// Guided-setup wizard. Collects scenario / intent / target (plus two
// adaptive toggles), then calls `chain init --answers` to PREVIEW the
// assembled plan and `--apply` to write the config. All the policy lives
// in the Rust deterministic engine (chain_core::guided_setup) — this is
// a thin UI over the CLI, so the logic never diverges.
//
// NOTE: the dropdown option labels are humanised from the canonical
// kebab-case enum values (trying-out → "Trying Out"); localising those
// per option is a follow-up. The structural UI + the applied plan
// (rendered from the CLI's localisable output) are the meaningful parts.

import 'dart:io';

import 'package:flutter/material.dart';

import '../data/error_presentation.dart';
import '../data/system_actions.dart';
import '../l10n/app_localizations.dart';

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

  /// Launch the wizard as a modal dialog.
  static Future<void> show(BuildContext context) => showDialog<void>(
        context: context,
        builder: (_) => const GuidedSetupDialog(),
      );

  @override
  State<GuidedSetupDialog> createState() => _GuidedSetupDialogState();
}

class _GuidedSetupDialogState extends State<GuidedSetupDialog> {
  // Canonical SetupAnswers enum values (serde kebab-case in Rust).
  static const _scenarios = <String>[
    'trying-out',
    'team-hub',
    'regulated-production',
    'building-modules',
  ];
  static const _intents = <String>[
    'hello-world',
    'extract-text',
    'extract-summarize',
    'classify-documents',
    'build-module',
  ];
  static const _targets = <String>[
    'this-laptop',
    'home-server',
    'air-gapped-server',
    'container',
  ];

  int _step = 0; // 0 = answers, 1 = review/apply
  String _scenario = 'trying-out';
  String _intent = 'extract-summarize';
  String _target = 'this-laptop';
  bool _requireApproval = false;
  bool _dataLocal = false;
  bool _busy = false;
  String? _preview;
  String? _applied;

  String _humanize(String kebab) => kebab
      .split('-')
      .map((w) => w.isEmpty ? w : '${w[0].toUpperCase()}${w.substring(1)}')
      .join(' ');

  String _answersYaml() => 'scenario: $_scenario\n'
      'intent: $_intent\n'
      'target: $_target\n'
      'require_approval: $_requireApproval\n'
      'data_must_stay_local: $_dataLocal\n';

  Future<String> _writeAnswers() async {
    final f = File('${Directory.systemTemp.path}/chain-setup-answers.yaml');
    await f.writeAsString(_answersYaml());
    return f.path;
  }

  Future<void> _goReview() async {
    setState(() {
      _busy = true;
      _preview = null;
    });
    final path = await _writeAnswers();
    final r = await SystemActions.chainInit(['--answers', path]);
    if (!mounted) return;
    setState(() => _busy = false);
    if (r.ok) {
      setState(() {
        _preview = r.stdout.trim();
        _step = 1;
      });
    } else {
      showFaiProcessError(context, 'chain init --answers', r.stdout, r.stderr);
    }
  }

  Future<void> _apply() async {
    setState(() => _busy = true);
    final path = await _writeAnswers();
    final r = await SystemActions.chainInit(
      ['--answers', path, '--apply', '--force'],
    );
    if (!mounted) return;
    setState(() => _busy = false);
    if (r.ok) {
      setState(() => _applied = r.stdout.trim());
    } else {
      showFaiProcessError(context, 'chain init --apply', r.stdout, r.stderr);
    }
  }

  @override
  Widget build(BuildContext context) {
    final l = AppLocalizations.of(context)!;
    return AlertDialog(
      title: Text(l.guidedSetupTitle),
      content: SizedBox(
        width: 460,
        child: SingleChildScrollView(
          child: _step == 0 ? _answersStep(l) : _reviewStep(l),
        ),
      ),
      actions: _actions(l),
    );
  }

  Widget _answersStep(AppLocalizations l) {
    return Column(
      mainAxisSize: MainAxisSize.min,
      crossAxisAlignment: CrossAxisAlignment.start,
      children: [
        Text(l.guidedSetupIntro),
        const SizedBox(height: 16),
        _dropdown(l.guidedSetupScenario, _scenarios, _scenario,
            (v) => setState(() => _scenario = v)),
        const SizedBox(height: 12),
        _dropdown(l.guidedSetupIntent, _intents, _intent,
            (v) => setState(() => _intent = v)),
        const SizedBox(height: 12),
        _dropdown(l.guidedSetupTarget, _targets, _target,
            (v) => setState(() => _target = v)),
        const SizedBox(height: 8),
        SwitchListTile(
          contentPadding: EdgeInsets.zero,
          title: Text(l.guidedSetupApproval),
          value: _requireApproval,
          onChanged: (v) => setState(() => _requireApproval = v),
        ),
        SwitchListTile(
          contentPadding: EdgeInsets.zero,
          title: Text(l.guidedSetupDataLocal),
          value: _dataLocal,
          onChanged: (v) => setState(() => _dataLocal = v),
        ),
      ],
    );
  }

  Widget _dropdown(
    String label,
    List<String> items,
    String value,
    ValueChanged<String> onChanged,
  ) {
    return InputDecorator(
      decoration: InputDecoration(
        labelText: label,
        border: const OutlineInputBorder(),
        isDense: true,
      ),
      child: DropdownButtonHideUnderline(
        child: DropdownButton<String>(
          isExpanded: true,
          value: value,
          items: [
            for (final i in items)
              DropdownMenuItem<String>(value: i, child: Text(_humanize(i))),
          ],
          onChanged: (v) {
            if (v != null) onChanged(v);
          },
        ),
      ),
    );
  }

  Widget _reviewStep(AppLocalizations l) {
    final applied = _applied;
    return Column(
      mainAxisSize: MainAxisSize.min,
      crossAxisAlignment: CrossAxisAlignment.start,
      children: [
        Text(applied != null
            ? l.guidedSetupApplied
            : l.guidedSetupReviewHeading),
        const SizedBox(height: 12),
        Container(
          width: double.infinity,
          padding: const EdgeInsets.all(12),
          decoration: BoxDecoration(
            color: Theme.of(context).colorScheme.surfaceContainerHighest,
            borderRadius: BorderRadius.circular(6),
          ),
          // SelectableText keeps the plan copyable (project rule:
          // anything an operator might want to keep is selectable).
          child: SelectableText(
            applied ?? _preview ?? '',
            style: Theme.of(context).textTheme.bodySmall,
          ),
        ),
      ],
    );
  }

  List<Widget> _actions(AppLocalizations l) {
    if (_busy) {
      return const [
        Padding(
          padding: EdgeInsets.all(12),
          child: SizedBox(
            width: 18,
            height: 18,
            child: CircularProgressIndicator(strokeWidth: 2),
          ),
        ),
      ];
    }
    if (_applied != null) {
      return [
        FilledButton(
          onPressed: () => Navigator.of(context).pop(),
          child: Text(l.guidedSetupClose),
        ),
      ];
    }
    if (_step == 0) {
      return [
        TextButton(
          onPressed: () => Navigator.of(context).pop(),
          child: Text(l.guidedSetupCancel),
        ),
        FilledButton(onPressed: _goReview, child: Text(l.guidedSetupNext)),
      ];
    }
    return [
      TextButton(
        onPressed: () => setState(() => _step = 0),
        child: Text(l.guidedSetupBack),
      ),
      FilledButton(onPressed: _apply, child: Text(l.guidedSetupApply)),
    ];
  }
}