UT-Course-Sentinel/background.js at main · akshaygajjala1/UT-Course-Sentinel · GitHub

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const timers = {};

chrome.runtime.onStartup.addListener(() => {
    chrome.storage.local.get("watchlist", (data) => {
        const list = data.watchlist || [];
        list.forEach(startCourseMonitor);
    });
})

chrome.runtime.onMessage.addListener((message) => {
    if (message.action === "AddToWatchlist") {
        addCourse(message.course);
    }
    else if (message.action === "RmvFromWatchlist") {
        removeCourse(message.course);
    }
    else if (message.action == "UpdateInterval") {
        updateInterval(message.course, message.interval);
    }
});

function addCourse(course) {
    chrome.storage.local.get("watchlist", (data) => {
        const list = data.watchlist || [];
        if (!list.some(c => c.unique === course.unique)) {
            course.interval = 60;
            startCourseMonitor(course);
            list.push(course);
            chrome.storage.local.set({ watchlist: list}, () => {
            });
        }
    });
}

function removeCourse(course) {
    stopCourseMonitor(course);
    chrome.storage.local.get("watchlist", (data) => {
        let list = data.watchlist || [];
        list = list.filter(c => c.unique !== course.unique)
        chrome.storage.local.set({ watchlist: list}, () => {
        });
    });
}

function updateInterval(course, interval) {
    chrome.storage.local.get("watchlist", (data) => {
        let list = data.watchlist || [];
        const item = list.find(c => c.unique === course.unique);
        if (!item) {
            console.log("debug - no course found for current slider")
            return;
        }
        item.interval = interval
        chrome.storage.local.set({watchlist: list});
        stopCourseMonitor(item);
        startCourseMonitor(item);
    });
}

//with confirmation of checking (sound)
// async function startCourseMonitor(course) {
//     if (timers[course.unique]) {
//         return;
//     }

//     await ensureOffscreenDocument();
//     const id = setInterval(() => {
//         chrome.runtime.sendMessage({
//             action: "playSound",
//             file: "alert.mp3"
//         });
//         checkCourseUpdate(course);
//     }, course.interval * 1000);

//     timers[course.unique] = id;
// }

function startCourseMonitor(course) {
    if (timers[course.unique]) {
        return;
    }

    const id = setInterval(() => {
        checkCourseUpdate(course);
    }, course.interval * 1000);

    timers[course.unique] = id;
}

function stopCourseMonitor(course) {
    const id = timers[course.unique];
    if (id) {
        clearInterval(id);
        delete timers[course.unique];
    }
}

function compareStatus(course, newCourseStatus) {
    if (course.status !== newCourseStatus) {
        courseStatusChanged(course, course.status, newCourseStatus);
    }
}

async function courseStatusChanged(course, oldStatus, newStatus) {
    course.status = newStatus;
    stopCourseMonitor(course);
    await ensureOffscreenDocument();
    chrome.runtime.sendMessage({
        action: "playSound",
        file: "alert.mp3"
    });

    chrome.storage.local.get("updates", (data) => {
        let updates = data.updates || [];

        updates.unshift({
            unique: course.unique,
            oldStatus,
            newStatus,
            timestamp: Date.now()
        });

        chrome.storage.local.set({ updates });
    });
}

async function checkCourseUpdate(course) {
    try {
        const newData = await fetchCoursePage(course);
        compareStatus(course, newData.status);
    }
    catch (err) {
        console.error(`Error checking course ${course.unique}:`, err)
    }
}

async function fetchCoursePage(course) {
    const response = await fetch(course.url);
    const html = await response.text();
    await ensureOffscreenDocument();
    return new Promise((resolve) => {
        chrome.runtime.sendMessage(
            {
                action: "parseHTML",
                html,
                unique: course.unique
            },
            (result) => resolve(result)
        );
    })
}

async function ensureOffscreenDocument() {
    if (await chrome.offscreen.hasDocument()) return;

    await chrome.offscreen.createDocument({
        url: chrome.runtime.getURL("offscreen.html"),
        reasons: ["DOM_PARSER"],
        justification: "Parse UT HTML"
    });
}