/**
 * PDF Editor Module
 */

let pdfBeforeUrl = null;
let pdfAfterUrl = null;
let isSplitView = false;
let pdfStepIndicator = null;

// Config storage key and expiry (24 hours)
const PDF_CONFIG_KEY = 'pdfEditorConfig';
const CONFIG_EXPIRY_MS = 24 * 60 * 60 * 1000;

function savePdfConfig() {
  const config = {
    remove_pages: document.getElementById('remove_pages').value,
    unit: document.getElementById('unit').value,
    top: document.getElementById('top').value,
    bottom: document.getElementById('bottom').value,
    left: document.getElementById('left').value,
    right: document.getElementById('right').value,
    watermark_text: document.getElementById('watermark_text').value,
    watermark_size: document.getElementById('watermark_size').value,
    watermark_rotate: document.getElementById('watermark_rotate').value,
    output_name: document.getElementById('output_name').value,
    savedAt: Date.now()
  };
  localStorage.setItem(PDF_CONFIG_KEY, JSON.stringify(config));
}

function loadPdfConfig() {
  try {
    const stored = localStorage.getItem(PDF_CONFIG_KEY);
    if (!stored) return null;
    
    const config = JSON.parse(stored);
    
    // Check if expired (24 hours)
    if (Date.now() - config.savedAt > CONFIG_EXPIRY_MS) {
      localStorage.removeItem(PDF_CONFIG_KEY);
      return null;
    }
    
    return config;
  } catch {
    return null;
  }
}

function applyPdfConfig(config) {
  if (!config) return;
  
  if (config.remove_pages) document.getElementById('remove_pages').value = config.remove_pages;
  if (config.unit) document.getElementById('unit').value = config.unit;
  if (config.top) document.getElementById('top').value = config.top;
  if (config.bottom) document.getElementById('bottom').value = config.bottom;
  if (config.left) document.getElementById('left').value = config.left;
  if (config.right) document.getElementById('right').value = config.right;
  if (config.watermark_text) document.getElementById('watermark_text').value = config.watermark_text;
  if (config.watermark_size) document.getElementById('watermark_size').value = config.watermark_size;
  if (config.watermark_rotate) document.getElementById('watermark_rotate').value = config.watermark_rotate;
  if (config.output_name) document.getElementById('output_name').value = config.output_name;
}

function clearPdfConfig() {
  localStorage.removeItem(PDF_CONFIG_KEY);
  document.getElementById('remove_pages').value = '';
  document.getElementById('unit').value = 'mm';
  document.getElementById('top').value = '';
  document.getElementById('bottom').value = '';
  document.getElementById('left').value = '';
  document.getElementById('right').value = '';
  document.getElementById('watermark_text').value = '';
  document.getElementById('watermark_size').value = '36';
  document.getElementById('watermark_rotate').value = '45';
  document.getElementById('output_name').value = 'cropped.pdf';
  showToast('Config Cleared', 'Settings reset to defaults', 'success', 2000);
}

function initPdfEditor() {
  const elements = {
    btnBefore: document.getElementById('btnBefore'),
    btnAfter: document.getElementById('btnAfter'),
    frameBefore: document.getElementById('frameBefore'),
    frameAfter: document.getElementById('frameAfter'),
    splitFrameBefore: document.getElementById('splitFrameBefore'),
    splitFrameAfter: document.getElementById('splitFrameAfter'),
    previewTabs: document.querySelectorAll('.preview-tab'),
    dropZone: document.getElementById('pdfDropZone'),
    fileInput: document.getElementById('pdf_file'),
    urlInput: document.getElementById('pdf_url'),
    progress: document.getElementById('pdfProgress'),
    btnSplitView: document.getElementById('btnSplitView'),
    btnFullscreen: document.getElementById('btnFullscreen'),
    splitView: document.getElementById('splitView'),
    fullscreenOverlay: document.getElementById('fullscreenOverlay'),
    fullscreenFrame: document.getElementById('fullscreenFrame'),
    fullscreenClose: document.getElementById('fullscreenClose'),
    previewBefore: document.getElementById('preview-before'),
    previewAfter: document.getElementById('preview-after')
  };

  // Initialize step indicator
  pdfStepIndicator = new StepIndicator('pdfStepIndicator', [
    'Upload PDF',
    'Configure',
    'Preview',
    'Download'
  ]);

  // Load saved config (if within 24 hours)
  const savedConfig = loadPdfConfig();
  if (savedConfig) {
    applyPdfConfig(savedConfig);
    showToast('Config Restored', 'Previous settings loaded', 'info', 2000);
  }

  // Auto-save config on input changes
  const configInputs = ['remove_pages', 'unit', 'top', 'bottom', 'left', 'right', 
                        'watermark_text', 'watermark_size', 'watermark_rotate', 'output_name'];
  configInputs.forEach(id => {
    const el = document.getElementById(id);
    if (el) {
      el.addEventListener('change', savePdfConfig);
      el.addEventListener('input', savePdfConfig);
    }
  });

  // Show empty state in preview
  showPreviewEmpty(elements.previewBefore.querySelector('.preview-frame'));
  showPreviewEmpty(elements.previewAfter.querySelector('.preview-frame'));

  // Initialize drag & drop
  if (elements.dropZone && elements.fileInput) {
    initDropZone(elements.dropZone, elements.fileInput, {
      accept: 'application/pdf',
      maxSize: 100 * 1024 * 1024,
      onFile: (file) => {
        if (file) {
          showToast('File Selected', file.name, 'success');
          elements.urlInput.value = '';
          pdfStepIndicator.setStep(1); // Move to Configure step
        }
      }
    });
  }

  // URL input change - update step
  elements.urlInput.addEventListener('input', () => {
    if (elements.urlInput.value.trim()) {
      pdfStepIndicator.setStep(1);
    }
    clearFieldError(elements.urlInput.closest('.form-group'));
  });

  // Preview tab switching
  elements.previewTabs.forEach(tab => {
    tab.addEventListener('click', () => {
      if (isSplitView) return;
      const target = tab.dataset.preview;
      switchPreview(target, elements.previewTabs);
    });
  });

  // Split view toggle
  elements.btnSplitView.addEventListener('click', () => {
    isSplitView = !isSplitView;
    elements.btnSplitView.classList.toggle('active', isSplitView);
    elements.splitView.classList.toggle('active', isSplitView);
    
    document.getElementById('preview-before').style.display = isSplitView ? 'none' : '';
    document.getElementById('preview-after').style.display = isSplitView ? 'none' : '';
    
    if (!isSplitView) {
      const activeTab = document.querySelector('.preview-tab.active');
      switchPreview(activeTab?.dataset.preview || 'before', elements.previewTabs);
    }
    
    // Sync frames
    if (pdfBeforeUrl) {
      elements.splitFrameBefore.src = pdfBeforeUrl;
    }
    if (pdfAfterUrl) {
      elements.splitFrameAfter.src = pdfAfterUrl;
    }
  });

  // Fullscreen toggle
  elements.btnFullscreen.addEventListener('click', () => {
    const activeTab = document.querySelector('.preview-tab.active');
    const url = activeTab?.dataset.preview === 'after' ? pdfAfterUrl : pdfBeforeUrl;
    
    if (url) {
      elements.fullscreenFrame.src = url;
      elements.fullscreenOverlay.classList.add('active');
    } else {
      showToast('No Preview', 'Load a PDF first', 'info');
    }
  });

  elements.fullscreenClose.addEventListener('click', () => {
    elements.fullscreenOverlay.classList.remove('active');
    elements.fullscreenFrame.src = '';
  });

  // Close fullscreen on ESC
  document.addEventListener('keydown', (e) => {
    if (e.key === 'Escape' && elements.fullscreenOverlay.classList.contains('active')) {
      elements.fullscreenOverlay.classList.remove('active');
      elements.fullscreenFrame.src = '';
    }
  });

  // Button handlers
  elements.btnBefore.addEventListener('click', () => handlePreviewOriginal(elements));
  elements.btnAfter.addEventListener('click', () => handleProcessPdf(elements));
  
  // Clear config button
  const btnClearConfig = document.getElementById('btnClearConfig');
  if (btnClearConfig) {
    btnClearConfig.addEventListener('click', clearPdfConfig);
  }

  // URL validation
  elements.urlInput.addEventListener('blur', () => {
    const value = elements.urlInput.value.trim();
    if (value) validateUrl(elements.urlInput);
  });

  elements.urlInput.addEventListener('input', () => {
    clearFieldError(elements.urlInput.closest('.form-group'));
  });

  // Keyboard shortcuts
  registerShortcut('ctrl+p', () => {
    if (document.getElementById('page-pdf').classList.contains('active')) {
      elements.btnBefore.click();
    }
  });

  registerShortcut('ctrl+enter', () => {
    if (document.getElementById('page-pdf').classList.contains('active')) {
      elements.btnAfter.click();
    }
  });
}

/**
 * Watermark Removal Feature (separate page)
 */
function initWatermarkRemoval() {
  const dropZone = document.getElementById('wmDropZone');
  const fileInput = document.getElementById('wm_file');
  const urlInput = document.getElementById('wm_url');
  const btnRemove = document.getElementById('btnRemoveWatermark');
  const btnPreview = document.getElementById('btnWmPreview');
  const intensitySlider = document.getElementById('wm_intensity');
  const intensityValue = document.getElementById('wm_intensity_value');
  const progress = document.getElementById('wmProgress');

  // Initialize drag & drop
  if (dropZone && fileInput) {
    initDropZone(dropZone, fileInput, {
      accept: 'application/pdf',
      maxSize: 100 * 1024 * 1024,
      onFile: (file) => {
        if (file) {
          showToast('File Selected', file.name, 'success');
          if (urlInput) urlInput.value = '';
        }
      }
    });
  }

  // Update intensity display
  if (intensitySlider && intensityValue) {
    intensitySlider.addEventListener('input', () => {
      intensityValue.textContent = intensitySlider.value;
    });
  }

  if (btnPreview) {
    btnPreview.addEventListener('click', handleWatermarkPreview);
  }

  if (btnRemove) {
    btnRemove.addEventListener('click', handleRemoveWatermark);
  }
}

async function handleWatermarkPreview() {
  const urlInput = document.getElementById('wm_url');
  const fileInput = document.getElementById('wm_file');
  const btn = document.getElementById('btnWmPreview');
  const previewCard = document.getElementById('wmPreviewCard');
  const originalImg = document.getElementById('wmPreviewOriginal');
  const processedImg = document.getElementById('wmPreviewProcessed');

  const hasUrl = urlInput && urlInput.value.trim();
  const hasFile = fileInput && fileInput.files.length > 0;

  if (!hasUrl && !hasFile) {
    showToast('No PDF', 'Upload a file or enter a URL first', 'error');
    return;
  }

  setButtonLoading(btn, true, 'Loading...');

  try {
    const fd = new FormData();
    
    if (hasUrl) fd.append('url', urlInput.value.trim());
    if (hasFile) fd.append('file', fileInput.files[0]);
    
    fd.append('page', '0');
    fd.append('method', document.getElementById('wm_method').value || 'inpaint');
    fd.append('intensity', document.getElementById('wm_intensity').value || '50');

    const res = await fetch('/api/watermark-preview', { method: 'POST', body: fd });

    if (!res.ok) {
      let err = { detail: 'Request failed' };
      try { err = await res.json(); } catch {}
      throw new Error(err.detail || 'Request failed');
    }

    const data = await res.json();
    
    // Show preview images
    originalImg.src = 'data:image/png;base64,' + data.original;
    processedImg.src = 'data:image/png;base64,' + data.processed;
    previewCard.style.display = 'block';
    
    // Scroll to preview
    previewCard.scrollIntoView({ behavior: 'smooth', block: 'start' });
    
    showToast('Preview Ready', 'Compare original vs processed', 'success', 2000);

  } catch (e) {
    showToast('Error', e.message, 'error');
  } finally {
    setButtonLoading(btn, false);
  }
}

async function handleRemoveWatermark() {
  const urlInput = document.getElementById('wm_url');
  const fileInput = document.getElementById('wm_file');
  const btn = document.getElementById('btnRemoveWatermark');
  const progress = document.getElementById('wmProgress');

  const hasUrl = urlInput && urlInput.value.trim();
  const hasFile = fileInput && fileInput.files.length > 0;

  if (!hasUrl && !hasFile) {
    showToast('No PDF', 'Upload a file or enter a URL first', 'error');
    return;
  }

  setButtonLoading(btn, true, 'Processing...');
  showProgress(progress, true, true);

  try {
    const fd = new FormData();
    
    if (hasUrl) fd.append('url', urlInput.value.trim());
    if (hasFile) fd.append('file', fileInput.files[0]);
    
    fd.append('output_name', document.getElementById('wm_output_name').value || 'cleaned.pdf');
    fd.append('watermark_text', document.getElementById('wm_text').value || 'Educated Nepal');
    fd.append('method', document.getElementById('wm_method').value || 'inpaint');
    fd.append('intensity', document.getElementById('wm_intensity').value || '50');
    fd.append('dpi', document.getElementById('wm_dpi').value || '150');
    fd.append('quality', document.getElementById('wm_quality').value || '85');

    const res = await fetch('/api/remove-watermark', { method: 'POST', body: fd });

    if (!res.ok) {
      let err = { detail: 'Request failed' };
      try { err = await res.json(); } catch {}
      throw new Error(err.detail || 'Request failed');
    }

    const blob = await res.blob();
    const filename = document.getElementById('wm_output_name').value || 'cleaned.pdf';

    // Download
    const url = URL.createObjectURL(blob);
    const a = document.createElement('a');
    a.href = url;
    a.download = filename.endsWith('.pdf') ? filename : filename + '.pdf';
    document.body.appendChild(a);
    a.click();
    a.remove();
    URL.revokeObjectURL(url);

    showSuccessAnimation('Watermark Removed!', `${filename} has been downloaded`);
    
    // Add to recent files
    if (typeof addToRecentFiles === 'function') {
      addToRecentFiles(filename, 'watermark-removal');
    }

  } catch (e) {
    showToast('Error', e.message, 'error');
  } finally {
    setButtonLoading(btn, false);
    showProgress(progress, false);
  }
}

function switchPreview(name, tabs) {
  tabs.forEach(t => t.classList.toggle('active', t.dataset.preview === name));
  document.getElementById('preview-before').classList.toggle('active', name === 'before');
  document.getElementById('preview-after').classList.toggle('active', name === 'after');
}

function validatePdfForm() {
  const urlInput = document.getElementById('pdf_url');
  const fileInput = document.getElementById('pdf_file');
  
  const hasUrl = urlInput.value.trim();
  const hasFile = fileInput.files.length > 0;
  
  if (!hasUrl && !hasFile) {
    showToast('No PDF', 'Upload a file or enter a URL', 'error');
    return false;
  }
  
  if (hasUrl && !validateUrl(urlInput)) {
    return false;
  }
  
  return true;
}

function buildPdfFormData(includeProcessOptions) {
  const fd = new FormData();
  
  const url = document.getElementById('pdf_url').value.trim();
  const file = document.getElementById('pdf_file').files[0];
  
  if (url) fd.append('url', url);
  if (file) fd.append('file', file);
  
  fd.append('output_name', document.getElementById('output_name').value.trim() || 'cropped.pdf');

  if (includeProcessOptions) {
    fd.append('remove_pages', document.getElementById('remove_pages').value.trim());
    fd.append('unit', document.getElementById('unit').value);
    fd.append('top', document.getElementById('top').value || '0');
    fd.append('bottom', document.getElementById('bottom').value || '0');
    fd.append('left', document.getElementById('left').value || '0');
    fd.append('right', document.getElementById('right').value || '0');
    fd.append('watermark_text', document.getElementById('watermark_text').value || '');
    fd.append('watermark_size', document.getElementById('watermark_size').value || '36');
    fd.append('watermark_rotate', document.getElementById('watermark_rotate').value || '45');
  }
  
  return fd;
}

async function postForBlob(endpoint, formData) {
  const res = await fetch(endpoint, { method: 'POST', body: formData });
  
  if (!res.ok) {
    let err = { detail: 'Request failed' };
    try { err = await res.json(); } catch {}
    throw new Error(err.detail || 'Request failed');
  }
  
  return await res.blob();
}

async function handlePreviewOriginal(elements) {
  if (!validatePdfForm()) return;
  
  setButtonLoading(elements.btnBefore, true, 'Loading...');
  elements.btnAfter.disabled = true;
  showProgress(elements.progress, true, true);
  pdfStepIndicator.setStep(2); // Preview step

  try {
    const blob = await postForBlob('/api/fetch', buildPdfFormData(false));
    
    if (pdfBeforeUrl) URL.revokeObjectURL(pdfBeforeUrl);
    pdfBeforeUrl = URL.createObjectURL(blob);
    
    // Clear empty state and show iframe
    elements.previewBefore.querySelector('.preview-frame').innerHTML = '<iframe id="frameBefore"></iframe>';
    elements.frameBefore = document.getElementById('frameBefore');
    elements.frameBefore.src = pdfBeforeUrl;
    elements.splitFrameBefore.src = pdfBeforeUrl;
    
    if (!isSplitView) {
      switchPreview('before', elements.previewTabs);
    }
    
    showToast('Preview Ready', 'Original PDF loaded', 'success');
  } catch (e) {
    showToast('Error', e.message, 'error');
    pdfStepIndicator.setStep(1); // Back to configure
  } finally {
    setButtonLoading(elements.btnBefore, false);
    elements.btnAfter.disabled = false;
    showProgress(elements.progress, false);
  }
}

async function handleProcessPdf(elements) {
  if (!validatePdfForm()) return;
  
  setButtonLoading(elements.btnAfter, true, 'Processing...');
  elements.btnBefore.disabled = true;
  showProgress(elements.progress, true, true);
  pdfStepIndicator.setStep(3); // Download step

  try {
    const outName = document.getElementById('output_name').value.trim() || 'cropped.pdf';
    const filename = outName.toLowerCase().endsWith('.pdf') ? outName : outName + '.pdf';

    const blob = await postForBlob('/api/process', buildPdfFormData(true));
    
    if (pdfAfterUrl) URL.revokeObjectURL(pdfAfterUrl);
    pdfAfterUrl = URL.createObjectURL(blob);
    
    // Clear empty state and show iframe
    elements.previewAfter.querySelector('.preview-frame').innerHTML = '<iframe id="frameAfter"></iframe>';
    elements.frameAfter = document.getElementById('frameAfter');
    elements.frameAfter.src = pdfAfterUrl;
    elements.splitFrameAfter.src = pdfAfterUrl;

    // Download
    const a = document.createElement('a');
    a.href = pdfAfterUrl;
    a.download = filename;
    document.body.appendChild(a);
    a.click();
    a.remove();

    if (!isSplitView) {
      switchPreview('after', elements.previewTabs);
    }
    
    pdfStepIndicator.complete();
    
    // Show success animation
    showSuccessAnimation('PDF Processed!', `${filename} has been downloaded`);
  } catch (e) {
    showToast('Error', e.message, 'error');
    pdfStepIndicator.setStep(2);
  } finally {
    setButtonLoading(elements.btnAfter, false);
    elements.btnBefore.disabled = false;
    showProgress(elements.progress, false);
  }
}