// Logo upload handling for the Content Editor: PNG validation, timestamped
// backup and atomic binary replace.
const fs = require('fs');
const path = require('path');

const MAX_LOGO_BYTES = 1024 * 1024; // 1 MiB — plenty for a logo
const PNG_MAGIC = Buffer.from([0x89, 0x50, 0x4e, 0x47, 0x0d, 0x0a, 0x1a, 0x0a]);

// WHY fixed targets instead of a client-supplied filename: arbitrary write
// paths would be a traversal risk; the two known logos are the only assets
// the site consumes.
const LOGO_TARGETS = {
  icon: 'mozdit_logo.png',        // CMS login page
  header: 'mozdit_logo_text.png', // website Header
};

function isPng(buffer) {
  return Buffer.isBuffer(buffer) && buffer.length >= PNG_MAGIC.length && buffer.subarray(0, PNG_MAGIC.length).equals(PNG_MAGIC);
}

function saveLogoAtomically(publicDir, targetKey, buffer, backupDir) {
  const fileName = LOGO_TARGETS[targetKey];
  if (!fileName) throw new Error('Ismeretlen logó célpont');
  const targetFile = path.join(publicDir, fileName);

  const timestamp = new Date().toISOString().replace(/[:.]/g, '-');
  const backupName = `${fileName}.${timestamp}.bak`;
  fs.mkdirSync(backupDir, { recursive: true, mode: 0o700 });
  fs.copyFileSync(targetFile, path.join(backupDir, backupName));

  const tempFile = `${targetFile}.${process.pid}.${Date.now()}.tmp`;
  fs.writeFileSync(tempFile, buffer, { mode: 0o644 });
  fs.renameSync(tempFile, targetFile);
  return { targetFile, backupName };
}

// WHY: partner logos are a variable set — the filename comes from the editor,
// so it must be sanitized to a safe slug (no traversal, no separators).
function slugifyName(raw) {
  return String(raw)
    .toLowerCase()
    .replace(/[^a-z0-9_-]+/g, '-')
    .replace(/^-+|-+$/g, '')
    .slice(0, 64);
}

function savePartnerLogo(publicDir, filename, buffer) {
  const slug = slugifyName(filename) || `partner-${Date.now()}`;
  const dir = path.join(publicDir, 'partners');
  fs.mkdirSync(dir, { recursive: true, mode: 0o755 });
  const targetFile = path.join(dir, `${slug}.png`);
  const tempFile = `${targetFile}.${process.pid}.${Date.now()}.tmp`;
  fs.writeFileSync(tempFile, buffer, { mode: 0o644 });
  fs.renameSync(tempFile, targetFile);
  return `/partners/${slug}.png`;
}

// WHY: route handling lives here so content-editor.js stays under the
// 400-line limit. Returns true when the request was handled.
function handleLogoRoutes({ req, res, u, publicDir, backupDir, writeAudit, clientAddress, user, logoPage }) {
  if (req.method === 'GET' && u.pathname === '/branding') {
    res.writeHead(200, { 'Content-Type': 'text/html; charset=utf-8', 'Cache-Control': 'no-store' });
    res.end(logoPage());
    return true;
  }

  if (req.method === 'POST' && u.pathname === '/logo') {
    const target = u.searchParams.get('target') || '';
    if (!LOGO_TARGETS[target]) {
      res.writeHead(400, { 'Content-Type': 'application/json' });
      res.end(JSON.stringify({ ok: false, error: 'Ismeretlen logó célpont.' }));
      return true;
    }
    const chunks = [];
    let total = 0;
    let tooLarge = false;
    req.on('data', c => {
      total += c.length;
      if (total > MAX_LOGO_BYTES) { tooLarge = true; return; }
      chunks.push(c);
    });
    req.on('end', () => {
      const buffer = Buffer.concat(chunks);
      if (tooLarge) {
        writeAudit('logo_updated', { clientAddress, user, target, result: 'request_too_large' });
        res.writeHead(413, { 'Content-Type': 'application/json' });
        res.end(JSON.stringify({ ok: false, error: `A fájl túl nagy (maximum ${MAX_LOGO_BYTES} byte).` }));
        return;
      }
      if (!isPng(buffer)) {
        writeAudit('logo_updated', { clientAddress, user, target, result: 'invalid_type' });
        res.writeHead(415, { 'Content-Type': 'application/json' });
        res.end(JSON.stringify({ ok: false, error: 'Csak érvényes PNG fájl tölthető fel.' }));
        return;
      }
      try {
        const { backupName } = saveLogoAtomically(publicDir, target, buffer, backupDir);
        writeAudit('logo_updated', { clientAddress, user, target, result: 'ok', backup: backupName });
        res.writeHead(200, { 'Content-Type': 'application/json' });
        res.end(JSON.stringify({ ok: true, backup: backupName }));
      } catch (e) {
        writeAudit('logo_updated', { clientAddress, user, target, result: 'error' });
        res.writeHead(500, { 'Content-Type': 'application/json' });
        res.end(JSON.stringify({ ok: false, error: e.message }));
      }
    });
    return true;
  }

  if (req.method === 'POST' && u.pathname === '/partner-logo') {
    const filename = u.searchParams.get('name') || '';
    if (!slugifyName(filename)) {
      res.writeHead(400, { 'Content-Type': 'application/json' });
      res.end(JSON.stringify({ ok: false, error: 'Adj meg egy érvényes fájlnevet.' }));
      return true;
    }
    const chunks = [];
    let total = 0;
    let tooLarge = false;
    req.on('data', c => {
      total += c.length;
      if (total > MAX_LOGO_BYTES) { tooLarge = true; return; }
      chunks.push(c);
    });
    req.on('end', () => {
      const buffer = Buffer.concat(chunks);
      if (tooLarge) {
        writeAudit('partner_logo_upload', { clientAddress, user, result: 'request_too_large' });
        res.writeHead(413, { 'Content-Type': 'application/json' });
        res.end(JSON.stringify({ ok: false, error: `A fájl túl nagy (maximum ${MAX_LOGO_BYTES} byte).` }));
        return;
      }
      if (!isPng(buffer)) {
        writeAudit('partner_logo_upload', { clientAddress, user, result: 'invalid_type' });
        res.writeHead(415, { 'Content-Type': 'application/json' });
        res.end(JSON.stringify({ ok: false, error: 'Csak érvényes PNG fájl tölthető fel.' }));
        return;
      }
      try {
        const publicPath = savePartnerLogo(publicDir, filename, buffer);
        writeAudit('partner_logo_upload', { clientAddress, user, result: 'ok', path: publicPath });
        res.writeHead(200, { 'Content-Type': 'application/json' });
        res.end(JSON.stringify({ ok: true, path: publicPath }));
      } catch (e) {
        writeAudit('partner_logo_upload', { clientAddress, user, result: 'error' });
        res.writeHead(500, { 'Content-Type': 'application/json' });
        res.end(JSON.stringify({ ok: false, error: e.message }));
      }
    });
    return true;
  }

  return false;
}

module.exports = { MAX_LOGO_BYTES, LOGO_TARGETS, isPng, saveLogoAtomically, savePartnerLogo, slugifyName, handleLogoRoutes };