import 'package:flutter_riverpod/flutter_riverpod.dart';
import 'package:isar/isar.dart';

import '../../../core/providers/app_providers.dart';
import '../../../data/local/models/models.dart';
import '../../scoring/application/scoring_service.dart';

/// Pure-data summary of local archery statistics, derived from completed
/// [PointRecord]s. All display strings are localized in zh-CN.
class StatsSummary {
  const StatsSummary({
    this.todayArrowCount = 0,
    this.trainingDays = 0,
    this.totalArrowCount = 0,
    this.averageScore,
    this.scoreDistribution = const <ScoreBucket>[],
    this.hitPoints = const <HitPoint>[],
  });

  final int todayArrowCount;
  final int trainingDays;
  final int totalArrowCount;
  final double? averageScore;
  final List<ScoreBucket> scoreDistribution;
  final List<HitPoint> hitPoints;

  bool get hasData => totalArrowCount > 0;

  double get todayCalories => todayArrowCount * 1.6;

  /// Capped at 10 per PRD: todayArrows * 5 / 60.
  double get todayIntensityRaw {
    final v = todayArrowCount * 5 / 60.0;
    return v > 10 ? 10 : v;
  }

  String get todayIntensityLabel {
    final v = todayIntensityRaw;
    if (v > 6) return '重度';
    if (v >= 4) return '中度';
    return '轻度';
  }

  String get averageScoreLabel =>
      averageScore == null ? '-' : averageScore!.toStringAsFixed(1);
}

/// One bucket in the ring-value distribution. [label] follows the
/// "M / X / 1~10" convention from the PRD.
class ScoreBucket {
  const ScoreBucket({required this.label, required this.count});

  final String label;
  final int count;
}

final statsProvider = FutureProvider<StatsSummary>((ref) async {
  // Re-compute whenever the records list changes.
  ref.watch(pointRecordsProvider);

  final isar = await ref.watch(isarProvider.future);
  final records = await isar.pointRecords
      .filter()
      .statusEqualTo(PointRecordStatus.completed)
      .sortByCreatedAtDesc()
      .findAll();

  return _compute(records);
});

StatsSummary _compute(List<PointRecord> records) {
  if (records.isEmpty) return const StatsSummary();

  final today = DateTime.now();
  final todayDate = DateTime(today.year, today.month, today.day);

  int todayArrows = 0;
  int totalArrows = 0;
  double scoreSum = 0;
  int scoredArrows = 0;
  final days = <DateTime>{};
  final allHits = <HitPoint>[];
  final counts = <String, int>{};

  for (final r in records) {
    final day = DateTime(r.createdAt.year, r.createdAt.month, r.createdAt.day);
    days.add(day);
    totalArrows += r.scores.length;
    if (day == todayDate) {
      todayArrows += r.scores.length;
    }
    for (final s in r.scores) {
      scoreSum += s;
      scoredArrows += 1;
      final key = _bucketLabel(s);
      counts[key] = (counts[key] ?? 0) + 1;
    }
    allHits.addAll(r.hitPoints);
  }

  final order = const [
    'X',
    '10',
    '9',
    '8',
    '7',
    '6',
    '5',
    '4',
    '3',
    '2',
    '1',
    'M',
  ];
  final distribution = <ScoreBucket>[];
  for (final label in order) {
    final c = counts[label] ?? 0;
    if (c > 0) distribution.add(ScoreBucket(label: label, count: c));
  }

  return StatsSummary(
    todayArrowCount: todayArrows,
    trainingDays: days.length,
    totalArrowCount: totalArrows,
    averageScore: scoredArrows == 0 ? null : scoreSum / scoredArrows,
    scoreDistribution: distribution,
    hitPoints: allHits,
  );
}

String _bucketLabel(int score) {
  if (score == 0) return 'M';
  if (score == 10) return '10';
  return '$score';
}