/**
 * CV Template Renderer - Node.js + Puppeteer
 * 
 * Merges a JSON CV Template (layout positions) with User CV Data (actual candidate info)
 * and renders a pixel-perfect A4 PDF using absolute CSS positioning.
 */

const puppeteer = require('puppeteer');
const fs = require('fs');
const path = require('path');

// ============================================================
// CSS GENERATION
// ============================================================

/**
 * Generate CSS for the A4 canvas and all positioned blocks.
 * Gridstack uses a 12-column grid. We convert x,y,w,h into
 * absolute pixel positions on a 794x1123 canvas.
 */
function generateCanvasCSS(template) {
  const { canvas, blocks } = template;
  const colWidth = canvas.width / canvas.columns;
  const rowHeight = 10; // Gridstack default cell height in px (we use compact mode)

  let css = `
/* A4 Canvas */
.cv-page {
  width: ${canvas.width}px;
  height: ${canvas.height}px;
  background: white;
  position: relative;
  overflow: hidden;
  font-family: 'Georgia', 'Times New Roman', serif;
  color: #1a1a1a;
  font-size: 13px;
  line-height: 1.5;
  box-sizing: border-box;
  padding: 0;
  margin: 0 auto;
}

/* Each block is absolutely positioned using the grid coordinates */
.cv-block {
  position: absolute;
  box-sizing: border-box;
  padding: 12px 16px;
  overflow: hidden;
}

/* Block type-specific styling */
.cv-block-PersonalDetails {
  border-bottom: 2px solid #2c3e50;
  padding-bottom: 16px;
}

.cv-block-PersonalDetails .cv-name {
  font-size: 26px;
  font-weight: 700;
  color: #2c3e50;
  margin: 0 0 4px 0;
}

.cv-block-PersonalDetails .cv-title {
  font-size: 15px;
  color: #555;
  margin: 0 0 6px 0;
}

.cv-block-PersonalDetails .cv-contact {
  font-size: 12px;
  color: #777;
  display: flex;
  flex-wrap: wrap;
  gap: 12px;
}

.cv-block-PersonalDetails .cv-contact span {
  display: inline-flex;
  align-items: center;
  gap: 4px;
}

/* Section headers */
.cv-section-title {
  font-size: 14px;
  font-weight: 700;
  color: #2c3e50;
  text-transform: uppercase;
  letter-spacing: 1.5px;
  border-bottom: 1px solid #ddd;
  padding-bottom: 4px;
  margin-bottom: 8px;
}

/* Work Experience */
.cv-block-WorkExperience .exp-entry {
  margin-bottom: 10px;
}

.cv-block-WorkExperience .exp-role {
  font-size: 14px;
  font-weight: 600;
  color: #333;
}

.cv-block-WorkExperience .exp-company {
  font-size: 13px;
  font-weight: 500;
  color: #555;
}

.cv-block-WorkExperience .exp-date {
  font-size: 11px;
  color: #888;
}

.cv-block-WorkExperience .exp-desc {
  font-size: 12px;
  color: #444;
  margin-top: 4px;
}

.cv-block-WorkExperience .exp-achievements {
  margin: 4px 0 0 16px;
  padding: 0;
  font-size: 12px;
  color: #444;
}

.cv-block-WorkExperience .exp-achievements li {
  margin-bottom: 2px;
}

/* Education */
.cv-block-Education .edu-entry {
  margin-bottom: 8px;
}

.cv-block-Education .edu-degree {
  font-size: 13px;
  font-weight: 600;
  color: #333;
}

.cv-block-Education .edu-school {
  font-size: 12px;
  color: #555;
}

.cv-block-Education .edu-date {
  font-size: 11px;
  color: #888;
}

/* Skills */
.cv-block-SkillsList .skill-group {
  margin-bottom: 6px;
}

.cv-block-SkillsList .skill-cat {
  font-size: 12px;
  font-weight: 600;
  color: #2c3e50;
  margin-bottom: 2px;
}

.cv-block-SkillsList .skill-items {
  font-size: 12px;
  color: #444;
}

.cv-block-SkillsList .skill-item {
  display: inline;
}

.cv-block-SkillsList .skill-item::after {
  content: " • ";
  color: #aaa;
}

.cv-block-SkillsList .skill-item:last-child::after {
  content: "";
}

.cv-block-SkillsList .skill-years {
  font-size: 10px;
  color: #999;
}

/* Certifications */
.cv-block-Certifications .cert-entry {
  margin-bottom: 6px;
}

.cv-block-Certifications .cert-name {
  font-size: 13px;
  font-weight: 600;
  color: #333;
}

.cv-block-Certifications .cert-issuer {
  font-size: 12px;
  color: #777;
}

/* Summary */
.cv-block-ProfessionalSummary {
  font-size: 13px;
  color: #444;
  text-align: justify;
}

/* Custom Text */
.cv-block-CustomText {
  font-size: 13px;
  color: #333;
  white-space: pre-wrap;
}

/* Footer */
.cv-block-Footer {
  font-size: 10px;
  color: #aaa;
  text-align: center;
  border-top: 1px solid #eee;
  padding-top: 8px;
}

/* Two-column layouts */
.cv-sidebar {
  background: #f8f9fa;
  border-left: 2px solid #2c3e50;
}

/* Print reset */
@media print {
  body { margin: 0; padding: 0; }
  @page { size: A4; margin: 0; }
}
`;

  // Generate position CSS for each block
  for (const block of blocks) {
    const left = block.x * colWidth;
    const width = block.w * colWidth;
    const top = block.y * rowHeight;
    const height = block.h * rowHeight;
    
    css += `
/* Block: ${block.blockId} (${block.type}) */
#block-${block.blockId} {
  left: ${left}px;
  top: ${top}px;
  width: ${width}px;
  height: ${height}px;
}
`;
  }

  return css;
}

// ============================================================
// HTML GENERATION
// ============================================================

/**
 * Build the HTML content for a single block by injecting CV data
 * into the block based on its type.
 */
function renderBlockHTML(block, cvData, options) {
  const { type, blockId } = block;
  const opts = options || {};
  const genDate = opts.generationDate || new Date().toISOString().split('T')[0];
  
  // Helper: format date range
  const fmtDate = (d) => {
    if (!d) return '';
    try {
      const date = new Date(d);
      return date.toLocaleDateString('en-US', { year: 'numeric', month: 'short' });
    } catch { return d; }
  };

  // Helper: calculate years between dates
  const calcYears = (start, end, refDate) => {
    if (!start) return 0;
    const endDate = end ? new Date(end) : new Date(refDate);
    const startDate = new Date(start);
    const diff = (endDate - startDate) / (365.25 * 24 * 3600 * 1000);
    return Math.round(diff * 10) / 10;
  };

  switch (type) {
    case 'PersonalDetails':
      const c = cvData.candidate || cvData;
      const contactParts = [];
      if (c.email) contactParts.push(`<span>📧 ${c.email}</span>`);
      if (c.phone) contactParts.push(`<span>📞 ${c.phone}</span>`);
      if (c.address) contactParts.push(`<span>📍 ${c.address}</span>`);
      if (c.linkedin) contactParts.push(`<span>🔗 ${c.linkedin}</span>`);
      if (c.github) contactParts.push(`<span>💻 ${c.github}</span>`);
      if (c.website) contactParts.push(`<span>🌐 ${c.website}</span>`);
      return `
        <div id="block-${blockId}" class="cv-block cv-block-${type}">
          <h1 class="cv-name">${c.first_name || ''} ${c.last_name || ''}</h1>
          ${c.summary ? `<div class="cv-title">${c.summary.split('.')[0]}.</div>` : ''}
          <div class="cv-contact">${contactParts.join('')}</div>
        </div>
      `;

    case 'ProfessionalSummary':
      const summary = cvData.candidate?.summary || cvData.summary || '';
      return `
        <div id="block-${blockId}" class="cv-block cv-block-${type}">
          <div class="cv-section-title">${block.title || 'Professional Summary'}</div>
          <p>${summary}</p>
        </div>
      `;

    case 'WorkExperience':
      const experiences = cvData.experience || [];
      const showAch = block.config?.showAchievements !== false;
      const showSkills = block.config?.showSkillsUsed === true;
      const maxItems = block.config?.maxItems;
      let expHTML = experiences.slice(0, maxItems || experiences.length).map(e => {
        const ach = Array.isArray(e.achievements) ? e.achievements : 
                    (typeof e.achievements === 'string' ? JSON.parse(e.achievements || '[]') : []);
        const skillsUsed = Array.isArray(e.skills_used) ? e.skills_used :
                          (typeof e.skills_used === 'string' ? JSON.parse(e.skills_used || '[]') : []);
        const startStr = fmtDate(e.start_date);
        const endStr = e.end_date ? fmtDate(e.end_date) : 'Present';
        return `
          <div class="exp-entry">
            <div class="exp-role">${e.position || ''}</div>
            <div class="exp-company">${e.company || ''}${e.location ? ' — ' + e.location : ''}</div>
            <div class="exp-date">${startStr} — ${endStr}</div>
            ${e.description ? `<div class="exp-desc">${e.description}</div>` : ''}
            ${showAch && ach.length ? `<ul class="exp-achievements">${ach.map(a => `<li>${a}</li>`).join('')}</ul>` : ''}
            ${showSkills && skillsUsed.length ? `<div class="exp-desc"><em>Skills: ${skillsUsed.join(', ')}</em></div>` : ''}
          </div>
        `;
      }).join('');
      return `
        <div id="block-${blockId}" class="cv-block cv-block-${type}">
          <div class="cv-section-title">${block.title || 'Work Experience'}</div>
          ${expHTML || '<p style="color:#999">No experience data</p>'}
        </div>
      `;

    case 'Education':
      const educations = cvData.education || [];
      let eduHTML = educations.map(e => `
        <div class="edu-entry">
          <div class="edu-degree">${e.degree || ''}${e.field_of_study ? ' in ' + e.field_of_study : ''}</div>
          <div class="edu-school">${e.institution || ''}</div>
          <div class="edu-date">${e.start_date ? fmtDate(e.start_date) : ''} — ${e.end_date ? fmtDate(e.end_date) : ''}</div>
          ${e.grade ? `<div class="edu-school">Grade: ${e.grade}</div>` : ''}
        </div>
      `).join('');
      return `
        <div id="block-${blockId}" class="cv-block cv-block-${type}">
          <div class="cv-section-title">${block.title || 'Education'}</div>
          ${eduHTML || '<p style="color:#999">No education data</p>'}
        </div>
      `;

    case 'SkillsList':
      const skills = cvData.skills || [];
      const groupByCat = block.config?.groupByCategory !== false;
      const showYears = block.config?.showYears === true;
      const showProf = block.config?.showProficiency === true;
      
      if (groupByCat) {
        const groups = {};
        for (const s of skills) {
          const cat = s.skill_category || 'Other';
          if (!groups[cat]) groups[cat] = [];
          groups[cat].push(s);
        }
        let skillsHTML = Object.entries(groups).map(([cat, items]) => `
          <div class="skill-group">
            <div class="skill-cat">${cat}</div>
            <div class="skill-items">
              ${items.map(s => {
                let txt = `<span class="skill-item">${s.skill_name}`;
                if (showProf && s.proficiency) txt += ` (${s.proficiency})`;
                if (showYears && s.years_experience) txt += ` <span class="skill-years">${s.years_experience}y</span>`;
                txt += '</span>';
                return txt;
              }).join('')}
            </div>
          </div>
        `).join('');
        return `
          <div id="block-${blockId}" class="cv-block cv-block-${type} ${block.config?.sidebar ? 'cv-sidebar' : ''}">
            <div class="cv-section-title">${block.title || 'Skills'}</div>
            ${skillsHTML || '<p style="color:#999">No skills data</p>'}
          </div>
        `;
      } else {
        let skillsHTML = skills.map(s => {
          let txt = `<span class="skill-item">${s.skill_name}`;
          if (showProf && s.proficiency) txt += ` (${s.proficiency})`;
          if (showYears && s.years_experience) txt += ` <span class="skill-years">${s.years_experience}y</span>`;
          txt += '</span>';
          return txt;
        }).join('');
        return `
          <div id="block-${blockId}" class="cv-block cv-block-${type} ${block.config?.sidebar ? 'cv-sidebar' : ''}">
            <div class="cv-section-title">${block.title || 'Skills'}</div>
            <div class="skill-items">${skillsHTML}</div>
          </div>
        `;
      }

    case 'Certifications':
      const certs = cvData.certifications || [];
      let certHTML = certs.map(c => `
        <div class="cert-entry">
          <div class="cert-name">${c.name || ''}</div>
          ${c.issuer ? `<div class="cert-issuer">${c.issuer}</div>` : ''}
          ${c.issue_date ? `<div class="cert-issuer">${fmtDate(c.issue_date)}${c.expiry_date ? ' — ' + fmtDate(c.expiry_date) : ''}</div>` : ''}
        </div>
      `).join('');
      return `
        <div id="block-${blockId}" class="cv-block cv-block-${type}">
          <div class="cv-section-title">${block.title || 'Certifications'}</div>
          ${certHTML || '<p style="color:#999">No certifications</p>'}
        </div>
      `;

    case 'CustomText':
      return `
        <div id="block-${blockId}" class="cv-block cv-block-${type}">
          ${block.config?.title ? `<div class="cv-section-title">${block.config.title}</div>` : ''}
          <div>${block.config?.content || ''}</div>
        </div>
      `;

    case 'Footer':
      return `
        <div id="block-${blockId}" class="cv-block cv-block-${type}">
          ${block.config?.content || 'Generated on ' + genDate}
        </div>
      `;

    default:
      return `<div id="block-${blockId}" class="cv-block">Unknown block type: ${type}</div>`;
  }
}

// ============================================================
// FULL HTML PAGE ASSEMBLY
// ============================================================

/**
 * Build a complete HTML document from a template + CV data.
 */
function buildHTML(template, cvData, options) {
  const css = generateCanvasCSS(template);
  const blocksHTML = template.blocks.map(block => renderBlockHTML(block, cvData, options)).join('\n');
  
  return `<!DOCTYPE html>
<html lang="en">
<head>
  <meta charset="UTF-8">
  <meta name="viewport" content="width=device-width, initial-scale=1.0">
  <title>CV - ${cvData.candidate?.first_name || ''} ${cvData.candidate?.last_name || ''}</title>
  <style>${css}</style>
</head>
<body>
  <div class="cv-page" id="cv-page">
    ${blocksHTML}
  </div>
</body>
</html>`;
}

// ============================================================
// PUPPETEER PDF RENDERER
// ============================================================

/**
 * Render a CV Template + CV Data to a pixel-perfect A4 PDF.
 * 
 * @param {Object} template - The JSON CV Template (layout definition)
 * @param {Object} cvData - The candidate's CV data
 * @param {Object} options - { generationDate, outputDir }
 * @returns {Promise<{html: string, pdfPath: string}>}
 */
async function renderToPDF(template, cvData, options = {}) {
  const html = buildHTML(template, cvData, options);
  const outputDir = options.outputDir || path.join(__dirname, 'output');
  fs.mkdirSync(outputDir, { recursive: true });
  
  const candidateName = `${cvData.candidate?.first_name || 'candidate'}_${cvData.candidate?.last_name || ''}`.trim().replace(/\s+/g, '_');
  const templateName = (template.templateName || 'cv').replace(/\s+/g, '_');
  const timestamp = Date.now();
  const htmlPath = path.join(outputDir, `${candidateName}_${templateName}_${timestamp}.html`);
  const pdfPath = path.join(outputDir, `${candidateName}_${templateName}_${timestamp}.pdf`);
  
  // Save HTML for debugging
  fs.writeFileSync(htmlPath, html);
  
  // Auto-detect puppeteer chrome path
  const chromePaths = [
    path.join(process.env.HOME || '/root', '.cache', 'puppeteer', 'chrome', 'linux-150.0.7871.24', 'chrome-linux64', 'chrome'),
  ];
  // Also search for any chrome version in the puppeteer cache
  const pptrCache = path.join(process.env.HOME || '/root', '.cache', 'puppeteer', 'chrome');
  if (fs.existsSync(pptrCache)) {
    for (const dir of fs.readdirSync(pptrCache)) {
      const candidate = path.join(pptrCache, dir, 'chrome-linux64', 'chrome');
      if (fs.existsSync(candidate)) { chromePaths.unshift(candidate); break; }
    }
  }
  const chromePath = chromePaths.find(p => fs.existsSync(p));
  
  // Launch Puppeteer and render
  const browser = await puppeteer.launch({
    headless: 'new',
    args: ['--no-sandbox', '--disable-setuid-sandbox', '--disable-dev-shm-usage'],
    executablePath: chromePath,
  });
  
  try {
    const page = await browser.newPage();
    
    // Set the viewport to exact A4 size at 96 DPI
    await page.setViewport({
      width: template.canvas.width,
      height: template.canvas.height,
      deviceScaleFactor: 2, // Retina quality
    });
    
    // Load the HTML
    await page.setContent(html, { waitUntil: 'domcontentloaded', timeout: 60000 });
    
    // Wait a bit for any font loading
    await new Promise(r => setTimeout(r, 500));
    
    // Generate PDF with exact A4 dimensions, no margins
    await page.pdf({
      path: pdfPath,
      width: `${template.canvas.width}px`,
      height: `${template.canvas.height}px`,
      printBackground: true,
      margin: { top: 0, right: 0, bottom: 0, left: 0 },
      preferCSSPageSize: false,
    });
    
    return { html, htmlPath, pdfPath };
  } finally {
    await browser.close();
  }
}

// ============================================================
// CLI ENTRY POINT (for testing)
// ============================================================

if (require.main === module) {
  // Example template
  const exampleTemplate = {
    templateId: 'template_modern_01',
    templateName: 'Modern Two-Column Layout',
    canvas: { width: 794, height: 1123, columns: 12 },
    blocks: [
      { blockId: 'header', type: 'PersonalDetails', x: 0, y: 0, w: 12, h: 10 },
      { blockId: 'summary', type: 'ProfessionalSummary', x: 0, y: 10, w: 12, h: 5 },
      { blockId: 'experience', type: 'WorkExperience', x: 0, y: 15, w: 8, h: 50, config: { showAchievements: true } },
      { blockId: 'skills', type: 'SkillsList', x: 8, y: 15, w: 4, h: 30, config: { groupByCategory: true, showYears: true, sidebar: true } },
      { blockId: 'education', type: 'Education', x: 8, y: 45, w: 4, h: 20 },
      { blockId: 'footer', type: 'Footer', x: 0, y: 100, w: 12, h: 5, config: { content: 'Confidential — Generated by CV Application' } }
    ]
  };

  // Example CV data
  const exampleCVData = {
    candidate: {
      first_name: 'John',
      last_name: 'Smith',
      email: 'john.smith@email.com',
      phone: '+1-555-123-4567',
      address: 'Cape Town, South Africa',
      linkedin: 'linkedin.com/in/johnsmith',
      summary: 'Experienced software engineer with 8+ years in full-stack development specializing in .NET technologies and cloud architecture.'
    },
    experience: [
      {
        position: 'Senior Software Engineer',
        company: 'TechCorp International',
        location: 'Cape Town',
        start_date: '2022-01-01',
        end_date: null,
        description: 'Led a team building cloud-native microservices on Azure.',
        achievements: ['Reduced deployment time by 70%', 'Architected event-driven system with Azure Service Bus'],
        skills_used: ['C#', 'Azure', 'Docker', 'Kubernetes']
      },
      {
        position: 'Software Engineer',
        company: 'DataSoft Solutions',
        location: 'Johannesburg',
        start_date: '2019-03-01',
        end_date: '2021-12-01',
        description: 'Developed ASP.NET Core APIs serving 100k+ daily requests.',
        achievements: ['Built React admin dashboard', 'Implemented Entity Framework data layer'],
        skills_used: ['C#', 'ASP.NET Core', 'React', 'TypeScript']
      }
    ],
    education: [
      { degree: 'BSc Computer Science', field_of_study: 'Computer Science', institution: 'University of Cape Town', start_date: '2014-01-01', end_date: '2017-12-01', grade: 'First Class Honours' }
    ],
    skills: [
      { skill_name: 'C# / .NET', skill_category: 'Programming', proficiency: 'Expert', years_experience: 8.5 },
      { skill_name: 'Azure Cloud', skill_category: 'Cloud', proficiency: 'Advanced', years_experience: 6.5 },
      { skill_name: 'React / TypeScript', skill_category: 'Frontend', proficiency: 'Advanced', years_experience: 5.5 },
      { skill_name: 'SQL Server', skill_category: 'Database', proficiency: 'Expert', years_experience: 8.5 },
      { skill_name: 'Docker / Kubernetes', skill_category: 'DevOps', proficiency: 'Advanced', years_experience: 4.5 }
    ],
    certifications: [
      { name: 'Azure Developer Associate', issuer: 'Microsoft', issue_date: '2021-06-01' },
      { name: 'CKAD', issuer: 'CNCF', issue_date: '2022-03-01' }
    ]
  };

  renderToPDF(exampleTemplate, exampleCVData, { generationDate: '2026-07-15' })
    .then(result => {
      console.log('PDF generated successfully:');
      console.log('  HTML:', result.htmlPath);
      console.log('  PDF:', result.pdfPath);
    })
    .catch(err => {
      console.error('Render failed:', err);
      process.exit(1);
    });
}

module.exports = { renderToPDF, buildHTML, generateCanvasCSS };