const express = require('express');
const fs = require('fs').promises;
const { spawn } = require('child_process');
const chokidar = require('chokidar');

const paths = require('../utils/paths');
const ConfigParser = require('../utils/config-parser');

const router = express.Router();

// Security function to validate configuration overrides
function validateConfigOverrides(configOverrides) {
  if (!configOverrides || typeof configOverrides !== 'object') {
    return {};
  }

  const sanitized = {};
  
  // Whitelist of allowed configuration parameters
  const allowedConfigKeys = [
    'port', 'bind', 'name', 'motd', 'max_users', 'password', 'default_game',
    'enable_damage', 'creative_mode', 'enable_rollback_recording', 'disallow_empty_password',
    'server_announce', 'serverlist_url', 'enable_pvp', 'time_speed', 'day_night_ratio',
    'max_simultaneous_block_sends_per_client', 'max_block_send_distance',
    'max_block_generate_distance', 'secure', 'enable_client_modding', 'csm_restriction_flags',
    'csm_restriction_noderange', 'player_transfer_distance', 'max_packets_per_iteration',
    'dedicated_server_step', 'ignore_world_load_errors', 'remote_media'
  ];

  for (const [key, value] of Object.entries(configOverrides)) {
    // Validate key
    if (!allowedConfigKeys.includes(key) || !/^[a-z_]+$/.test(key)) {
      continue; // Skip invalid keys
    }

    // Validate and sanitize value
    let sanitizedValue = String(value).trim();
    
    // Remove control characters
    sanitizedValue = sanitizedValue.replace(/[\x00-\x1F\x7F]/g, '');
    
    // Limit length
    if (sanitizedValue.length > 200) {
      continue; // Skip overly long values
    }

    // Type-specific validation
    if (['port', 'max_users', 'time_speed', 'max_simultaneous_block_sends_per_client',
         'max_block_send_distance', 'max_block_generate_distance', 'csm_restriction_noderange',
         'player_transfer_distance', 'max_packets_per_iteration', 'dedicated_server_step'].includes(key)) {
      const numValue = parseInt(sanitizedValue, 10);
      if (!isNaN(numValue) && numValue >= 0 && numValue <= 65535) {
        sanitized[key] = numValue.toString();
      }
    } else if (['enable_damage', 'creative_mode', 'enable_rollback_recording', 'disallow_empty_password',
               'server_announce', 'enable_pvp', 'secure', 'enable_client_modding', 'ignore_world_load_errors'].includes(key)) {
      if (['true', 'false'].includes(sanitizedValue.toLowerCase())) {
        sanitized[key] = sanitizedValue.toLowerCase();
      }
    } else if (['bind', 'name', 'motd', 'password', 'default_game', 'serverlist_url'].includes(key)) {
      // String values - ensure they don't contain shell metacharacters
      if (!/[;&|`$(){}[\]<>\\]/.test(sanitizedValue)) {
        sanitized[key] = sanitizedValue;
      }
    } else {
      // Floating point values
      const floatValue = parseFloat(sanitizedValue);
      if (!isNaN(floatValue) && isFinite(floatValue)) {
        sanitized[key] = floatValue.toString();
      }
    }
  }

  return sanitized;
}

// Global server state
let serverProcess = null;
let serverStatus = 'stopped';
let serverLogs = [];
let logWatcher = null;

// Server management page
router.get('/', async (req, res) => {
  try {
    paths.ensureDirectories();
    
    // Get available worlds for dropdown
    let worlds = [];
    try {
      const worldDirs = await fs.readdir(paths.worldsDir);
      for (const worldDir of worldDirs) {
        try {
          const worldPath = paths.getWorldPath(worldDir);
          const configPath = paths.getWorldConfigPath(worldDir);
          const stats = await fs.stat(worldPath);
          if (stats.isDirectory()) {
            const config = await ConfigParser.parseWorldConfig(configPath);
            worlds.push({
              name: worldDir,
              displayName: config.server_name || worldDir
            });
          }
        } catch {}
      }
    } catch {}
    
    // Get recent logs
    let recentLogs = [];
    try {
      const logContent = await fs.readFile(paths.debugFile, 'utf8');
      const lines = logContent.split('\n').filter(line => line.trim());
      recentLogs = lines.slice(-50); // Last 50 lines
    } catch {
      // Debug file might not exist
    }
    
    const serverInfo = {
      status: serverStatus,
      pid: serverProcess ? serverProcess.pid : null,
      uptime: serverProcess ? Date.now() - serverProcess.startTime : 0,
      logs: [...recentLogs, ...serverLogs.map(log => log.message || log)].slice(-100)
    };
    
    res.render('server/index', {
      title: 'Server Management',
      server: serverInfo,
      worlds: worlds,
      currentPage: 'server',
      scripts: ['server.js']
    });
  } catch (error) {
    console.error('Error loading server page:', error);
    res.status(500).render('error', {
      error: 'Failed to load server management',
      message: error.message
    });
  }
});

// Get server status (API)
router.get('/api/status', (req, res) => {
  res.json({
    status: serverStatus,
    pid: serverProcess ? serverProcess.pid : null,
    uptime: serverProcess ? Date.now() - serverProcess.startTime : 0
  });
});

// Get server logs (API)
router.get('/api/logs', async (req, res) => {
  try {
    const limit = parseInt(req.query.limit) || 100;
    const offset = parseInt(req.query.offset) || 0;
    
    let fileLogs = [];
    try {
      const logContent = await fs.readFile(paths.debugFile, 'utf8');
      const lines = logContent.split('\n').filter(line => line.trim());
      fileLogs = lines.slice(-1000);
    } catch {}
    
    const allLogs = [...fileLogs, ...serverLogs.map(log => log.message || log)];
    const paginatedLogs = allLogs.slice(offset, offset + limit);
    
    res.json({
      logs: paginatedLogs,
      total: allLogs.length,
      offset,
      limit
    });
  } catch (error) {
    console.error('Error getting logs:', error);
    res.status(500).json({ error: 'Failed to get logs' });
  }
});

// Start server
router.post('/start', async (req, res) => {
  try {
    if (serverProcess && serverStatus === 'running') {
      return res.status(409).json({ error: 'Server is already running' });
    }
    
    const { worldName, configOverrides } = req.body;
    
    if (!worldName || !paths.isValidWorldName(worldName)) {
      if (req.headers.accept && req.headers.accept.includes('application/json')) {
        return res.status(400).json({ error: 'Valid world name required' });
      } else {
        return res.redirect('/server?error=Valid+world+name+required');
      }
    }
    
    const worldPath = paths.getWorldPath(worldName);
    
    try {
      await fs.access(worldPath);
    } catch {
      if (req.headers.accept && req.headers.accept.includes('application/json')) {
        return res.status(404).json({ error: 'World not found' });
      } else {
        return res.redirect('/server?error=World+not+found');
      }
    }
    
    const args = [
      '--server',
      '--world', worldPath,
      '--logfile', paths.debugFile
    ];
    
    if (configOverrides) {
      const sanitizedOverrides = validateConfigOverrides(configOverrides);
      for (const [key, value] of Object.entries(sanitizedOverrides)) {
        args.push(`--${key}`, value);
      }
    }
    
    serverProcess = spawn('luanti', args, {
      stdio: ['pipe', 'pipe', 'pipe'],
      detached: false
    });
    
    serverProcess.startTime = Date.now();
    serverStatus = 'starting';
    serverLogs = [];
    
    // Get Socket.IO instance from main app
    const { io } = require('../app');
    
    serverProcess.stdout.on('data', (data) => {
      const logLine = data.toString().trim();
      if (logLine) {
        const logEntry = {
          timestamp: new Date().toISOString(),
          level: 'info',
          message: logLine
        };
        serverLogs.push(logEntry);
        if (serverLogs.length > 1000) {
          serverLogs = serverLogs.slice(-1000);
        }
        
        if (io) {
          io.emit('serverLog', logEntry);
        }
      }
    });
    
    serverProcess.stderr.on('data', (data) => {
      const logLine = data.toString().trim();
      if (logLine) {
        const logEntry = {
          timestamp: new Date().toISOString(),
          level: 'error',
          message: logLine
        };
        serverLogs.push(logEntry);
        if (serverLogs.length > 1000) {
          serverLogs = serverLogs.slice(-1000);
        }
        
        if (io) {
          io.emit('serverLog', logEntry);
        }
      }
    });
    
    serverProcess.on('spawn', () => {
      serverStatus = 'running';
      console.log('Luanti server started');
      
      if (io) {
        io.emit('serverStatus', {
          status: serverStatus,
          pid: serverProcess.pid,
          uptime: Date.now() - serverProcess.startTime
        });
      }
    });
    
    serverProcess.on('error', (error) => {
      console.error('Server error:', error);
      serverStatus = 'error';
      const logEntry = {
        timestamp: new Date().toISOString(),
        level: 'error',
        message: `Server error: ${error.message}`
      };
      serverLogs.push(logEntry);
      
      if (io) {
        io.emit('serverLog', logEntry);
        io.emit('serverStatus', {
          status: serverStatus,
          pid: null,
          uptime: 0
        });
      }
    });
    
    serverProcess.on('exit', (code, signal) => {
      console.log(`Server exited with code ${code}, signal ${signal}`);
      serverStatus = 'stopped';
      const logEntry = {
        timestamp: new Date().toISOString(),
        level: 'info',
        message: `Server stopped (code: ${code}, signal: ${signal})`
      };
      serverLogs.push(logEntry);
      serverProcess = null;
      
      if (io) {
        io.emit('serverLog', logEntry);
        io.emit('serverStatus', {
          status: serverStatus,
          pid: null,
          uptime: 0
        });
      }
    });
    
    // Watch debug log file
    if (logWatcher) {
      logWatcher.close();
    }
    
    logWatcher = chokidar.watch(paths.debugFile, { persistent: true });
    logWatcher.on('change', async () => {
      try {
        const logContent = await fs.readFile(paths.debugFile, 'utf8');
        const lines = logContent.split('\n');
        const newLines = lines.slice(-10);
        
        for (const line of newLines) {
          if (line.trim() && !serverLogs.some(log => (log.message || log) === line.trim())) {
            const logEntry = {
              timestamp: new Date().toISOString(),
              level: 'info',
              message: line.trim()
            };
            serverLogs.push(logEntry);
            
            if (io) {
              io.emit('serverLog', logEntry);
            }
          }
        }
        
        if (serverLogs.length > 1000) {
          serverLogs = serverLogs.slice(-1000);
        }
      } catch {}
    });
    
    if (req.headers.accept && req.headers.accept.includes('application/json')) {
      res.json({ message: 'Server starting', pid: serverProcess.pid });
    } else {
      res.redirect('/server?started=true');
    }
  } catch (error) {
    console.error('Error starting server:', error);
    if (req.headers.accept && req.headers.accept.includes('application/json')) {
      res.status(500).json({ error: 'Failed to start server' });
    } else {
      res.redirect(`/server?error=${encodeURIComponent(error.message)}`);
    }
  }
});

// Stop server
router.post('/stop', (req, res) => {
  try {
    if (!serverProcess || serverStatus !== 'running') {
      if (req.headers.accept && req.headers.accept.includes('application/json')) {
        return res.status(409).json({ error: 'Server is not running' });
      } else {
        return res.redirect('/server?error=Server+is+not+running');
      }
    }
    
    serverStatus = 'stopping';
    
    serverProcess.kill('SIGTERM');
    
    setTimeout(() => {
      if (serverProcess && serverStatus === 'stopping') {
        serverProcess.kill('SIGKILL');
      }
    }, 10000);
    
    if (logWatcher) {
      logWatcher.close();
      logWatcher = null;
    }
    
    const { io } = require('../app');
    if (io) {
      io.emit('serverStatus', {
        status: serverStatus,
        pid: serverProcess ? serverProcess.pid : null,
        uptime: serverProcess ? Date.now() - serverProcess.startTime : 0
      });
    }
    
    if (req.headers.accept && req.headers.accept.includes('application/json')) {
      res.json({ message: 'Server stopping' });
    } else {
      res.redirect('/server?stopped=true');
    }
  } catch (error) {
    console.error('Error stopping server:', error);
    if (req.headers.accept && req.headers.accept.includes('application/json')) {
      res.status(500).json({ error: 'Failed to stop server' });
    } else {
      res.redirect(`/server?error=${encodeURIComponent(error.message)}`);
    }
  }
});

// Send command to server
router.post('/command', (req, res) => {
  try {
    if (!serverProcess || serverStatus !== 'running') {
      return res.status(409).json({ error: 'Server is not running' });
    }
    
    const { command } = req.body;
    
    if (!command) {
      return res.status(400).json({ error: 'Command required' });
    }
    
    // Validate and sanitize the command using ServerManager's validation
    const ServerManager = require('../utils/server-manager');
    const serverManager = new ServerManager();
    
    try {
      const sanitizedCommand = serverManager.validateServerCommand(command);
      serverProcess.stdin.write(sanitizedCommand + '\n');
      
      const logEntry = {
        timestamp: new Date().toISOString(),
        level: 'command',
        message: `> ${sanitizedCommand}`
      };
      serverLogs.push(logEntry);
      
      const { io } = require('../app');
      if (io) {
        io.emit('serverLog', logEntry);
      }
      
      res.json({ message: 'Command sent successfully' });
    } catch (validationError) {
      return res.status(400).json({ error: validationError.message });
    }
    
  } catch (error) {
    console.error('Error sending command:', error);
    res.status(500).json({ error: 'Failed to send command' });
  }
});

// Export server state for use in main app
router.getServerState = () => ({
  process: serverProcess,
  status: serverStatus,
  logs: serverLogs
});

module.exports = router;