// Guided-setup wizard. Collects scenario / intent / target (plus two
// adaptive toggles) across three explained steps, then previews the
// assembled plan in localized PLAIN LANGUAGE and applies it. All the
// policy lives in the Rust deterministic engine
// (chain_core::guided_setup); this is a thin UI over `chain init`.
//
// The preview is rendered from `chain init --answers … --plan-json`
// (a structured SetupPlan), so the operator sees a German/English
// plain-language summary — never the CLI's English prose. Every
// option carries a one-line explanation of what it configures.

import 'dart:convert';
import 'dart:io';

import 'package:flutter/material.dart';

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

/// A selectable setup option: the stable kebab wire value plus the
/// localized label + one-line explanation resolved at build time.
class _Option {
  final String value;
  final String Function(AppLocalizations) label;
  final String Function(AppLocalizations) sub;
  const _Option(this.value, this.label, this.sub);
}

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

  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 wire values (serde kebab-case in Rust) with
  // their localized label + explanation.
  static final _scenarios = <_Option>[
    _Option('trying-out', (l) => l.setupScenTryingOut, (l) => l.setupScenTryingOutSub),
    _Option('team-hub', (l) => l.setupScenTeamHub, (l) => l.setupScenTeamHubSub),
    _Option('regulated-production', (l) => l.setupScenRegulated, (l) => l.setupScenRegulatedSub),
    _Option('building-modules', (l) => l.setupScenBuildModules, (l) => l.setupScenBuildModulesSub),
  ];
  static final _intents = <_Option>[
    _Option('hello-world', (l) => l.setupIntentHello, (l) => l.setupIntentHelloSub),
    _Option('extract-text', (l) => l.setupIntentExtract, (l) => l.setupIntentExtractSub),
    _Option('extract-summarize', (l) => l.setupIntentExtractSummarize, (l) => l.setupIntentExtractSummarizeSub),
    _Option('classify-documents', (l) => l.setupIntentClassify, (l) => l.setupIntentClassifySub),
    _Option('build-module', (l) => l.setupIntentBuildModule, (l) => l.setupIntentBuildModuleSub),
  ];
  static final _targets = <_Option>[
    _Option('this-laptop', (l) => l.setupTargetLaptop, (l) => l.setupTargetLaptopSub),
    _Option('home-server', (l) => l.setupTargetHomeServer, (l) => l.setupTargetHomeServerSub),
    _Option('air-gapped-server', (l) => l.setupTargetAirgapped, (l) => l.setupTargetAirgappedSub),
    _Option('container', (l) => l.setupTargetContainer, (l) => l.setupTargetContainerSub),
  ];

  static const _totalSteps = 3; // three answer steps; the review is step 4

  int _step = 0; // 0..2 answers, 3 = review/apply
  String _scenario = 'trying-out';
  String _intent = 'extract-summarize';
  String _target = 'this-laptop';
  bool _requireApproval = false;
  bool _dataLocal = false;
  bool _busy = false;
  Map<String, dynamic>? _plan; // parsed SetupPlan from --plan-json
  bool _applied = false;

  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;
  }

  /// True when a config file already exists (so applying overwrites it).
  bool _configExists() {
    final home =
        Platform.environment['HOME'] ?? Platform.environment['USERPROFILE'];
    if (home == null) return false;
    final sep = Platform.pathSeparator;
    return File('$home$sep.chain${sep}config.yaml').existsSync();
  }

  Future<void> _goReview() async {
    setState(() {
      _busy = true;
      _plan = null;
    });
    final path = await _writeAnswers();
    final r = await SystemActions.chainInit(['--answers', path, '--plan-json']);
    if (!mounted) return;
    setState(() => _busy = false);
    if (r.ok) {
      try {
        final plan = jsonDecode(r.stdout.trim()) as Map<String, dynamic>;
        setState(() {
          _plan = plan;
          _step = _totalSteps; // review
        });
      } catch (_) {
        showFaiProcessError(context, 'chain init --plan-json', r.stdout, r.stderr);
      }
    } else {
      showFaiProcessError(context, 'chain init --plan-json', 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 = true);
    } else {
      showFaiProcessError(context, 'chain init --apply', r.stdout, r.stderr);
    }
  }

  @override
  Widget build(BuildContext context) {
    final l = AppLocalizations.of(context)!;
    final reviewing = _step >= _totalSteps;
    return AlertDialog(
      title: Text(reviewing ? l.setupReviewTitle : _stepTitle(l)),
      content: SizedBox(
        width: 480,
        child: SingleChildScrollView(
          child: reviewing ? _reviewStep(l) : _answerStep(l),
        ),
      ),
      actions: _actions(l),
    );
  }

  String _stepTitle(AppLocalizations l) => switch (_step) {
    0 => l.setupStep1Title,
    1 => l.setupStep2Title,
    _ => l.setupStep3Title,
  };

  Widget _answerStep(AppLocalizations l) {
    final (options, selected, onSelect) = switch (_step) {
      0 => (_scenarios, _scenario, (String v) => setState(() => _scenario = v)),
      1 => (_intents, _intent, (String v) => setState(() => _intent = v)),
      _ => (_targets, _target, (String v) => setState(() => _target = v)),
    };
    return Column(
      mainAxisSize: MainAxisSize.min,
      crossAxisAlignment: CrossAxisAlignment.start,
      children: [
        Padding(
          padding: const EdgeInsets.only(bottom: ChainSpace.sm),
          child: Text(
            l.setupStepOf(_step + 1, _totalSteps),
            style: Theme.of(context).textTheme.labelSmall?.copyWith(
              color: Theme.of(context).colorScheme.onSurfaceVariant,
            ),
          ),
        ),
        for (final o in options)
          _OptionCard(
            title: o.label(l),
            subtitle: o.sub(l),
            selected: selected == o.value,
            onTap: () => onSelect(o.value),
          ),
        // The two adaptive toggles live on the last answer step, in
        // plain language (no "air-gapped" jargon).
        if (_step == 2) ...[
          const SizedBox(height: ChainSpace.sm),
          SwitchListTile(
            contentPadding: EdgeInsets.zero,
            title: Text(l.setupApprovalPlain),
            value: _requireApproval,
            onChanged: (v) => setState(() => _requireApproval = v),
          ),
          SwitchListTile(
            contentPadding: EdgeInsets.zero,
            title: Text(l.setupDataLocalPlain),
            value: _dataLocal,
            onChanged: (v) => setState(() => _dataLocal = v),
          ),
        ],
      ],
    );
  }

  Widget _reviewStep(AppLocalizations l) {
    final plan = _plan;
    if (plan == null) return const SizedBox.shrink();
    final theme = Theme.of(context);
    final lines = _planLines(l, plan);
    return Column(
      mainAxisSize: MainAxisSize.min,
      crossAxisAlignment: CrossAxisAlignment.start,
      children: [
        if (_applied) ...[
          Row(
            children: [
              Icon(Icons.check_circle, color: ChainColors.success, size: 20),
              const SizedBox(width: ChainSpace.sm),
              Text(l.setupApplied, style: theme.textTheme.titleSmall),
            ],
          ),
          const SizedBox(height: ChainSpace.md),
          Text(l.setupNextTitle, style: theme.textTheme.labelLarge),
          const SizedBox(height: 4),
          _next(l.setupNextHubStart),
          if ((plan['modules'] as List?)?.isNotEmpty ?? false)
            _next(l.setupNextInstall),
          _next(l.setupNextRunFlow),
        ] else ...[
          for (final line in lines)
            Padding(
              padding: const EdgeInsets.only(bottom: 6),
              child: Row(
                crossAxisAlignment: CrossAxisAlignment.start,
                children: [
                  Text('·  ', style: theme.textTheme.bodyMedium),
                  Expanded(
                    child: Text(line, style: theme.textTheme.bodyMedium),
                  ),
                ],
              ),
            ),
          if (_configExists()) ...[
            const SizedBox(height: ChainSpace.sm),
            Row(
              crossAxisAlignment: CrossAxisAlignment.start,
              children: [
                Icon(Icons.info_outline, size: 16, color: theme.colorScheme.tertiary),
                const SizedBox(width: 6),
                Expanded(
                  child: Text(
                    l.setupPlanOverwriteWarn,
                    style: theme.textTheme.bodySmall?.copyWith(
                      color: theme.colorScheme.tertiary,
                    ),
                  ),
                ),
              ],
            ),
          ],
        ],
      ],
    );
  }

  Widget _next(String label) => Padding(
    padding: const EdgeInsets.only(top: 4),
    child: Row(
      children: [
        Icon(Icons.arrow_right, size: 18, color: Theme.of(context).colorScheme.primary),
        const SizedBox(width: 4),
        Expanded(child: Text(label, style: Theme.of(context).textTheme.bodyMedium)),
      ],
    ),
  );

  /// Build the localized plain-language plan lines from the structured
  /// SetupPlan (never the CLI prose).
  List<String> _planLines(AppLocalizations l, Map<String, dynamic> plan) {
    final lines = <String>[];
    switch (plan['profile'] as String? ?? '') {
      case 'air-gapped':
        lines.add(l.setupPlanIntroAirgapped);
      case 'enterprise':
        lines.add(l.setupPlanIntroEnterprise);
      default:
        lines.add(l.setupPlanIntroDev);
    }
    if (plan['require_signatures'] == true) lines.add(l.setupPlanSignatures);
    if (plan['worm_audit'] == true) lines.add(l.setupPlanWorm);
    if (plan['approval_step'] == true) lines.add(l.setupPlanApproval);
    final modules = (plan['modules'] as List?)?.cast<String>() ?? const [];
    if (modules.isNotEmpty) lines.add(l.setupPlanModules(modules.join(', ')));
    final flow = plan['starter_flow'] as String? ?? '';
    if (flow.isNotEmpty) lines.add(l.setupPlanFlow(flow));
    lines.add(l.setupPlanFileChanged('~/.chain/config.yaml'));
    return lines;
  }

  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) {
      return [
        FilledButton(
          onPressed: () => Navigator.of(context).pop(),
          child: Text(l.guidedSetupClose),
        ),
      ];
    }
    if (_step < _totalSteps) {
      return [
        TextButton(
          onPressed: _step == 0
              ? () => Navigator.of(context).pop()
              : () => setState(() => _step -= 1),
          child: Text(_step == 0 ? l.guidedSetupCancel : l.guidedSetupBack),
        ),
        FilledButton(
          onPressed: _step < _totalSteps - 1
              ? () => setState(() => _step += 1)
              : _goReview,
          child: Text(l.guidedSetupNext),
        ),
      ];
    }
    // Review step.
    return [
      TextButton(
        onPressed: () => setState(() => _step = _totalSteps - 1),
        child: Text(l.guidedSetupBack),
      ),
      FilledButton(onPressed: _apply, child: Text(l.guidedSetupApply)),
    ];
  }
}

/// A selectable card: title + one-line explanation, highlighted when
/// selected. Replaces the bare dropdowns so every choice explains
/// itself in place (zero-learning-curve).
class _OptionCard extends StatelessWidget {
  final String title;
  final String subtitle;
  final bool selected;
  final VoidCallback onTap;

  const _OptionCard({
    required this.title,
    required this.subtitle,
    required this.selected,
    required this.onTap,
  });

  @override
  Widget build(BuildContext context) {
    final theme = Theme.of(context);
    final accent = theme.colorScheme.primary;
    return Padding(
      padding: const EdgeInsets.only(bottom: ChainSpace.sm),
      child: Material(
        color: selected
            ? accent.withValues(alpha: 0.10)
            : theme.colorScheme.surfaceContainerHighest,
        borderRadius: BorderRadius.circular(ChainRadius.md),
        child: InkWell(
          borderRadius: BorderRadius.circular(ChainRadius.md),
          onTap: onTap,
          child: Container(
            padding: const EdgeInsets.symmetric(
              horizontal: ChainSpace.md,
              vertical: ChainSpace.sm,
            ),
            decoration: BoxDecoration(
              borderRadius: BorderRadius.circular(ChainRadius.md),
              border: Border.all(
                color: selected ? accent : theme.colorScheme.outlineVariant,
                width: selected ? 1.5 : 1,
              ),
            ),
            child: Row(
              crossAxisAlignment: CrossAxisAlignment.start,
              children: [
                Icon(
                  selected
                      ? Icons.radio_button_checked
                      : Icons.radio_button_unchecked,
                  size: 18,
                  color: selected ? accent : theme.colorScheme.onSurfaceVariant,
                ),
                const SizedBox(width: ChainSpace.sm),
                Expanded(
                  child: Column(
                    crossAxisAlignment: CrossAxisAlignment.start,
                    children: [
                      Text(
                        title,
                        style: theme.textTheme.titleSmall?.copyWith(
                          fontWeight: FontWeight.w600,
                        ),
                      ),
                      const SizedBox(height: 2),
                      Text(
                        subtitle,
                        style: theme.textTheme.bodySmall?.copyWith(
                          color: theme.colorScheme.onSurfaceVariant,
                        ),
                      ),
                    ],
                  ),
                ),
              ],
            ),
          ),
        ),
      ),
    );
  }
}