import 'dart:io';

class TrafficControlService {
  static Future<void> setSpeedLimit(String peerIP, int bytesPerSecond) async {
    final mark = _getMarkForIP(peerIP);
    
    // Handle unlimited speed (-1)
    if (bytesPerSecond == -1) {
      print('Removing speed limit for peer $peerIP (unlimited)');
      await _removeSpeedLimit(peerIP, mark);
      return;
    }
    
    final kbps = (bytesPerSecond * 8 / 1000).round(); // Convert bytes/s to kbps
    print('Setting speed limit for peer $peerIP to ${bytesPerSecond} bytes/s (${kbps}kbps, mark: $mark)');

    try {
      // Ensure HTB qdisc exists on wg0
      print('Setting up HTB qdisc on wg0...');
      try {
        await _runTcCommand(['qdisc', 'add', 'dev', 'wg0', 'root', 'handle', '1:', 'htb', 'default', '30']);
      } catch (e) {
        if (e.toString().contains('File exists') || e.toString().contains('Exclusivity flag')) {
          print('HTB qdisc already exists, continuing...');
        } else {
          rethrow;
        }
      }
      
      try {
        await _runTcCommand(['class', 'add', 'dev', 'wg0', 'parent', '1:', 'classid', '1:1', 'htb', 'rate', '1000mbit']);
      } catch (e) {
        if (e.toString().contains('File exists')) {
          print('HTB root class already exists, continuing...');
        } else {
          rethrow;
        }
      }
      
      // Create separate classes for upload and download
      final uploadMark = mark;
      final downloadMark = mark + 1000; // Offset to avoid conflicts
      
      print('Running iptables MARK commands for $peerIP...');
      // Clean existing mangle rules for this peer first
      try {
        await _runIptablesCommand(['-t', 'mangle', '-D', 'POSTROUTING', '-s', peerIP, '-j', 'MARK', '--set-mark', uploadMark.toString()]);
      } catch (e) { /* Rule doesn't exist, ignore */ }
      try {
        await _runIptablesCommand(['-t', 'mangle', '-D', 'FORWARD', '-d', peerIP, '-j', 'MARK', '--set-mark', downloadMark.toString()]);
      } catch (e) { /* Rule doesn't exist, ignore */ }
      
      // Mark upload traffic (FROM peer) with uploadMark - use POSTROUTING for upload
      await _runIptablesCommand(['-t', 'mangle', '-I', 'POSTROUTING', '-s', peerIP, '-j', 'MARK', '--set-mark', uploadMark.toString()]);
      // Mark download traffic (TO peer) with downloadMark - use FORWARD for download
      await _runIptablesCommand(['-t', 'mangle', '-I', 'FORWARD', '-d', peerIP, '-j', 'MARK', '--set-mark', downloadMark.toString()]);
      
      // Detect outgoing interface dynamically
      print('Detecting outgoing interface...');
      final outgoingInterface = await _detectOutgoingInterface();
      print('Setting up upload limiting on outgoing interface: $outgoingInterface');
      
      // Setup HTB on outgoing interface for upload limiting
      try {
        await _runTcCommand(['qdisc', 'add', 'dev', outgoingInterface, 'root', 'handle', '2:', 'htb', 'default', '30']);
      } catch (e) {
        if (e.toString().contains('File exists') || e.toString().contains('Exclusivity flag')) {
          print('HTB qdisc already exists on $outgoingInterface, continuing...');
        } else {
          rethrow;
        }
      }
      
      try {
        await _runTcCommand(['class', 'add', 'dev', outgoingInterface, 'parent', '2:', 'classid', '2:1', 'htb', 'rate', '1000mbit']);
      } catch (e) {
        if (e.toString().contains('File exists')) {
          print('HTB root class already exists on $outgoingInterface, continuing...');
        } else {
          rethrow;
        }
      }
      
      print('Running tc class add/change commands for upload and download...');
      
      // Upload class on outgoing interface (traffic FROM peer going out)
      try {
        await _runTcCommand(['class', 'add', 'dev', outgoingInterface, 'parent', '2:1', 'classid', '2:$uploadMark', 'htb', 'rate', '${kbps}kbit', 'ceil', '${kbps}kbit']);
      } catch (e) {
        if (e.toString().contains('File exists')) {
          print('Upload class exists, updating...');
          await _runTcCommand(['class', 'change', 'dev', outgoingInterface, 'classid', '2:$uploadMark', 'htb', 'rate', '${kbps}kbit', 'ceil', '${kbps}kbit']);
        } else {
          rethrow;
        }
      }
      
      // Download class on wg0 (traffic TO peer)
      try {
        await _runTcCommand(['class', 'add', 'dev', 'wg0', 'parent', '1:1', 'classid', '1:$downloadMark', 'htb', 'rate', '${kbps}kbit', 'ceil', '${kbps}kbit']);
      } catch (e) {
        if (e.toString().contains('File exists')) {
          print('Download class exists, updating...');
          await _runTcCommand(['class', 'change', 'dev', 'wg0', 'classid', '1:$downloadMark', 'htb', 'rate', '${kbps}kbit', 'ceil', '${kbps}kbit']);
        } else {
          rethrow;
        }
      }
      
      print('Running tc filter add commands...');
      // Upload filter on outgoing interface
      try {
        await _runTcCommand(['filter', 'add', 'dev', outgoingInterface, 'protocol', 'ip', 'parent', '2:', 'prio', '1', 'handle', uploadMark.toString(), 'fw', 'flowid', '2:$uploadMark']);
      } catch (e) {
        if (!e.toString().contains('File exists')) rethrow;
      }
      
      // Download filter on wg0
      try {
        await _runTcCommand(['filter', 'add', 'dev', 'wg0', 'protocol', 'ip', 'parent', '1:', 'prio', '1', 'handle', downloadMark.toString(), 'fw', 'flowid', '1:$downloadMark']);
      } catch (e) {
        if (!e.toString().contains('File exists')) rethrow;
      }
      
      print('Speed limit set successfully for $peerIP');
    } catch (e) {
      print('ERROR setting speed limit for $peerIP: $e');
      // Don't rethrow if it's just because qdisc already exists
      if (!e.toString().contains('File exists')) {
        rethrow;
      }
    }
  }

  static Future<void> setDataCap(String peerIP, int quotaBytes) async {
    // Handle unlimited data cap (-1)
    if (quotaBytes == -1) {
      print('Removing data cap for peer $peerIP (unlimited)');
      await _removeDataCap(peerIP);
      return;
    }
    
    print('Setting data cap for peer $peerIP to $quotaBytes bytes');
    
    // Remove existing data cap rules first
    await _removeDataCap(peerIP);
    
    await _runIptablesCommand(['-I', 'FORWARD', '-s', peerIP, '-m', 'quota', '--quota', quotaBytes.toString(), '-j', 'ACCEPT']);
    await _runIptablesCommand(['-I', 'FORWARD', '-d', peerIP, '-m', 'quota', '--quota', quotaBytes.toString(), '-j', 'ACCEPT']);
    await _runIptablesCommand(['-A', 'FORWARD', '-s', peerIP, '-j', 'DROP']);
    await _runIptablesCommand(['-A', 'FORWARD', '-d', peerIP, '-j', 'DROP']);
  }

  static int _getMarkForIP(String ip) {
    // Use last octet of IP + 10 to ensure small, valid class IDs (10-255)
    final lastOctet = int.parse(ip.split('.').last);
    return lastOctet + 10;
  }

  static Future<String> _detectOutgoingInterface() async {
    try {
      // Get default route interface
      final result = await Process.run('ip', ['route', 'show', 'default']);
      if (result.exitCode == 0) {
        final output = result.stdout.toString();
        final match = RegExp(r'dev (\w+)').firstMatch(output);
        if (match != null) {
          return match.group(1)!;
        }
      }
    } catch (e) {
      print('Failed to detect outgoing interface: $e');
    }
    // Fallback to eth0
    return 'eth0';
  }

  static Future<void> _removeSpeedLimit(String peerIP, int mark) async {
    final uploadMark = mark;
    final downloadMark = mark + 1000;
    
    print('Removing speed limit rules for $peerIP...');
    
    // Remove iptables mangle rules
    try {
      await _runIptablesCommand(['-t', 'mangle', '-D', 'POSTROUTING', '-s', peerIP, '-j', 'MARK', '--set-mark', uploadMark.toString()]);
    } catch (e) { /* Rule doesn't exist, ignore */ }
    try {
      await _runIptablesCommand(['-t', 'mangle', '-D', 'FORWARD', '-d', peerIP, '-j', 'MARK', '--set-mark', downloadMark.toString()]);
    } catch (e) { /* Rule doesn't exist, ignore */ }
    
    // Remove tc classes and filters
    final outgoingInterface = await _detectOutgoingInterface();
    
    try {
      await _runTcCommand(['filter', 'del', 'dev', outgoingInterface, 'protocol', 'ip', 'parent', '2:', 'prio', '1', 'handle', uploadMark.toString(), 'fw']);
    } catch (e) { /* Filter doesn't exist, ignore */ }
    try {
      await _runTcCommand(['filter', 'del', 'dev', 'wg0', 'protocol', 'ip', 'parent', '1:', 'prio', '1', 'handle', downloadMark.toString(), 'fw']);
    } catch (e) { /* Filter doesn't exist, ignore */ }
    
    try {
      await _runTcCommand(['class', 'del', 'dev', outgoingInterface, 'classid', '2:$uploadMark']);
    } catch (e) { /* Class doesn't exist, ignore */ }
    try {
      await _runTcCommand(['class', 'del', 'dev', 'wg0', 'classid', '1:$downloadMark']);
    } catch (e) { /* Class doesn't exist, ignore */ }
    
    print('Speed limit removed for $peerIP');
  }

  static Future<void> _removeDataCap(String peerIP) async {
    print('Removing data cap rules for $peerIP...');
    
    // Remove quota rules (these are harder to target specifically, so we try common patterns)
    try {
      await _runIptablesCommand(['-D', 'FORWARD', '-s', peerIP, '-j', 'DROP']);
    } catch (e) { /* Rule doesn't exist, ignore */ }
    try {
      await _runIptablesCommand(['-D', 'FORWARD', '-d', peerIP, '-j', 'DROP']);
    } catch (e) { /* Rule doesn't exist, ignore */ }
    
    // Remove quota rules by flushing and re-adding basic rules
    // This is a bit aggressive but necessary since quota rules are hard to target specifically
    try {
      final result = await Process.run('iptables', ['-S', 'FORWARD']);
      if (result.exitCode == 0) {
        final lines = result.stdout.toString().split('\n');
        for (final line in lines) {
          if (line.contains(peerIP) && line.contains('quota')) {
            // Extract the rule and convert -A to -D to delete it
            final deleteRule = line.replaceFirst('-A', '-D');
            try {
              await Process.run('iptables', deleteRule.split(' ').skip(1).toList());
            } catch (e) { /* Ignore individual failures */ }
          }
        }
      }
    } catch (e) {
      print('Failed to remove specific quota rules: $e');
    }
    
    print('Data cap removed for $peerIP');
  }

  static Future<void> _runIptablesCommand(List<String> args) async {
    final command = 'iptables ${args.join(' ')}';
    print('Executing: $command');
    final result = await Process.run('iptables', args);
    print('iptables exit code: ${result.exitCode}');
    if (result.stdout.toString().isNotEmpty) {
      print('iptables stdout: ${result.stdout}');
    }
    if (result.stderr.toString().isNotEmpty) {
      print('iptables stderr: ${result.stderr}');
    }
    if (result.exitCode != 0) {
      throw Exception('iptables command failed: ${result.stderr}');
    }
  }

  static Future<void> _runTcCommand(List<String> args) async {
    final command = 'tc ${args.join(' ')}';
    print('Executing: $command');
    final result = await Process.run('tc', args);
    print('tc exit code: ${result.exitCode}');
    if (result.stdout.toString().isNotEmpty) {
      print('tc stdout: ${result.stdout}');
    }
    if (result.stderr.toString().isNotEmpty) {
      print('tc stderr: ${result.stderr}');
    }
    if (result.exitCode != 0) {
      throw Exception('tc command failed: ${result.stderr}');
    }
  }
}