const zone = document.getElementById('drop-zone');
const input = document.getElementById('fileInput');
const uploadBtn = document.getElementById('uploadBtn');
const cancelBtn = document.getElementById('cancelBtn');

const progressText = document.getElementById("progress-text");
const statsText = document.getElementById("stats-text");
const speedText = document.getElementById("speed-text");
const etaText = document.getElementById("eta-text");
const progressBar = document.getElementById("progress-bar");
const progressContainer = document.getElementById("progress-container");

let currentXhr = null;

function formatBytes(bytes, decimals = 2) {
    if (bytes === 0) return '0 Bytes';
    const k = 1024;
    const dm = decimals < 0 ? 0 : decimals;
    const sizes = ['Bytes', 'KB', 'MB', 'GB', 'TB'];
    const i = Math.floor(Math.log(bytes) / Math.log(k));
    return parseFloat((bytes / Math.pow(k, i)).toFixed(dm)) + ' ' + sizes[i];
}

function formatTime(seconds) {
    if (!isFinite(seconds) || seconds < 0) return "--:--";
    const h = Math.floor(seconds / 3600);
    const m = Math.floor((seconds % 3600) / 60);
    const s = Math.floor(seconds % 60);
    return [
        h > 0 ? h : null,
        (h > 0 ? m.toString().padStart(2, '0') : m),
        s.toString().padStart(2, '0')
    ].filter(x => x !== null).join(':');
}

zone.onclick = () => input.click();

zone.ondragover = (e) => {
    e.preventDefault();
    zone.classList.add('active');
};
zone.ondragleave = () => zone.classList.remove('active');

zone.ondrop = (e) => {
    e.preventDefault();
    zone.classList.remove('active');
    if (e.dataTransfer.files.length) {
        input.files = e.dataTransfer.files;
        input.dispatchEvent(new Event('change'));
    }
};

input.onchange = () => {
    if (input.files.length) {
        showFiles(input.files);
        uploadBtn.disabled = false;
    } else {
        uploadBtn.disabled = true;
    }
};

function showFiles(fileList) {
    const files = Array.from(fileList || []);
    if (files.length === 0) return;
    const total = files.reduce((acc, f) => acc + f.size, 0);
    if (files.length === 1) {
        document.getElementById('dz-text').innerText =
            `${files[0].name}  [${formatBytes(files[0].size)}]`;
    } else {
        document.getElementById('dz-text').innerText =
            `${files.length} FILES  [${formatBytes(total)}]  — will be zipped`;
    }
}

uploadBtn.onclick = () => {
    if (!input.files.length) return;
    if (input.files.length === 1) {
        handleUploadSingle(input.files[0]);
    } else {
        handleUploadMulti(input.files);
    }
};

cancelBtn.onclick = (e) => {
    e.stopPropagation();
    if (currentXhr) {
        currentXhr.abort();
        alert("Upload cancelled.");
        location.reload();
    }
};

function commonFormData() {
    const fd = new FormData();
    fd.append("once", document.getElementById("once").checked ? "true" : "false");
    const hours = parseInt(document.getElementById("duration").value, 10);
    fd.append("duration", hours);
    return fd;
}

function startUploadUI() {
    uploadBtn.disabled = true;
    uploadBtn.innerText = "UPLOADING...";
    cancelBtn.classList.remove('hidden');
    progressContainer.classList.remove("hidden");
    progressText.classList.remove("hidden");
    statsText.classList.remove("hidden");
}

function setupXHRHandlers(xhr) {
    let startTime = Date.now();

    xhr.upload.onprogress = (e) => {
        if (e.lengthComputable) {
            const percent = Math.round((e.loaded / e.total) * 100);
            progressBar.style.width = percent + "%";
            progressText.innerText = percent + "%";

            const elapsedSeconds = (Date.now() - startTime) / 1000;
            if (elapsedSeconds > 0) {
                const bytesPerSecond = e.loaded / elapsedSeconds;
                const remainingBytes = e.total - e.loaded;
                const secondsRemaining = remainingBytes / bytesPerSecond;
                speedText.innerText = formatBytes(bytesPerSecond) + "/S";
                etaText.innerText = formatTime(secondsRemaining);
            }
        }
    };

    xhr.onload = () => {
        if (xhr.status >= 200 && xhr.status < 300) {
            try {
                const data = JSON.parse(xhr.responseText);
                if (data.error) throw new Error(data.error);
                window.location.href = "/f/" + data.view_key;
            } catch (err) {
                console.error("Invalid response:", xhr.responseText);
                alert("Server error");
            }
        } else {
            alert("Upload failed");
        }
    };

    xhr.onerror = () => {
        if (xhr.statusText !== "abort") {
            alert("Upload failed");
            location.reload();
        }
    };
}

function handleUploadSingle(file) {
    startUploadUI();
    const fd = commonFormData();
    fd.append("file", file);
    const xhr = new XMLHttpRequest();
    currentXhr = xhr;
    setupXHRHandlers(xhr);
    xhr.open("POST", "/api/files/upload");
    xhr.send(fd);
}

function handleUploadMulti(fileList) {
    startUploadUI();
    const fd = commonFormData();
    Array.from(fileList).forEach(f => fd.append("files", f));
    const xhr = new XMLHttpRequest();
    currentXhr = xhr;
    setupXHRHandlers(xhr);
    xhr.open("POST", "/api/files/upload-multi");
    xhr.send(fd);
}

function copy(id) {
    const el = document.getElementById(id);
    el.select();
    document.execCommand('copy');
}