const fileInput = document.querySelector("#file-upload");
const fileCount = document.querySelector("#upload-file-count");
const fileList = document.querySelector(".upload-file-list");
const dropzone = document.querySelector(".upload-dropzone");
const uploadForm = document.querySelector(".upload-form");
const uploadStatus = document.querySelector(".upload-statusbar span:first-child");

function formatBytes(bytes) {
    const units = ["B", "KB", "MB", "GB"];
    let size = bytes;
    let unitIndex = 0;

    while (size >= 1024 && unitIndex < units.length - 1) {
        size /= 1024;
        unitIndex += 1;
    }

    if (unitIndex === 0) {
        return `${size} ${units[unitIndex]}`;
    }

    return `${size.toFixed(1)} ${units[unitIndex]}`;
}

function updateStatus(message) {
    if (uploadStatus) {
        uploadStatus.textContent = message;
    }
}

function updateSelectedFiles(files) {
    const selectedFiles = Array.from(files || []);

    if (fileCount) {
        fileCount.textContent = `${selectedFiles.length} ${selectedFiles.length === 1 ? "file" : "files"}`;
    }

    if (!fileList) {
        return;
    }

    fileList.replaceChildren();

    if (!selectedFiles.length) {
        const emptyState = document.createElement("p");
        emptyState.className = "upload-empty-state";
        emptyState.textContent = "No files selected";
        fileList.append(emptyState);
        updateStatus("Ready");
        return;
    }

    const fragment = document.createDocumentFragment();

    selectedFiles.forEach((file) => {
        const row = document.createElement("div");
        row.className = "upload-file-row";

        const icon = document.createElement("span");
        icon.className = "upload-file-icon";
        icon.setAttribute("aria-hidden", "true");

        const name = document.createElement("span");
        name.className = "upload-file-name";
        name.textContent = file.name;
        name.title = file.name;

        const size = document.createElement("span");
        size.className = "upload-file-size";
        size.textContent = formatBytes(file.size);

        row.append(icon, name, size);
        fragment.append(row);
    });

    fileList.append(fragment);
    updateStatus("Files selected");
}

if (fileInput) {
    fileInput.addEventListener("change", () => {
        updateSelectedFiles(fileInput.files);
    });
}

if (fileInput && dropzone) {
    dropzone.addEventListener("dragover", (event) => {
        event.preventDefault();
        dropzone.classList.add("is-dragging");
    });

    dropzone.addEventListener("dragleave", () => {
        dropzone.classList.remove("is-dragging");
    });

    dropzone.addEventListener("drop", (event) => {
        event.preventDefault();
        dropzone.classList.remove("is-dragging");

        if (!event.dataTransfer.files.length) {
            return;
        }

        fileInput.files = event.dataTransfer.files;
        updateSelectedFiles(fileInput.files);
    });
}

if (uploadForm && fileInput) {
    uploadForm.addEventListener("submit", async (event) => {
        event.preventDefault();

        if (!fileInput.files.length) {
            updateStatus("Choose files first");
            return;
        }

        updateStatus("Uploading...");

        try {
            const response = await fetch(uploadForm.action, {
                method: "POST",
                body: new FormData(uploadForm),
            });

            if (!response.ok) {
                throw new Error("Upload failed");
            }

            const result = await response.json();
            updateStatus(`Uploaded to ${result.box_url}`);
        } catch (error) {
            updateStatus("Upload failed");
        }
    });
}