/**
 * Setup and configure a Puppeteer page
 * @param {Browser} browser - Puppeteer browser instance
 * @param {Object} options - Configuration options
 * @param {number} options.width - Page width
 * @param {number} options.height - Page height
 * @returns {Promise<Page>} Configured Puppeteer page
 */
async function setupPage(browser, { width, height }) {
  const page = await browser.newPage();
  
  // Reduce memory usage by disabling caching
  await page.setCacheEnabled(false);
  
  // Inject CSS early to prevent white flash during page load
  await page.evaluateOnNewDocument(() => {
    const style = document.createElement('style');
    style.textContent = `
      html, body {
        background-color: #000 !important;
      }
    `;
    document.head?.appendChild(style) || document.documentElement.appendChild(style);
  });

  return page;
}

/**
 * Wait for page to be fully loaded with stylesheet
 * @param {Page} page - Puppeteer page
 * @param {string} url - URL to navigate to
 * @returns {Promise<boolean>} True if page loaded successfully
 */
async function waitForPageFullyLoaded(page, url) {
  try {
    // Wait for DOM content to load - no artificial delay, stream starts immediately
    await page.goto(url, { waitUntil: 'domcontentloaded', timeout: 30000 });
    
    return true;
  } catch (err) {
    console.error('Page load error:', err.message);
    // Still show the page even if timeout occurs
    return true;
  }
}

/**
 * Hide logo elements on the page
 * @param {Page} page - Puppeteer page
 */
async function hideLogo(page) {
  try {
    await page.evaluate(() => {
      const images = document.querySelectorAll('img');
      images.forEach(img => {
        if (img.src && img.src.includes('Logo3.png')) {
          img.style.display = 'none';
        }
      });
    });
  } catch (err) {
    // Silent
  }
}

/**
 * Start smooth auto-scrolling on the page
 * @param {Page} page - Puppeteer page
 * @param {Object} options - Scrolling options
 * @param {number} options.pauseAtTop - Seconds to wait at top before scrolling (default: 30)
 * @param {number} options.fps - Frame rate for smooth scrolling (default: 30)
 * @returns {Function} Stop function to cancel scrolling
 */
async function startAutoScroll(page, { pauseAtTop = 30, fps = 30 } = {}) {
  let stopScrolling = false;
  
  const stopFunction = () => {
    stopScrolling = true;
  };
  
  // Inject scrolling logic into the page
  await page.evaluate((pauseMs, captureFrameRate) => {
    window.__autoScrollState = {
      stopScrolling: false,
      isScrolling: false
    };
    
    function smoothScroll() {
      if (window.__autoScrollState.stopScrolling) return;
      
      const maxScroll = Math.max(
        document.body.scrollHeight,
        document.documentElement.scrollHeight
      ) - window.innerHeight;
      
      if (maxScroll <= 0) {
        // Page is not scrollable, just wait
        setTimeout(() => {
          if (!window.__autoScrollState.stopScrolling) {
            smoothScroll();
          }
        }, pauseMs);
        return;
      }
      
      // Wait at top, then start smooth scroll
      setTimeout(() => {
        if (window.__autoScrollState.stopScrolling) return;
        
        // Slow scroll speed for smooth appearance
        // At 60fps with 30px/s = 0.5 pixels per frame
        const pixelsPerSecond = 30;
        const pixelsPerFrame = pixelsPerSecond / captureFrameRate;
        const frameInterval = 1000 / captureFrameRate;
        
        function scrollDown() {
          if (window.__autoScrollState.stopScrolling) return;
          
          let currentPos = window.scrollY;
          
          const interval = setInterval(() => {
            if (window.__autoScrollState.stopScrolling) {
              clearInterval(interval);
              return;
            }
            
            currentPos += pixelsPerFrame;
            
            if (currentPos >= maxScroll) {
              window.scrollTo(0, maxScroll);
              clearInterval(interval);
              setTimeout(() => {
                if (!window.__autoScrollState.stopScrolling) {
                  scrollUp();
                }
              }, 2000);
            } else {
              window.scrollTo(0, currentPos);
            }
          }, frameInterval);
        }
        
        function scrollUp() {
          if (window.__autoScrollState.stopScrolling) return;
          
          let currentPos = window.scrollY;
          
          const interval = setInterval(() => {
            if (window.__autoScrollState.stopScrolling) {
              clearInterval(interval);
              return;
            }
            
            currentPos -= pixelsPerFrame;
            
            if (currentPos <= 0) {
              window.scrollTo(0, 0);
              clearInterval(interval);
              if (!window.__autoScrollState.stopScrolling) {
                smoothScroll();
              }
            } else {
              window.scrollTo(0, currentPos);
            }
          }, frameInterval);
        }
        
        scrollDown();
      }, pauseMs);
    }
    
    // Start scrolling
    smoothScroll();
  }, pauseAtTop * 1000, fps);
  
  return stopFunction;
}

module.exports = {
  setupPage,
  waitForPageFullyLoaded,
  hideLogo,
  startAutoScroll
};