import type { APIRoute } from "astro";
import chromium from 'chrome-aws-lambda';
import puppeteerCore from 'puppeteer-core';

// Check if running on Vercel
const IS_VERCEL = process.env.VERCEL === '1' || process.env.VERCEL === 'true';

// Import puppeteer dynamically for ESM compatibility
import puppeteer from 'puppeteer';

// Decide which Puppeteer to use based on environment
const puppeteerInstance = IS_VERCEL ? puppeteerCore : puppeteer;

// Helper function to extract comic slugs from a ComicK user list page
async function scrapeComicList(userId: string, limit: number = 10): Promise<string[]> {
  let browser;
  
  if (IS_VERCEL) {
    // Use chrome-aws-lambda for Vercel environment
    console.log('Running on Vercel - using chrome-aws-lambda');
    browser = await puppeteerCore.launch({
      args: chromium.args,
      defaultViewport: chromium.defaultViewport,
      executablePath: await chromium.executablePath,
      headless: chromium.headless,
      ignoreHTTPSErrors: true,
    });
  } else {
    // Use regular Puppeteer for local development
    browser = await puppeteerInstance.launch({
      headless: true,
      args: ['--no-sandbox', '--disable-setuid-sandbox']
    });
  }
  
  try {
    const page = await browser.newPage();
    
    // Set a user agent to mimic a real browser
    await page.setUserAgent('Mozilla/5.0 (Windows NT 10.0; Win64; x64) AppleWebKit/537.36 (KHTML, like Gecko) Chrome/123.0.0.0 Safari/537.36');
    
    console.log(`Navigating to ComicK user page: ${userId}`);
    
    // Navigate to the user's list page
    await page.goto(`https://comick.io/user/${userId}/list`, {
      waitUntil: 'networkidle0', // Wait until there are no network connections for at least 500ms
      timeout: 60000 // Longer timeout to ensure everything loads
    });
    
    // Wait directly for the Next.js data script to load (the most reliable approach)
    console.log('Waiting for Next.js data to load...');
    
    try {
      await page.waitForFunction(
        () => document.getElementById('__NEXT_DATA__') !== null,
        { timeout: 10000 }
      );
      console.log('Next.js data script found!');
    } catch (e) {
      console.log('Next.js data script not found, page might not be fully loaded');
    }
    
    // Minimal page interaction - Next.js will load the data we need
    console.log('Ensuring Next.js data is fully loaded...');
    
    // Wait a bit for any dynamic data to populate
    await new Promise(resolve => setTimeout(resolve, 3000));
    
    // Verify Next.js data is available and complete
    const dataLoaded = await page.evaluate(() => {
      const script = document.getElementById('__NEXT_DATA__');
      if (!script) return false;
      
      try {
        const data = JSON.parse(script.textContent || '{}');
        // Check if the follows data is present
        return !!data?.props?.pageProps?.follows;
      } catch (e) {
        return false;
      }
    });
    
    if (!dataLoaded) {
      console.log('Next.js data not fully loaded, waiting a bit longer...');
      await new Promise(resolve => setTimeout(resolve, 3000));
    } else {
      console.log('Next.js data confirmed loaded!');
    }
    
    console.log('Page loaded, extracting comic data...');
    
    // Extract the HTML structure for debugging
    const pageHtml = await page.content();
    console.log('Page HTML length:', pageHtml.length);
    
    // Extract comic slugs using only Next.js data - no CSS selectors
    const slugs = await page.evaluate(() => {
      console.log('Extracting comics directly from Next.js data structure...');
      
      try {
        // Find the __NEXT_DATA__ script which contains all the comic data
        const nextDataScript = document.getElementById('__NEXT_DATA__');
        if (!nextDataScript) {
          console.log('ERROR: __NEXT_DATA__ script not found!');
          return [];
        }
        
        console.log('Found Next.js data script!');
        const nextData = JSON.parse(nextDataScript.textContent || '{}');
        
        // Navigate to the follows data in the structure
        const follows = nextData?.props?.pageProps?.follows || [];
        console.log(`Found ${follows.length} comics in Next.js data`);
        
        if (follows.length > 0) {
          // Extract slugs from the follows array
          const comicSlugs = follows.map(follow => {
            const comic = follow.md_comics;
            if (comic && comic.slug) {
              console.log(`Found comic: ${comic.title} with slug: ${comic.slug}`);
              return comic.slug;
            }
            return null;
          }).filter(Boolean);
          
          console.log(`Successfully extracted ${comicSlugs.length} comics from Next.js data`);
          return comicSlugs;
        } else {
          console.log('No follows data found in Next.js data');
          
          // Try to locate comics in a different location in the data structure
          const alternative = nextData?.props?.pageProps?.user_info?.user_comic_follow_count;
          if (alternative) {
            console.log(`Found user has ${alternative} comics according to user_info`);
          }
          
          return [];
        }
      } catch (e) {
        console.log('Error extracting from Next.js data:', e);
        return [];
      }
    });
    
    // Remove duplicates by using a Set
    const uniqueSlugs = Array.from(new Set(slugs));
    console.log(`Extracted ${slugs.length} comics from page (${uniqueSlugs.length} unique)`);
    
    // Limit the number of comics to the specified limit
    const limitedSlugs = uniqueSlugs.slice(0, limit);
    
    console.log(`Returning ${limitedSlugs.length} comics (limit: ${limit})`);
    return limitedSlugs as string[];
  } finally {
    await browser.close();
  }
}

// Define timeout for Vercel environment
const VERCEL_TIMEOUT = 10000; // 10 seconds for Vercel functions
const LOCAL_TIMEOUT = 60000; // 60 seconds for local development
const FUNCTION_TIMEOUT = IS_VERCEL ? VERCEL_TIMEOUT : LOCAL_TIMEOUT;

export const GET: APIRoute = async ({ request }) => {
  // Ensure the function doesn't exceed Vercel's timeout limits
  let timeoutId: NodeJS.Timeout;
  
  // Create a promise that rejects after the timeout
  const timeoutPromise = new Promise<never>((_, reject) => {
    timeoutId = setTimeout(() => {
      reject(new Error(`Function timed out after ${FUNCTION_TIMEOUT}ms`));
    }, FUNCTION_TIMEOUT);
  });
  
  try {
    const url = new URL(request.url);
    const userId = url.searchParams.get('userId');
    
    // Get limit parameter from query string (default to 10 if not provided)
    const limitParam = url.searchParams.get('limit');
    const limit = limitParam ? parseInt(limitParam, 10) : 10;
    
    // Ensure limit is a valid number
    const validLimit = isNaN(limit) || limit <= 0 ? 10 : Math.min(limit, 100);

    if (!userId) {
      return new Response(JSON.stringify({ error: 'Missing user ID' }), {
        status: 400,
        headers: {
          'Content-Type': 'application/json'
        }
      });
    }

    // Extract user ID from URL if full URL was provided
    let cleanUserId = userId;
    if (userId.includes('comick.io/user/')) {
      const match = userId.match(/comick\.io\/user\/([a-zA-Z0-9-]+)/);
      if (match && match[1]) {
        cleanUserId = match[1];
      }
    }

    // Validate the UUID format
    const uuidRegex = /^[0-9a-f]{8}-[0-9a-f]{4}-[0-9a-f]{4}-[0-9a-f]{4}-[0-9a-f]{12}$/i;
    if (!uuidRegex.test(cleanUserId)) {
      return new Response(JSON.stringify({ error: 'Invalid user ID format. Must be a UUID like: 8da7d6cf-a2ac-4972-a465-770ba975ee2a' }), {
        status: 400,
        headers: {
          'Content-Type': 'application/json'
        }
      });
    }

    console.log(`Scraping comics for user: ${cleanUserId} with limit: ${validLimit}`);
    
    // Use Puppeteer to scrape the user's comic list with the specified limit
    const comics = await scrapeComicList(cleanUserId, validLimit);
    
    // Calculate total
    const totalComics = comics.length;
    
    // Check if the list is empty
    if (totalComics === 0) {
      console.log('No comics found for user, returning empty list');
      const response = new Response(JSON.stringify({
        success: false,
        error: "No comics found in this user's list. Make sure the user ID is correct and the list is not empty.",
        data: {
          comics: [],
          total: 0,
          limit: validLimit,
          userId: cleanUserId
        }
      }), {
        status: 404,
        headers: {
          'Content-Type': 'application/json'
        }
      });
      
      // Clear the timeout to prevent memory leaks
      clearTimeout(timeoutId);
      return response;
    }
    
    console.log(`Returning ${totalComics} comics found for user ${cleanUserId}`);

    const response = new Response(JSON.stringify({
      success: true,
      data: {
        comics,
        total: totalComics,
        limit: validLimit,
        userId: cleanUserId
      }
    }), {
      status: 200,
      headers: {
        'Content-Type': 'application/json',
        'Cache-Control': 'max-age=3600' // Cache for 1 hour
      }
    });
    
    // Clear the timeout to prevent memory leaks
    clearTimeout(timeoutId);
    return response;
  } catch (error) {
    console.error('Error fetching user comics:', error);
    
    // Try to generate a helpful error message based on the error
    let errorMessage = 'Failed to fetch user comics';
    let statusCode = 500;
    
    if (error instanceof Error) {
      // Handle specific error types
      if (error.message.includes('Failed to fetch') || 
          error.message.includes('network') ||
          error.message.includes('ECONNREFUSED')) {
        errorMessage = 'Could not connect to ComicK API. Please try again later.';
      } else if (error.message.includes('timeout')) {
        errorMessage = 'Request timed out. The ComicK API might be experiencing high load.';
      } else if (error.message.includes('parsing')) {
        errorMessage = 'Received invalid data from ComicK API. Their API structure might have changed.';
      }
    }
    
    // Clear the timeout to prevent memory leaks
    clearTimeout(timeoutId);
    
    return new Response(
      JSON.stringify({ 
        success: false,
        error: errorMessage,
        details: error instanceof Error ? error.message : String(error)
      }), {
        status: statusCode,
        headers: {
          'Content-Type': 'application/json'
        }
      }
    );
  }
};