import "package:flutter/material.dart";
import "package:flutter/services.dart";
import "package:provider/provider.dart";

import "../app/app_router.dart";
import "../app/app_state.dart";
import "../services/api.dart";
import "../services/auth_storage.dart";

enum SignupStep { phone, otp, profile }

class SignupScreen extends StatefulWidget {
  const SignupScreen({super.key});

  @override
  State<SignupScreen> createState() => _SignupScreenState();
}

class _SignupScreenState extends State<SignupScreen> {
  SignupStep _currentStep = SignupStep.phone;

  // Phone step
  final _phoneController = TextEditingController();

  // OTP step
  final _otpController = TextEditingController();
  String _uuid = "";
  String _phone = "";

  // Profile step
  final _firstNameController = TextEditingController();
  final _lastNameController = TextEditingController();
  final _emailController = TextEditingController();

  bool _isLoading = false;
  String? _errorMessage;
  int? _userId;
  String? _token;

  @override
  void dispose() {
    _phoneController.dispose();
    _otpController.dispose();
    _firstNameController.dispose();
    _lastNameController.dispose();
    _emailController.dispose();
    super.dispose();
  }

  String _formatPhoneNumber(String input) {
    // Remove all non-digits
    final digits = input.replaceAll(RegExp(r'[^\d]'), '');
    // Remove leading 1 if 11 digits
    if (digits.length == 11 && digits.startsWith('1')) {
      return digits.substring(1);
    }
    return digits;
  }

  Future<void> _handleSendOtp() async {
    final phone = _formatPhoneNumber(_phoneController.text);

    if (phone.length != 10) {
      setState(() {
        _errorMessage = "Please enter a valid 10-digit phone number";
      });
      return;
    }

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

    try {
      final response = await Api.sendOtp(phone: phone);

      if (!mounted) return;

      if (response.uuid.isEmpty) {
        setState(() {
          _errorMessage = "Server returned empty UUID - please try again";
          _isLoading = false;
        });
        return;
      }

      setState(() {
        _uuid = response.uuid;
        _phone = phone;
        _currentStep = SignupStep.otp;
        _isLoading = false;
      });
    } catch (e) {
      if (!mounted) return;
      setState(() {
        _errorMessage = "Error: ${e.toString().replaceFirst("StateError: ", "")}";
        _isLoading = false;
      });
    }
  }

  Future<void> _handleVerifyOtp() async {
    // Validate UUID first
    if (_uuid.isEmpty) {
      setState(() {
        _errorMessage = "Session expired - UUID is empty. Please go back and resend code.";
      });
      return;
    }

    final otp = _otpController.text.trim();

    if (otp.length != 6) {
      setState(() {
        _errorMessage = "Please enter the 6-digit code";
      });
      return;
    }

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

    try {
      print('[Signup] Calling verifyOtp...');
      final response = await Api.verifyOtp(uuid: _uuid, otp: otp);
      print('[Signup] verifyOtp success: userId=${response.userId}, needsProfile=${response.needsProfile}');

      if (!mounted) return;

      _userId = response.userId;
      _token = response.token;

      // Save credentials for persistent login
      await AuthStorage.saveAuth(
        userId: response.userId,
        token: response.token,
      );
      print('[Signup] Auth saved, token set');

      if (response.needsProfile) {
        print('[Signup] Profile needed, going to profile step');
        // Go to profile step
        setState(() {
          _currentStep = SignupStep.profile;
          _isLoading = false;
        });
      } else {
        print('[Signup] Profile complete, finishing signup');
        // Profile already complete - go to app
        _completeSignup();
      }
    } catch (e) {
      print('[Signup] verifyOtp error: $e');
      if (!mounted) return;
      setState(() {
        _errorMessage = e.toString().replaceFirst("StateError: ", "");
        _isLoading = false;
      });
    }
  }

  Future<void> _handleCompleteProfile() async {
    final firstName = _firstNameController.text.trim();
    final lastName = _lastNameController.text.trim();
    final email = _emailController.text.trim();

    if (firstName.isEmpty) {
      setState(() => _errorMessage = "First name is required");
      return;
    }
    if (lastName.isEmpty) {
      setState(() => _errorMessage = "Last name is required");
      return;
    }
    if (email.isEmpty || !email.contains("@")) {
      setState(() => _errorMessage = "Please enter a valid email address");
      return;
    }

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

    try {
      print('[Signup] Calling completeProfile: firstName=$firstName, lastName=$lastName, email=$email');
      await Api.completeProfile(
        firstName: firstName,
        lastName: lastName,
        email: email,
      );
      print('[Signup] completeProfile success');

      if (!mounted) return;

      _completeSignup();
    } catch (e) {
      print('[Signup] completeProfile error: $e');
      if (!mounted) return;
      setState(() {
        _errorMessage = e.toString().replaceFirst("StateError: ", "");
        _isLoading = false;
      });
    }
  }

  void _completeSignup() {
    final appState = context.read<AppState>();
    if (_userId != null) {
      appState.setUserId(_userId!);
    }

    // Show success and navigate
    ScaffoldMessenger.of(context).showSnackBar(
      SnackBar(
        content: const Text("Account created! Check your email to confirm.", style: TextStyle(color: Colors.black)),
        backgroundColor: const Color(0xFF90EE90),
        behavior: SnackBarBehavior.floating,
        margin: const EdgeInsets.only(bottom: 80, left: 16, right: 16),
      ),
    );

    // Navigate to main app
    if (Navigator.of(context).canPop()) {
      Navigator.of(context).pop();
    } else {
      Navigator.of(context).pushReplacementNamed(AppRoutes.splash);
    }
  }

  Future<void> _handleResendOtp() async {
    setState(() {
      _isLoading = true;
      _errorMessage = null;
    });

    try {
      final response = await Api.resendOtp(phone: _phone);

      if (!mounted) return;

      setState(() {
        _uuid = response.uuid;
        _isLoading = false;
      });

      ScaffoldMessenger.of(context).showSnackBar(
        SnackBar(
          content: const Text("New code sent!", style: TextStyle(color: Colors.black)),
          backgroundColor: const Color(0xFF90EE90),
          behavior: SnackBarBehavior.floating,
          margin: const EdgeInsets.only(bottom: 80, left: 16, right: 16),
        ),
      );
    } catch (e) {
      if (!mounted) return;
      setState(() {
        _errorMessage = e.toString().replaceFirst("StateError: ", "");
        _isLoading = false;
      });
    }
  }

  @override
  Widget build(BuildContext context) {
    return Scaffold(
      appBar: AppBar(
        title: Text(_getStepTitle()),
      ),
      body: Center(
        child: SingleChildScrollView(
          padding: const EdgeInsets.all(24),
          child: ConstrainedBox(
            constraints: const BoxConstraints(maxWidth: 400),
            child: Column(
              mainAxisAlignment: MainAxisAlignment.center,
              crossAxisAlignment: CrossAxisAlignment.stretch,
              children: [
                // Progress indicator
                _buildProgressIndicator(),
                const SizedBox(height: 32),

                // Step content
                if (_currentStep == SignupStep.phone) _buildPhoneStep(),
                if (_currentStep == SignupStep.otp) _buildOtpStep(),
                if (_currentStep == SignupStep.profile) _buildProfileStep(),

                // Error message
                if (_errorMessage != null) ...[
                  const SizedBox(height: 16),
                  _buildErrorMessage(),
                ],
              ],
            ),
          ),
        ),
      ),
    );
  }

  String _getStepTitle() {
    switch (_currentStep) {
      case SignupStep.phone:
        return "Create Account";
      case SignupStep.otp:
        return "Verify Phone";
      case SignupStep.profile:
        return "Your Info";
    }
  }

  Widget _buildProgressIndicator() {
    return Row(
      children: [
        _buildStepDot(0, _currentStep.index >= 0),
        Expanded(child: _buildStepLine(_currentStep.index >= 1)),
        _buildStepDot(1, _currentStep.index >= 1),
        Expanded(child: _buildStepLine(_currentStep.index >= 2)),
        _buildStepDot(2, _currentStep.index >= 2),
      ],
    );
  }

  Widget _buildStepDot(int step, bool isActive) {
    return Container(
      width: 32,
      height: 32,
      decoration: BoxDecoration(
        shape: BoxShape.circle,
        color: isActive
            ? Theme.of(context).colorScheme.primary
            : Theme.of(context).colorScheme.surfaceContainerHighest,
      ),
      child: Center(
        child: Text(
          "${step + 1}",
          style: TextStyle(
            color: isActive
                ? Theme.of(context).colorScheme.onPrimary
                : Theme.of(context).colorScheme.onSurfaceVariant,
            fontWeight: FontWeight.bold,
          ),
        ),
      ),
    );
  }

  Widget _buildStepLine(bool isActive) {
    return Container(
      height: 2,
      color: isActive
          ? Theme.of(context).colorScheme.primary
          : Theme.of(context).colorScheme.surfaceContainerHighest,
    );
  }

  Widget _buildPhoneStep() {
    return Column(
      crossAxisAlignment: CrossAxisAlignment.stretch,
      children: [
        const Text(
          "PAYFRIT",
          textAlign: TextAlign.center,
          style: TextStyle(
            fontSize: 32,
            fontWeight: FontWeight.bold,
            letterSpacing: 2,
          ),
        ),
        const SizedBox(height: 8),
        const Text(
          "Enter your phone number to get started",
          textAlign: TextAlign.center,
          style: TextStyle(
            fontSize: 16,
            color: Colors.grey,
          ),
        ),
        const SizedBox(height: 32),
        TextFormField(
          controller: _phoneController,
          decoration: const InputDecoration(
            labelText: "Phone Number",
            hintText: "(555) 123-4567",
            border: OutlineInputBorder(),
            prefixIcon: Icon(Icons.phone),
            prefixText: "+1 ",
          ),
          keyboardType: TextInputType.phone,
          inputFormatters: [
            FilteringTextInputFormatter.digitsOnly,
            LengthLimitingTextInputFormatter(10),
          ],
          enabled: !_isLoading,
          onFieldSubmitted: (_) => _handleSendOtp(),
        ),
        const SizedBox(height: 24),
        FilledButton(
          onPressed: _isLoading ? null : _handleSendOtp,
          child: _isLoading
              ? const SizedBox(
                  height: 20,
                  width: 20,
                  child: CircularProgressIndicator(
                    strokeWidth: 2,
                    valueColor: AlwaysStoppedAnimation<Color>(Colors.white),
                  ),
                )
              : const Text("Send Verification Code"),
        ),
        const SizedBox(height: 16),
        TextButton(
          onPressed: _isLoading
              ? null
              : () {
                  Navigator.of(context).pushReplacementNamed(AppRoutes.login);
                },
          child: const Text("Already have an account? Login"),
        ),
      ],
    );
  }

  Widget _buildOtpStep() {
    final formattedPhone = _phone.length == 10
        ? "(${_phone.substring(0, 3)}) ${_phone.substring(3, 6)}-${_phone.substring(6)}"
        : _phone;

    return Column(
      crossAxisAlignment: CrossAxisAlignment.stretch,
      children: [
        Icon(
          Icons.sms,
          size: 64,
          color: Theme.of(context).colorScheme.primary,
        ),
        const SizedBox(height: 16),
        Text(
          "We sent a code to",
          textAlign: TextAlign.center,
          style: Theme.of(context).textTheme.titleMedium,
        ),
        const SizedBox(height: 4),
        Text(
          formattedPhone,
          textAlign: TextAlign.center,
          style: Theme.of(context).textTheme.titleLarge?.copyWith(
                fontWeight: FontWeight.bold,
              ),
        ),
        const SizedBox(height: 24),
        TextFormField(
          controller: _otpController,
          decoration: const InputDecoration(
            labelText: "Verification Code",
            hintText: "123456",
            border: OutlineInputBorder(),
            prefixIcon: Icon(Icons.lock),
          ),
          keyboardType: TextInputType.number,
          inputFormatters: [
            FilteringTextInputFormatter.digitsOnly,
            LengthLimitingTextInputFormatter(6),
          ],
          textAlign: TextAlign.center,
          style: const TextStyle(
            fontSize: 24,
            letterSpacing: 8,
            fontWeight: FontWeight.bold,
          ),
          enabled: !_isLoading,
          onFieldSubmitted: (_) => _handleVerifyOtp(),
        ),
        const SizedBox(height: 24),
        FilledButton(
          onPressed: _isLoading ? null : _handleVerifyOtp,
          child: _isLoading
              ? const SizedBox(
                  height: 20,
                  width: 20,
                  child: CircularProgressIndicator(
                    strokeWidth: 2,
                    valueColor: AlwaysStoppedAnimation<Color>(Colors.white),
                  ),
                )
              : const Text("Verify"),
        ),
        const SizedBox(height: 16),
        Row(
          mainAxisAlignment: MainAxisAlignment.center,
          children: [
            TextButton(
              onPressed: _isLoading ? null : _handleResendOtp,
              child: const Text("Resend Code"),
            ),
            const SizedBox(width: 16),
            TextButton(
              onPressed: _isLoading
                  ? null
                  : () {
                      setState(() {
                        _currentStep = SignupStep.phone;
                        _otpController.clear();
                        _errorMessage = null;
                      });
                    },
              child: const Text("Change Number"),
            ),
          ],
        ),
      ],
    );
  }

  Widget _buildProfileStep() {
    return Column(
      crossAxisAlignment: CrossAxisAlignment.stretch,
      children: [
        Icon(
          Icons.person_add,
          size: 64,
          color: Theme.of(context).colorScheme.primary,
        ),
        const SizedBox(height: 16),
        Text(
          "Almost done!",
          textAlign: TextAlign.center,
          style: Theme.of(context).textTheme.titleLarge?.copyWith(
                fontWeight: FontWeight.bold,
              ),
        ),
        const SizedBox(height: 8),
        Text(
          "Tell us a bit about yourself",
          textAlign: TextAlign.center,
          style: Theme.of(context).textTheme.bodyMedium?.copyWith(
                color: Colors.grey,
              ),
        ),
        const SizedBox(height: 32),
        TextFormField(
          controller: _firstNameController,
          decoration: const InputDecoration(
            labelText: "First Name",
            border: OutlineInputBorder(),
            prefixIcon: Icon(Icons.person),
          ),
          textCapitalization: TextCapitalization.words,
          textInputAction: TextInputAction.next,
          enabled: !_isLoading,
        ),
        const SizedBox(height: 16),
        TextFormField(
          controller: _lastNameController,
          decoration: const InputDecoration(
            labelText: "Last Name",
            border: OutlineInputBorder(),
            prefixIcon: Icon(Icons.person_outline),
          ),
          textCapitalization: TextCapitalization.words,
          textInputAction: TextInputAction.next,
          enabled: !_isLoading,
        ),
        const SizedBox(height: 16),
        TextFormField(
          controller: _emailController,
          decoration: const InputDecoration(
            labelText: "Email Address",
            border: OutlineInputBorder(),
            prefixIcon: Icon(Icons.email),
            helperText: "We'll send a confirmation email",
          ),
          keyboardType: TextInputType.emailAddress,
          textInputAction: TextInputAction.done,
          enabled: !_isLoading,
          onFieldSubmitted: (_) => _handleCompleteProfile(),
        ),
        const SizedBox(height: 24),
        FilledButton(
          onPressed: _isLoading ? null : _handleCompleteProfile,
          child: _isLoading
              ? const SizedBox(
                  height: 20,
                  width: 20,
                  child: CircularProgressIndicator(
                    strokeWidth: 2,
                    valueColor: AlwaysStoppedAnimation<Color>(Colors.white),
                  ),
                )
              : const Text("Complete Sign Up"),
        ),
      ],
    );
  }

  Widget _buildErrorMessage() {
    return Container(
      padding: const EdgeInsets.all(12),
      decoration: BoxDecoration(
        color: Colors.red.shade50,
        borderRadius: BorderRadius.circular(8),
        border: Border.all(color: Colors.red.shade300),
      ),
      child: Row(
        children: [
          Icon(Icons.error_outline, color: Colors.red.shade700),
          const SizedBox(width: 12),
          Expanded(
            child: Text(
              _errorMessage!,
              style: TextStyle(color: Colors.red.shade900),
            ),
          ),
        ],
      ),
    );
  }
}