const form = document.getElementById('predictForm');
const fileInput = document.getElementById('fileInput');
const dropZone = document.getElementById('dropZone');
const selectedFileName = document.getElementById('selectedFileName');
const submitBtn = document.getElementById('submitBtn');
const submitText = document.getElementById('submitText');
let submitIcon = document.getElementById('submitIcon');
const alertBox = document.getElementById('alertBox');
const alertIconWrap = document.getElementById('alertIconWrap');
const alertIcon = document.getElementById('alertIcon');
const alertTitle = document.getElementById('alertTitle');
const alertMessage = document.getElementById('alertMessage');
const alertClose = document.getElementById('alertClose');
const inlineResult = document.getElementById('inlineResult');
const resultPlaceholder = document.getElementById('resultPlaceholder');
const resultContent = document.getElementById('resultContent');
const resultImage = document.getElementById('resultImage');
const resultImportanceWrap = document.getElementById('resultImportanceWrap');
const resultImportanceImage = document.getElementById('resultImportanceImage');
const excelBtn = document.getElementById('excelBtn');
const resultPageBtn = document.getElementById('resultPageBtn');
let selectedFile = null;
let alertTimer = null;
let alertHideTimer = null;

function hideAlert() {
  clearTimeout(alertTimer);
  clearTimeout(alertHideTimer);
  alertBox.classList.remove('opacity-100', 'translate-y-0');
  alertBox.classList.add('pointer-events-none', 'opacity-0', 'translate-y-3');
  alertHideTimer = setTimeout(() => {
    alertBox.classList.add('hidden');
  }, 200);
}

function showAlert(message, type='error', title) {
  clearTimeout(alertTimer);
  clearTimeout(alertHideTimer);
  alertBox.classList.remove('hidden', 'border-red-200', 'border-blue-200');
  alertIconWrap.classList.remove('bg-dangerSoft', 'text-dangerText', 'bg-blueSoft', 'text-primary');
  if (type === 'error') {
    alertBox.classList.add('border-red-200');
    alertIconWrap.classList.add('bg-dangerSoft', 'text-dangerText');
    alertIcon.textContent = 'priority_high';
    alertTitle.textContent = title || '需要补充文件';
  } else {
    alertBox.classList.add('border-blue-200');
    alertIconWrap.classList.add('bg-blueSoft', 'text-primary');
    alertIcon.textContent = 'check_circle';
    alertTitle.textContent = title || '处理完成';
  }
  alertMessage.textContent = message;
  requestAnimationFrame(() => {
    alertBox.classList.remove('pointer-events-none', 'opacity-0', 'translate-y-3');
    alertBox.classList.add('opacity-100', 'translate-y-0');
  });
  alertTimer = setTimeout(() => {
    hideAlert();
  }, 10000);
}

alertClose.addEventListener('click', hideAlert);

function updateSelectedFile(file) {
  selectedFile = file;
  selectedFileName.textContent = '已选择文件：' + file.name;
  selectedFileName.classList.remove('hidden');
}

function renderResult(data) {
  resultImage.src = data.image_url;
  if (data.importance_url) {
    resultImportanceImage.src = data.importance_url;
    resultImportanceWrap.classList.remove('hidden');
  } else {
    resultImportanceWrap.classList.add('hidden');
    resultImportanceImage.removeAttribute('src');
  }
  excelBtn.href = data.excel_url;
  resultPageBtn.href = data.result_url;
  resultPlaceholder.classList.add('hidden');
  resultContent.classList.remove('hidden');
  resultContent.classList.add('flex');
}

fileInput.addEventListener('change', () => {
  const file = fileInput.files[0];
  if (!file) return;
  updateSelectedFile(file);
});

['dragenter', 'dragover'].forEach(evt => dropZone.addEventListener(evt, e => {
  e.preventDefault();
  e.stopPropagation();
  e.dataTransfer.dropEffect = 'copy';
  dropZone.classList.add('border-primary', 'bg-blue-50');
}));

dropZone.addEventListener('dragleave', e => {
  e.preventDefault();
  e.stopPropagation();
  dropZone.classList.remove('border-primary', 'bg-blue-50');
});

dropZone.addEventListener('drop', e => {
  e.preventDefault();
  e.stopPropagation();
  dropZone.classList.remove('border-primary', 'bg-blue-50');

  const file = e.dataTransfer.files[0];
  if (!file) return;

  if (window.DataTransfer) {
    const transfer = new DataTransfer();
    transfer.items.add(file);
    fileInput.files = transfer.files;
  }

  updateSelectedFile(file);
});

form.addEventListener('submit', async (e) => {
  e.preventDefault();
  hideAlert();
  if (!selectedFile) {
    showAlert('点击上传区域选择电子表格或逗号分隔值文件，也可以直接把文件拖放到上传框内。', 'error', '请先选择文件');
    dropZone.classList.add('border-red-300', 'bg-red-50', 'ring-4', 'ring-red-100');
    dropZone.scrollIntoView({ behavior: 'smooth', block: 'center' });
    setTimeout(() => {
      dropZone.classList.remove('border-red-300', 'bg-red-50', 'ring-4', 'ring-red-100');
    }, 2400);
    return;
  }

  submitBtn.disabled = true;
  submitText.textContent = '预测中...';
  submitIcon.replaceWith(Object.assign(document.createElement('span'), { id: 'submitSpinner', className: 'spinner' }));

  try {
    const formData = new FormData(form);
    formData.set('file', selectedFile);
    const resp = await fetch(form.action, { method: 'POST', body: formData });
    const data = await resp.json();
    if (!resp.ok) {
      showAlert(data.error || '预测失败，请稍后重试。');
      return;
    }
    renderResult(data);
    showAlert('预测完成，已生成图表与电子表格报告。', 'success');
    inlineResult.scrollIntoView({ behavior: 'smooth', block: 'nearest' });
  } catch (err) {
    showAlert('请求失败，请检查后端服务是否正常。');
  } finally {
    submitBtn.disabled = false;
    submitText.textContent = '分析并预测';
    const restoredIcon = Object.assign(document.createElement('span'), { id: 'submitIcon', className: 'material-symbols-outlined', textContent: 'analytics' });
    document.getElementById('submitSpinner')?.replaceWith(restoredIcon);
    submitIcon = restoredIcon;
  }
});