import type { RequestHandler } from './$types.js';
import type { LaunchOptions } from 'puppeteer';
import puppeteer from 'puppeteer';
import * as cheerio from 'cheerio';
import path from 'path';
import { opendir, writeFile, mkdtemp, copyFile } from 'fs/promises';
import { tmpdir } from 'os';

export const prerender = true;

const cwd = process.cwd();

// PDF generation configuration
const PDF_CONFIG = {
  format: 'A4' as const,
  printBackground: true,
  preferCSSPageSize: true,
  margin: {
    top: '20mm',
    right: '20mm',
    bottom: '20mm',
    left: '20mm',
  },
};

// Browser launch options for different environments
const getLaunchOptions = (): LaunchOptions => {
  const chromePath = process.env.PUPPETEER_EXECUTABLE_PATH;
  const options: LaunchOptions = {
    headless: true,
  };
  if (chromePath) {
    options.executablePath = chromePath;
  }
  return options;
};

export const GET: RequestHandler = async ({ url, fetch }) => {
  const tmpDir = await mkdtemp(path.join(tmpdir(), 'cv-pdf-genration-'));
  const tmpFile = (url: string) => {
    const filename = path.basename(url);
    const tempFile = path.join(tmpDir, filename);
    return tempFile;
  };

  try {
    // Launch browser
    const browser = await puppeteer.launch(getLaunchOptions());
    const page = await browser.newPage();
    const printResponse = await fetch('/print/');
    const html = await printResponse.text();
    const $ = cheerio.load(html);

    const fileDownloads: Record<string, string> = {};

    $('script[src], link[rel="stylesheet"], img[src]').each((i, el) => {
      if (el.tagName === 'link') {
        const href = $(el).attr('href');
        if (href) {
          const tempFile = (fileDownloads[href] ||= tmpFile(href));
          $(el).attr('href', `file://${tempFile}`);
        }
      } else {
        const src = $(el).attr('src');
        if (src) {
          const tempFile = (fileDownloads[src] ||= tmpFile(src));
          $(el).attr('src', `file://${tempFile}`);
        }
      }
    });

    $('style[src]').each((i, el) => {
      const src = $(el).attr('src');
      if (src) {
        const tempFile = (fileDownloads[src] ||= tmpFile(src));
        $(el).attr('src', `file://${tempFile}`);
      }
    });

    $('style:not([src])').each((i, el) => {
      const content = $(el).text();
      $(el).text(
        content.replaceAll(/(?<=url\(".+?)(?=")/g, (match) => {
          const url = match[0];
          const tempFile = (fileDownloads[url] ||= tmpFile(url));
          return `file://${tempFile}`;
        })
      );
    });

    const dir = await opendir('.svelte-kit/output/client/_app/immutable/assets');
    for await (const file of dir) {
      await copyFile(path.join(file.parentPath, file.name), tmpFile(file.name));
    }

    const htmlFile = path.join(tmpDir, 'index.html');
    await writeFile(htmlFile, $.root().html() ?? '');

    // Navigate to the PDF page with increased timeout
    // waitUntil: 'networkidle2' waits for 2 network connections to be idle
    // This is more lenient than 'networkidle0' which waits for 0 connections
    await page.goto(`file://${htmlFile}`, { waitUntil: 'networkidle2' });
    // Wait for fonts to load
    await page.evaluateHandle('document.fonts.ready');

    // Generate PDF
    const pdfBuffer = await page.pdf(PDF_CONFIG);

    // Close browser
    await browser.close();

    // Create Blob from buffer for Response
    const pdfBlob = new Blob([Buffer.from(pdfBuffer).buffer], { type: 'application/pdf' });

    // Return PDF with appropriate headers
    return new Response(pdfBlob, {
      status: 200,
      headers: {
        'Content-Type': 'application/pdf',
        'Cache-Control': 'public, max-age=3600', // Cache for 1 hour
      },
    });
  } catch (error) {
    console.error('PDF generation error:', error);

    return new Response(
      JSON.stringify({
        error: 'Failed to generate PDF',
        message: error instanceof Error ? error.message : 'Unknown error',
      }),
      {
        status: 500,
        headers: { 'Content-Type': 'application/json' },
      }
    );
  }
};