import 'dart:async';

import 'package:flutter/gestures.dart';
import 'package:flutter/material.dart';

import '../../../../core/logging/logger.dart';
import '../../../../core/network/api_problem.dart';
import '../../../../core/network/api_problem_mapper.dart';
import '../../../settings/presentation/models/legal_document_type.dart';
import '../../../settings/presentation/screens/legal_document_screen.dart';
import '../../../settings/presentation/utils/legal_document_assets.dart';
import '../../../../l10n/app_localizations.dart';
import '../../../../shared/theme/design_tokens.dart';
import '../../../../shared/widgets/toast/toast.dart';
import '../../../../shared/widgets/toast/toast_type.dart';

class LoginScreen extends StatefulWidget {
  const LoginScreen({
    super.key,
    required this.onRequestOtp,
    required this.onLoginWithOtp,
    required this.onLocaleChanged,
    required this.currentLocale,
  });

  final Future<void> Function(String email) onRequestOtp;
  final Future<void> Function(String email, String otp) onLoginWithOtp;
  final ValueChanged<Locale> onLocaleChanged;
  final Locale currentLocale;

  @override
  State<LoginScreen> createState() => _LoginScreenState();
}

class _LoginScreenState extends State<LoginScreen> {
  final Logger _logger = getLogger('features.auth.login');
  final TextEditingController _emailController = TextEditingController();
  final TextEditingController _codeController = TextEditingController();
  Timer? _timer;
  int _countdown = 0;
  bool _isSending = false;
  bool _agreementChecked = false;

  bool get _isValidEmail {
    return RegExp(
      r'^[a-zA-Z0-9._%+-]+@[a-zA-Z0-9.-]+\.[a-zA-Z]{2,}$',
    ).hasMatch(_emailController.text.trim());
  }

  @override
  void dispose() {
    _timer?.cancel();
    _emailController.dispose();
    _codeController.dispose();
    super.dispose();
  }

  void _showMessage(String message) {
    Toast.show(context, message, type: ToastType.info);
  }

  Future<void> _sendCode() async {
    final l10n = AppLocalizations.of(context)!;
    if (!_isValidEmail) {
      _showMessage(l10n.invalidEmail);
      return;
    }
    if (_countdown > 0 || _isSending) {
      return;
    }

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

    try {
      await widget.onRequestOtp(_emailController.text.trim());
      if (!mounted) {
        return;
      }
      setState(() {
        _isSending = false;
        _countdown = 60;
      });

      _timer = Timer.periodic(const Duration(seconds: 1), (timer) {
        if (!mounted) {
          timer.cancel();
          return;
        }
        if (_countdown <= 1) {
          timer.cancel();
          setState(() {
            _countdown = 0;
          });
        } else {
          setState(() {
            _countdown -= 1;
          });
        }
      });
    } catch (error, stackTrace) {
      _logger.error(
        message: 'Send OTP failed',
        error: error,
        stackTrace: stackTrace,
      );
      if (!mounted) {
        return;
      }
      setState(() {
        _isSending = false;
      });
      _showMessage(_safeErrorMessage(error));
    }
  }

  Future<void> _login() async {
    final l10n = AppLocalizations.of(context)!;
    if (!_isValidEmail) {
      _showMessage(l10n.invalidEmail);
      return;
    }
    if (_codeController.text.length != 6) {
      _showMessage(l10n.invalidCode);
      return;
    }
    if (!_agreementChecked) {
      _showMessage(l10n.agreementRequired);
      return;
    }

    try {
      await widget.onLoginWithOtp(
        _emailController.text.trim(),
        _codeController.text,
      );
      if (!mounted) {
        return;
      }
    } catch (error, stackTrace) {
      _logger.error(
        message: 'Login with OTP failed',
        error: error,
        stackTrace: stackTrace,
      );
      _showMessage(_safeErrorMessage(error));
    }
  }

  String _safeErrorMessage(Object error) {
    final l10n = AppLocalizations.of(context)!;
    if (error is ApiProblem) {
      return mapApiProblemToMessage(error, l10n);
    }
    return l10n.errorRequestGeneric;
  }

  void _showPolicyDialog(String title, String content) {
    showDialog<void>(
      context: context,
      builder: (context) {
        return AlertDialog(
          title: Text(title),
          content: Text(content),
          actions: [
            TextButton(
              onPressed: () => Navigator.of(context).pop(),
              child: Text(AppLocalizations.of(context)!.dialogConfirm),
            ),
          ],
        );
      },
    );
  }

  Future<void> _openLegalDocument(LegalDocumentType type) async {
    final l10n = AppLocalizations.of(context)!;
    await Navigator.of(context).push<void>(
      MaterialPageRoute<void>(
        builder: (_) => LegalDocumentScreen(
          title: legalDocumentTitle(l10n, type),
          assetPath: legalDocumentAssetPath(
            Localizations.localeOf(context),
            type,
          ),
        ),
      ),
    );
  }

  @override
  Widget build(BuildContext context) {
    final l10n = AppLocalizations.of(context)!;
    final colors = Theme.of(context).colorScheme;
    final canLogin =
        _isValidEmail && _codeController.text.length == 6 && _agreementChecked;

    return Scaffold(
      body: GestureDetector(
        onTap: () => FocusScope.of(context).unfocus(),
        child: SafeArea(
          child: Padding(
            padding: const EdgeInsets.symmetric(
              horizontal: AppSpacing.xl,
              vertical: AppSpacing.lg,
            ),
            child: Column(
              crossAxisAlignment: CrossAxisAlignment.start,
              children: [
                const SizedBox(height: AppSpacing.xxl),
                Container(
                  width: double.infinity,
                  padding: const EdgeInsets.all(AppSpacing.xl),
                  decoration: BoxDecoration(
                    color: colors.surface,
                    borderRadius: BorderRadius.circular(AppRadius.lg),
                  ),
                  child: Column(
                    crossAxisAlignment: CrossAxisAlignment.start,
                    children: [
                      Text(
                        l10n.welcomeLogin,
                        style: Theme.of(context).textTheme.headlineMedium,
                      ),
                      const SizedBox(height: AppSpacing.sm),
                      Text(
                        l10n.loginSubtitleEmail,
                        style: Theme.of(context).textTheme.bodyLarge,
                      ),
                    ],
                  ),
                ),
                const SizedBox(height: AppSpacing.xxl),
                Container(
                  decoration: BoxDecoration(
                    color: colors.surface,
                    borderRadius: BorderRadius.circular(AppRadius.lg),
                  ),
                  child: TextField(
                    controller: _emailController,
                    keyboardType: TextInputType.emailAddress,
                    onChanged: (_) => setState(() {}),
                    decoration: InputDecoration(
                      hintText: l10n.emailHint,
                      border: OutlineInputBorder(
                        borderRadius: BorderRadius.circular(AppRadius.lg),
                        borderSide: BorderSide.none,
                      ),
                      contentPadding: const EdgeInsets.symmetric(
                        horizontal: AppSpacing.lg,
                        vertical: AppSpacing.lg,
                      ),
                    ),
                  ),
                ),
                const SizedBox(height: AppSpacing.lg),
                Row(
                  children: [
                    Expanded(
                      child: Container(
                        decoration: BoxDecoration(
                          color: colors.surface,
                          borderRadius: BorderRadius.circular(AppRadius.lg),
                        ),
                        child: TextField(
                          controller: _codeController,
                          keyboardType: TextInputType.number,
                          maxLength: 6,
                          onChanged: (_) => setState(() {}),
                          decoration: InputDecoration(
                            counterText: '',
                            hintText: l10n.codeHint,
                            border: OutlineInputBorder(
                              borderRadius: BorderRadius.circular(AppRadius.lg),
                              borderSide: BorderSide.none,
                            ),
                            contentPadding: const EdgeInsets.symmetric(
                              horizontal: AppSpacing.lg,
                              vertical: AppSpacing.lg,
                            ),
                          ),
                        ),
                      ),
                    ),
                    const SizedBox(width: AppSpacing.sm),
                    SizedBox(
                      width: 130,
                      height: 48,
                      child: FilledButton(
                        style: FilledButton.styleFrom(
                          backgroundColor: colors.surfaceContainerHighest,
                          foregroundColor: colors.primary,
                          shape: RoundedRectangleBorder(
                            borderRadius: BorderRadius.circular(AppRadius.full),
                          ),
                        ),
                        onPressed: _sendCode,
                        child: Text(
                          _isSending
                              ? l10n.sending
                              : _countdown > 0
                              ? l10n.retryAfter(_countdown)
                              : l10n.sendCode,
                        ),
                      ),
                    ),
                  ],
                ),
                const SizedBox(height: AppSpacing.xl),
                SizedBox(
                  width: double.infinity,
                  child: FilledButton(
                    style: FilledButton.styleFrom(
                      backgroundColor: colors.primary,
                      foregroundColor: colors.onPrimary,
                      shape: RoundedRectangleBorder(
                        borderRadius: BorderRadius.circular(AppRadius.full),
                      ),
                      padding: const EdgeInsets.symmetric(
                        vertical: AppSpacing.md,
                      ),
                    ),
                    onPressed: canLogin ? _login : null,
                    child: Text(
                      l10n.login,
                      style: const TextStyle(fontSize: 16),
                    ),
                  ),
                ),
                const SizedBox(height: AppSpacing.md),
                Center(
                  child: Row(
                    mainAxisSize: MainAxisSize.min,
                    children: [
                      Checkbox(
                        value: _agreementChecked,
                        onChanged: (value) {
                          setState(() {
                            _agreementChecked = value ?? false;
                          });
                        },
                      ),
                      Flexible(
                        child: RichText(
                          text: TextSpan(
                            style: Theme.of(context).textTheme.bodySmall,
                            children: [
                              TextSpan(text: l10n.agreementPrefix),
                              TextSpan(
                                text: l10n.privacyPolicy,
                                style: TextStyle(
                                  color: colors.primary,
                                  decoration: TextDecoration.underline,
                                ),
                                recognizer: TapGestureRecognizer()
                                  ..onTap = () => _openLegalDocument(
                                    LegalDocumentType.privacyPolicy,
                                  ),
                              ),
                              TextSpan(text: l10n.agreementSeparator),
                              TextSpan(
                                text: l10n.termsOfService,
                                style: TextStyle(
                                  color: colors.primary,
                                  decoration: TextDecoration.underline,
                                ),
                                recognizer: TapGestureRecognizer()
                                  ..onTap = () => _openLegalDocument(
                                    LegalDocumentType.termsOfService,
                                  ),
                              ),
                              TextSpan(text: l10n.agreementAnd),
                              TextSpan(
                                text: l10n.disclaimer,
                                style: TextStyle(
                                  color: colors.primary,
                                  decoration: TextDecoration.underline,
                                ),
                                recognizer: TapGestureRecognizer()
                                  ..onTap = () => _showPolicyDialog(
                                    l10n.disclaimer,
                                    l10n.disclaimerContent,
                                  ),
                              ),
                            ],
                          ),
                        ),
                      ),
                    ],
                  ),
                ),
                const Spacer(),
                Center(
                  child: Text(
                    l10n.icp,
                    style: Theme.of(context).textTheme.bodySmall?.copyWith(
                      color: colors.primary,
                      fontWeight: FontWeight.w700,
                    ),
                  ),
                ),
                const SizedBox(height: AppSpacing.sm),
              ],
            ),
          ),
        ),
      ),
    );
  }
}