// Slide thumbnail capture helpers for player-sourced screenshots.

const fs = require('fs');
const path = require('path');
const {
  escapeHtml,
  mediaKind,
  renderEditorJsContent,
  sanitizeFontFamily,
  sanitizeFontSize,
  sanitizeTextColor
} = require('#src/player/render-helpers');
const { createRequestAuthHeaders } = require('#src/request-auth');

const SYSTEM_CHROMIUM_PATHS = [
  process.env.PUPPETEER_EXECUTABLE_PATH,
  process.env.CHROMIUM_PATH,
  '/usr/bin/chromium',
  '/usr/bin/chromium-browser',
  '/usr/local/bin/chromium',
  '/snap/bin/chromium'
].filter(Boolean);
const PLAYER_VIEWPORT = {
  width: 1920,
  height: 1080,
  deviceScaleFactor: 1
};
const THUMBNAIL_MAX_SIZE = {
  width: 480,
  height: 270
};

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 getCanvasSize(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 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 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);
}

async function loadChromium() {
  const chromiumModule = await import('@sparticuz/chromium');
  const resolved = chromiumModule && chromiumModule.default ? chromiumModule.default : chromiumModule;
  return resolved;
}

async function loadPuppeteer() {
  return require('puppeteer-core');
}

function loadSharp() {
  return require('sharp');
}

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)
  };
}

async function launchBrowser() {
  const puppeteer = await loadPuppeteer();
  const chromium = await loadChromium();
  let executablePath = SYSTEM_CHROMIUM_PATHS.find(function (candidate) {
    return fs.existsSync(candidate);
  }) || '';
  const usingSystemChromium = Boolean(executablePath);

  if (!executablePath && chromium && typeof chromium.executablePath === 'function') {
    executablePath = await chromium.executablePath();
  }

  if (!executablePath || !fs.existsSync(executablePath)) {
    throw new Error('Chromium executable was not found.');
  }

  if (usingSystemChromium) {
    return puppeteer.launch({
      args: [
        '--no-sandbox',
        '--disable-setuid-sandbox',
        '--disable-dev-shm-usage',
        '--disable-gpu'
      ],
      defaultViewport: { width: 1920, height: 1080, deviceScaleFactor: 1 },
      executablePath: executablePath,
      headless: true
    });
  }

  return puppeteer.launch({
    args: puppeteer.defaultArgs({
      args: chromium && chromium.args ? chromium.args : [],
      headless: 'shell'
    }),
    defaultViewport: chromium && chromium.defaultViewport ? chromium.defaultViewport : null,
    executablePath: executablePath,
    headless: 'shell'
  });
}

async function captureSlideThumbnail(options) {
  const sharp = loadSharp();
  const pool = options && options.pool;
  const common = options && options.common;
  const mediaDir = String(options && options.mediaDir || '').trim();
  const baseUrl = normalizeBaseUrl(options && options.baseUrl);
  const slideId = Number(options && options.slideId || 0);
  const previousThumbnailPath = String(options && options.previousThumbnailPath || '').trim();

  if (!pool || !common || !mediaDir || !Number.isFinite(slideId) || slideId <= 0) {
    throw new Error('captureSlideThumbnail requires pool, common, mediaDir, and slideId.');
  }

  const slide = await common.fetchSlideById(pool, slideId);
  if (!slide) {
    throw new Error('Slide not found.');
  }

  const thumbnailDir = path.join(mediaDir, 'thumbnails');
  const thumbnailRelativePath = String(slide.thumbnail_path || '').trim() || '/media/thumbnails/slides/slide-' + slide.id + '.png';
  const filePath = path.join(mediaDir, thumbnailRelativePath.replace(/^\/+media\//, ''));
  const fullSizePath = filePath.replace(/\.png$/i, '.full.png');
  const thumbnailTempPath = filePath.replace(/\.png$/i, '.tmp.png');
  const thumbnailPath = thumbnailRelativePath;

  await fs.promises.mkdir(path.dirname(filePath), { recursive: true });

  async function waitForThumbnailRender(page) {
    await page.waitForFunction(function () {
      return document.readyState === 'complete' && Boolean(document.querySelector('#popup-preview-canvas'));
    }, { timeout: 30000 });

    await page.waitForFunction(function () {
      var canvas = document.querySelector('#popup-preview-canvas');
      if (!canvas) {
        return false;
      }

      var images = Array.prototype.slice.call(canvas.querySelectorAll('img'));
      return images.every(function (image) {
        return image.complete && typeof image.naturalWidth === 'number';
      });
    }, { timeout: 30000 });

    await page.evaluate(async function () {
      if (document.fonts && document.fonts.ready) {
        try {
          await document.fonts.ready;
        } catch (_error) {
          // Ignore font readiness failures and fall back to the rendered frame.
        }
      }
    });

    await page.evaluate(function () {
      return new Promise(function (resolve) {
        window.requestAnimationFrame(function () {
          window.requestAnimationFrame(resolve);
        });
      });
    });
  }

  const browser = await launchBrowser();
  try {
    const page = await browser.newPage();
    try {
      const previewPath = '/api/internal/slide-thumbnails/' + slide.id + '/popup-preview';
      const previewUrl = baseUrl + previewPath;
      const previewPayload = buildThumbnailPreviewPayload(slide, {
        baseUrl: baseUrl,
        fontStylesheetHref: options && options.fontStylesheetHref ? options.fontStylesheetHref : ''
      });
        await page.setViewport({
          width: Math.max(1, Number(previewPayload.canvasWidth || PLAYER_VIEWPORT.width)),
          height: Math.max(1, Number(previewPayload.canvasHeight || PLAYER_VIEWPORT.height)),
          deviceScaleFactor: 1
        });
      await page.setExtraHTTPHeaders(createRequestAuthHeaders({
        method: 'GET',
        pathname: previewPath
      }));
      await page.goto(previewUrl, { waitUntil: 'domcontentloaded', timeout: 30000 });
      await waitForThumbnailRender(page);
      const canvas = await page.$('#popup-preview-canvas');
      if (!canvas) {
        throw new Error('Popup preview did not produce a slide canvas.');
      }
      await canvas.screenshot({ path: fullSizePath });
    } finally {
      await page.close().catch(function () {
        return null;
      });
    }
  } finally {
    await browser.close().catch(function () {
      return null;
    });
  }

  await sharp(fullSizePath)
    .resize({
      width: THUMBNAIL_MAX_SIZE.width,
      height: THUMBNAIL_MAX_SIZE.height,
      fit: 'inside',
      withoutEnlargement: true
    })
    .png()
    .toFile(thumbnailTempPath);

  await fs.promises.rm(filePath, { force: true });
  await fs.promises.rename(thumbnailTempPath, filePath);
  await fs.promises.unlink(fullSizePath).catch(function (error) {
    if (!error || error.code !== 'ENOENT') {
      throw error;
    }
  });

  await pool.query('UPDATE c_slides SET thumbnail_path = ? WHERE id = ?', [thumbnailPath, slide.id]);
  return {
    slideId: slide.id,
    thumbnailPath: thumbnailPath,
    filePath: filePath,
    fullSizePath: fullSizePath,
    mediaKind: mediaKind('')
  };
}

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