NodeRED Function to Download OVO Smart-meter Readings

OVO_readings.js

// This function uses a companion HTTP Request node to load data from the OVO API
// service, with the HTTP response looped back into this node's input.
//
// -  Hence an initiating request will be cycled through this node many times
//.
// -  The state and context is maintained in msg using the msg.state object.
//
// -  msg.state.id used to sequence the cycles.
//
// -  The initiating cycle has a null state with msg.user and msg.pwd containing
//    the OVE creds, and msg.body the dates for the last download.
//
// -  Each of the subsequent cycles processes the results of the previous OVO
//    request optionally creating a SQL insert to load the data in the DB and a
//    URL request for the OVO API service to load the next data chunk.

const MYOVO = 'my.ovoenergy.com';
const PAYMAPI = 'smartpaymapi.ovoenergy.com';
let body = msg.payload;

Object.assign(msg, {                           //  Override various msg properties
    headers: {
        'User-Agent': 'Mozilla/5.0',
        'Accept': 'application/json,text/html',
        'Accept-Language': 'en-GB,en;q=0.5',
        'DNT': '1',
        'Host': PAYMAPI,
        'Connection': 'keep-alive'
    },
    method: 'GET',
    cookies: (msg.responseCookies || msg.cookies || {}),
    payload: null,
    responseCookies: null,
});

if (!msg.state) { msg.state = { id: -1 }; }
const state = msg.state;
state.id++;

const setDataURL = s => {
    let start = new Date(s.start);
    start.setDate(start.getDate() + 1);
    s.start = start.toISOString().substring(0, 10);
    return `https://${PAYMAPI}/usage/api/half-hourly/${s.account}?date=${s.start}`;
};

const extDate = d => (new Date(d)).toISOString().substring(0, 10);  // extract YYYY-MM-DD
const nextDay = d => {
    let start = new Date(d); start.setDate(start.getDate() + 1);
    return start.toISOString().substring(0, 10);
};

const processingStage = [
    () => {                     //  On first page move stuff to state
        state.user = msg.user;
        state.pwd = msg.pwd;
        state.dailyStart = extDate(body[0][0].date);
        state.meterStart = extDate(body[1][0].date);
        msg.url = '/login';
        msg.headers.Host = MYOVO;
        delete msg.user; delete msg.pwd; delete msg.topic;
        return [null, msg];
    },
    () => {                     // Now do OVO loging to establish credentials
        msg.method = 'POST';
        msg.payload = { username: state.user, password: state.pwd, rememberMe: true };
        msg.url = '/api/v2/auth/login';
        msg.headers.Host = MYOVO;
        return [null, msg];
    },
    () => {                     // Setup API session
        msg.url = '/first-login/api/bootstrap/v2/';
        return [null, msg];
    },
    () => {                     // Lookup account details
        state.account = body.selectedAccountId;
        state.customer = body.customerId;
        msg.url = '/orex/api/plans/' + state.account;
        return [null, msg];
    },
    () => {                     // Cache account details and request meter readings
        const contract = body.electricity;
        state.mpxn = contract.mpxn;
        state.msn = contract.msn;
        state.price = { standingCharge: contract.standingCharge.amount };
        for (let r of contract.unitRates) { state.price[r.name] = r.unitRate.amount; }
        msg.url = '/rlc/rac-public-api/api/v5/supplypoints/electricity/' +
            `${state.mpxn}/meters/${state.msn}/readings?from=${state.dailyStart}`;
        return [null, msg];
    },
    () => {                         // save daily readings in MySQL and start daily ½hr reading poll
        const v = body.map(e => ({
            dts: e.readingDateTime.substring(0, 10),
            peak: Number(e.tiers[0].meterRegisterReading),
            offpeak: Number(e.tiers[1].meterRegisterReading)
        })).filter(e => e.dts > state.dailyStart);

        let BV = [];
        for (let i = v.length - 2; i >= 0; i--) {
            const P = state.price;
            const [e, el] = [v[i], v[i + 1]];
            const [p, op] = [e.peak - el.peak, e.offpeak - el.offpeak];
            const Rs = P.standingCharge;
            const [Rp, Rop] = [P.day, P.night];
            const cost = ((Rp * p) + (Rop * op)).toFixed(3);
            BV.push([el.dts, (p + op).toFixed(3), cost, p.toFixed(3), op.toFixed(3), Rs, Rp, Rop]);
        }
        const updateExtTempSQL = `
            UPDATE daily_readings, meter_readings
                   (SELECT date(dts) AS Tdate,
                           substring(substring_index(value,',',3),
                                     length(substring_index(value,',',2))+2) AS temp
                    FROM  eventlog
                    WHERE event='external-temp' AND
                    dts > '${state.dailyStart}') AS T
            SET   extTemp = T.temp
            WHERE daily_readings.dts = T.Tdate
            AND   daily_readings.extTemp IS NULL;`;

        state.start = nextDay(state.meterStart);
        msg.url = `/usage/api/half-hourly/${state.account}?date=${state.start}`;
        return [[{
            topic: 'INSERT INTO daily_readings(dts,Duse,cost,Puse,Ouse,Rstand,Rpeak,Roffp) VALUES ?;',
            payload: [BV]
        },
        { topic: updateExtTempSQL }],
            msg];
    },
    () => {                     // save half-hourly readings in MySQL
        if (!body.electricity) return [null, null];
        let BV = [];
        for (const h of body.electricity.data) {
            const t = h.interval.start;
            BV.push([t.substring(0, 10) + ' ' + t.substring(11, 16), h.consumption]);
        }
        state.start = nextDay(state.start);
        state.id--;
        msg.url = `/usage/api/half-hourly/${state.account}?date=${state.start}`;
        if (!body.electricity.next) { msg = null; }  // turn off next query if next is false
        return [{
            topic: 'INSERT INTO meter_readings(dts,`use`) VALUES ?;',
            payload: [BV]
        }, msg];
    }
];

try {
    try {body = JSON.parse(body);} catch (e) {} // nearly all bodies are JSON
    const [SQLmsg, URLmsg] = processingStage[state.id]();
    if (URLmsg) {
        URLmsg.url = `https://${URLmsg.headers.Host}` + URLmsg.url;
    }
    return [SQLmsg, URLmsg];
} catch (e) { // after last batch add ext temp field for new daily_readings rows
    node.warn(e.stack); return null;
}