document.addEventListener('DOMContentLoaded', function () {
    const form = document.getElementById('prediction-form');
    const predictBtn = document.getElementById('predict-btn');
    const spinner = predictBtn.querySelector('.spinner-border');
    const resultsArea = document.getElementById('results-area');
    const errorAlert = document.getElementById('error-alert');
    const consentCheckbox = document.getElementById('consent-checkbox');
    const dataFileInput = document.getElementById('data-file');
    const downloadTemplateLink = document.getElementById('download-template');

    downloadTemplateLink.addEventListener('click', function(e) {
        e.preventDefault();
        const csvContent = "protein_sequence,substrate_smiles\n" +
                           "MTEITAAMVKELRESTGAGMMDCKNALSETNGDFDKAVQLLREKGLGKAAKKADRLAAEG,CC(=O)O\n" +
                           "MKAVQLLREKGLGKAAKKADRLAAEGTKAVQLLREKGLGKAAKKADRLAAEGGKAAKKADR,C(C(=O)O)N";
        const blob = new Blob([csvContent], { type: 'text/csv;charset=utf-8;' });
        const link = document.createElement("a");
        const url = URL.createObjectURL(blob);
        link.setAttribute("href", url);
        link.setAttribute("download", "template.csv");
        link.style.visibility = 'hidden';
        document.body.appendChild(link);
        link.click();
        document.body.removeChild(link);
    });

    form.addEventListener('submit', async function (event) {
        event.preventDefault();

        predictBtn.disabled = true;
        spinner.classList.remove('d-none');
        resultsArea.classList.add('d-none');
        errorAlert.classList.add('d-none');

        const file = dataFileInput.files[0];
        if (!file) {
            showError("错误：请先选择一个文件。");
            return;
        }

        const formData = new FormData();
        formData.append('data_file', file);
        formData.append('consent_given', consentCheckbox.checked);

        try {
            const response = await fetch('/predict', {
                method: 'POST',
                body: formData,
            });

            if (!response.ok) {
                const errorData = await response.json();
                throw new Error(errorData.error || '服务器返回了一个未知错误。');
            }

            const blob = await response.blob();
            
            const contentDisposition = response.headers.get('Content-Disposition');
            let filename = 'predictions.csv';
            
            if (contentDisposition) {
                const filenameMatch = contentDisposition.match(/filename="(.+)"/);
                if (filenameMatch && filenameMatch.length > 1) {
                    filename = filenameMatch[1];
                }
            }
            
            const url = window.URL.createObjectURL(blob);
            const a = document.createElement('a');
            a.style.display = 'none';
            a.href = url;
            a.download = filename;
            document.body.appendChild(a);
            a.click();
            window.URL.revokeObjectURL(url);
            document.body.removeChild(a);

            resultsArea.classList.remove('d-none');

        } catch (error) {
            showError('错误: ' + error.message);
        } finally {
            predictBtn.disabled = false;
            spinner.classList.add('d-none');
        }
    });
    
    function showError(message) {
        errorAlert.textContent = message;
        errorAlert.classList.remove('d-none');
        predictBtn.disabled = false;
        spinner.classList.add('d-none');
    }
});