import 'package:flutter/material.dart';

import '../data/models.dart';
import '../data/repository.dart';
import '../theme/reclaim_tokens.dart';
import '../widgets/mode_banner.dart';
import '../widgets/heatmap_grid.dart';
import '../widgets/jurisdiction_badge.dart';
import '../widgets/reclaim_card.dart';
import '../widgets/tier_badge.dart';
import 'norm_detail_page.dart';

class HeatmapPage extends StatefulWidget {
  const HeatmapPage({super.key, required this.repository});

  final EvaluationRepository repository;

  @override
  State<HeatmapPage> createState() => _HeatmapPageState();
}

class _HeatmapPageState extends State<HeatmapPage> {
  late Future<List<Evaluation>> _future;

  @override
  void initState() {
    super.initState();
    _future = widget.repository.list();
  }

  @override
  Widget build(BuildContext context) {
    final t = Theme.of(context).textTheme;
    return Column(
      children: [
        ModeBanner(repository: widget.repository),
        Expanded(
          child: Padding(
            padding: const EdgeInsets.all(ReclaimSpace.xl),
            child: FutureBuilder<List<Evaluation>>(
              future: _future,
              builder: (context, snap) {
                if (!snap.hasData) {
                  return const Center(
                      child: CircularProgressIndicator());
                }
                final items = snap.data!;
                return Column(
                  crossAxisAlignment: CrossAxisAlignment.start,
                  children: [
                    Text('Heatmap', style: t.displaySmall),
                    const SizedBox(height: ReclaimSpace.xs),
                    Text(
                      'Schaden × Nutzen × Betroffenheit pro Norm. '
                      'Klick auf einen Punkt öffnet das Detail mit '
                      'Pflichten, Quellen und Gesetzestext.',
                      style: t.bodyLarge?.copyWith(
                        color: ReclaimColors.mute,
                      ),
                    ),
                    const SizedBox(height: ReclaimSpace.lg),
                    Expanded(
                      child: items.isEmpty
                          ? _EmptyHubState(repository: widget.repository)
                          : ReclaimCard(
                              accent: true,
                              expand: true,
                              child: HeatmapGrid(
                                evaluations: items,
                                onTap: (e) {
                                  Navigator.of(context).push(
                                    MaterialPageRoute(
                                      builder: (_) => NormDetailPage(
                                        repository: widget.repository,
                                        evaluation: e,
                                      ),
                                    ),
                                  );
                                },
                              ),
                            ),
                    ),
                    if (items.isNotEmpty) ...[
                      const SizedBox(height: ReclaimSpace.md),
                      const _LegendCard(),
                    const SizedBox(height: ReclaimSpace.lg),
                    Wrap(
                      spacing: ReclaimSpace.md,
                      runSpacing: ReclaimSpace.sm,
                      children: [
                        for (final e in items)
                          InkWell(
                            onTap: () {
                              Navigator.of(context).push(
                                MaterialPageRoute(
                                  builder: (_) => NormDetailPage(
                                    repository: widget.repository,
                                    evaluation: e,
                                  ),
                                ),
                              );
                            },
                            child: ReclaimCard(
                              padding: const EdgeInsets.symmetric(
                                horizontal: ReclaimSpace.md,
                                vertical: ReclaimSpace.sm,
                              ),
                              child: Row(
                                mainAxisSize: MainAxisSize.min,
                                children: [
                                  JurisdictionBadge(
                                      jurisdiction: e.norm.jurisdiction,
                                      compact: true),
                                  const SizedBox(
                                      width: ReclaimSpace.xs),
                                  TierBadge(
                                      tier: e.tierLowest, compact: true),
                                  const SizedBox(
                                      width: ReclaimSpace.sm),
                                  Text(
                                    '${e.norm.jurabk} ${e.norm.paragraph}',
                                    style: t.labelLarge,
                                  ),
                                  Text(
                                    '  ·  ',
                                    style: t.labelLarge?.copyWith(
                                      color: ReclaimColors.mute,
                                    ),
                                  ),
                                  Text(
                                    e.norm.title,
                                    style: t.labelLarge?.copyWith(
                                      color: ReclaimColors.mute,
                                      fontWeight: FontWeight.w400,
                                    ),
                                  ),
                                ],
                              ),
                            ),
                          ),
                      ],
                    ),
                    ],
                  ],
                );
              },
            ),
          ),
        ),
      ],
    );
  }
}

/// Axis + circle legend below the heatmap.
///
/// Collapsed default: one-line header row with mini-labels for
/// Schaden / Nutzen / Betroffenheit / Evidenz-Stufe + chevron —
/// keeps the heatmap visually dominant and gives back vertical
/// space to the plot. Tap anywhere on the header expands the
/// full reading-instructions (axes, scale, sources, Tier rules).
class _LegendCard extends StatefulWidget {
  const _LegendCard();

  @override
  State<_LegendCard> createState() => _LegendCardState();
}

class _LegendCardState extends State<_LegendCard> {
  bool _expanded = false;

  @override
  Widget build(BuildContext context) {
    final t = Theme.of(context).textTheme;
    return ReclaimCard(
      padding: const EdgeInsets.symmetric(
        horizontal: ReclaimSpace.lg,
        vertical: ReclaimSpace.sm,
      ),
      child: InkWell(
        onTap: () => setState(() => _expanded = !_expanded),
        borderRadius:
            const BorderRadius.all(ReclaimRadius.sm),
        child: Padding(
          padding: const EdgeInsets.symmetric(
            vertical: ReclaimSpace.xs,
          ),
          child: Column(
            crossAxisAlignment: CrossAxisAlignment.start,
            children: [
              Row(
                children: [
                  Text('Legende',
                      style: t.titleMedium?.copyWith(
                        color: ReclaimColors.mute,
                      )),
                  const SizedBox(width: ReclaimSpace.lg),
                  const Expanded(
                    child: Wrap(
                      spacing: ReclaimSpace.lg,
                      runSpacing: ReclaimSpace.xs,
                      children: [
                        _MiniLabel(symbol: '→', text: 'Schaden'),
                        _MiniLabel(symbol: '↑', text: 'Nutzen'),
                        _MiniLabel(
                            symbol: '●', text: 'Betroffenheit'),
                        _MiniLabel(
                            symbol: '◐', text: 'Evidenz-Stufe'),
                        _MiniLabel(
                            symbol: '⌖', text: 'Geltungsbereich'),
                      ],
                    ),
                  ),
                  Icon(
                    _expanded
                        ? Icons.expand_less
                        : Icons.expand_more,
                    color: ReclaimColors.mute,
                  ),
                ],
              ),
              AnimatedSize(
                duration: const Duration(milliseconds: 180),
                curve: Curves.easeOut,
                child: _expanded
                    ? const Padding(
                        padding:
                            EdgeInsets.only(top: ReclaimSpace.lg),
                        child: Column(
                          crossAxisAlignment:
                              CrossAxisAlignment.start,
                          children: [
                            _LegendRow(
                              symbol: '→',
                              axis: 'Abszisse (X)',
                              label: 'Schaden',
                              description:
                                  'Bürokratiekosten pro Jahr in Euro, '
                                  'logarithmisch skaliert (10⁴ = 10 k, '
                                  '10⁶ = 1 Mio, 10⁹ = 1 Mrd). '
                                  'Berechnet nach Standardkostenmodell '
                                  'P × F × T × h (Studie §3.1).',
                            ),
                            SizedBox(height: ReclaimSpace.sm),
                            _LegendRow(
                              symbol: '↑',
                              axis: 'Ordinate (Y)',
                              label: 'Nutzen',
                              description:
                                  'Komposit-Score von 0–5, Mittelwert '
                                  'aus den sieben Dimensionen '
                                  'Schutz · Markt · Rechtssicherheit · '
                                  'EU-Binnenmarkt · Sicherheit · '
                                  'Umwelt · Einnahmen (Studie §3.2). '
                                  'Jede Dimension einzeln '
                                  'quellen-begründet.',
                            ),
                            SizedBox(height: ReclaimSpace.sm),
                            _LegendRow(
                              symbol: '●',
                              axis: 'Punktgröße',
                              label: 'Betroffenheit',
                              description:
                                  'Anzahl der Adressaten (KMU, Bürger, '
                                  'Behörden), wurzel-skaliert. Mehr '
                                  'Adressaten → größerer Kreis. '
                                  'Quellen: DESTATIS Unternehmensregister, '
                                  'IHK-/Handwerkskammer-Mitgliederzahlen.',
                            ),
                            SizedBox(height: ReclaimSpace.sm),
                            _LegendRow(
                              symbol: '◐',
                              axis: 'Farb-Kante',
                              label: 'Evidenz-Stufe',
                              description:
                                  'Jeder Wert trägt eine von vier Stufen — '
                                  'T1 amtlich (NKR, DESTATIS, ifo, ZEW), '
                                  'T2 Verband (DIHK, IHK, ZDH, BDI), '
                                  'T3 eigene Erhebung, '
                                  'T4 qualitatives Signal. '
                                  'Eine Zahl bekommt die Stufe ihrer '
                                  'schwächsten Eingangs-Variable — wenn h '
                                  'nur geschätzt ist (T4), ist die ganze '
                                  'SKM-Zahl T4. Petrol → warm = stark → '
                                  'schwach.',
                            ),
                            SizedBox(height: ReclaimSpace.sm),
                            _LegendRow(
                              symbol: '⌖',
                              axis: 'Chip-Symbol',
                              label: 'Geltungsbereich',
                              description:
                                  'Jede Norm trägt ein Scope-Chip — '
                                  'BE Berlin (Landesrecht, Senat/Bezirk), '
                                  'DE Deutschland (Bundesrecht, NKR/'
                                  'Bundestag), EU (Reform-Hebel in Brüssel), '
                                  'INT International (WTO/OECD/UN). Es zeigt '
                                  'an, auf welcher Ebene der Reform-Hebel '
                                  'ansetzt: eine EU-Norm lässt sich nicht '
                                  'durch nationale Streichung entlasten.',
                            ),
                          ],
                        ),
                      )
                    : const SizedBox.shrink(),
              ),
            ],
          ),
        ),
      ),
    );
  }
}

/// Shown in place of the heatmap when the repository returns zero
/// evaluations — almost always live-hub mode against a hub that
/// has no Recl∆Im `flow.completed` events yet (or is unreachable).
/// Tells the reader exactly how to get data on screen instead of
/// leaving a blank plot.
class _EmptyHubState extends StatelessWidget {
  const _EmptyHubState({required this.repository});

  final EvaluationRepository repository;

  @override
  Widget build(BuildContext context) {
    final t = Theme.of(context).textTheme;
    final down = repository.mode == 'hub-down';
    return ReclaimCard(
      accent: true,
      expand: true,
      child: Center(
        child: ConstrainedBox(
          constraints: const BoxConstraints(maxWidth: 460),
          child: Column(
            mainAxisSize: MainAxisSize.min,
            crossAxisAlignment: CrossAxisAlignment.start,
            children: [
              Icon(
                down ? Icons.cloud_off_outlined : Icons.inbox_outlined,
                size: 40,
                color: ReclaimColors.mute,
              ),
              const SizedBox(height: ReclaimSpace.md),
              Text(
                down
                    ? 'Hub nicht erreichbar'
                    : 'Noch keine Auswertungen im Hub',
                style: t.headlineSmall,
              ),
              const SizedBox(height: ReclaimSpace.sm),
              Text(
                down
                    ? 'Verbunden mit ${repository.hubLabel}. Läuft '
                        '`chain serve`? Sonst im Hub-Reiter den '
                        'Demo-Modus aktivieren — dann zeigt die '
                        'Heatmap das Fixture-Korpus.'
                    : 'Der Hub liefert keine flow.completed-Events. '
                        'Einen Recl∆Im-Flow laufen lassen, z. B.\n'
                        '  chain run flows/durchstich-from-file.yaml '
                        '--input content=@norm.xml --input '
                        'cohort_id=berlin-kmu\n'
                        'und im Hub/Studio freigeben — oder im '
                        'Hub-Reiter den Demo-Modus aktivieren.',
                style: t.bodyLarge?.copyWith(
                  color: ReclaimColors.mute,
                  height: 1.4,
                ),
              ),
            ],
          ),
        ),
      ),
    );
  }
}

class _MiniLabel extends StatelessWidget {
  const _MiniLabel({required this.symbol, required this.text});

  final String symbol;
  final String text;

  @override
  Widget build(BuildContext context) {
    final t = Theme.of(context).textTheme;
    return Row(
      mainAxisSize: MainAxisSize.min,
      crossAxisAlignment: CrossAxisAlignment.baseline,
      textBaseline: TextBaseline.alphabetic,
      children: [
        Text(symbol,
            style: t.titleMedium?.copyWith(
              color: ReclaimColors.signal,
            )),
        const SizedBox(width: 6),
        Text(text, style: t.labelLarge),
      ],
    );
  }
}

class _LegendRow extends StatelessWidget {
  const _LegendRow({
    required this.symbol,
    required this.axis,
    required this.label,
    required this.description,
  });

  final String symbol;
  final String axis;
  final String label;
  final String description;

  @override
  Widget build(BuildContext context) {
    final t = Theme.of(context).textTheme;
    return Row(
      crossAxisAlignment: CrossAxisAlignment.start,
      children: [
        SizedBox(
          width: 28,
          child: Text(
            symbol,
            style: t.titleMedium?.copyWith(
              color: ReclaimColors.signal,
              fontSize: 18,
            ),
          ),
        ),
        SizedBox(
          width: 140,
          child: Column(
            crossAxisAlignment: CrossAxisAlignment.start,
            children: [
              Text(
                axis,
                style: t.labelSmall?.copyWith(
                  color: ReclaimColors.mute,
                  letterSpacing: 0.4,
                ),
              ),
              Text(
                label,
                style: t.titleMedium,
              ),
            ],
          ),
        ),
        const SizedBox(width: ReclaimSpace.md),
        Expanded(
          child: Padding(
            padding: const EdgeInsets.only(top: 2),
            child: Text(
              description,
              style: t.bodyLarge?.copyWith(
                color: ReclaimColors.mute,
                height: 1.5,
              ),
            ),
          ),
        ),
      ],
    );
  }
}