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

import '../l10n/app_localizations.dart';
import '../utils/navigation.dart';
import '../viewmodels/registration_view_model.dart';
import '../viewmodels/remote_sync_view_model.dart';

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

  @override
  State<RegistrationView> createState() => _RegistrationViewState();
}

class _RegistrationViewState extends State<RegistrationView> {
  final _deviceNameController = TextEditingController(text: 'Bar terminal 1');
  final _regCodeController = TextEditingController();
  final _formKey = GlobalKey<FormState>();

  @override
  void initState() {
    super.initState();
    WidgetsBinding.instance.addPostFrameCallback((_) {
      context.read<RegistrationViewModel>().fetchVenues();
    });
  }

  AppLocalizations get _l10n => AppLocalizations.of(context);

  @override
  void dispose() {
    _deviceNameController.dispose();
    _regCodeController.dispose();
    super.dispose();
  }

  @override
  Widget build(BuildContext context) {
    final vm = context.watch<RegistrationViewModel>();
    final l10n = AppLocalizations.of(context);

    return Scaffold(
      backgroundColor: Theme.of(context).colorScheme.surface,
      appBar: AppBar(
        backgroundColor: Colors.transparent,
        leading: IconButton(
          tooltip: l10n.cancel,
          onPressed: () => context.popOrGo('/admin'),
          icon: const Icon(Icons.close_rounded),
        ),
      ),
      body: SafeArea(
        child: Center(
          child: SingleChildScrollView(
            padding: const EdgeInsets.symmetric(horizontal: 32, vertical: 24),
            child: ConstrainedBox(
              constraints: const BoxConstraints(maxWidth: 480),
              child: _buildStep(vm, l10n),
            ),
          ),
        ),
      ),
    );
  }

  Widget _buildStep(RegistrationViewModel vm, AppLocalizations l10n) {
    switch (vm.step) {
      case RegistrationStep.loadingVenues:
        return _buildLoading();
      case RegistrationStep.error:
        return _buildError(vm);
      case RegistrationStep.venuesLoaded:
        if (vm.selectedVenue == null) {
          return _buildVenueSelection(vm, l10n);
        }
        return _buildDeviceDetails(vm, l10n);
      case RegistrationStep.registering:
        return _buildRegistering();
      case RegistrationStep.registered:
        return _buildSuccess(vm, l10n);
      case RegistrationStep.initial:
        return _buildLoading();
    }
  }

  Widget _buildLoading() {
    return Column(
      mainAxisSize: MainAxisSize.min,
      children: [
        const SizedBox(height: 60),
        Icon(
          Icons.cloud_outlined,
          size: 64,
          color: Theme.of(context).colorScheme.primary.withValues(alpha: 0.5),
        ),
        const SizedBox(height: 24),
        const CircularProgressIndicator(strokeWidth: 3),
        const SizedBox(height: 16),
        Text(
          _l10n.connectingToServer,
          style: Theme.of(context).textTheme.titleMedium,
        ),
      ],
    );
  }

  Widget _buildError(RegistrationViewModel vm) {
    return Column(
      mainAxisSize: MainAxisSize.min,
      children: [
        const SizedBox(height: 60),
        Icon(
          Icons.cloud_off_rounded,
          size: 64,
          color: Theme.of(context).colorScheme.error,
        ),
        const SizedBox(height: 24),
        Text(
          _l10n.failedToConnect,
          style: Theme.of(context).textTheme.titleLarge,
        ),
        const SizedBox(height: 12),
        Text(
          vm.errorMessage ?? _l10n.unknownError,
          textAlign: TextAlign.center,
          style: Theme.of(context).textTheme.bodyMedium?.copyWith(
            color: Theme.of(
              context,
            ).colorScheme.onSurface.withValues(alpha: 0.6),
          ),
        ),
        const SizedBox(height: 24),
        FilledButton.icon(
          onPressed: () => vm.retry(),
          icon: const Icon(Icons.refresh),
          label: Text(_l10n.retry),
        ),
      ],
    );
  }

  Widget _buildVenueSelection(RegistrationViewModel vm, AppLocalizations l10n) {
    return Column(
      mainAxisSize: MainAxisSize.min,
      crossAxisAlignment: CrossAxisAlignment.stretch,
      children: [
        const SizedBox(height: 40),
        Icon(
          Icons.cloud_outlined,
          size: 48,
          color: Theme.of(context).colorScheme.primary.withValues(alpha: 0.5),
        ),
        const SizedBox(height: 16),
        Text(
          _l10n.connectToRemoteServer,
          textAlign: TextAlign.center,
          style: Theme.of(context).textTheme.headlineSmall,
        ),
        const SizedBox(height: 8),
        Text(
          _l10n.selectVenueToLink,
          textAlign: TextAlign.center,
          style: Theme.of(context).textTheme.bodyMedium?.copyWith(
            color: Theme.of(
              context,
            ).colorScheme.onSurface.withValues(alpha: 0.6),
          ),
        ),
        const SizedBox(height: 32),
        Text(
          _l10n.selectVenue,
          style: Theme.of(context).textTheme.labelLarge?.copyWith(
            color: Theme.of(
              context,
            ).colorScheme.onSurface.withValues(alpha: 0.7),
          ),
        ),
        const SizedBox(height: 8),
        Container(
          decoration: BoxDecoration(
            border: Border.all(
              color: Theme.of(
                context,
              ).colorScheme.onSurface.withValues(alpha: 0.15),
            ),
            borderRadius: BorderRadius.circular(12),
          ),
          child: Column(
            children: [
              for (final venue in vm.venues)
                Material(
                  color: Colors.transparent,
                  child: InkWell(
                    onTap: () => vm.selectVenue(venue),
                    child: Padding(
                      padding: const EdgeInsets.symmetric(
                        horizontal: 16,
                        vertical: 14,
                      ),
                      child: Row(
                        children: [
                          Icon(
                            Icons.store_outlined,
                            color: Theme.of(context).colorScheme.primary,
                          ),
                          const SizedBox(width: 12),
                          Expanded(
                            child: Text(
                              venue.name,
                              style: Theme.of(context).textTheme.bodyLarge,
                            ),
                          ),
                          Icon(
                            Icons.chevron_right_rounded,
                            color: Theme.of(
                              context,
                            ).colorScheme.onSurface.withValues(alpha: 0.3),
                          ),
                        ],
                      ),
                    ),
                  ),
                ),
            ],
          ),
        ),
        const SizedBox(height: 24),
        TextButton(
          onPressed: () => vm.retry(),
          child: Text(_l10n.refreshVenues),
        ),
      ],
    );
  }

  Widget _buildDeviceDetails(RegistrationViewModel vm, AppLocalizations l10n) {
    return Form(
      key: _formKey,
      child: Column(
        mainAxisSize: MainAxisSize.min,
        crossAxisAlignment: CrossAxisAlignment.stretch,
        children: [
          const SizedBox(height: 40),
          Icon(
            Icons.store_outlined,
            size: 48,
            color: Theme.of(context).colorScheme.primary.withValues(alpha: 0.5),
          ),
          const SizedBox(height: 16),
          Text(
            vm.selectedVenue!.name,
            textAlign: TextAlign.center,
            style: Theme.of(context).textTheme.headlineSmall,
          ),
          const SizedBox(height: 8),
          Text(
            _l10n.enterDeviceDetails,
            textAlign: TextAlign.center,
            style: Theme.of(context).textTheme.bodyMedium?.copyWith(
              color: Theme.of(
                context,
              ).colorScheme.onSurface.withValues(alpha: 0.6),
            ),
          ),
          const SizedBox(height: 32),
          TextFormField(
            controller: _deviceNameController,
            decoration: InputDecoration(
              labelText: _l10n.deviceName,
              hintText: 'e.g. Bar terminal 1',
              border: OutlineInputBorder(),
            ),
            validator: (v) =>
                v == null || v.trim().isEmpty ? _l10n.deviceNameRequired : null,
          ),
          const SizedBox(height: 16),
          TextFormField(
            controller: _regCodeController,
            decoration: InputDecoration(
              labelText: _l10n.registrationCode,
              hintText: '6-character code from dashboard',
              border: OutlineInputBorder(),
              counterText: '',
            ),
            maxLength: 6,
            textCapitalization: TextCapitalization.characters,
            validator: (v) => v == null || v.trim().length < 6
                ? _l10n.enterRegistrationCode
                : null,
          ),
          const SizedBox(height: 8),
          if (vm.errorMessage != null)
            Padding(
              padding: const EdgeInsets.only(bottom: 8),
              child: Text(
                vm.errorMessage!,
                style: TextStyle(
                  color: Theme.of(context).colorScheme.error,
                  fontSize: 13,
                ),
              ),
            ),
          const SizedBox(height: 16),
          Row(
            children: [
              TextButton(
                onPressed: () {
                  vm.reset();
                },
                child: Text(_l10n.back),
              ),
              const SizedBox(width: 12),
              Expanded(
                child: FilledButton(
                  onPressed: () async {
                    if (!_formKey.currentState!.validate()) return;
                    await vm.registerDevice(
                      deviceName: _deviceNameController.text.trim(),
                      registrationCode: _regCodeController.text
                          .trim()
                          .toUpperCase(),
                    );
                  },
                  child: Text(_l10n.register),
                ),
              ),
            ],
          ),
        ],
      ),
    );
  }

  Widget _buildRegistering() {
    return Column(
      mainAxisSize: MainAxisSize.min,
      children: [
        const SizedBox(height: 60),
        const CircularProgressIndicator(strokeWidth: 3),
        const SizedBox(height: 24),
        Text(
          _l10n.registeringDevice,
          style: Theme.of(context).textTheme.titleMedium,
        ),
      ],
    );
  }

  Widget _buildSuccess(RegistrationViewModel vm, AppLocalizations l10n) {
    return Column(
      mainAxisSize: MainAxisSize.min,
      children: [
        const SizedBox(height: 40),
        Icon(
          Icons.check_circle_rounded,
          size: 80,
          color: Theme.of(context).colorScheme.primary,
        ),
        const SizedBox(height: 24),
        Text(
          _l10n.deviceRegistered,
          textAlign: TextAlign.center,
          style: Theme.of(context).textTheme.headlineSmall,
        ),
        const SizedBox(height: 12),
        Text(
          '${vm.selectedVenue?.name ?? "Venue"} is now linked.',
          textAlign: TextAlign.center,
          style: Theme.of(context).textTheme.bodyMedium?.copyWith(
            color: Theme.of(
              context,
            ).colorScheme.onSurface.withValues(alpha: 0.6),
          ),
        ),
        const SizedBox(height: 8),
        Text(
          _l10n.openTabsWillSync,
          textAlign: TextAlign.center,
          style: Theme.of(context).textTheme.bodySmall?.copyWith(
            color: Theme.of(
              context,
            ).colorScheme.onSurface.withValues(alpha: 0.5),
          ),
        ),
        const SizedBox(height: 32),
        FilledButton.icon(
          // Once configured, the router redirects to /bar by itself.
          onPressed: () => context.read<RemoteSyncViewModel>().activate(),
          icon: const Icon(Icons.arrow_forward),
          label: Text(_l10n.done),
        ),
      ],
    );
  }
}