// packages/server/src/services/screenshotService.ts
//
// Takes REAL screenshots of Interac emails using Puppeteer (headless Chrome).
// During the scan pipeline, after fetching email HTML from Gmail:
//   1. Renders the full email HTML in a headless browser
//   2. Takes a full-page screenshot → "Courriel original"
//   3. Takes a screenshot of just the Interac visual body → "Aperçu du virement"
//   4. Saves both as PNG files on disk
//   5. Returns the file paths for storage in the database

import path from 'path';
import fs from 'fs';

// Lazy-load puppeteer — it may not be installed in production
let puppeteer: any = null;
type Browser = any;

async function loadPuppeteer() {
  if (!puppeteer) {
    try {
      puppeteer = (await import('puppeteer')).default;
    } catch {
      return null;
    }
  }
  return puppeteer;
}

// ═══════════════════════════════════════════
// CONFIGURATION
// ═══════════════════════════════════════════

const SCREENSHOTS_DIR = process.env.SCREENSHOTS_DIR
  || path.join(process.cwd(), 'data', 'screenshots');

// Viewport dimensions to render the email at
const VIEWPORT = { width: 680, height: 900, deviceScaleFactor: 2 }; // 2x for retina quality

// Reuse a single browser instance for performance
let browserInstance: Browser | null = null;

async function getBrowser(): Promise<Browser | null> {
  if (!browserInstance || !browserInstance.connected) {
    const pptr = await loadPuppeteer();
    if (!pptr) return null;
    browserInstance = await pptr.launch({
      headless: true,
      args: [
        '--no-sandbox',
        '--disable-setuid-sandbox',
        '--disable-dev-shm-usage',
        '--disable-gpu',
        '--disable-web-security',     // Allow loading inline images
        '--font-render-hinting=none', // Consistent font rendering
      ],
    });
  }
  return browserInstance;
}

// ═══════════════════════════════════════════
// MAIN FUNCTION — Take screenshots of an email
// ═══════════════════════════════════════════

export interface EmailScreenshots {
  originalPath: string;   // Full email screenshot → "Courriel original"
  previewPath: string;    // Interac visual body → "Aperçu du virement"
}

/**
 * Renders the email HTML in a headless browser and takes two screenshots:
 *   - original: The full email as it appears (complete page)
 *   - preview:  Just the Interac body/visual section (cropped)
 *
 * @param emailHtml  - The raw HTML content of the email (from Gmail API)
 * @param emailText  - The plain text version of the email
 * @param emailId    - Unique email ID (used for filename)
 * @returns Paths to both screenshot files
 */
export async function captureEmailScreenshots(
  emailHtml: string,
  emailText: string,
  emailId: string
): Promise<EmailScreenshots> {
  const safeId = emailId.replace(/[^a-zA-Z0-9_-]/g, '_');
  const originalPath = path.join(SCREENSHOTS_DIR, `${safeId}_original.png`);
  const previewPath = path.join(SCREENSHOTS_DIR, `${safeId}_preview.png`);

  // If puppeteer is not available, return empty paths
  const pptr = await loadPuppeteer();
  if (!pptr) {
    return { originalPath: '', previewPath: '' };
  }

  // Ensure screenshots directory exists
  if (!fs.existsSync(SCREENSHOTS_DIR)) {
    fs.mkdirSync(SCREENSHOTS_DIR, { recursive: true });
  }

  const browser = await getBrowser();
  if (!browser) return { originalPath: '', previewPath: '' };
  let page = null;

  try {
    page = await browser.newPage();
    await page.setViewport(VIEWPORT);

    // ─────────────────────────────────────
    // SCREENSHOT 1: "Courriel original"
    // Full email as-is from Gmail
    // ─────────────────────────────────────

    if (emailHtml && emailHtml.trim().length > 50) {
      // Render the actual HTML email
      const wrappedHtml = wrapEmailHtml(emailHtml);
      await page.setContent(wrappedHtml, { waitUntil: 'domcontentloaded', timeout: 5000 });
    } else {
      // Fallback: render plain text in a nice container
      const textHtml = wrapPlainText(emailText);
      await page.setContent(textHtml, { waitUntil: 'domcontentloaded', timeout: 10000 });
    }

    // Brief wait for images (max 1.5s)
    await page.evaluate(() => {
      return new Promise<void>((resolve) => {
        const images = document.querySelectorAll('img');
        if (images.length === 0) return resolve();
        let loaded = 0;
        const total = images.length;
        const done = () => { loaded++; if (loaded >= total) resolve(); };
        images.forEach((img) => {
          if (img.complete) done();
          else { img.onload = done; img.onerror = done; }
        });
        setTimeout(resolve, 1500);
      });
    });

    // Take full-page screenshot
    await page.screenshot({
      path: originalPath,
      fullPage: true,
      type: 'png',
    });

    console.log(`[Screenshot] Original saved: ${originalPath}`);

    // ─────────────────────────────────────
    // SCREENSHOT 2: "Aperçu du virement"
    // Just the Interac visual body section
    // ─────────────────────────────────────

    if (emailHtml && emailHtml.trim().length > 50) {
      // Try to find the main Interac visual container
      const bodyBounds = await page.evaluate(() => {
        const selectors = [
          'table[align="center"]',
          'table[width="600"]',
          'table[width="580"]',
          'div[style*="max-width"]',
          'center > table',
          'body > table',
          'body > div > table',
          '.email-body',
          '#email-content',
        ];

        for (const sel of selectors) {
          const el = document.querySelector(sel);
          if (el) {
            const rect = el.getBoundingClientRect();
            if (rect.height > 100) {
              return { x: rect.x, y: rect.y, width: rect.width, height: rect.height };
            }
          }
        }

        // Fallback: screenshot the entire body
        const body = document.body;
        const rect = body.getBoundingClientRect();
        return { x: 0, y: 0, width: rect.width, height: rect.height };
      });

      // Take a cropped screenshot of just the Interac body
      await page.screenshot({
        path: previewPath,
        type: 'png',
        clip: {
          x: Math.max(0, bodyBounds.x - 10),
          y: Math.max(0, bodyBounds.y),
          width: Math.min(bodyBounds.width + 20, VIEWPORT.width),
          height: bodyBounds.height,
        },
      });
    } else {
      // No HTML — use the same screenshot for preview
      fs.copyFileSync(originalPath, previewPath);
    }

    console.log(`[Screenshot] Preview saved: ${previewPath}`);

  } catch (error: any) {
    console.error(`[Screenshot] Error capturing ${emailId}:`, error.message);

    // Create fallback screenshots if capture fails
    if (!fs.existsSync(originalPath)) {
      await createFallbackScreenshot(originalPath, emailText, 'original');
    }
    if (!fs.existsSync(previewPath)) {
      await createFallbackScreenshot(previewPath, emailText, 'preview');
    }
  } finally {
    if (page) {
      await page.close().catch(() => {});
    }
  }

  return { originalPath, previewPath };
}

// ═══════════════════════════════════════════
// HTML WRAPPERS
// ═══════════════════════════════════════════

function wrapEmailHtml(html: string): string {
  return `<!DOCTYPE html>
<html>
<head>
  <meta charset="UTF-8">
  <meta name="viewport" content="width=device-width, initial-scale=1.0">
  <style>
    * { box-sizing: border-box; }
    body {
      margin: 0;
      padding: 0;
      background: #f5f5f5;
      font-family: Arial, Helvetica, sans-serif;
      -webkit-font-smoothing: antialiased;
    }
    img { max-width: 100%; height: auto; }
    table { max-width: 100% !important; }
    a { color: #1a73e8; text-decoration: none; }
  </style>
</head>
<body>
  ${html}
</body>
</html>`;
}

function wrapPlainText(text: string): string {
  const escaped = text
    .replace(/&/g, '&amp;')
    .replace(/</g, '&lt;')
    .replace(/>/g, '&gt;')
    .replace(/\n/g, '<br>');

  return `<!DOCTYPE html>
<html>
<head>
  <meta charset="UTF-8">
  <style>
    body {
      margin: 0;
      padding: 32px;
      background: #ffffff;
      font-family: 'Courier New', Courier, monospace;
      font-size: 13px;
      line-height: 1.7;
      color: #333;
      max-width: 640px;
    }
    .header-line {
      color: #1a73e8;
      font-weight: 600;
    }
  </style>
</head>
<body>${escaped}</body>
</html>`;
}

// ═══════════════════════════════════════════
// FALLBACK — When Puppeteer fails, create a
// simple text-based image via canvas
// ═══════════════════════════════════════════

async function createFallbackScreenshot(
  filePath: string,
  text: string,
  type: 'original' | 'preview'
): Promise<void> {
  const browser = await getBrowser();
  let page = null;
  try {
    page = await browser.newPage();
    await page.setViewport({ width: 640, height: 400, deviceScaleFactor: 2 });

    const label = type === 'original' ? 'Courriel Original' : 'Aperçu du Virement';
    const html = `<!DOCTYPE html>
<html><head><meta charset="UTF-8"><style>
  body { margin:0; padding:40px; background:#f8f9fa; font-family:Arial,sans-serif; }
  .box { background:#fff; border:1px solid #e0e0e0; border-radius:12px; padding:32px; max-width:560px; margin:0 auto; }
  .title { font-size:14px; color:#666; margin-bottom:16px; text-align:center; }
  .text { font-size:12px; color:#333; line-height:1.6; white-space:pre-wrap; font-family:monospace; }
</style></head><body>
  <div class="box">
    <div class="title">${label} — Capture non disponible</div>
    <div class="text">${text.substring(0, 500).replace(/</g, '&lt;').replace(/>/g, '&gt;')}</div>
  </div>
</body></html>`;

    await page.setContent(html, { waitUntil: 'domcontentloaded' });
    await page.screenshot({ path: filePath, fullPage: true, type: 'png' });
  } catch {
    // Last resort: write a 1x1 transparent PNG
    const emptyPng = Buffer.from(
      'iVBORw0KGgoAAAANSUhEUgAAAAEAAAABCAYAAAAfFcSJAAAADUlEQVR42mNk+M9QDwADhgGAWjR9awAAAABJRU5ErkJggg==',
      'base64'
    );
    fs.writeFileSync(filePath, emptyPng);
  } finally {
    if (page) await page.close().catch(() => {});
  }
}

// ═══════════════════════════════════════════
// CLEANUP — Close browser on shutdown
// ═══════════════════════════════════════════

export async function closeScreenshotBrowser(): Promise<void> {
  if (browserInstance) {
    await browserInstance.close().catch(() => {});
    browserInstance = null;
  }
}

// Close browser on process exit
process.on('SIGTERM', closeScreenshotBrowser);
process.on('SIGINT', closeScreenshotBrowser);