import 'dart:convert';

import 'package:chain_client_sdk/chain_client_sdk.dart' as chain;

import 'hub_endpoint.dart';
import 'models.dart';
import 'repository.dart';

/// Live `EvaluationRepository` backed by a Ch∆In hub over gRPC.
///
/// Reads flow.completed events from the hub's audit log, parses
/// each event's `detail` JSON as a Recl∆Im-shaped output bag
/// (see flows/durchstich-gewo-14.yaml), and converts the bag to
/// an Evaluation the UI can render. Events from non-Recl∆Im
/// flows are silently skipped (detected by absence of the
/// `norm` + `skm` keys).
///
/// Sort order matches MockRepository: highest €/Jahr first.
/// If the hub has zero matching flow.completed events the list
/// returns empty — the UI shows a "noch keine Auswertungen, '
/// `chain run flows/durchstich-gewo-14.yaml` aufrufen"-Hinweis.
class HubRepository implements EvaluationRepository {
  HubRepository._(this._client, this.settings, this._healthy);

  final chain.HubClient _client;
  final HubSettings settings;
  final bool _healthy;

  static Future<HubRepository> connect(HubSettings settings) async {
    final endpoint = chain.HubEndpoint(
      host: settings.host,
      port: settings.port,
      secure: settings.secure,
    );
    final client = chain.HubClient(
      endpoint: endpoint,
      authToken: settings.authToken,
    );
    // The probe must NEVER throw out of connect(): main() awaits
    // this before runApp(), so any uncaught error here leaves the
    // app on a blank page. A timeout maps to false; so does any
    // transport error (e.g. a gRPC-web call against a plain-gRPC
    // hub, or a refused connection) — the app then comes up in
    // 'hub-down' state and shows the empty-state hint.
    bool ok;
    try {
      ok = await client.healthy().timeout(
            const Duration(seconds: 4),
            onTimeout: () => false,
          );
    } catch (_) {
      ok = false;
    }
    return HubRepository._(client, settings, ok);
  }

  bool get isHealthy => _healthy;

  chain.HubClient get client => _client;

  @override
  Future<List<Evaluation>> list() async {
    if (!_healthy) return const [];
    final events = await _client.eventLog(
      limit: 200,
      types: const ['flow.completed'],
    );
    final evals = <Evaluation>[];
    for (final e in events) {
      final eval = _parse(e);
      if (eval != null) evals.add(eval);
    }
    evals.sort((a, b) => b.skmEurPerYear.compareTo(a.skmEurPerYear));
    return evals;
  }

  @override
  Future<Evaluation?> byEli(String eli) async {
    final all = await list();
    for (final e in all) {
      if (e.norm.eli == eli) return e;
    }
    return null;
  }

  @override
  String get mode => _healthy ? 'hub-live' : 'hub-down';

  @override
  String get hubLabel => '${settings.url}'
      '${_healthy ? '' : ' — Verbindung gestört'}';

  /// Decode one flow.completed event into an Evaluation, or
  /// return null when the event doesn't look like a Recl∆Im
  /// flow. We're permissive about field absence so a partially
  /// failed flow run still surfaces what it produced.
  Evaluation? _parse(chain.LoggedEvent event) {
    Map<String, dynamic>? bag;
    try {
      final decoded = jsonDecode(event.detail);
      if (decoded is Map<String, dynamic>) bag = decoded;
    } catch (_) {
      return null;
    }
    if (bag == null) return null;

    final normJson = _asMap(bag['norm']);
    if (normJson == null) return null;
    final skmJson = _asMap(bag['skm']);

    final eli = (normJson['eli'] as String?) ?? 'eli/unknown';
    final norm = Norm(
      eli: eli,
      title: (normJson['title'] as String?) ?? '(ohne Titel)',
      jurabk: (normJson['jurabk'] as String?) ?? '',
      paragraph: (normJson['paragraph'] as String?) ?? '',
      jurisdiction: JurisdictionLabel.parse(
        normJson['scope'] as String?,
        eli: eli,
      ),
      standDate: _parseTimestamp(event.timestamp),
      sourceUrl: (normJson['source_url'] as String?) ?? '',
      sourceSha256: (normJson['source_sha256'] as String?) ?? '',
      freshness: _parseFreshness(normJson['freshness']),
      supersededNote: normJson['superseded_note'] as String?,
      paragraphs: _parseParagraphs(normJson['paragraphs']),
    );

    final cohortJson = _asMap(bag['cohort']);
    final affected = _asInt(cohortJson?['count']);

    // SKM may be missing if the flow only ran the normalize-/
    // cohort-arm (e.g. flows/durchstich-from-file.yaml). Default
    // to zero and let the tier fall back to the cohort source's
    // tier — that's still the most-honest reading.
    final skmEur = _asDouble(skmJson?['total_eur_per_year']);
    final tierLowest = skmJson != null
        ? _parseTier(skmJson['tier_lowest'])
        : _parseTier(cohortJson?['tier']);

    final benefitJson = _asMap(bag['benefit']);
    final benefit = _asDouble(benefitJson?['total']);

    final frustJson = _asMap(bag['frust']);
    final frust = _asDouble(frustJson?['composite_frust']);

    return Evaluation(
      norm: norm,
      skmEurPerYear: skmEur,
      benefitScore: benefit,
      affectedCount: affected,
      frustScore: frust,
      tierLowest: tierLowest,
      duties: _parseDuties(bag['duties']),
      sources: _parseSources(cohortJson),
      auditEventId: event.eventId,
      notes: 'Live aus Hub-Flow ${event.flowName} '
          '(execution ${event.flowExecution.substring(0, 8.clamp(0, event.flowExecution.length))}).',
      // Jurist sign-off is recorded by the approval, not the flow
      // bag. Until the review-rewrite wires approvals in, these stay
      // null (= unreviewed) unless the bag carries them explicitly.
      reviewedBy: bag['reviewed_by'] as String?,
      reviewedAt: DateTime.tryParse(
          (bag['reviewed_at'] as String?) ?? ''),
    );
  }

  static Freshness _parseFreshness(dynamic v) {
    switch ((v as String?)?.trim().toLowerCase()) {
      case 'superseded' || 'amended' || 'geändert' || 'stale':
        return Freshness.superseded;
      case 'unknown' || 'ungeprüft':
        return Freshness.unknown;
      default:
        return Freshness.current;
    }
  }

  static Map<String, dynamic>? _asMap(dynamic v) =>
      v is Map<String, dynamic> ? v : null;

  static double _asDouble(dynamic v) {
    if (v is num) return v.toDouble();
    if (v is String) return double.tryParse(v) ?? 0.0;
    return 0.0;
  }

  static int _asInt(dynamic v) {
    if (v is num) return v.toInt();
    if (v is String) return int.tryParse(v) ?? 0;
    return 0;
  }

  static EvidenceTier _parseTier(dynamic v) {
    final s = (v as String?)?.toUpperCase() ?? 'T4';
    return switch (s) {
      'T1' => EvidenceTier.t1,
      'T2' => EvidenceTier.t2,
      'T3' => EvidenceTier.t3,
      _ => EvidenceTier.t4,
    };
  }

  static DateTime _parseTimestamp(String iso) =>
      DateTime.tryParse(iso) ?? DateTime.now();

  static List<NormParagraph> _parseParagraphs(dynamic v) {
    if (v is! List) return const [];
    return v.whereType<Map<String, dynamic>>().map((p) {
      return NormParagraph(
        number: (p['number'] as String?) ?? '',
        text: (p['text'] as String?) ?? '',
      );
    }).toList();
  }

  static List<Duty> _parseDuties(dynamic v) {
    final outer = _asMap(v);
    final inner = outer?['duties'];
    if (inner is! List) return const [];
    return inner.whereType<Map<String, dynamic>>().map((d) {
      return Duty(
        modality: (d['modality'] as String?) ?? '?',
        addressee: (d['addressee'] as String?) ?? '',
        action: (d['action'] as String?) ?? '',
        frequency: (d['frequency'] as String?) ?? '',
        sourceNorm: (d['source_norm'] as String?) ?? '',
        authority: d['authority'] as String?,
        consequence: d['consequence'] as String?,
      );
    }).toList();
  }

  /// Hub-mode sources are minimal: we surface the cohort source
  /// as a T1/T2 reference (the field is set by stats.cohort_size)
  /// plus an audit-log pointer. Richer source attribution comes
  /// when the flow has a dedicated `sources.collect` step.
  static List<Source> _parseSources(Map<String, dynamic>? cohort) {
    final out = <Source>[];
    final label = cohort?['source'] as String?;
    final tierStr = (cohort?['tier'] as String?)?.toUpperCase() ?? 'T2';
    if (label != null && label.isNotEmpty) {
      final tier = switch (tierStr) {
        'T1' => EvidenceTier.t1,
        'T2' => EvidenceTier.t2,
        'T3' => EvidenceTier.t3,
        _ => EvidenceTier.t4,
      };
      out.add(Source(label: label, url: '', tier: tier));
    }
    return out;
  }
}