class UserData {
    constructor(dataRow) {
        this.userId = dataRow[0];
        this.uName = dataRow[1];
        this.fName = dataRow[3];
        this.sName = dataRow[5];
    }
}

class EnrollmentData {
    constructor(dataRow) {
        this.orgUnitId = dataRow[0];
        this.userId = dataRow[1];
        this.roleName = dataRow[2];
        this.timestamp = dataRow[3];
        this.roleId = dataRow[5];
        this.fName = "N/A";
        this.sName = "N/A";
        this.uName = "N/A";
    }
}

// Create empty Maps to store the filtered enrollment data and user info in
// These will be cross checked later to generate the list of all instructors
const users = new Map();
const enrollments = new Map();

let states = {
    enrollments: false,
    users: false
}

function filterEnrollments(document) {
    let fileInput = document.getElementById('userEnrollmentsCsv');
    let filterValue = "KV Instructor";
    document.getElementById('downloadBtn')
    if (!fileInput.files.length) {
        alert('Please select a CSV file.');
        return;
    }

    const file = fileInput.files[0];

    Papa.parse(file, {
        complete: function(results) {
            // Iterate over the entire data set
            results.data.forEach(row => {
                // Create an EnrollmentData object with it:
                const enrollmentData = new EnrollmentData(row);
                // If the row contains the filter string and is not in the 'seen' Set
                if (row.some(cell => cell.includes(filterValue)) && !enrollments.has(enrollmentData.userId)) {
                    // Add it to the data array
                    enrollments.set(enrollmentData.userId, enrollmentData);
                }
            });

            states.enrollments = "Filtered";
            refreshStatus(document);
        },
        error: function(error) {
            console.error(error);
            alert('An error occurred while processing the file.');
        }
    });
}

const parseUsers = (usersFileInputs, document) => {
    if (!usersFileInputs.files.length) {
        alert('Please select a CSV file.');
        return;
    }

    const usersFile = usersFileInputs.files[0];

    Papa.parse(usersFile, {
        complete: function(results) {
            // Iterate over the entire data set
            results.data.forEach(row => {
                // Create an object with it:
                const userData = new UserData(row);
                // Add it to the data array
                users.set(userData.userId, userData);
            });
            states.users = "Parsed";
            refreshStatus(document);
        },
        error: function(error) {
            console.error(error);
            alert('An error occurred while processing the Users.csv file.');
        }
    });
}

const generateList = (document) => {
    const preCSV = [
        "UserId,Timestamp,FirstName,LastName,Username"
    ];
    enrollments.forEach(e => {
        // Get the associated user
        const user = users.get(e.userId);
        preCSV.push(`${user.userId},${e.timestamp}.${user.fName},${user.sName},${user.uName}`);
    });

    generateCSV(preCSV, document);
}

const generateCSV = (input, document) => {
    const downloadLink = document.getElementById("downloadBtn");

    const blob = new Blob([input], { type: 'text/csv' });
    const url = URL.createObjectURL(blob);

    downloadLink.onclick = `window.location = ${url}`
    downloadLink.style.display = 'block';
    downloadLink.textContent = 'Download Filtered CSV';
}

function refreshStatus(document) {
    let statusString = "";
    let statusSpan = document.getElementById('statusIndicator')
    states.enrollments ? statusString += "Enrollments: Filtered" : statusString += "Enrollments: Not Filtered";
    states.users ? statusString += "<br />Users: Parsed" : statusString += "<br />Users: Not Parsed"
    statusSpan.innerHTML = statusString;

    if (states.enrollments && states.users) {
        let refreshBtn = document.getElementById('refreshStatusBtn');
        let downloadBtn = document.getElementById('downloadBtn');
        refreshBtn.style = "display: none";
        downloadBtn.style = "display: block";
    }
}