(() => {
    const dropzone = document.getElementById('dropzone');
    const fileInput = document.getElementById('file-input');
    const options = document.getElementById('options');
    const uploadBtn = document.getElementById('upload-btn');
    const progressSection = document.getElementById('progress-section');
    const progressFilename = document.getElementById('progress-filename');
    const progressFill = document.getElementById('progress-fill');
    const progressText = document.getElementById('progress-text');
    const result = document.getElementById('result');
    const resultUrl = document.getElementById('result-url');
    const copyBtn = document.getElementById('copy-btn');
    const resultDelete = document.getElementById('result-delete');
    const resultExpiry = document.getElementById('result-expiry');
    const errorDiv = document.getElementById('error');

    let selectedFile = null;

    // Drag and drop
    dropzone.addEventListener('dragover', (e) => {
        e.preventDefault();
        dropzone.classList.add('drag-over');
    });

    dropzone.addEventListener('dragleave', () => {
        dropzone.classList.remove('drag-over');
    });

    dropzone.addEventListener('drop', (e) => {
        e.preventDefault();
        dropzone.classList.remove('drag-over');
        if (e.dataTransfer.files.length > 0) {
            selectFile(e.dataTransfer.files[0]);
        }
    });

    dropzone.addEventListener('click', () => fileInput.click());

    fileInput.addEventListener('change', () => {
        if (fileInput.files.length > 0) {
            selectFile(fileInput.files[0]);
        }
    });

    function selectFile(file) {
        selectedFile = file;
        dropzone.querySelector('p').textContent = file.name + ' (' + formatSize(file.size) + ')';
        options.classList.remove('hidden');
        result.classList.add('hidden');
        errorDiv.classList.add('hidden');
    }

    uploadBtn.addEventListener('click', () => {
        if (!selectedFile) return;
        upload(selectedFile);
    });

    function upload(file) {
        const formData = new FormData();
        formData.append('file', file);

        const expires = document.getElementById('expires').value;
        if (expires) formData.append('expires_in', expires);

        const password = document.getElementById('password').value;
        if (password) formData.append('password', password);

        const xhr = new XMLHttpRequest();

        // Show progress
        options.classList.add('hidden');
        dropzone.classList.add('hidden');
        progressSection.classList.remove('hidden');
        progressFilename.textContent = file.name;
        errorDiv.classList.add('hidden');

        xhr.upload.addEventListener('progress', (e) => {
            if (e.lengthComputable) {
                const pct = Math.round((e.loaded / e.total) * 100);
                progressFill.style.width = pct + '%';
                progressText.textContent = pct + '% — ' + formatSize(e.loaded) + ' / ' + formatSize(e.total);
            }
        });

        xhr.addEventListener('load', () => {
            progressSection.classList.add('hidden');

            if (xhr.status === 201) {
                const data = JSON.parse(xhr.responseText);
                showResult(data);
            } else {
                showError(xhr.responseText || 'Upload failed');
            }
        });

        xhr.addEventListener('error', () => {
            progressSection.classList.add('hidden');
            showError('Network error — upload failed');
        });

        xhr.open('POST', '/upload');
        xhr.send(formData);
    }

    function showResult(data) {
        result.classList.remove('hidden');
        resultUrl.value = data.url;

        resultDelete.textContent = 'Delete: curl -X DELETE -H "Authorization: Bearer ' + data.delete_token + '" ' + data.delete_url;

        if (data.expires_at) {
            resultExpiry.textContent = 'Expires: ' + new Date(data.expires_at).toLocaleString();
        } else {
            resultExpiry.textContent = '';
        }

        // Reset for another upload
        dropzone.classList.remove('hidden');
        dropzone.querySelector('p').innerHTML = 'Drop a file here or <label for="file-input" class="link">browse</label>';
        selectedFile = null;
    }

    function showError(msg) {
        errorDiv.textContent = msg;
        errorDiv.classList.remove('hidden');
        dropzone.classList.remove('hidden');
        dropzone.querySelector('p').innerHTML = 'Drop a file here or <label for="file-input" class="link">browse</label>';
        selectedFile = null;
    }

    copyBtn.addEventListener('click', () => {
        resultUrl.select();
        navigator.clipboard.writeText(resultUrl.value).then(() => {
            copyBtn.textContent = 'Copied!';
            setTimeout(() => { copyBtn.textContent = 'Copy'; }, 2000);
        });
    });

    function formatSize(bytes) {
        if (bytes < 1024) return bytes + ' B';
        if (bytes < 1024 * 1024) return (bytes / 1024).toFixed(1) + ' KB';
        if (bytes < 1024 * 1024 * 1024) return (bytes / (1024 * 1024)).toFixed(1) + ' MB';
        return (bytes / (1024 * 1024 * 1024)).toFixed(2) + ' GB';
    }
})();