import 'package:flutter/material.dart';

import 'package:go_router/go_router.dart';

import 'package:provider/provider.dart';

import 'package:sxchnge_analytics/sxchnge_analytics.dart';

import 'package:sxchnge_auth/sxchnge_auth.dart';

import '../auth/brand_panel.dart';
import '../auth/validation.dart';
import '../routing/routes.dart';

import '../generated/i18n/app_localizations.dart';

class VerificationPage extends StatefulWidget {
  const VerificationPage({super.key, this.email, this.token, this.delivery});
  final String? email;
  final String? token;
  final VerificationDelivery? delivery;

  @override
  State<VerificationPage> createState() => _VerificationPageState();
}

class _VerificationPageState extends State<VerificationPage> {
  final _form = GlobalKey<FormState>();
  late final _email = TextEditingController(
    text: widget.delivery?.email ?? widget.email,
  );
  late final _provider = VerificationProvider(
    context.read<VerificationService>(),
    delivery: widget.delivery,
  );
  final _emailFocus = FocusNode();
  String? _recipient;
  bool _initialized = false;
  bool _lastWasSend = false;
  bool _validated = false;

  @override
  void didChangeDependencies() {
    super.didChangeDependencies();
    if (!_initialized) {
      _initialized = true;
      WidgetsBinding.instance.addPostFrameCallback((_) {
        if (!mounted) return;
        if (widget.token != null) {
          _provider.confirm(widget.token!);
        } else if (widget.delivery == null && _email.text.isNotEmpty) {
          _send();
        }
      });
    } else if (_validated) {
      WidgetsBinding.instance.addPostFrameCallback((_) {
        if (mounted) _form.currentState?.validate();
      });
    }
  }

  @override
  void didUpdateWidget(covariant VerificationPage oldWidget) {
    super.didUpdateWidget(oldWidget);
    if (oldWidget.token == widget.token &&
        oldWidget.email == widget.email &&
        identical(oldWidget.delivery, widget.delivery)) {
      return;
    }
    if (oldWidget.token != widget.token) {
      context.read<JourneyRecorder>().abandon(JourneyExit.navigation);
    }
    _provider.reset(delivery: widget.delivery);
    _lastWasSend = false;
    _validated = false;
    _recipient = null;
    _email.text = widget.delivery?.email ?? widget.email ?? '';
    WidgetsBinding.instance.addPostFrameCallback((_) {
      if (!mounted) return;
      if (widget.token != null) {
        _provider.confirm(widget.token!);
      } else if (widget.delivery == null && _email.text.isNotEmpty) {
        _send();
      }
    });
  }

  void _send() {
    if (_provider.state.isLoading) return;
    _validated = true;
    if (_provider.state.status != VerificationStatus.sent &&
        !(_form.currentState?.validate() ?? false)) {
      return;
    }
    _recipient = _email.text.trim();
    FocusScope.of(context).unfocus();
    _lastWasSend = true;
    _provider.send(
      email: _email.text,
      locale: Localizations.localeOf(context).languageCode,
    );
  }

  void _changeEmail() {
    _lastWasSend = true;
    _validated = false;
    _provider.reset();
    WidgetsBinding.instance.addPostFrameCallback((_) {
      if (mounted) _emailFocus.requestFocus();
    });
  }

  @override
  void dispose() {
    _provider.dispose();
    _email.dispose();
    _emailFocus.dispose();
    super.dispose();
  }

  @override
  Widget build(BuildContext context) => ListenableBuilder(
    listenable: _provider,
    builder: (context, _) {
      final l = AppLocalizations.of(context)!;
      final theme = Theme.of(context);
      final colors = theme.colorScheme;
      final state = _provider.state;
      final status = state.status;
      final failed = [
        VerificationStatus.expired,
        VerificationStatus.invalid,
        VerificationStatus.error,
      ].contains(status);
      final verified = status == VerificationStatus.verified;
      final demo =
          (_provider.service is SimulationInfo &&
              (_provider.service as SimulationInfo).isSimulated) ||
          state.isSimulated;
      final sent = status == VerificationStatus.sent;
      final needsAssistance = state.error == VerificationError.needsAssistance;
      final retryConfirmation =
          status == VerificationStatus.error &&
          !needsAssistance &&
          !_lastWasSend &&
          widget.token != null;
      final title = switch (status) {
        VerificationStatus.sent => l.checkInbox,
        VerificationStatus.sending => l.verificationSending,
        VerificationStatus.checking => l.verificationChecking,
        VerificationStatus.verified => l.verificationVerified,
        VerificationStatus.expired => l.verificationExpired,
        VerificationStatus.invalid => l.verificationInvalid,
        VerificationStatus.error => l.verificationInternal,
        VerificationStatus.idle =>
          widget.token != null && !_lastWasSend
              ? l.verificationChecking
              : l.verificationRequest,
      };
      final body = needsAssistance
          ? l.authSignupNeedsAssistance
          : switch (status) {
              VerificationStatus.sent => l.verificationSent,
              VerificationStatus.verified => l.verificationVerifiedBody,
              VerificationStatus.expired => l.verificationExpiredBody,
              VerificationStatus.invalid => l.verificationInvalidBody,
              VerificationStatus.error => l.verificationInternalBody,
              _ => null,
            };
      return Scaffold(
        body: SafeArea(
          child: SingleChildScrollView(
            padding: const EdgeInsets.all(24),
            child: Center(
              child: ConstrainedBox(
                constraints: const BoxConstraints(maxWidth: 520),
                child: Column(
                  crossAxisAlignment: CrossAxisAlignment.stretch,
                  children: [
                    const Align(
                      alignment: Alignment.centerLeft,
                      child: BrandWordmark(),
                    ),
                    const SizedBox(height: 48),
                    Align(
                      alignment: Alignment.centerLeft,
                      child: Container(
                        padding: const EdgeInsets.all(20),
                        decoration: BoxDecoration(
                          color: failed
                              ? colors.errorContainer
                              : colors.primaryContainer,
                          borderRadius: BorderRadius.circular(24),
                        ),
                        child: state.isLoading
                            ? const SizedBox(
                                width: 32,
                                height: 32,
                                child: CircularProgressIndicator(),
                              )
                            : Icon(
                                verified
                                    ? Icons.mark_email_read_outlined
                                    : failed
                                    ? Icons.error_outline
                                    : Icons.mark_email_unread_outlined,
                                size: 32,
                                color: failed
                                    ? colors.onErrorContainer
                                    : colors.onPrimaryContainer,
                              ),
                      ),
                    ),
                    const SizedBox(height: 28),
                    Text(
                      l.verificationStep,
                      style: theme.textTheme.labelLarge?.copyWith(
                        color: colors.primary,
                      ),
                    ),
                    const SizedBox(height: 12),
                    Semantics(
                      liveRegion: true,
                      header: true,
                      child: Text(
                        title,
                        key: ValueKey('verification-${status.name}'),
                        style: theme.textTheme.displaySmall,
                      ),
                    ),
                    if (body != null) ...[
                      const SizedBox(height: 20),
                      Text(
                        body,
                        style: theme.textTheme.bodyLarge?.copyWith(
                          color: colors.onSurfaceVariant,
                        ),
                      ),
                    ],
                    if (sent) ...[
                      const SizedBox(height: 20),
                      Text(
                        l.verificationRecipient,
                        style: theme.textTheme.labelLarge,
                      ),
                      Text(
                        _recipient ?? _email.text,
                        key: const ValueKey('verification-recipient'),
                      ),
                      TextButton(
                        key: const ValueKey('verification-change-email'),
                        onPressed: _changeEmail,
                        child: Text(l.verificationChangeEmail),
                      ),
                      if (demo)
                        FilledButton(
                          key: const ValueKey('demo-confirmation'),
                          onPressed: () => context.goNamed(
                            AppRoutes.verifyEmail,
                            queryParameters: {'token': 'demo-valid'},
                          ),
                          child: Text(
                            l.verificationDemoLink,
                            textAlign: TextAlign.center,
                          ),
                        ),
                      const SizedBox(height: 12),
                      OutlinedButton(
                        key: const ValueKey('verification-resend'),
                        onPressed: _send,
                        child: Text(
                          l.verificationResend,
                          textAlign: TextAlign.center,
                        ),
                      ),
                      if (!demo) ...[
                        const SizedBox(height: 16),
                        Text(
                          l.verificationHint,
                          style: theme.textTheme.bodyMedium,
                        ),
                      ],
                    ],
                    if (!verified &&
                        !sent &&
                        !retryConfirmation &&
                        status != VerificationStatus.checking) ...[
                      const SizedBox(height: 28),
                      Form(
                        key: _form,
                        child: TextFormField(
                          key: const ValueKey('verification-email'),
                          controller: _email,
                          focusNode: _emailFocus,
                          autocorrect: false,
                          enabled: !state.isLoading,
                          keyboardType: TextInputType.emailAddress,
                          autofillHints: const [AutofillHints.email],
                          textInputAction: TextInputAction.send,
                          validator: (value) => AuthValidation.email(value, l),
                          onFieldSubmitted: (_) => _send(),
                          decoration: InputDecoration(
                            labelText: l.email,
                            hintText: l.emailHint,
                            errorMaxLines: 3,
                            prefixIcon: const Icon(Icons.alternate_email),
                          ),
                        ),
                      ),
                      const SizedBox(height: 16),
                      FilledButton(
                        key: const ValueKey('verification-resend'),
                        onPressed: state.isLoading ? null : _send,
                        child: Text(
                          state.isLoading
                              ? l.authWorking
                              : l.verificationRequest,
                          textAlign: TextAlign.center,
                        ),
                      ),
                    ],
                    if (retryConfirmation) ...[
                      const SizedBox(height: 12),
                      FilledButton(
                        key: const ValueKey('verification-retry'),
                        onPressed: () => _provider.confirm(widget.token!),
                        child: Text(l.verificationRetry),
                      ),
                      TextButton(
                        onPressed: _changeEmail,
                        child: Text(l.verificationRequest),
                      ),
                    ],
                    if (verified) ...[
                      const SizedBox(height: 16),
                      FilledButton(
                        key: const ValueKey('verification-continue'),
                        onPressed: () => context.goNamed(
                          AppRoutes.login,
                          extra: state.result?.verifiedEmail,
                        ),
                        child: Text(l.verificationContinue),
                      ),
                    ],
                    if (!verified) ...[
                      const SizedBox(height: 16),
                      TextButton(
                        onPressed: () => context.goNamed(AppRoutes.login),
                        child: Text(l.verificationBack),
                      ),
                    ],
                  ],
                ),
              ),
            ),
          ),
        ),
      );
    },
  );
}