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

/**
 * Startup Log Utility
 * Displays comprehensive system information and branding on server start
 */

function getSystemInfo() {
  return {
    hostname: os.hostname(),
    platform: os.platform(),
    arch: os.arch(),
    nodeVersion: process.version,
    cpuCores: os.cpus().length,
    totalMemory: (os.totalmem() / 1024 / 1024 / 1024).toFixed(2) + ' GB',
    freeMemory: (os.freemem() / 1024 / 1024 / 1024).toFixed(2) + ' GB',
    uptime: process.uptime().toFixed(2) + 's'
  };
}

function getProcessInfo() {
  const memUsage = process.memoryUsage();
  return {
    pid: process.pid,
    heapUsed: (memUsage.heapUsed / 1024 / 1024).toFixed(2) + ' MB',
    heapTotal: (memUsage.heapTotal / 1024 / 1024).toFixed(2) + ' MB',
    external: (memUsage.external / 1024 / 1024).toFixed(2) + ' MB'
  };
}

function checkDirectories(dirs) {
  const status = {};
  dirs.forEach(({ name, path: dirPath }) => {
    status[name] = {
      exists: fs.existsSync(dirPath),
      path: dirPath,
      writable: false
    };
    
    // Check write permissions if directory exists
    if (status[name].exists) {
      try {
        fs.accessSync(dirPath, fs.constants.W_OK);
        status[name].writable = true;
      } catch (err) {
        status[name].writable = false;
      }
    }
  });
  return status;
}

function getAppVersion() {
  try {
    const packagePath = path.join(__dirname, '../../package.json');
    if (fs.existsSync(packagePath)) {
      const pkg = JSON.parse(fs.readFileSync(packagePath, 'utf8'));
      return pkg.version || 'unknown';
    }
  } catch (err) {
    // Silently fail
  }
  return 'unknown';
}

function logStartupBanner(config = {}) {
  const {
    appName = 'BREEDR',
    port = 3000,
    environment = 'development',
    dataDir = './data',
    uploadPath = './uploads',
    staticPath = './static',
    dbStatus = 'unknown'
  } = config;

  const version = getAppVersion();
  const sysInfo = getSystemInfo();
  const procInfo = getProcessInfo();
  const timestamp = new Date().toISOString();

  const directories = [
    { name: 'Data', path: dataDir },
    { name: 'Uploads', path: uploadPath },
    { name: 'Static', path: staticPath }
  ];
  const dirStatus = checkDirectories(directories);

  // ASCII Banner
  console.log('\n');
  console.log('╔══════════════════════════════════════════════════════════╗');
  console.log('║                                                          ║');
  console.log('║   ██████╗ ██████╗ ███████╗███████╗██████╗ ██████╗       ║');
  console.log('║   ██╔══██╗██╔══██╗██╔════╝██╔════╝██╔══██╗██╔══██╗      ║');
  console.log('║   ██████╔╝██████╔╝█████╗  █████╗  ██║  ██║██████╔╝      ║');
  console.log('║   ██╔══██╗██╔══██╗██╔══╝  ██╔══╝  ██║  ██║██╔══██╗      ║');
  console.log('║   ██████╔╝██║  ██║███████╗███████╗██████╔╝██║  ██║      ║');
  console.log('║   ╚═════╝ ╚═╝  ╚═╝╚══════╝╚══════╝╚═════╝ ╚═╝  ╚═╝      ║');
  console.log('║                                                          ║');
  console.log('║        Dog Breeding Genealogy Management System          ║');
  console.log('║                                                          ║');
  console.log('╚══════════════════════════════════════════════════════════╝');
  console.log('');

  // Application Info
  console.log('┌─────────────────────────────────────────────────────────┐');
  console.log('│ 📦 APPLICATION INFO                                     │');
  console.log('├─────────────────────────────────────────────────────────┤');
  console.log(`│ Version      : ${version.padEnd(40)} │`);
  console.log(`│ Environment  : ${environment.padEnd(40)} │`);
  console.log(`│ Started      : ${timestamp.padEnd(40)} │`);
  console.log(`│ Node.js      : ${sysInfo.nodeVersion.padEnd(40)} │`);
  console.log('└─────────────────────────────────────────────────────────┘');
  console.log('');

  // Server Configuration
  console.log('┌─────────────────────────────────────────────────────────┐');
  console.log('│ 🌐 SERVER CONFIGURATION                                 │');
  console.log('├─────────────────────────────────────────────────────────┤');
  console.log(`│ Port         : ${String(port).padEnd(40)} │`);
  console.log(`│ Access URL   : http://localhost:${port}${' '.repeat(27)} │`);
  console.log(`│ Database     : ${dbStatus.padEnd(40)} │`);
  console.log('└─────────────────────────────────────────────────────────┘');
  console.log('');

  // Directory Status
  console.log('┌─────────────────────────────────────────────────────────┐');
  console.log('│ 📁 DIRECTORY STATUS                                     │');
  console.log('├─────────────────────────────────────────────────────────┤');
  Object.entries(dirStatus).forEach(([name, status]) => {
    const statusIcon = status.exists ? (status.writable ? '✓' : '⚠') : '✗';
    const statusText = status.exists ? (status.writable ? 'OK' : 'READ-ONLY') : 'MISSING';
    console.log(`│ ${statusIcon} ${name.padEnd(10)} : ${statusText.padEnd(10)} ${status.path.substring(0, 25).padEnd(25)} │`);
  });
  console.log('└─────────────────────────────────────────────────────────┘');
  console.log('');

  // System Resources
  console.log('┌─────────────────────────────────────────────────────────┐');
  console.log('│ 💻 SYSTEM RESOURCES                                     │');
  console.log('├─────────────────────────────────────────────────────────┤');
  console.log(`│ Hostname     : ${sysInfo.hostname.padEnd(40)} │`);
  console.log(`│ Platform     : ${sysInfo.platform.padEnd(40)} │`);
  console.log(`│ Architecture : ${sysInfo.arch.padEnd(40)} │`);
  console.log(`│ CPU Cores    : ${String(sysInfo.cpuCores).padEnd(40)} │`);
  console.log(`│ Total Memory : ${sysInfo.totalMemory.padEnd(40)} │`);
  console.log(`│ Free Memory  : ${sysInfo.freeMemory.padEnd(40)} │`);
  console.log('└─────────────────────────────────────────────────────────┘');
  console.log('');

  // Process Info
  console.log('┌─────────────────────────────────────────────────────────┐');
  console.log('│ ⚙️  PROCESS INFO                                         │');
  console.log('├─────────────────────────────────────────────────────────┤');
  console.log(`│ PID          : ${String(procInfo.pid).padEnd(40)} │`);
  console.log(`│ Heap Used    : ${procInfo.heapUsed.padEnd(40)} │`);
  console.log(`│ Heap Total   : ${procInfo.heapTotal.padEnd(40)} │`);
  console.log(`│ External     : ${procInfo.external.padEnd(40)} │`);
  console.log(`│ Uptime       : ${sysInfo.uptime.padEnd(40)} │`);
  console.log('└─────────────────────────────────────────────────────────┘');
  console.log('');

  // Ready message
  console.log('🚀 Server is ready and listening for connections');
  console.log('━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━');
  console.log('');
}

module.exports = {
  logStartupBanner,
  getSystemInfo,
  getProcessInfo,
  checkDirectories,
  getAppVersion
};