let examSchedule = {};

function dark_mode() {
    if (document.querySelector("body").getAttribute("mode") == "dark") {
        document.querySelector("body").setAttribute("mode", "light");
        // localStorage.removeItem("projects_color_mode");
        localStorage.setItem("projects_color_mode", "light");
    } else {
        document.querySelector("body").setAttribute("mode", "dark");
        localStorage.setItem("projects_color_mode", "dark");
    }
}

function get_exam_time(classDays, classTime) {
    const toMinutes = t => {
        const [h, m] = t.split(":").map(Number);
        return h * 60 + m;
    };
    const [hours, minutes] = classTime.split(":").map(Number);
    // One credit courses will test on the last day of the regularly scheduled class period.
    if (classDays.length === 1) {
        // Get the last date of the class given 'earliest_date' in examSchedule
        const earliestDate = new Date(examSchedule.earliest_date);
        const classDay = classDays[0];
        let lastDate = new Date(earliestDate);
        lastDate.setDate(lastDate.getDate() - 1);
        let dayMap = { "M": 1, "T": 2, "W": 3, "Th": 4, "F": 5 };

        while (lastDate.getDay() !== dayMap[classDay]) {
            lastDate.setDate(lastDate.getDate() - 1);
        }
        // Set the time to the class time
        lastDate.setHours(hours, minutes, 0, 0);
        return lastDate;
    }
    // Classes that meet on the quarter or three quarter hour (i.e. 2:15 or 2:45)
    //  will need to check with the instructor for the finals schedule.
    if (minutes === 15 || minutes === 45) { return null; }
    // Normal classes will test according to the exam schedule.
    for (let schedule of examSchedule.schedule) {
        if (
            schedule.day === classDays[0] &&
            toMinutes(schedule.start_time) <= toMinutes(classTime) &&
            toMinutes(schedule.end_time) >= toMinutes(classTime)
        ) {
            return new Date(schedule.exam_datetime);
        }
    }
    return null;
}

function remove_class(event) {
    if (event.target.classList.contains("remove-class")) {
        let row = event.target.closest("tr");
        row.remove();
    }
    if (document.querySelector("#class-list").children.length === 0) {
        document.querySelector(".class-list").classList.add("no-classes");
    }
}

function add_class() {
    if (document.querySelector(".class-list").classList.contains("no-classes")) {
        document.querySelector(".class-list").classList.remove("no-classes");
    }

    let className = document.querySelector("#class-name").value.trim();
    let classDaysReset = [];
    let classDays = [];
    if (document.querySelector("#Mon").checked) {classDaysReset.push("#Mon"); classDays.push("M");}
    if (document.querySelector("#Tue").checked) {classDaysReset.push("#Tue"); classDays.push("T");}
    if (document.querySelector("#Wed").checked) {classDaysReset.push("#Wed"); classDays.push("W");}
    if (document.querySelector("#Thu").checked) {classDaysReset.push("#Thu"); classDays.push("Th");}
    if (document.querySelector("#Fri").checked) {classDaysReset.push("#Fri"); classDays.push("F");}
    let classTime = document.querySelector("#time").value.trim();

    let examTime = get_exam_time(classDays, classTime);
    let examTime_formatted = "";
    if (examTime) {
        examTime_formatted = examTime.toLocaleString('en-US', {
            weekday: 'long',
            month: 'long',
            day: 'numeric',
            hour: 'numeric',
            minute: '2-digit',
            hour12: true
        });
    } else {
        examTime_formatted = "Check with instructor for final schedule";
    }

    if (className && classDays.length > 0 && classTime) {
        let newRow = document.createElement("tr");
        newRow.innerHTML = `
            <td>${className}</td>
            <td>${classDays.join(", ")}</td>
            <td>${classTime}</td>
            <td colspan="2">${examTime_formatted}</td>
            <td><button class="remove-class">Remove</button></td>
        `;
        document.querySelector("#class-list").appendChild(newRow);
        document.querySelector("#class-name").value = "";
        document.querySelector("#time").value = "";
        classDaysReset.forEach(day => {
            if (document.querySelector(day).checked) {
                document.querySelector(day).checked = false;
            }
        });
        newRow.querySelector(".remove-class").addEventListener("click", remove_class);
    }
}

function schedule_loaded() {
    document.querySelector('h1 .semester').innerText = examSchedule.semester;
    document.querySelector('#official-schedule').href = examSchedule.url;
    document.querySelector('#official-schedule').innerText = "Snow College Official Final Exam Schedule";
}

function main() {
    document.querySelector("#dark").addEventListener("click", dark_mode);
    document.querySelector("#add-class").addEventListener("click", add_class);

    const savedMode = localStorage.getItem("projects_color_mode");
    const isDarkMode = window.matchMedia && window.matchMedia('(prefers-color-scheme: dark)').matches;
    if (savedMode) {
        document.querySelector("body").setAttribute("mode", savedMode);
    } else if (isDarkMode) {
        document.querySelector("body").setAttribute("mode", "dark");
    }

    fetch('./final_exams.json')
        .then(response => response.json())
        .then(data => {
            examSchedule = data;
            schedule_loaded();
        })
        .catch(error => {
            console.error('Error fetching exam schedule:', error);
            document.querySelector('h1 .semester').innerText = 'Error loading exam schedule';
        });
}

document.addEventListener('DOMContentLoaded', main);