#!/usr/bin/env node

/* eslint-env es2020 */

const API_URL = process.env.API_URL;
const API_KEY = process.env.API_KEY;
const VERBOSE = !!process.env.VERBOSE;

async function main() {
    const config = await fetchConfig();
    const devicesStatus = await fetchDevicesStatus();
    const connectionsStatus = await fetchConnections();

    for (const {deviceID, name} of config.devices) {
        const {connected} = connectionsStatus.connections[deviceID];
        const {lastSeen: lastSeenString} = devicesStatus[deviceID];
        const lastSeenDate = new Date(lastSeenString);
        const {completion, needItems} = await fetchCompletion(deviceID);
        //console.log(name, await fetchCompletion(deviceID));

        checkDevice({name, connected, lastSeenDate, completion, needItems});
    }
}

async function checkDevice({name, connected, lastSeenDate, completion, needItems}) {
    if (VERBOSE) {
        console.error('checkDevice', {name, connected, lastSeenDate, completion, needItems});
    }

    if (lastSeenDate.getTime() === 0 || connected) {
        return;
    }

    if (lastSeenDate < newDateDays(-10)) {
        console.log(`Alert! '${name}' has been missing since ` +
                lastSeenDate.toISOString().replace(/T.*/, ''));
    }
    if (needItems > 0 || completion < 100) {
        console.log(`Alert! '${name}' is out of sync! ` +
                `${Math.round(completion)}%, missing ${needItems} files.`);
    }
}

function newDateDays(days) {
    return new Date(Date.now() + days * 24 * 3600 * 1000);
}

async function fetchConfig() {
    const response = await fetchSyncthing('/rest/config');
    await assertResponseOk(response);
    return response.json();
}

async function fetchDevicesStatus() {
    const response = await fetchSyncthing('/rest/stats/device');
    await assertResponseOk(response);
    return response.json();
}

async function fetchConnections() {
    const response = await fetchSyncthing('/rest/system/connections');
    await assertResponseOk(response);
    return response.json();
}

async function fetchCompletion(deviceID) {
    const response = await fetchSyncthing(`/rest/db/completion?device=${deviceID}`);
    await assertResponseOk(response);
    return response.json();
}

async function fetchSyncthing(path) {
    return fetch(`${API_URL}${path}`, {
        headers: {
            'X-API-Key': API_KEY,
        }
    });
}

async function assertResponseOk(response) {
    if (response.ok) {
        return;
    }
    throw new Error(
        'Response error! ' +
            response.status + ' ' + response.statusText +
            ' -- ' + (await response.text())
    );
}

main().catch((err) => {
    console.error('Exiting due to error!', err);
    process.exit(1);
});