const configManager = require('../../config/configManager.js');
const REALTIME_URL = process.env.REALTIME_URL;

/**
 * Autentica il sensore per connetterlo al server.
 * Il token viene inviato al server, che restituisce un token temporaneo per la connessione websocket.
 * @returns {Promise<{socketToken: string, sensorId: string, expiresIn: number}|null>}
 */
async function authenticate() {
    const SENSOR_CODE = configManager.getSensorCode();
    const SENSOR_NAME = configManager.getSensorName();

    if (!REALTIME_URL || !SENSOR_CODE || !SENSOR_NAME) {
        console.error('[REALTIME|AUTH] REALTIME_URL, SENSOR_CODE o SENSOR_NAME non configurati');
        return null;
    }

    try {
        const response = await fetch(`${REALTIME_URL}/connect`, {
            method: 'POST',
            headers: { 'Content-Type': 'application/json' },
            body: JSON.stringify({
                name: SENSOR_NAME,
                code: SENSOR_CODE
            })
        });

        if (!response.ok) {
            const err = await response.json().catch(() => ({}));
            console.error(`[REALTIME|AUTH] auth error (${response.status}):`, err.error || 'unknown');
            return null;
        }

        const data = await response.json();
        // Server risponde { s: 'ok', t: token }
        if (data.s !== 'ok' || !data.t) {
            console.error('[REALTIME|AUTH] Risposta inattesa:', data);
            return null;
        }

        console.log(`[REALTIME|AUTH] Autenticato: ${SENSOR_NAME}, token valido 5s`);
        return { socketToken: data.t };

    } catch (error) {
        console.error(`[REALTIME|AUTH] error: ${error.message}`);
        return null;
    }
}

module.exports = { authenticate };