/**
 * Benchmark: 测量不同 HTML 大小下 page.pdf() 的实际渲染时间
 */
const http = require('http');
const fs = require('fs');

const BACKEND_PORT = process.env.PORT || 7861;
const BACKEND_URL = `http://localhost:${BACKEND_PORT}`;

// CSS from buildDocumentCss
const CSS = `@media print { @page { size: A4; margin: 15mm 10mm; } body { -webkit-print-color-adjust: exact; } }
body { font-family: -apple-system, sans-serif; font-size: 14px; line-height: 1.6; max-width: 746px; margin: 0 auto; padding: 20px; }
h1,h2,h3 { font-weight: 600; margin: 16px 0 8px; }
pre { background: #f6f8fa; padding: 16px; border-radius: 6px; overflow-x: auto; border: 1px solid #e1e4e8; }
code { font-family: monospace; font-size: 13px; }
p { margin: 8px 0; } table { border-collapse: collapse; width: 100%; margin: 12px 0; }
th,td { border: 1px solid #dfe2e5; padding: 8px 12px; } th { background: #f1f3f4; }
.chat-container { display: flex; flex-direction: column; gap: 16px; }
.message-row { display: flex; gap: 10px; } .message-bubble { max-width: 85%; padding: 12px 16px; border-radius: 12px; }
.ai-bubble { background: #fff; border: 1px solid #eee; } .user-bubble { background: #e8f0fe; }
.avatar { width: 32px; height: 32px; border-radius: 50%; display: flex; align-items: center; justify-content: center; }`;

function E(s) { return s.replace(/&/g,'&amp;').replace(/</g,'&lt;').replace(/>/g,'&gt;'); }

// Shiki-style colored code token
function shikiWrap(token, color) {
  return `<span style="color:${color}">${E(token)}</span>`;
}

// Generate code with Shiki-style spans (simulating real output)
function generateShikiCode(lines) {
  return lines.map(line => {
    const parts = [];
    const tokens = line.split(/(\s+|[^a-zA-Z0-9_\s]+)/g);
    for (const tok of tokens) {
      if (!tok) continue;
      if (/^\s+$/.test(tok)) { parts.push(tok); continue; }
      let color = '#c9d1d9'; // plain
      if (/^(const|let|var|function|return|if|else|for|async|await|import|from|export|class|extends|new|try|catch|throw|typeof|this|switch|case|break|continue|while|do|of|in|static|get|set|super|interface|type|void|null|undefined|true|false)$/.test(tok)) color = '#ff7b72';
      else if (/^(console|log|error|fetch|Promise|Math|Date|JSON|Map|Set|Array|Object|String|Number|Error|setTimeout|clearTimeout|AbortController|AbortSignal|require|module|exports|process)$/.test(tok)) color = '#d2a8ff';
      else if (/^\d+$/.test(tok)) color = '#79c0ff';
      else if (/^[{}()\[\];,\.:=+\-*/<>!&|?%@~^'"`]+$/.test(tok)) color = '#c9d1d9';
      else if (/^[A-Z]/.test(tok) && tok.length > 1) color = '#ffa657';
      parts.push(shikiWrap(tok, color));
    }
    return parts.join('');
  }).join('\n');
}

const CODE_LINES = [
  'async function fetchData(url, options = {}) {',
  '  const controller = new AbortController();',
  '  const timeout = setTimeout(() => controller.abort(), 30000);',
  '  try {',
  '    const response = await fetch(url, {',
  '      ...options,',
  '      signal: controller.signal,',
  "      headers: { 'Content-Type': 'application/json' },",
  '    });',
  '    if (!response.ok) {',
  '      throw new Error(`HTTP ${response.status}: ${response.statusText}`);',
  '    }',
  '    const data = await response.json();',
  "    console.log('Data received:', data);",
  '    return data;',
  '  } catch (error) {',
  "    console.error('Fetch failed:', error.message);",
  '    throw error;',
  '  } finally {',
  '    clearTimeout(timeout);',
  '  }',
  '}',
];

function buildHtml(targetSizeMB, opts = {}) {
  const shikiRatio = opts.shikiRatio || 0.5; // fraction of content that is Shiki code
  const textContent = opts.textContent || '<p>This is a typical AI response explaining a concept with some details and examples.</p>';

  const shikiCode = generateShikiCode(CODE_LINES);
  const codeBlock = `<pre data-language="javascript"><code class="language-javascript">${shikiCode}</code></pre>`;
  const codeBlockSize = Buffer.byteLength(codeBlock, 'utf8');

  const textBlockSize = Buffer.byteLength(textContent, 'utf8');

  const overhead = 2048; // HTML wrapper + CSS
  const targetBytes = targetSizeMB * 1024 * 1024 - overhead;

  let html = `<!DOCTYPE html><html><head><meta charset="UTF-8"><style>${CSS}</style></head><body><div class="chat-container">`;

  // Build a mix of code blocks and text
  const codeWeight = shikiRatio;
  const textWeight = 1 - shikiRatio;
  const codeBytes = targetBytes * codeWeight;
  const textBytes = targetBytes * textWeight;

  const codeIterations = Math.ceil(codeBytes / codeBlockSize);
  const textIterations = Math.ceil(textBytes / textBlockSize);

  let i = 0, j = 0;
  const totalIterations = codeIterations + textIterations;

  while (i < codeIterations || j < textIterations) {
    // Alternate between code and text
    if (i < codeIterations) {
      html += `<div class="message-row"><div class="avatar">&#129302;</div><div class="message-bubble ai-bubble">${codeBlock}</div></div>`;
      i++;
    }
    if (j < textIterations) {
      html += `<div class="message-row"><div class="avatar">&#128100;</div><div class="message-bubble user-bubble">${textContent}</div></div>`;
      j++;
    }
  }

  html += '</div></body></html>';

  const actualSize = (Buffer.byteLength(html, 'utf8') / 1024 / 1024).toFixed(2);
  return html;
}

async function sendPdfRequest(html, label) {
  const payload = JSON.stringify({
    html,
    codeTheme: 'github',
    showWatermark: false,
    imageCount: 0,
    totalImageSizeMB: 0,
    platform: 'Benchmark',
    language: 'en-US',
    extensionVersion: '2.0.2',
    exportCount: 0, exportPdf: 0, exportMd: 0,
    exportTxt: 0, exportDocx: 0, exportJson: 0,
    exportClipboard: 0, exportNotion: 0,
  });

  return new Promise((resolve, reject) => {
    const startTime = Date.now();
    const options = {
      hostname: 'localhost',
      port: BACKEND_PORT,
      path: '/api/generate_pdf',
      method: 'POST',
      headers: { 'Content-Type': 'application/json', 'Content-Length': Buffer.byteLength(payload) },
      timeout: 600000,
    };

    const req = http.request(options, (res) => {
      const chunks = [];
      res.on('data', (chunk) => chunks.push(chunk));
      res.on('end', () => {
        const elapsed = ((Date.now() - startTime) / 1000).toFixed(1);
        if (res.statusCode === 200) {
          const pdfSizeMB = (Buffer.concat(chunks).length / 1024 / 1024).toFixed(2);
          resolve({ ok: true, elapsed: parseFloat(elapsed), pdfSizeMB });
        } else {
          const body = Buffer.concat(chunks).toString();
          const errorMatch = body.match(/details":"([^"]+)"/);
          resolve({ ok: false, elapsed: parseFloat(elapsed), error: errorMatch ? errorMatch[1] : body, status: res.statusCode });
        }
      });
    });

    req.on('error', (e) => reject(e));
    req.on('timeout', () => { req.destroy(); reject(new Error('HTTP timeout')); });
    req.write(payload);
    req.end();
  });
}

async function runBenchmark() {
  console.log('=== PDF Rendering Benchmark ===\n');
  console.log(`Backend: ${BACKEND_URL}\n`);

  const testCases = [
    { size: 0.5, shikiRatio: 0,   label: '0.5 MB, 纯文本' },
    { size: 0.5, shikiRatio: 0.5, label: '0.5 MB, 50% Shiki' },
    { size: 1,   shikiRatio: 0,   label: '1.0 MB, 纯文本' },
    { size: 1,   shikiRatio: 0.5, label: '1.0 MB, 50% Shiki' },
    { size: 2,   shikiRatio: 0,   label: '2.0 MB, 纯文本' },
    { size: 2,   shikiRatio: 0.5, label: '2.0 MB, 50% Shiki' },
    { size: 3,   shikiRatio: 0,   label: '3.0 MB, 纯文本' },
    { size: 3,   shikiRatio: 0.5, label: '3.0 MB, 50% Shiki' },
    { size: 5,   shikiRatio: 0,   label: '5.0 MB, 纯文本' },
    { size: 5,   shikiRatio: 0.5, label: '5.0 MB, 50% Shiki' },
  ];

  const results = [];

  for (const tc of testCases) {
    const html = buildHtml(tc.size, { shikiRatio: tc.shikiRatio });
    const actualSizeMB = (Buffer.byteLength(html, 'utf8') / 1024 / 1024).toFixed(2);

    process.stdout.write(`\n[${tc.label}] HTML=${actualSizeMB} MB ... `);

    try {
      const result = await sendPdfRequest(html, tc.label);
      results.push({
        label: tc.label,
        htmlSizeMB: parseFloat(actualSizeMB),
        success: result.ok,
        time: result.elapsed,
        pdfSizeMB: result.pdfSizeMB || 'N/A',
        error: result.error || '',
      });

      if (result.ok) {
        process.stdout.write(`OK ${result.elapsed}s (PDF: ${result.pdfSizeMB} MB)\n`);
      } else {
        process.stdout.write(`FAIL ${result.elapsed}s - ${result.error}\n`);
      }
    } catch (err) {
      process.stdout.write(`ERROR: ${err.message}\n`);
      results.push({ label: tc.label, htmlSizeMB: parseFloat(actualSizeMB), success: false, time: 0, error: err.message });
    }
  }

  // Summary table
  console.log('\n\n=== Results Summary ===\n');
  console.log('| HTML Size | Content Type | Time (s) | PDF Size | Status |');
  console.log('|-----------|-------------|----------|----------|--------|');

  for (const r of results) {
    const status = r.success ? 'OK' : `FAIL (${r.error})`;
    console.log(`| ${r.htmlSizeMB} MB | ${r.label.split(', ')[1]} | ${r.time.toFixed(1)}s | ${r.pdfSizeMB || '-'} MB | ${status} |`);
  }

  // Calculate per-MB render time
  console.log('\n=== Per-MB Analysis ===\n');
  const successResults = results.filter(r => r.success);
  if (successResults.length >= 2) {
    // Linear regression: time = base + rate * size
    const n = successResults.length;
    let sumX = 0, sumY = 0, sumXY = 0, sumX2 = 0;
    for (const r of successResults) {
      sumX += r.htmlSizeMB;
      sumY += r.time;
      sumXY += r.htmlSizeMB * r.time;
      sumX2 += r.htmlSizeMB * r.htmlSizeMB;
    }
    const rate = (n * sumXY - sumX * sumY) / (n * sumX2 - sumX * sumX);
    const base = (sumY - rate * sumX) / n;

    console.log(`Base overhead (browser launch etc.): ${base.toFixed(1)}s`);
    console.log(`Per-MB PDF render time: ${rate.toFixed(2)}s/MB`);
    console.log('');
    console.log('Recommended timeout formula:');
    console.log(`  pdfTimeout = ${Math.ceil(base)}s + sizeMB * ${Math.ceil(rate * 3)}s  (3x safety margin)`);
    console.log('');

    // Predicted timeouts at various sizes
    console.log('Predicted timeouts (with 3x safety margin):');
    for (const size of [1, 2, 3, 5, 7, 10]) {
      const predicted = base + rate * size;
      const withMargin = Math.ceil(base + rate * size * 3);
      console.log(`  ${size} MB: actual ~${predicted.toFixed(0)}s, recommended timeout = ${withMargin}s`);
    }
  }
}

runBenchmark();