDeviceCode(clientId) {
    const params = new URLSearchParams({
        client_id: clientId,
        scope: 'SDPOnDemand.requests.READ',
        grant_type: 'device_request',
        access_type: 'offline'
    });

    const res = await axios.post('https://accounts.zoho.com/oauth/v3/device/code', params);
    return res.data;
}

function pollForToken(clientId, clientSecret, deviceCode, interval, expiresIn) {
    const pollParams = new URLSearchParams({
        client_id: clientId,
        client_secret: clientSecret,
        code: deviceCode,
        grant_type: 'device_token'
    });

    return new Promise((resolve, reject) => {
        const deadline = Date.now() + (expiresIn || 300) * 1000;

        const timer = setInterval(async () => {
            if (Date.now() > deadline) {
                clearInterval(timer);
                reject(new Error('Expired try again.'));
                return;
            }

            try {
                const res = await axios.post('https://accounts.zoho.com/oauth/v3/device/token', pollParams);
                if (res.data.access_token) {
                    clearInterval(timer);
                    resolve(res.data.access_token);
                }
            } catch (err) {
            }
        }, interval + 500);
    });
}

async function startAuthentication({ clientId, clientSecret, state }) {
    state.auth = 'pending';
    state.lastError = null;

    const deviceData = await getDeviceCode(clientId);
    state.verificationUrl = deviceData.verification_uri_complete;
    state.userCode = deviceData.user_code;

    console.log('Open this URL and authorize:', deviceData.verification_uri_complete);
    console.log('Code: ', deviceData.user_code);

    try {
        const accessToken = await pollForToken(
            clientId,
            clientSecret,
            deviceData.device_code,
            deviceData.interval,
            deviceData.expires_in
        );

        state.auth = 'connected';
        state.verificationUrl = null;
        state.userCode = null;
        return { accessToken };
    } catch (err) {
        state.auth = 'error';
        state.lastError = err.message;
        state.verificationUrl = null;
        state.userCode = null;
        return null;
    }
}

module.exports = {
    startAuthentication
};