background.js

let logCache = ``;
const MILLISECONDS_PER_MINUTE = 60000;
let lastStorageWrite = new Date();

chrome.runtime.onInstalled.addListener(function () {
    initStorage(`maximumScrollNumber`, `9`);
    initStorage(`groupName`, `6cM`);
    initStorage(`logHistory`, ``);

    chrome.declarativeContent.onPageChanged.removeRules(undefined, function () {
        chrome.declarativeContent.onPageChanged.addRules([
            {
                conditions: [
                    new chrome.declarativeContent.PageStateMatcher({
                        pageUrl: { hostContains: `ancestry.com` },
                    }),
                ],
                actions: [new chrome.declarativeContent.ShowPageAction()],
            },
        ]);
    });
});

chrome.runtime.onConnect.addListener(function (port) {
    if (port.name == `clear`) {
        port.onMessage.addListener(function () {
            logCache = '';
            chrome.storage.sync.set({ logHistory: logCache });
            console.log(`log cleared.`);
            lastStorageWrite = new Date();
        });
    }

    if (port.name == `log`) {
        port.onMessage.addListener(function (message) {
            logCache = logCache == '' ? message.content : logCache + `\n` + message.content;

            let okayToWrite = isOkayToWriteToStorage();
            console.log(`log <${message.content}> and writtenToStorage <${okayToWrite}>`);

            if (okayToWrite) {
                chrome.storage.sync.get(`logHistory`, function (data) {
                    logCache = data.logHistory == '' ? logCache : data.logHistory + logCache;
                    if (logCache.length > 7000) {
                        // real limit is 8k (8192) - playing it safe
                        logCache = logCache.substring(Math.max(logCache.length - 7000, 0), logCache.length);
                    }

                    chrome.storage.sync.set({ logHistory: logCache });
                    console.log(`log persisted to storage. logBytesInUse <${logCache.length}>`);
                    logCache = '';
                    lastStorageWrite = new Date();
                });
            }
        });

        port.onDisconnect.addListener(function () {
            console.log(`log port onDisconnect - persisting log cache to storage: logCache.length ${logCache.length}`);
            logCache = logCache.substring(Math.max(logCache.length - 7000, 0), logCache.length);
            chrome.storage.sync.set({ logHistory: logCache });
        });
    }
});

function isOkayToWriteToStorage() {
    // get the current date time minus 1 minute to compare
    let currentDateTimeMinusThreshold = new Date(Date.now() - MILLISECONDS_PER_MINUTE);

    // delay writing to storage to avoid limit on 120 writes per minute and limit on 1800 writes per hour
    let storageWriteTimeCompare = lastStorageWrite.getTime() < currentDateTimeMinusThreshold.getTime();
    return storageWriteTimeCompare;
}

function initStorage(key, value) {
    chrome.storage.sync.get(key, function (data) {
        console.log(`init <${key}> found is <${data[key]}>`);

        if (data[key] == undefined) {
            chrome.storage.sync.set({ [`${key}`]: value }, function () {
                console.log(`init <${key}> set <${value}>`);
            });
        }
    });
}