// Pure thumbnail preview payload helpers shared by routes and screenshot capture.

const {
  escapeHtml,
  renderEditorJsContent,
  sanitizeFontFamily,
  sanitizeFontSize,
  sanitizeTextColor
} = require('#src/player/render-helpers');

function normalizeBaseUrl(baseUrl) {
  return String(baseUrl || '').trim().replace(/\/$/, '');
}

function resolveAssetUrl(baseUrl, value) {
  const raw = String(value || '').trim();
  if (!raw) {
    return '';
  }
  if (/^(?:https?:)?\/\//i.test(raw) || raw.startsWith('data:')) {
    return raw;
  }
  const normalizedBaseUrl = normalizeBaseUrl(baseUrl);
  if (!normalizedBaseUrl) {
    return raw;
  }
  if (raw.startsWith('/')) {
    return normalizedBaseUrl + raw;
  }
  return normalizedBaseUrl + '/' + raw.replace(/^\/+/, '');
}

function getThumbnailCanvasSize(slide) {
  const template = slide && slide.template ? slide.template : null;
  return {
    width: Math.max(1, Number(template && template.canvas_size_width ? template.canvas_size_width : 1920)),
    height: Math.max(1, Number(template && template.canvas_size_height ? template.canvas_size_height : 1080))
  };
}

function getRegionContent(slide, region) {
  const content = slide && slide.content && slide.content[region.region_key] ? slide.content[region.region_key] : {};
  return content && typeof content === 'object' ? content : { value: content };
}

function buildThumbnailRegionStyle(region, canvasWidth, canvasHeight) {
  const left = Number.isFinite(Number(region && region.x)) && canvasWidth > 0 ? (Number(region.x) / canvasWidth) * 100 : 0;
  const top = Number.isFinite(Number(region && region.y)) && canvasHeight > 0 ? (Number(region.y) / canvasHeight) * 100 : 0;
  const width = Number.isFinite(Number(region && region.width)) && canvasWidth > 0 ? (Number(region.width) / canvasWidth) * 100 : 0;
  const height = Number.isFinite(Number(region && region.height)) && canvasHeight > 0 ? (Number(region.height) / canvasHeight) * 100 : 0;

  return 'left:' + left + '%;top:' + top + '%;width:' + width + '%;height:' + height + '%;z-index:' + Number(region && region.z_index || 0) + ';';
}

function hasVisibleContent(html) {
  return Boolean(String(html || '').replace(/<[^>]+>/g, '').trim());
}

function buildTextRegionMarkup(region, regionContent) {
  const fontFamily = sanitizeFontFamily(regionContent.font_family || region.font_family);
  const fontSize = sanitizeFontSize(regionContent.font_size || region.font_size);
  const fontColor = sanitizeTextColor(regionContent.font_color || region.font_color);
  const renderedBody = renderEditorJsContent(regionContent.value || '');
  if (!hasVisibleContent(renderedBody)) {
    return '';
  }

  return '<div class="slide-preview-region slide-preview-text-region" style="' + region.baseStyle + '"><div class="slide-preview-text-content" style="width:' + region.pixelWidth + 'px;height:' + region.pixelHeight + 'px;overflow:hidden;' + (fontFamily ? 'font-family:' + escapeHtml(fontFamily) + ';' : '') + 'font-size:' + fontSize + 'px;color:' + escapeHtml(fontColor || '#000000') + ';">' + renderedBody + '</div></div>';
}

function buildRegionInnerHtml(region, regionContent, baseUrl) {
  const regionType = String(regionContent.type || region.region_type || 'text').trim().toLowerCase();
  const rawValue = regionContent && regionContent.value !== undefined ? regionContent.value : '';

  if (regionType === 'image') {
    const src = resolveAssetUrl(baseUrl, rawValue);
    return src
      ? '<div class="slide-preview-region slide-preview-image-region" style="' + region.baseStyle + '"><img class="slide-preview-image" src="' + escapeHtml(src) + '" alt="' + escapeHtml(region.label || region.region_key || 'image') + '" /></div>'
      : '';
  }

  if (regionType === 'video') {
    const src = resolveAssetUrl(baseUrl, rawValue);
    return src
      ? '<div class="slide-preview-region slide-preview-video-region" style="' + region.baseStyle + '"><video class="slide-preview-video" src="' + escapeHtml(src) + '" title="' + escapeHtml(region.label || region.region_key || 'video') + '" muted playsinline preload="metadata"></video></div>'
      : '';
  }

  if (regionType === 'webpage') {
    const src = resolveAssetUrl(baseUrl, rawValue);
    return src
      ? '<div class="slide-preview-region slide-preview-webpage-region" style="' + region.baseStyle + '"><iframe src="' + escapeHtml(src) + '" title="' + escapeHtml(region.label || region.region_key || 'webpage') + '" loading="eager" referrerpolicy="no-referrer" scrolling="no"></iframe></div>'
      : '';
  }

  if (regionType === 'qr-code') {
    const src = String(regionContent.qr_preview || '').trim();
    const borderRadius = Math.max(0, Math.round(Number(regionContent.qr_border_radius || 0)));
    const radiusStyle = borderRadius > 0 ? ' style="border-radius:' + borderRadius + 'px;overflow:hidden;"' : '';
    return src
      ? '<div class="slide-preview-region slide-preview-qr-code-region" style="' + region.baseStyle + radiusStyle + '"><img class="slide-preview-image" src="' + escapeHtml(src) + '" alt="' + escapeHtml(region.label || region.region_key || 'qr code') + '" /></div>'
      : '';
  }

  if (regionType === 'html') {
    const html = String(rawValue || '').trim();
    return html
      ? '<div class="slide-preview-region slide-preview-html-region" style="' + region.baseStyle + '"><iframe sandbox="" srcdoc="<!doctype html><html><head><style>html,body{margin:0;width:100%;height:100%;overflow:hidden;background:transparent;}</style></head><body>' + escapeHtml(html) + '</body></html>" title="' + escapeHtml(region.label || region.region_key || 'html') + '" loading="eager" scrolling="no"></iframe></div>'
      : '';
  }

  if (regionType === 'rtmp') {
    const label = String(rawValue || '').trim() || 'RTMP source';
    return '<div class="slide-preview-region slide-preview-rtmp-region" style="' + region.baseStyle + '"><div class="slide-preview-rtmp-placeholder">' + escapeHtml(label) + '</div></div>';
  }

  return buildTextRegionMarkup(region, regionContent);
}

function buildThumbnailPreviewMarkup(slide, baseUrl) {
  const template = slide && slide.template ? slide.template : null;
  if (!template) {
    return '';
  }

  const canvasSize = getThumbnailCanvasSize(slide);
  const normalizedBaseUrl = normalizeBaseUrl(baseUrl);
  return (Array.isArray(template.regions) ? template.regions : []).map(function (region) {
    const regionContent = getRegionContent(slide, region);
    const previewRegion = Object.assign({}, region, {
      baseStyle: buildThumbnailRegionStyle(region, canvasSize.width, canvasSize.height),
      pixelWidth: Math.max(1, Math.round(Number(region && region.width || 0) || 1)),
      pixelHeight: Math.max(1, Math.round(Number(region && region.height || 0) || 1))
    });
    return buildRegionInnerHtml(previewRegion, regionContent, normalizedBaseUrl);
  }).join('');
}

function buildThumbnailPreviewPayload(slide, options) {
  const template = slide && slide.template ? slide.template : null;
  const canvasSize = getThumbnailCanvasSize(slide);
  return {
    thumbnailPreview: true,
    canvasWidth: canvasSize.width,
    canvasHeight: canvasSize.height,
    backgroundColor: template && template.background_color ? String(template.background_color) : '#111111',
    backgroundImagePath: template && template.background_image_path ? String(template.background_image_path) : '',
    fontStylesheetHref: String(options && options.fontStylesheetHref || '').trim(),
    html: buildThumbnailPreviewMarkup(slide, options && options.baseUrl)
  };
}

module.exports = {
  buildThumbnailPreviewPayload: buildThumbnailPreviewPayload,
  buildThumbnailPreviewMarkup: buildThumbnailPreviewMarkup
};