const FILE_CHUNK_SIZE = 16384;
const MAX_FILES = 256;

const fileInputContainer = document.getElementById('file_input_container');
const fileInput = document.getElementById('file_input');
const fileInputMessage = document.getElementById('file_input_message');

const fileListContainer = document.getElementById('file_list_container');
const fileList = document.getElementById('file_list');

const uploadButton = document.getElementById('upload');

const downloadLinkContainer = document.getElementById('download_link_container');
const downloadLink = document.getElementById('download_link');

const progressContainer = document.getElementById('progress_container');
const progress = document.getElementById('progress');
const progressBarFilled = document.getElementById('progress_bar_filled');

let files = [];

let socket = null;
let fileIndex = 0;
let byteIndex = 0;
let bytesSent = 0;
let totalBytes = 0;

function sendMetadata() {
    const metadata = files.map((file) => ({
        name: file.name,
        size: file.size,
        modtime: file.lastModified,
    }));
    socket.send(JSON.stringify(metadata));
}

function finishSending() {
    if (socket.bufferedAmount > 0) {
        window.setTimeout(finishSending, 1000);
        return;
    }
    socket.close();
    progressContainer.textContent = "Upload complete!";
}

function sendData() {
    if (fileIndex >= files.length) {
        finishSending();
        return;
    }
    const currentFile = files[fileIndex];
    if (byteIndex < currentFile.size) {
        const endpoint = Math.min(byteIndex+FILE_CHUNK_SIZE, currentFile.size);
        const data = currentFile.slice(byteIndex, endpoint);
        socket.send(data);
        byteIndex = endpoint;
        bytesSent += data.size;
        updateProgress();
    } else {
        fileIndex += 1;
        byteIndex = 0;
        sendData();
    }
}

function updateProgress() {
    let percentage;
    if (totalBytes === 0) {
        percentage = "0%";
    } else {
        percentage = `${(bytesSent*100/totalBytes).toFixed(1)}%`;
    }
    progress.textContent = percentage;
    progressBarFilled.style.width = percentage;
}

function updateFiles() {
    totalBytes = files.reduce((acc, file) => acc + file.size, 0);

    if (files.length === 0) {
        fileInputMessage.textContent = 'Select files to upload...';
        fileListContainer.style.display = 'none';
        uploadButton.style.display = 'none';
    } else {
        fileInputMessage.textContent = 'Select more files to upload...';
        fileListContainer.style.display = '';
        uploadButton.textContent = `Upload ${files.length} file${files.length > 1 ? 's' : ''} (${displaySize(totalBytes)})`;
        uploadButton.style.display = '';
    }
    fileInput.disabled = (files.length >= MAX_FILES);
}

updateFiles();
downloadLinkContainer.style.display = 'none';
progressContainer.style.display = 'none';

function addFile(newFile) {
    if (files.length >= MAX_FILES) { return; }
    if (files.some((oldFile) => newFile.name === oldFile.name)) { return; }

    files.push(newFile);

    addListEntry(newFile);
}

function addListEntry(file) {
    const listEntry = document.createElement('tr');

    const deleteButtonCell = document.createElement('td');
    const deleteButton = document.createElement('button');
    deleteButtonCell.appendChild(deleteButton);
    deleteButton.className = 'file_delete';
    deleteButton.textContent = 'x';
    deleteButton.addEventListener('click', () => {
        removeFile(file.name);
        listEntry.remove();
        updateFiles();
    });

    const sizeCell = document.createElement('td');
    sizeCell.className = 'file_size';
    sizeCell.textContent = displaySize(file.size);

    const nameCell = document.createElement('td');
    nameCell.className = 'file_name';
    nameCell.textContent = file.name;

    listEntry.appendChild(deleteButtonCell);
    listEntry.appendChild(sizeCell);
    listEntry.appendChild(nameCell);

    fileList.appendChild(listEntry);
}

function removeFile(name) {
    files = files.filter((file) => file.name !== name);
}

fileInput.addEventListener('input', (e) => {
    for (const file of e.target.files) { addFile(file); }
    updateFiles();
    e.target.value = '';
});

uploadButton.addEventListener('click', (e) => {
    if (files.length === 0) { return; }

    fileInputContainer.remove();
    for (const button of Array.from(document.getElementsByTagName('button'))) {
        button.remove();
    }

    socket = new WebSocket(`${window.location.protocol === 'http:' ? 'ws' : 'wss'}://${window.location.host}/upload`);
    socket.addEventListener('open', sendMetadata);
    socket.addEventListener('message', (msg) => {
        if (bytesSent === 0 && msg.data.match(/^[A-Za-z0-9]+$/)) {
            downloadLink.textContent = `${window.location.origin}/download/${msg.data}`;
            downloadLinkContainer.style.display = '';
            updateProgress();
            progressContainer.style.display = '';
            sendData();
        } else if (msg.data === 'ack') {
            sendData();
        }
    });
})