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");
const boxStatus = document.querySelector(".upload-statusbar span:last-child");

let selectedFiles = [];
let statusTimer = null;

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 stopStatusAnimation() {
    if (statusTimer) {
        clearInterval(statusTimer);
        statusTimer = null;
    }
}

function animateUploadStatus(getPrefix) {
    let dotCount = 0;
    stopStatusAnimation();

    statusTimer = setInterval(() => {
        dotCount = (dotCount % 3) + 1;
        updateStatus(`${getPrefix()} Uploading${".".repeat(dotCount)}`);
    }, 350);
}

function setBoxStatus(message) {
    if (boxStatus) {
        boxStatus.textContent = message;
        boxStatus.title = message;
    }
}

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

function setRowProgress(row, percent) {
    const progressBar = row.querySelector(".upload-progress-bar");
    if (progressBar) {
        progressBar.style.width = `${Math.max(0, Math.min(100, percent))}%`;
    }
}

function createFileRow(selectedFile) {
    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 = selectedFile.file.name;
    name.title = selectedFile.file.name;

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

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

    const progressBar = document.createElement("span");
    progressBar.className = "upload-progress-bar";
    progress.append(progressBar);

    row.append(icon, name, size, progress);
    selectedFile.row = row;
    return row;
}

function updateSelectedFiles(files) {
    selectedFiles = Array.from(files || []).map((file) => ({
        file,
        row: null,
        uploaded: false,
        failed: false,
    }));

    updateFileCount();

    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");
        setBoxStatus("WarpBox");
        return;
    }

    const fragment = document.createDocumentFragment();
    selectedFiles.forEach((selectedFile) => {
        fragment.append(createFileRow(selectedFile));
    });

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

async function createBox() {
    const response = await fetch("/box", { method: "POST" });
    if (!response.ok) {
        throw new Error("Could not create upload box");
    }

    return response.json();
}

function uploadFile(boxID, selectedFile, onComplete) {
    return new Promise((resolve, reject) => {
        const xhr = new XMLHttpRequest();
        const formData = new FormData();
        formData.append("file", selectedFile.file);

        xhr.open("POST", `/box/${boxID}/upload`);

        xhr.upload.addEventListener("loadstart", () => {
            setRowProgress(selectedFile.row, 2);
        });

        xhr.upload.addEventListener("progress", (event) => {
            if (!event.lengthComputable) {
                return;
            }

            setRowProgress(selectedFile.row, (event.loaded / event.total) * 100);
        });

        xhr.addEventListener("load", () => {
            if (xhr.status < 200 || xhr.status >= 300) {
                selectedFile.failed = true;
                selectedFile.row.classList.add("is-failed");
                reject(new Error("Upload failed"));
                return;
            }

            selectedFile.uploaded = true;
            selectedFile.row.classList.add("is-uploaded");
            setRowProgress(selectedFile.row, 100);
            onComplete();
            resolve();
        });

        xhr.addEventListener("error", () => {
            selectedFile.failed = true;
            selectedFile.row.classList.add("is-failed");
            reject(new Error("Upload failed"));
        });

        xhr.send(formData);
    });
}

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

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

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

        let completedCount = 0;
        const totalCount = selectedFiles.length;
        const statusPrefix = () => `${completedCount}/${totalCount}`;

        selectedFiles.forEach((selectedFile) => {
            selectedFile.uploaded = false;
            selectedFile.failed = false;
            selectedFile.row.classList.remove("is-uploaded", "is-failed");
            setRowProgress(selectedFile.row, 0);
        });

        updateStatus(`${statusPrefix()} Uploading.`);
        animateUploadStatus(statusPrefix);

        try {
            const box = await createBox();
            setBoxStatus(box.box_url);

            await Promise.allSettled(selectedFiles.map((selectedFile) => {
                return uploadFile(box.box_id, selectedFile, () => {
                    completedCount += 1;
                });
            }));

            stopStatusAnimation();
            const failedCount = selectedFiles.filter((selectedFile) => selectedFile.failed).length;
            if (failedCount > 0) {
                updateStatus(`${completedCount}/${totalCount} Uploaded, ${failedCount} failed`);
                return;
            }

            updateStatus(`${completedCount}/${totalCount} Uploaded`);
        } catch (error) {
            stopStatusAnimation();
            updateStatus("Upload failed");
        }
    });
}