import 'package:flutter/material.dart';
import '../../data/session/session_service.dart';
import '../../data/firebase/firebase_service.dart';
import '../../data/nostr/nostr_service.dart';
import '../../data/nostr/models/nostr_keypair.dart';

/// Screen for user session management (login/logout).
class SessionScreen extends StatefulWidget {
  final SessionService? sessionService;
  final FirebaseService? firebaseService;
  final NostrService? nostrService;
  final VoidCallback? onSessionChanged;

  const SessionScreen({
    super.key,
    this.sessionService,
    this.firebaseService,
    this.nostrService,
    this.onSessionChanged,
  });

  @override
  State<SessionScreen> createState() => _SessionScreenState();
}

class _SessionScreenState extends State<SessionScreen> {
  final TextEditingController _usernameController = TextEditingController();
  final TextEditingController _userIdController = TextEditingController();
  final TextEditingController _emailController = TextEditingController();
  final TextEditingController _passwordController = TextEditingController();
  final TextEditingController _nostrKeyController = TextEditingController();
  bool _isLoading = false;
  bool _useFirebaseAuth = false;
  bool _useNostrLogin = false;
  NostrKeyPair? _generatedKeyPair;

  @override
  void initState() {
    super.initState();
    // Check if Firebase Auth is available
    _useFirebaseAuth = widget.firebaseService?.isEnabled == true &&
        widget.firebaseService?.config.authEnabled == true;
  }

  @override
  void dispose() {
    _usernameController.dispose();
    _userIdController.dispose();
    _emailController.dispose();
    _passwordController.dispose();
    _nostrKeyController.dispose();
    super.dispose();
  }

  Future<void> _handleLogin() async {
    if (widget.sessionService == null) return;

    setState(() {
      _isLoading = true;
    });

    try {
      // Handle Nostr login
      if (_useNostrLogin) {
        final nostrKey = _nostrKeyController.text.trim();
        
        if (nostrKey.isEmpty) {
          if (mounted) {
            ScaffoldMessenger.of(context).showSnackBar(
              const SnackBar(
                content: Text('Please enter nsec or npub key'),
              ),
            );
          }
          return;
        }

        // Validate format
        if (!nostrKey.startsWith('nsec') && !nostrKey.startsWith('npub')) {
          if (mounted) {
            ScaffoldMessenger.of(context).showSnackBar(
              const SnackBar(
                content: Text('Invalid key format. Expected nsec or npub.'),
                backgroundColor: Colors.red,
              ),
            );
          }
          return;
        }

        // Login with Nostr
        await widget.sessionService!.loginWithNostr(nostrKey);

        if (mounted) {
          ScaffoldMessenger.of(context).showSnackBar(
            const SnackBar(
              content: Text('Nostr login successful'),
            ),
          );
          setState(() {});
          widget.onSessionChanged?.call();
        }
        return;
      }

      // Handle Firebase or regular login
      if (_useFirebaseAuth && widget.firebaseService != null) {
        // Use Firebase Auth for authentication
        final email = _emailController.text.trim();
        final password = _passwordController.text.trim();

        if (email.isEmpty || password.isEmpty) {
          if (mounted) {
            ScaffoldMessenger.of(context).showSnackBar(
              const SnackBar(
                content: Text('Please enter email and password'),
              ),
            );
          }
          return;
        }

        // Authenticate with Firebase
        final firebaseUser = await widget.firebaseService!.loginWithEmailPassword(
          email: email,
          password: password,
        );

        // Create session with Firebase user info
        await widget.sessionService!.login(
          id: firebaseUser.uid,
          username: firebaseUser.email?.split('@').first ?? firebaseUser.uid,
          token: await firebaseUser.getIdToken(),
        );

        if (mounted) {
          ScaffoldMessenger.of(context).showSnackBar(
            const SnackBar(
              content: Text('Login successful'),
            ),
          );
          setState(() {});
          // Notify parent that session state changed
          widget.onSessionChanged?.call();
        }
      } else {
        // Simple validation mode (no Firebase Auth)
        final username = _usernameController.text.trim();
        final userId = _userIdController.text.trim();

        if (username.isEmpty || userId.isEmpty) {
          if (mounted) {
            ScaffoldMessenger.of(context).showSnackBar(
              const SnackBar(
                content: Text('Please enter username and user ID'),
              ),
            );
          }
          return;
        }

        // Basic validation: require minimum length
        if (userId.length < 3) {
          if (mounted) {
            ScaffoldMessenger.of(context).showSnackBar(
              const SnackBar(
                content: Text('User ID must be at least 3 characters'),
              ),
            );
          }
          return;
        }

        if (username.length < 2) {
          if (mounted) {
            ScaffoldMessenger.of(context).showSnackBar(
              const SnackBar(
                content: Text('Username must be at least 2 characters'),
              ),
            );
          }
          return;
        }

        // Create session (demo mode - no real authentication)
        await widget.sessionService!.login(
          id: userId,
          username: username,
        );

        if (mounted) {
          ScaffoldMessenger.of(context).showSnackBar(
            const SnackBar(
              content: Text('Login successful (demo mode)'),
              backgroundColor: Colors.orange,
            ),
          );
          setState(() {});
          // Notify parent that session state changed
          widget.onSessionChanged?.call();
        }
      }
    } catch (e) {
      if (mounted) {
        ScaffoldMessenger.of(context).showSnackBar(
          SnackBar(
            content: Text('Login failed: ${e.toString().replaceAll('FirebaseException: ', '').replaceAll('SessionException: ', '')}'),
            backgroundColor: Colors.red,
          ),
        );
      }
    } finally {
      if (mounted) {
        setState(() {
          _isLoading = false;
        });
      }
    }
  }

  Future<void> _handleLogout() async {
    if (widget.sessionService == null) return;

    setState(() {
      _isLoading = true;
    });

    try {
      // Logout from session service first
      await widget.sessionService!.logout();

      // Also logout from Firebase Auth if enabled
      if (_useFirebaseAuth && widget.firebaseService != null) {
        try {
          await widget.firebaseService!.logout();
        } catch (e) {
          // Log error but don't fail logout - session is already cleared
          debugPrint('Warning: Firebase logout failed: $e');
        }
      }

      if (mounted) {
        ScaffoldMessenger.of(context).showSnackBar(
          const SnackBar(
            content: Text('Logout successful'),
          ),
        );
        setState(() {});
        // Notify parent that session state changed
        widget.onSessionChanged?.call();
      }
    } catch (e) {
      if (mounted) {
        ScaffoldMessenger.of(context).showSnackBar(
          SnackBar(
            content: Text('Logout failed: ${e.toString().replaceAll('SessionException: ', '')}'),
            backgroundColor: Colors.red,
          ),
        );
      }
    } finally {
      if (mounted) {
        setState(() {
          _isLoading = false;
        });
      }
    }
  }

  @override
  Widget build(BuildContext context) {
    final isLoggedIn = widget.sessionService?.isLoggedIn ?? false;
    final currentUser = widget.sessionService?.currentUser;

    return Scaffold(
      appBar: AppBar(
        title: const Text('Session'),
      ),
      body: _isLoading
          ? const Center(child: CircularProgressIndicator())
          : SingleChildScrollView(
              padding: const EdgeInsets.all(16),
              child: Column(
                crossAxisAlignment: CrossAxisAlignment.stretch,
                children: [
                  if (isLoggedIn && currentUser != null) ...[
                    Card(
                      child: Padding(
                        padding: const EdgeInsets.all(16),
                        child: Column(
                          crossAxisAlignment: CrossAxisAlignment.start,
                          children: [
                            const Text(
                              'Current Session',
                              style: TextStyle(
                                fontSize: 18,
                                fontWeight: FontWeight.bold,
                              ),
                            ),
                            const SizedBox(height: 12),
                            // Display Nostr profile if available
                            if (currentUser.nostrProfile != null) ...[
                              Row(
                                children: [
                                  if (currentUser.nostrProfile!.picture != null)
                                    CircleAvatar(
                                      radius: 30,
                                      backgroundImage: NetworkImage(
                                        currentUser.nostrProfile!.picture!,
                                      ),
                                      onBackgroundImageError: (_, __) {},
                                    )
                                  else
                                    const CircleAvatar(
                                      radius: 30,
                                      child: Icon(Icons.person),
                                    ),
                                  const SizedBox(width: 12),
                                  Expanded(
                                    child: Column(
                                      crossAxisAlignment: CrossAxisAlignment.start,
                                      children: [
                                        Text(
                                          currentUser.nostrProfile!.name ?? 
                                          currentUser.nostrProfile!.displayName,
                                          style: const TextStyle(
                                            fontSize: 18,
                                            fontWeight: FontWeight.bold,
                                          ),
                                        ),
                                        if (currentUser.nostrProfile!.about != null)
                                          Text(
                                            currentUser.nostrProfile!.about!,
                                            style: TextStyle(
                                              fontSize: 14,
                                              color: Colors.grey[600],
                                            ),
                                            maxLines: 2,
                                            overflow: TextOverflow.ellipsis,
                                          ),
                                      ],
                                    ),
                                  ),
                                ],
                              ),
                              const SizedBox(height: 12),
                              const Divider(),
                              const SizedBox(height: 12),
                            ],
                            // NIP-05 section
                            if (currentUser.nostrProfile?.nip05 != null &&
                                currentUser.nostrProfile!.nip05!.isNotEmpty)
                              _Nip05Section(
                                nip05: currentUser.nostrProfile!.nip05!,
                                publicKey: currentUser.id,
                                nostrService: widget.nostrService,
                              ),
                            if (currentUser.nostrProfile?.nip05 != null &&
                                currentUser.nostrProfile!.nip05!.isNotEmpty)
                              const SizedBox(height: 12),
                            Text('User ID: ${currentUser.id.substring(0, currentUser.id.length > 32 ? 32 : currentUser.id.length)}${currentUser.id.length > 32 ? '...' : ''}'),
                            Text('Username: ${currentUser.username}'),
                            Text(
                              'Created: ${DateTime.fromMillisecondsSinceEpoch(currentUser.createdAt).toString().split('.')[0]}',
                            ),
                          ],
                        ),
                      ),
                    ),
                    const SizedBox(height: 16),
                    ElevatedButton(
                      onPressed: _handleLogout,
                      style: ElevatedButton.styleFrom(
                        backgroundColor: Colors.red,
                        foregroundColor: Colors.white,
                      ),
                      child: const Text('Logout'),
                    ),
                  ] else ...[
                    const Icon(
                      Icons.person_outline,
                      size: 64,
                      color: Colors.grey,
                    ),
                    const SizedBox(height: 16),
                    const Text(
                      'Login',
                      style: TextStyle(
                        fontSize: 24,
                        fontWeight: FontWeight.bold,
                      ),
                      textAlign: TextAlign.center,
                    ),
                    if (!_useFirebaseAuth) ...[
                      const SizedBox(height: 8),
                      Container(
                        padding: const EdgeInsets.all(12),
                        decoration: BoxDecoration(
                          color: Colors.orange.shade50,
                          borderRadius: BorderRadius.circular(8),
                          border: Border.all(color: Colors.orange.shade200),
                        ),
                        child: Row(
                          children: [
                            Icon(Icons.info_outline, color: Colors.orange.shade700, size: 20),
                            const SizedBox(width: 8),
                            Expanded(
                              child: Text(
                                'Demo mode: No authentication required. Enter any valid user ID and username.',
                                style: TextStyle(
                                  fontSize: 12,
                                  color: Colors.orange.shade700,
                                ),
                              ),
                            ),
                          ],
                        ),
                      ),
                    ],
                    const SizedBox(height: 24),
                    // Login method selector
                    SegmentedButton<bool>(
                      segments: const [
                        ButtonSegment<bool>(
                          value: false,
                          label: Text('Regular'),
                        ),
                        ButtonSegment<bool>(
                          value: true,
                          label: Text('Nostr'),
                        ),
                      ],
                      selected: {_useNostrLogin},
                      onSelectionChanged: (Set<bool> newSelection) {
                        setState(() {
                          _useNostrLogin = newSelection.first;
                        });
                      },
                    ),
                    const SizedBox(height: 24),
                    if (_useNostrLogin) ...[
                      // Key pair generation section
                      if (widget.nostrService != null) ...[
                        Card(
                          child: Padding(
                            padding: const EdgeInsets.all(16),
                            child: Column(
                              crossAxisAlignment: CrossAxisAlignment.start,
                              children: [
                                Row(
                                  mainAxisAlignment: MainAxisAlignment.spaceBetween,
                                  children: [
                                    const Text(
                                      'Generate Key Pair',
                                      style: TextStyle(
                                        fontSize: 16,
                                        fontWeight: FontWeight.bold,
                                      ),
                                    ),
                                    ElevatedButton.icon(
                                      onPressed: () {
                                        setState(() {
                                          _generatedKeyPair = widget.nostrService!.generateKeyPair();
                                        });
                                      },
                                      icon: const Icon(Icons.refresh, size: 18),
                                      label: const Text('Generate'),
                                    ),
                                  ],
                                ),
                                if (_generatedKeyPair != null) ...[
                                  const SizedBox(height: 16),
                                  // npub display
                                  Row(
                                    children: [
                                      Expanded(
                                        child: Column(
                                          crossAxisAlignment: CrossAxisAlignment.start,
                                          children: [
                                            const Text(
                                              'npub (Public Key):',
                                              style: TextStyle(
                                                fontSize: 12,
                                                fontWeight: FontWeight.bold,
                                              ),
                                            ),
                                            const SizedBox(height: 4),
                                            SelectableText(
                                              _generatedKeyPair!.toNpub(),
                                              style: const TextStyle(
                                                fontSize: 11,
                                                fontFamily: 'monospace',
                                              ),
                                            ),
                                          ],
                                        ),
                                      ),
                                      const SizedBox(width: 8),
                                      IconButton(
                                        icon: const Icon(Icons.content_copy),
                                        tooltip: 'Copy to field',
                                        onPressed: () {
                                          _nostrKeyController.text = _generatedKeyPair!.toNpub();
                                        },
                                      ),
                                    ],
                                  ),
                                  const SizedBox(height: 12),
                                  // nsec display
                                  Row(
                                    children: [
                                      Expanded(
                                        child: Column(
                                          crossAxisAlignment: CrossAxisAlignment.start,
                                          children: [
                                            const Text(
                                              'nsec (Private Key):',
                                              style: TextStyle(
                                                fontSize: 12,
                                                fontWeight: FontWeight.bold,
                                              ),
                                            ),
                                            const SizedBox(height: 4),
                                            SelectableText(
                                              _generatedKeyPair!.toNsec(),
                                              style: const TextStyle(
                                                fontSize: 11,
                                                fontFamily: 'monospace',
                                              ),
                                            ),
                                          ],
                                        ),
                                      ),
                                      const SizedBox(width: 8),
                                      IconButton(
                                        icon: const Icon(Icons.content_copy),
                                        tooltip: 'Copy to field',
                                        onPressed: () {
                                          _nostrKeyController.text = _generatedKeyPair!.toNsec();
                                        },
                                      ),
                                    ],
                                  ),
                                ],
                              ],
                            ),
                          ),
                        ),
                        const SizedBox(height: 16),
                      ],
                      TextField(
                        controller: _nostrKeyController,
                        decoration: const InputDecoration(
                          labelText: 'Nostr Key (nsec or npub)',
                          hintText: 'Enter your nsec or npub key',
                          border: OutlineInputBorder(),
                          helperText: 'Enter your Nostr private key (nsec) or public key (npub)',
                        ),
                        maxLines: 3,
                        minLines: 1,
                      ),
                    ] else if (_useFirebaseAuth) ...[
                      TextField(
                        controller: _emailController,
                        decoration: const InputDecoration(
                          labelText: 'Email',
                          hintText: 'Enter your email',
                          border: OutlineInputBorder(),
                        ),
                        keyboardType: TextInputType.emailAddress,
                        autofillHints: const [AutofillHints.email],
                      ),
                      const SizedBox(height: 16),
                      TextField(
                        controller: _passwordController,
                        decoration: const InputDecoration(
                          labelText: 'Password',
                          hintText: 'Enter your password',
                          border: OutlineInputBorder(),
                        ),
                        obscureText: true,
                        autofillHints: const [AutofillHints.password],
                      ),
                    ] else ...[
                      TextField(
                        controller: _userIdController,
                        decoration: const InputDecoration(
                          labelText: 'User ID',
                          hintText: 'Enter user ID (min 3 characters)',
                          border: OutlineInputBorder(),
                        ),
                      ),
                      const SizedBox(height: 16),
                      TextField(
                        controller: _usernameController,
                        decoration: const InputDecoration(
                          labelText: 'Username',
                          hintText: 'Enter username (min 2 characters)',
                          border: OutlineInputBorder(),
                        ),
                      ),
                    ],
                    const SizedBox(height: 24),
                    ElevatedButton(
                      onPressed: _isLoading ? null : _handleLogin,
                      child: _isLoading
                          ? const SizedBox(
                              width: 20,
                              height: 20,
                              child: CircularProgressIndicator(strokeWidth: 2),
                            )
                          : const Text('Login'),
                    ),
                  ],
                ],
              ),
            ),
    );
  }
}

/// Widget for displaying NIP-05 information including domain and preferred relays.
class _Nip05Section extends StatefulWidget {
  final String nip05;
  final String publicKey;
  final NostrService? nostrService;

  const _Nip05Section({
    required this.nip05,
    required this.publicKey,
    this.nostrService,
  });

  @override
  State<_Nip05Section> createState() => _Nip05SectionState();
}

class _Nip05SectionState extends State<_Nip05Section> {
  List<String> _preferredRelays = [];
  bool _isLoading = false;
  String? _error;

  @override
  void initState() {
    super.initState();
    _loadPreferredRelays();
  }

  Future<void> _loadPreferredRelays() async {
    if (widget.nostrService == null) {
      setState(() {
        _error = 'Nostr service not available';
      });
      return;
    }

    setState(() {
      _isLoading = true;
      _error = null;
    });

    try {
      final relays = await widget.nostrService!.fetchPreferredRelaysFromNip05(
        widget.nip05,
        widget.publicKey,
      );
      setState(() {
        _preferredRelays = relays;
        _isLoading = false;
      });
    } catch (e) {
      setState(() {
        _error = e.toString().replaceAll('NostrException: ', '');
        _isLoading = false;
      });
    }
  }

  String _getDomain() {
    final parts = widget.nip05.split('@');
    if (parts.length == 2) {
      return parts[1];
    }
    return widget.nip05;
  }

  @override
  Widget build(BuildContext context) {
    return Column(
      crossAxisAlignment: CrossAxisAlignment.start,
      children: [
        const Text(
          'NIP-05',
          style: TextStyle(
            fontSize: 16,
            fontWeight: FontWeight.bold,
          ),
        ),
        const SizedBox(height: 8),
        Row(
          children: [
            const Icon(Icons.verified, size: 16, color: Colors.blue),
            const SizedBox(width: 8),
            Expanded(
              child: Text(
                widget.nip05,
                style: const TextStyle(
                  fontSize: 14,
                  fontWeight: FontWeight.w500,
                ),
              ),
            ),
          ],
        ),
        const SizedBox(height: 8),
        Text(
          'Domain: ${_getDomain()}',
          style: TextStyle(
            fontSize: 12,
            color: Colors.grey[600],
          ),
        ),
        const SizedBox(height: 12),
        const Text(
          'Preferred Relays',
          style: TextStyle(
            fontSize: 14,
            fontWeight: FontWeight.w600,
          ),
        ),
        const SizedBox(height: 8),
        if (_isLoading)
          const Padding(
            padding: EdgeInsets.symmetric(vertical: 8),
            child: SizedBox(
              height: 20,
              width: 20,
              child: CircularProgressIndicator(strokeWidth: 2),
            ),
          )
        else if (_error != null)
          Container(
            padding: const EdgeInsets.all(8),
            decoration: BoxDecoration(
              color: Colors.red.shade50,
              borderRadius: BorderRadius.circular(4),
              border: Border.all(color: Colors.red.shade200),
            ),
            child: Row(
              children: [
                Icon(Icons.error_outline, size: 16, color: Colors.red.shade700),
                const SizedBox(width: 8),
                Expanded(
                  child: Text(
                    _error!,
                    style: TextStyle(
                      fontSize: 12,
                      color: Colors.red.shade700,
                    ),
                  ),
                ),
              ],
            ),
          )
        else if (_preferredRelays.isEmpty)
          Text(
            'No preferred relays found',
            style: TextStyle(
              fontSize: 12,
              color: Colors.grey[600],
              fontStyle: FontStyle.italic,
            ),
          )
        else
          ..._preferredRelays.map((relay) => Padding(
                padding: const EdgeInsets.only(bottom: 4),
                child: Row(
                  children: [
                    Icon(
                      Icons.link,
                      size: 14,
                      color: Colors.grey[600],
                    ),
                    const SizedBox(width: 8),
                    Expanded(
                      child: Text(
                        relay,
                        style: TextStyle(
                          fontSize: 12,
                          color: Colors.grey[700],
                        ),
                      ),
                    ),
                  ],
                ),
              )),
      ],
    );
  }
}