import 'package:flutter/material.dart';

import '../models/office.dart';
import '../theme/m3_motion.dart';
import 'app_breakpoints.dart';

class _PickResult {
  const _PickResult(this.officeId);
  final String? officeId;
}

/// A tappable form field that opens a searchable office picker.
///
/// Replaces [DropdownButtonFormField] when the office list is large.
class OfficeSelectorField extends StatelessWidget {
  const OfficeSelectorField({
    super.key,
    required this.offices,
    required this.selectedOfficeId,
    required this.onChanged,
    this.allowUnassigned = false,
    this.labelText = 'Office',
  });

  final List<Office> offices;
  final String? selectedOfficeId;
  /// Null disables the field (shows dimmed, no tap).
  final ValueChanged<String?>? onChanged;
  /// When true, an "Unassigned" tile appears at the top of the picker.
  final bool allowUnassigned;
  final String labelText;

  String _displayText() {
    if (selectedOfficeId == null) {
      return allowUnassigned ? 'Unassigned' : 'Select office…';
    }
    try {
      return offices.firstWhere((o) => o.id == selectedOfficeId).name;
    } catch (_) {
      return 'Select office…';
    }
  }

  Future<void> _openPicker(BuildContext context) async {
    final sorted = List<Office>.from(offices)
      ..sort((a, b) => a.name.toLowerCase().compareTo(b.name.toLowerCase()));
    final result = await _showOfficePicker(
      context,
      offices: sorted,
      initialOfficeId: selectedOfficeId,
      allowUnassigned: allowUnassigned,
    );
    if (result != null) onChanged?.call(result.officeId);
  }

  @override
  Widget build(BuildContext context) {
    final isEnabled = onChanged != null;
    final cs = Theme.of(context).colorScheme;
    return InkWell(
      onTap: isEnabled ? () => _openPicker(context) : null,
      borderRadius: BorderRadius.circular(16),
      child: InputDecorator(
        decoration: InputDecoration(
          labelText: labelText,
          enabled: isEnabled,
          suffixIcon: Icon(
            Icons.search_rounded,
            color: isEnabled
                ? cs.onSurfaceVariant
                : cs.onSurface.withValues(alpha: 0.38),
          ),
        ),
        child: Text(
          _displayText(),
          style: Theme.of(context).textTheme.bodyMedium?.copyWith(
            color: isEnabled
                ? cs.onSurface
                : cs.onSurface.withValues(alpha: 0.38),
          ),
        ),
      ),
    );
  }
}

Future<_PickResult?> _showOfficePicker(
  BuildContext context, {
  required List<Office> offices,
  String? initialOfficeId,
  bool allowUnassigned = false,
}) {
  final isMobile = MediaQuery.sizeOf(context).width < AppBreakpoints.tablet;

  List<Widget> buildItems(
    String? selected,
    String search,
    void Function(String?) onPick,
    ColorScheme cs,
  ) {
    final filtered = search.isEmpty
        ? offices
        : offices
            .where((o) => o.name.toLowerCase().contains(search.toLowerCase()))
            .toList();
    return [
      if (allowUnassigned)
        ListTile(
          dense: true,
          leading: Icon(Icons.block_rounded, color: cs.onSurfaceVariant),
          title: const Text('Unassigned'),
          selected: selected == null,
          trailing: selected == null
              ? Icon(Icons.check_rounded, size: 18, color: cs.primary)
              : null,
          onTap: () => onPick(null),
        ),
      for (final office in filtered)
        ListTile(
          dense: true,
          leading: Icon(Icons.business_rounded, color: cs.onSurfaceVariant),
          title: Text(office.name),
          selected: selected == office.id,
          trailing: selected == office.id
              ? Icon(Icons.check_rounded, size: 18, color: cs.primary)
              : null,
          onTap: () => onPick(office.id),
        ),
      if (filtered.isEmpty)
        Padding(
          padding: const EdgeInsets.all(16),
          child: Text(
            'No offices match your search.',
            textAlign: TextAlign.center,
            style: TextStyle(color: cs.onSurfaceVariant),
          ),
        ),
    ];
  }

  if (isMobile) {
    return m3ShowBottomSheet<_PickResult>(
      context: context,
      isScrollControlled: true,
      builder: (sheetCtx) {
        String search = '';
        String? selected = initialOfficeId;
        return StatefulBuilder(
          builder: (ctx, setState) {
            final cs = Theme.of(ctx).colorScheme;
            return SafeArea(
              child: Padding(
                padding: EdgeInsets.only(
                  left: 16,
                  right: 16,
                  top: 8,
                  bottom: MediaQuery.viewInsetsOf(ctx).bottom + 16,
                ),
                child: Column(
                  mainAxisSize: MainAxisSize.min,
                  children: [
                    Row(
                      children: [
                        Expanded(
                          child: Text(
                            'Select Office',
                            style: Theme.of(ctx).textTheme.titleLarge,
                          ),
                        ),
                        IconButton(
                          icon: const Icon(Icons.close),
                          onPressed: () => Navigator.of(ctx).pop(),
                        ),
                      ],
                    ),
                    const SizedBox(height: 8),
                    TextField(
                      decoration: const InputDecoration(
                        hintText: 'Search office…',
                        prefixIcon: Icon(Icons.search_rounded),
                        isDense: true,
                      ),
                      onChanged: (v) => setState(() => search = v),
                    ),
                    const SizedBox(height: 4),
                    SizedBox(
                      height: 320,
                      child: ListView(
                        children: buildItems(
                          selected,
                          search,
                          (id) => Navigator.of(ctx).pop(_PickResult(id)),
                          cs,
                        ),
                      ),
                    ),
                  ],
                ),
              ),
            );
          },
        );
      },
    );
  }

  return m3ShowDialog<_PickResult>(
    context: context,
    builder: (dialogCtx) {
      String search = '';
      String? selected = initialOfficeId;
      return StatefulBuilder(
        builder: (ctx, setState) {
          final cs = Theme.of(ctx).colorScheme;
          return AlertDialog(
            title: const Text('Select Office'),
            contentPadding: const EdgeInsets.fromLTRB(0, 12, 0, 0),
            content: SizedBox(
              width: 400,
              child: Column(
                mainAxisSize: MainAxisSize.min,
                children: [
                  Padding(
                    padding: const EdgeInsets.fromLTRB(24, 0, 24, 8),
                    child: TextField(
                      decoration: const InputDecoration(
                        hintText: 'Search office…',
                        prefixIcon: Icon(Icons.search_rounded),
                        isDense: true,
                      ),
                      onChanged: (v) => setState(() => search = v),
                    ),
                  ),
                  SizedBox(
                    height: 280,
                    width: double.maxFinite,
                    child: ListView(
                      children: buildItems(
                        selected,
                        search,
                        (id) => Navigator.of(ctx).pop(_PickResult(id)),
                        cs,
                      ),
                    ),
                  ),
                ],
              ),
            ),
            actions: [
              TextButton(
                onPressed: () => Navigator.of(ctx).pop(),
                child: const Text('Cancel'),
              ),
            ],
          );
        },
      );
    },
  );
}