import 'dart:math' as math;

import 'package:fl_chart/fl_chart.dart';
import 'package:flutter/material.dart';
import 'package:intl/intl.dart';
import 'package:manager_api_new/api.dart';
import 'package:manager_app/Components/common_loader.dart';
import 'package:manager_app/Helpers/PDFHelper.dart';
import 'package:manager_app/Models/managerContext.dart';
import 'package:manager_app/app_context.dart';
import 'package:manager_app/Screens/Statistics/statistics_report.dart';
import 'package:manager_app/constants.dart';
import 'package:manager_app/l10n/app_localizations.dart';
import 'package:provider/provider.dart';

const _kUp = Color(0xFF1F6B4D);
const _kDown = Color(0xFFA8322A);
const _kTrack = Color(0xFFE7EBF1);
const _kMuted = Color(0xFFF3F5F8);
const _kLine = Color(0xFFD6DDE5);

/// Périodes proposées, en jours. `365` s'affiche « Année ».
const _kPeriods = [7, 30, 90, 365];

/// Au-delà de cette longueur, les bandes de week-end deviennent du bruit visuel.
const _kMaxDaysForWeekendBands = 62;

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

  @override
  State<StatisticsScreen> createState() => _StatisticsScreenState();
}

class _StatisticsScreenState extends State<StatisticsScreen> {
  int _selectedDays = 30;
  AppType? _selectedChannel;

  bool _loading = true;
  bool _failed = false;
  bool _exporting = false;

  /// Période courante, filtrée sur le canal sélectionné.
  StatsSummaryDTO? _current;

  /// Même durée, juste avant : sert uniquement aux variations des KPI.
  StatsSummaryDTO? _previous;

  /// Période courante tous canaux confondus : volumes des chips de canal.
  StatsSummaryDTO? _allChannels;

  DateTime _from = DateTime.now();
  DateTime _to = DateTime.now();

  @override
  void initState() {
    super.initState();
    WidgetsBinding.instance.addPostFrameCallback((_) => _load());
  }

  ManagerAppContext get _ctx =>
      Provider.of<AppContext>(context, listen: false).getContext() as ManagerAppContext;

  bool get _hasStats => _ctx.instanceDTO?.hasStats ?? false;

  bool get _hasAdvancedStats => _ctx.instanceDTO?.hasAdvancedStats ?? false;

  int get _statsHistoryDays => _ctx.instanceDTO?.statsHistoryDays ?? 30;

  /// La période précédente n'est comparable que si l'historique du plan la couvre
  /// entièrement : sinon le backend la tronque et la variation serait fausse.
  bool get _canComparePrevious =>
      _statsHistoryDays == 0 || _statsHistoryDays >= _selectedDays * 2;

  /// Canaux de l'instance : ceux qui sont déclarés, plus ceux qui ont produit des
  /// visites (un canal qui a de la donnée ne doit jamais disparaître du filtre).
  List<AppType> get _channels {
    final declared = (_ctx.instanceDTO?.applicationInstanceDTOs ?? const [])
        .map((app) => app.appType)
        .whereType<AppType>();
    final withData = AppType.values
        .where((type) => (_allChannels?.appTypeDistribution[type.name] ?? 0) > 0);
    final present = {...declared, ...withData};
    return AppType.values.where(present.contains).toList();
  }

  bool get _isMultiChannel => _channels.length >= 2;

  Future<void> _load() async {
    final instanceId = _ctx.instanceId;
    final api = _ctx.clientAPI?.statsApi;
    if (instanceId == null || api == null || !_hasStats) {
      setState(() => _loading = false);
      return;
    }

    final to = DateTime.now();
    final from = to.subtract(Duration(days: _selectedDays));
    final channel = _selectedChannel?.name;

    setState(() {
      _loading = true;
      _failed = false;
      _from = from;
      _to = to;
    });

    try {
      final results = await Future.wait<StatsSummaryDTO?>([
        api.statsGetSummary(instanceId, from: from, to: to, appType: channel),
        if (_canComparePrevious)
          api.statsGetSummary(
            instanceId,
            from: from.subtract(Duration(days: _selectedDays)),
            to: from,
            appType: channel,
          )
        else
          Future.value(),
        if (channel != null)
          api.statsGetSummary(instanceId, from: from, to: to)
        else
          Future.value(),
      ]);
      if (!mounted) return;
      setState(() {
        _current = results[0];
        _previous = results[1];
        _allChannels = results[2] ?? results[0];
        _loading = false;
      });
    } catch (_) {
      if (!mounted) return;
      setState(() {
        _failed = true;
        _loading = false;
      });
    }
  }

  void _selectPeriod(int days) {
    if (days == _selectedDays) return;
    _selectedDays = days;
    _load();
  }

  void _selectChannel(AppType? channel) {
    if (channel == _selectedChannel) return;
    _selectedChannel = channel;
    _load();
  }

  // --- Mise en forme -------------------------------------------------------

  NumberFormat get _numbers =>
      NumberFormat.decimalPattern(Localizations.localeOf(context).languageCode);

  String _count(num value) => _numbers.format(value);

  String _oneDecimal(double value) =>
      NumberFormat('0.#', Localizations.localeOf(context).languageCode).format(value);

  String _formatDuration(int seconds) {
    final l = AppLocalizations.of(context)!;
    if (seconds < 60) return l.statsDurationSec('$seconds');
    return l.statsDurationMinSec('${seconds ~/ 60}', '${seconds % 60}');
  }

  String _shortDate(DateTime date) =>
      MaterialLocalizations.of(context).formatShortMonthDay(date);

  String _plainTitle(String? raw, String? fallback) {
    final text = (raw ?? '').replaceAll(RegExp(r'<[^>]*>'), '').trim();
    return text.isNotEmpty ? text : (fallback ?? '—');
  }

  String _channelLabel(AppType channel) {
    final l = AppLocalizations.of(context)!;
    switch (channel.value) {
      case 0:
        return l.statsChannelMobile;
      case 1:
        return l.statsChannelTablet;
      case 2:
        return l.statsChannelWeb;
      case 3:
        return l.statsChannelVR;
      case 4:
        return l.statsChannelVoice;
      default:
        return channel.name;
    }
  }

  // --- Agrégats dérivés ----------------------------------------------------

  /// Toutes les consultations de contenu de la période (`visitsByDay` compte les
  /// `SectionView`), pas seulement celles du top 10.
  int _totalViews(StatsSummaryDTO stats) =>
      stats.visitsByDay.fold(0, (sum, day) => sum + day.total);

  double _contentsPerVisit(StatsSummaryDTO stats) =>
      stats.totalSessions == 0 ? 0 : _totalViews(stats) / stats.totalSessions;

  int _voiceSessions(StatsSummaryDTO stats) =>
      stats.appTypeDistribution[AppType.Voice.name] ?? 0;

  double _voiceShare(StatsSummaryDTO stats) => stats.totalSessions == 0
      ? 0
      : _voiceSessions(stats) / stats.totalSessions * 100;

  /// Série continue du premier au dernier jour : le backend n'émet que les jours
  /// qui ont des événements, et les trous fausseraient la courbe et les week-ends.
  List<_DayPoint> _dailySeries(StatsSummaryDTO stats) {
    final byDate = {for (final day in stats.visitsByDay) day.date: day.total};
    final start = DateTime(_from.year, _from.month, _from.day);
    final end = DateTime(_to.year, _to.month, _to.day);

    final points = <_DayPoint>[];
    for (var offset = 0; ; offset++) {
      final date = DateTime(start.year, start.month, start.day + offset);
      if (date.isAfter(end)) break;
      final key = '${date.year.toString().padLeft(4, '0')}-'
          '${date.month.toString().padLeft(2, '0')}-'
          '${date.day.toString().padLeft(2, '0')}';
      points.add(_DayPoint(date, byDate[key] ?? 0));
    }
    return points;
  }

  // --- Construction --------------------------------------------------------

  @override
  Widget build(BuildContext context) {
    final l = AppLocalizations.of(context)!;

    if (!_hasStats && !_loading) {
      return _emptyMessage(
        Icons.lock_outline,
        l.statsUnavailableTitle,
        l.statsUnavailableBody,
      );
    }

    return Column(
      crossAxisAlignment: CrossAxisAlignment.start,
      children: [
        _header(l),
        const SizedBox(height: 14),
        _filters(l),
        const SizedBox(height: 4),
        Expanded(child: _body(l)),
      ],
    );
  }

  Widget _body(AppLocalizations l) {
    if (_loading) return const CommonLoader();
    if (_failed) return _emptyMessage(Icons.cloud_off_outlined, l.statsLoadError, null);

    final stats = _current;
    if (stats == null || stats.totalSessions == 0) {
      return _emptyMessage(
        Icons.bar_chart_outlined,
        l.statsNoData,
        _selectedChannel == null ? null : l.statsNoDataForType(_channelLabel(_selectedChannel!)),
      );
    }

    return LayoutBuilder(
      builder: (context, constraints) {
        final wide = constraints.maxWidth >= 1040;
        return SingleChildScrollView(
          padding: const EdgeInsets.only(top: 16, bottom: 24),
          child: Column(
            crossAxisAlignment: CrossAxisAlignment.start,
            children: [
              _takeaway(l, stats),
              const SizedBox(height: 16),
              _kpiRow(l, stats, wide),
              const SizedBox(height: 16),
              _trendCard(l, stats),
              const SizedBox(height: 16),
              _distributionRow(l, stats, wide),
              const SizedBox(height: 16),
              _advancedSection(l, stats),
              _reportCard(l, stats),
            ],
          ),
        );
      },
    );
  }

  Widget _header(AppLocalizations l) {
    return Column(
      crossAxisAlignment: CrossAxisAlignment.start,
      children: [
        Text(
          l.statsAttendanceTitle,
          style: TextStyle(fontSize: 26, fontWeight: FontWeight.w600, color: kPrimaryColor),
        ),
        const SizedBox(height: 3),
        Text(
          l.statsPeriodRange(_shortDate(_from), _shortDate(_to)),
          style: TextStyle(fontSize: 14, color: kBodyTextColor.withValues(alpha: 0.75)),
        ),
      ],
    );
  }

  /// Période et canal sur la même ligne, même traitement visuel : ce sont deux
  /// filtres de même nature. Chaque canal porte son volume, pour qu'on voie où il
  /// y a de la matière avant de cliquer.
  Widget _filters(AppLocalizations l) {
    final channels = _channels;
    final total = _allChannels?.totalSessions ?? _current?.totalSessions ?? 0;

    return Container(
      padding: const EdgeInsets.symmetric(vertical: 10),
      decoration: const BoxDecoration(
        border: Border(
          top: BorderSide(color: _kLine),
          bottom: BorderSide(color: _kLine),
        ),
      ),
      child: Wrap(
        spacing: 8,
        runSpacing: 8,
        crossAxisAlignment: WrapCrossAlignment.center,
        children: [
          _filterLabel(l.statsFilterPeriod),
          ..._kPeriods.map((days) => _filterChip(
                label: days == 365 ? l.statsPeriodYear : l.statsPeriodDays(days),
                selected: _selectedDays == days,
                enabled: _statsHistoryDays == 0 || _statsHistoryDays >= days,
                onTap: () => _selectPeriod(days),
              )),
          if (_isMultiChannel) ...[
            const SizedBox(width: 4),
            _filterLabel(l.statsFilterChannel),
            _filterChip(
              label: l.statsAll,
              count: total,
              selected: _selectedChannel == null,
              onTap: () => _selectChannel(null),
            ),
            ...channels.map((channel) => _filterChip(
                  label: _channelLabel(channel),
                  count: _allChannels?.appTypeDistribution[channel.name] ?? 0,
                  selected: _selectedChannel == channel,
                  onTap: () => _selectChannel(channel),
                )),
          ],
        ],
      ),
    );
  }

  Widget _filterLabel(String text) {
    return Padding(
      padding: const EdgeInsets.only(right: 2),
      child: Text(
        text.toUpperCase(),
        style: TextStyle(
          fontSize: 11,
          letterSpacing: 0.9,
          fontWeight: FontWeight.w600,
          color: kBodyTextColor.withValues(alpha: 0.55),
        ),
      ),
    );
  }

  Widget _filterChip({
    required String label,
    required bool selected,
    required VoidCallback onTap,
    int? count,
    bool enabled = true,
  }) {
    final foreground = !enabled
        ? kBodyTextColor.withValues(alpha: 0.35)
        : selected
            ? kWhite
            : kBodyTextColor;

    return InkWell(
      onTap: enabled ? onTap : null,
      borderRadius: BorderRadius.circular(999),
      child: Container(
        padding: const EdgeInsets.symmetric(horizontal: 13, vertical: 7),
        decoration: BoxDecoration(
          color: selected ? kPrimaryColor : _kMuted,
          border: Border.all(color: selected ? kPrimaryColor : _kLine),
          borderRadius: BorderRadius.circular(999),
        ),
        child: Row(
          mainAxisSize: MainAxisSize.min,
          children: [
            Text(label, style: TextStyle(fontSize: 13, color: foreground)),
            if (count != null) ...[
              const SizedBox(width: 7),
              Text(
                _count(count),
                style: TextStyle(
                  fontSize: 12,
                  fontWeight: FontWeight.w600,
                  color: foreground.withValues(alpha: selected ? 0.8 : 0.6),
                ),
              ),
            ],
          ],
        ),
      ),
    );
  }

  /// Deux phrases en langage naturel : ce qu'un gestionnaire retient s'il n'ouvre
  /// l'écran que trois secondes. Règles simples, pas d'appel LLM.
  List<String> _takeawaySentences(AppLocalizations l, StatsSummaryDTO stats) {
    final sentences = <String>[];

    final before = _previous?.totalSessions;
    if (before != null && before > 0) {
      final variation = (stats.totalSessions - before) / before * 100;
      if (variation.abs() < 3) {
        sentences.add(l.statsTakeawayStable);
      } else if (variation > 0) {
        sentences.add(l.statsTakeawayUp(_oneDecimal(variation)));
      } else {
        sentences.add(l.statsTakeawayDown(_oneDecimal(variation.abs())));
      }
    } else {
      final days = math.max(1, _dailySeries(stats).length);
      sentences.add(l.statsTakeawayVolume(
        _count(stats.totalSessions),
        _oneDecimal(stats.totalSessions / days),
      ));
    }

    final second = _secondTakeaway(l, stats);
    if (second != null) sentences.add(second);

    return sentences;
  }

  Widget _takeaway(AppLocalizations l, StatsSummaryDTO stats) {
    final sentences = _takeawaySentences(l, stats);

    return Container(
      width: double.infinity,
      padding: const EdgeInsets.symmetric(horizontal: 18, vertical: 15),
      decoration: BoxDecoration(
        color: _kMuted,
        border: Border.all(color: _kLine),
        borderRadius: BorderRadius.circular(8),
      ),
      child: Column(
        crossAxisAlignment: CrossAxisAlignment.start,
        children: [
          for (final sentence in sentences)
            Padding(
              padding: EdgeInsets.only(top: sentence == sentences.first ? 0 : 6),
              child: Text(
                sentence,
                style: TextStyle(fontSize: 14.5, height: 1.45, color: kBodyTextColor),
              ),
            ),
        ],
      ),
    );
  }

  /// Multi-canal : la part du vocal, sinon le canal dominant. Mono-canal : il n'y
  /// a pas de canaux à comparer, l'information intéressante est le contenu phare.
  String? _secondTakeaway(AppLocalizations l, StatsSummaryDTO stats) {
    if (_isMultiChannel && _selectedChannel == null) {
      if (_voiceSessions(stats) > 0) {
        return l.statsTakeawayVoice(_oneDecimal(_voiceShare(stats)));
      }
      final distribution = stats.appTypeDistribution.entries.toList();
      if (distribution.isNotEmpty && stats.totalSessions > 0) {
        final top = distribution.reduce((a, b) => a.value > b.value ? a : b);
        final channel = AppType.values.firstWhere(
          (type) => type.name == top.key,
          orElse: () => AppType.Mobile,
        );
        return l.statsTakeawayChannel(
          _channelLabel(channel),
          _oneDecimal(top.value / stats.totalSessions * 100),
        );
      }
      return null;
    }

    final views = _totalViews(stats);
    if (stats.topSections.isEmpty || views == 0) return null;
    final top = stats.topSections.first;
    return l.statsTakeawayContent(
      _plainTitle(top.sectionTitle, top.sectionId),
      _oneDecimal(top.views / views * 100),
    );
  }

  List<_Kpi> _kpis(AppLocalizations l, StatsSummaryDTO stats) {
    final previous = _previous;

    return [
      _Kpi(
        l.statsKpiVisits,
        _count(stats.totalSessions),
        trend: _percentTrend(l, stats.totalSessions, previous?.totalSessions),
      ),
      _Kpi(
        l.statsKpiAvgDuration,
        _formatDuration(stats.avgVisitDurationSeconds),
        trend: _durationTrend(
          l,
          stats.avgVisitDurationSeconds,
          previous?.avgVisitDurationSeconds,
        ),
      ),
      _Kpi(
        l.statsKpiContentsPerVisit,
        _oneDecimal(_contentsPerVisit(stats)),
        trend: _percentTrend(
          l,
          _contentsPerVisit(stats),
          previous == null ? null : _contentsPerVisit(previous),
        ),
      ),
      if (_channels.contains(AppType.Voice))
        _Kpi(
          l.statsKpiVoiceShare,
          _oneDecimal(_voiceShare(stats)),
          unit: ' %',
          trend: _percentTrend(
            l,
            _voiceShare(stats),
            previous == null ? null : _voiceShare(previous),
          ),
        )
      else
        _Kpi(
          l.statsKpiTotalViews,
          _count(_totalViews(stats)),
          trend: _percentTrend(
            l,
            _totalViews(stats),
            previous == null ? null : _totalViews(previous),
          ),
        ),
    ];
  }

  Widget _kpiRow(AppLocalizations l, StatsSummaryDTO stats, bool wide) {
    return GridView.count(
      shrinkWrap: true,
      physics: const NeverScrollableScrollPhysics(),
      crossAxisCount: wide ? 4 : 2,
      crossAxisSpacing: 12,
      mainAxisSpacing: 12,
      childAspectRatio: wide ? 2.0 : 2.4,
      children: [
        for (final kpi in _kpis(l, stats))
          _kpiCard(
            label: kpi.label,
            value: _valueText(kpi.value, unit: kpi.unit),
            trend: kpi.trend,
          ),
      ],
    );
  }

  Widget _kpiCard({required String label, required Widget value, _Trend? trend}) {
    return Container(
      padding: const EdgeInsets.fromLTRB(17, 15, 17, 16),
      decoration: BoxDecoration(
        color: kWhite,
        border: Border.all(color: _kLine),
        borderRadius: BorderRadius.circular(8),
      ),
      child: Column(
        crossAxisAlignment: CrossAxisAlignment.start,
        mainAxisAlignment: MainAxisAlignment.center,
        children: [
          Text(
            label.toUpperCase(),
            maxLines: 1,
            overflow: TextOverflow.ellipsis,
            style: TextStyle(
              fontSize: 11.5,
              letterSpacing: 0.6,
              color: kBodyTextColor.withValues(alpha: 0.6),
            ),
          ),
          const SizedBox(height: 8),
          value,
          if (trend != null) ...[
            const SizedBox(height: 8),
            Row(
              mainAxisSize: MainAxisSize.min,
              children: [
                Icon(trend.icon, size: 13, color: trend.color),
                const SizedBox(width: 4),
                Flexible(
                  child: Text(
                    trend.label,
                    maxLines: 1,
                    overflow: TextOverflow.ellipsis,
                    style: TextStyle(fontSize: 12, color: trend.color),
                  ),
                ),
              ],
            ),
          ],
        ],
      ),
    );
  }

  Widget _valueText(String value, {String? unit}) {
    return Text.rich(
      TextSpan(
        text: value,
        children: unit == null
            ? null
            : [
                TextSpan(
                  text: unit,
                  style: TextStyle(
                    fontSize: 15,
                    fontWeight: FontWeight.w500,
                    color: kBodyTextColor,
                  ),
                ),
              ],
      ),
      maxLines: 1,
      overflow: TextOverflow.ellipsis,
      style: TextStyle(fontSize: 27, fontWeight: FontWeight.w700, color: kPrimaryColor),
    );
  }

  _Trend? _percentTrend(AppLocalizations l, num value, num? previous) {
    if (previous == null || previous == 0) return null;
    final variation = (value - previous) / previous * 100;
    if (variation.abs() < 3) {
      return _Trend(Icons.remove, l.statsTrendStable, kBodyTextColor.withValues(alpha: 0.6));
    }
    final up = variation > 0;
    return _Trend(
      up ? Icons.arrow_upward : Icons.arrow_downward,
      '${_oneDecimal(variation.abs())} % ${l.statsVsPrevious}',
      up ? _kUp : _kDown,
    );
  }

  _Trend? _durationTrend(AppLocalizations l, int seconds, int? previous) {
    if (previous == null || previous == 0) return null;
    final delta = seconds - previous;
    if (delta.abs() < 5) {
      return _Trend(Icons.remove, l.statsTrendStable, kBodyTextColor.withValues(alpha: 0.6));
    }
    final up = delta > 0;
    return _Trend(
      up ? Icons.arrow_upward : Icons.arrow_downward,
      _formatDuration(delta.abs()),
      up ? _kUp : _kDown,
    );
  }

  Widget _trendCard(AppLocalizations l, StatsSummaryDTO stats) {
    final series = _dailySeries(stats);
    if (series.isEmpty) return const SizedBox();

    final peakIndex = _peakIndex(series);
    final peak = series[peakIndex];
    final maxY = _roundedAxisMax(peak.visits);
    final showWeekends = series.length <= _kMaxDaysForWeekendBands;
    final labelInterval = math.max(1, (series.length / 6).ceil()).toDouble();

    return _card(
      title: l.statsVisitsByDay,
      subtitle: l.statsVisitsByDaySub,
      child: Column(
        crossAxisAlignment: CrossAxisAlignment.start,
        children: [
          SizedBox(
            height: 220,
            child: LineChart(
              LineChartData(
                minX: 0,
                maxX: (series.length - 1).toDouble(),
                minY: 0,
                maxY: maxY,
                clipData: const FlClipData.all(),
                gridData: FlGridData(
                  show: true,
                  drawVerticalLine: false,
                  horizontalInterval: maxY / 2,
                  getDrawingHorizontalLine: (_) =>
                      const FlLine(color: _kLine, strokeWidth: 1),
                ),
                rangeAnnotations: RangeAnnotations(
                  verticalRangeAnnotations: showWeekends
                      ? [
                          for (var i = 0; i < series.length; i++)
                            if (series[i].isWeekend)
                              VerticalRangeAnnotation(
                                x1: i - 0.5,
                                x2: i + 0.5,
                                color: _kTrack.withValues(alpha: 0.7),
                              ),
                        ]
                      : const [],
                ),
                titlesData: FlTitlesData(
                  rightTitles: const AxisTitles(),
                  topTitles: const AxisTitles(),
                  leftTitles: AxisTitles(
                    sideTitles: SideTitles(
                      showTitles: true,
                      reservedSize: 40,
                      interval: maxY / 2,
                      getTitlesWidget: (value, meta) => Padding(
                        padding: const EdgeInsets.only(right: 8),
                        child: Text(
                          _count(value.round()),
                          textAlign: TextAlign.right,
                          style: TextStyle(
                            fontSize: 11,
                            color: kBodyTextColor.withValues(alpha: 0.6),
                          ),
                        ),
                      ),
                    ),
                  ),
                  bottomTitles: AxisTitles(
                    sideTitles: SideTitles(
                      showTitles: true,
                      reservedSize: 26,
                      interval: labelInterval,
                      getTitlesWidget: (value, meta) {
                        final index = value.round();
                        if (index < 0 || index >= series.length) return const SizedBox();
                        return Padding(
                          padding: const EdgeInsets.only(top: 6),
                          child: Text(
                            _shortDate(series[index].date),
                            style: TextStyle(
                              fontSize: 11,
                              color: kBodyTextColor.withValues(alpha: 0.6),
                            ),
                          ),
                        );
                      },
                    ),
                  ),
                ),
                borderData: FlBorderData(show: false),
                lineTouchData: LineTouchData(
                  getTouchedSpotIndicator: (barData, indexes) => indexes
                      .map((_) => TouchedSpotIndicatorData(
                            FlLine(color: kPrimaryColor.withValues(alpha: 0.35), strokeWidth: 1),
                            FlDotData(
                              getDotPainter: (spot, percent, bar, index) =>
                                  FlDotCirclePainter(
                                radius: 4,
                                color: kPrimaryColor,
                                strokeWidth: 2,
                                strokeColor: kWhite,
                              ),
                            ),
                          ))
                      .toList(),
                  touchTooltipData: LineTouchTooltipData(
                    getTooltipColor: (_) => kPrimaryColor,
                    getTooltipItems: (spots) => spots.map((spot) {
                      final point = series[spot.x.round()];
                      return LineTooltipItem(
                        '${_shortDate(point.date)}\n${_count(point.visits)}',
                        const TextStyle(color: kWhite, fontSize: 12, fontWeight: FontWeight.w600),
                      );
                    }).toList(),
                  ),
                ),
                lineBarsData: [
                  LineChartBarData(
                    spots: [
                      for (var i = 0; i < series.length; i++)
                        FlSpot(i.toDouble(), series[i].visits.toDouble()),
                    ],
                    color: kPrimaryColor,
                    barWidth: 2,
                    isCurved: false,
                    dotData: FlDotData(
                      show: true,
                      checkToShowDot: (spot, bar) => spot.x.round() == peakIndex,
                      getDotPainter: (spot, percent, bar, index) => FlDotCirclePainter(
                        radius: 5,
                        color: kWhite,
                        strokeWidth: 2.5,
                        strokeColor: kPrimaryColor,
                      ),
                    ),
                    belowBarData: BarAreaData(
                      show: true,
                      gradient: LinearGradient(
                        begin: Alignment.topCenter,
                        end: Alignment.bottomCenter,
                        colors: [
                          kPrimaryColor.withValues(alpha: 0.28),
                          kPrimaryColor.withValues(alpha: 0.0),
                        ],
                      ),
                    ),
                  ),
                ],
              ),
            ),
          ),
          const SizedBox(height: 12),
          Wrap(
            spacing: 16,
            runSpacing: 6,
            crossAxisAlignment: WrapCrossAlignment.center,
            children: [
              if (showWeekends)
                Row(
                  mainAxisSize: MainAxisSize.min,
                  children: [
                    Container(
                      width: 13,
                      height: 11,
                      decoration: BoxDecoration(
                        color: _kTrack,
                        borderRadius: BorderRadius.circular(2),
                      ),
                    ),
                    const SizedBox(width: 6),
                    Text(l.statsWeekends, style: _captionStyle),
                  ],
                ),
              if (peak.visits > 0)
                Text(
                  l.statsPeakDay(_shortDate(peak.date), _count(peak.visits)),
                  style: _captionStyle,
                ),
            ],
          ),
        ],
      ),
    );
  }

  /// Le rapport reprend l'identité du premier canal actif, l'app mobile en
  /// priorité : `Instance` ne porte ni logo ni couleur, seuls les
  /// `ApplicationInstance` en ont.
  ApplicationInstanceDTO? get _brandingSource {
    final apps = _ctx.instanceDTO?.applicationInstanceDTOs ?? const [];
    if (apps.isEmpty) return null;
    for (final app in apps) {
      if (app.appType == AppType.Mobile) return app;
    }
    return apps.first;
  }

  int _brandArgb() {
    final hex = (_brandingSource?.primaryColor ?? '').replaceAll('#', '').trim();
    if (hex.length == 6) {
      final parsed = int.tryParse('FF$hex', radix: 16);
      if (parsed != null) return parsed;
    }
    return 0xFF264863;
  }

  Future<void> _exportReport(AppLocalizations l, StatsSummaryDTO stats) async {
    setState(() => _exporting = true);
    try {
      final series = _dailySeries(stats);
      final peak = series.isEmpty ? null : series[_peakIndex(series)];
      final interval = math.max(1, (series.length / 6).ceil());

      final channelBars = _channelBars(stats);
      final languageBars = _languageBars(stats);
      final instanceName = _ctx.instanceDTO?.name ?? '';

      final data = StatisticsReportData(
        instanceName: instanceName,
        title: l.statsReportTitle,
        periodLabel: l.statsPeriodRange(_shortDate(_from), _shortDate(_to)),
        takeaways: _takeawaySentences(l, stats),
        kpis: [
          for (final kpi in _kpis(l, stats))
            ReportKpi(kpi.label, '${kpi.value}${kpi.unit ?? ''}', kpi.trend?.label),
        ],
        chartTitle: l.statsVisitsByDay,
        chartSubtitle: l.statsTopContentsSub,
        series: [
          for (final point in series) ReportDayPoint(_shortDate(point.date), point.visits),
        ],
        axisLabels: [
          for (var i = 0; i < series.length; i += interval) i,
        ],
        peakLabel: peak == null || peak.visits == 0
            ? null
            : l.statsPeakDay(_shortDate(peak.date), _count(peak.visits)),
        barGroups: [
          if (stats.topSections.isNotEmpty)
            _reportBarGroup(l.statsTopContents, l.statsTopContentsSub, _contentBars(stats)),
          if (channelBars.isNotEmpty)
            _reportBarGroup(l.statsChannels, l.statsChannelsSub, channelBars),
          if (languageBars.isNotEmpty)
            _reportBarGroup(l.statsLanguages, l.statsLanguagesSub, languageBars),
        ],
        tables: [
          for (final table in _advancedTables(l, stats))
            ReportTable(table.title, table.headers, table.rows),
        ],
        generatedLabel: l.statsReportGenerated(_shortDate(DateTime.now())),
        brandArgb: _brandArgb(),
        logo: await fetchReportLogo(_brandingSource?.mainImageUrl),
      );

      PDFHelper.downloadBytes(
        await buildStatisticsReport(data),
        _reportFileName(l, instanceName),
      );
    } catch (_) {
      if (!mounted) return;
      ScaffoldMessenger.of(context).showSnackBar(
        SnackBar(content: Text(l.statsReportError), backgroundColor: Colors.redAccent),
      );
    } finally {
      if (mounted) setState(() => _exporting = false);
    }
  }

  ReportBarGroup _reportBarGroup(String title, String subtitle, List<_Bar> bars) {
    final max = bars.map((bar) => bar.value).reduce(math.max);
    return ReportBarGroup(title, subtitle, [
      for (final bar in bars)
        ReportBar(bar.label, _count(bar.value), max == 0 ? 0 : bar.value / max),
    ]);
  }

  String _reportFileName(AppLocalizations l, String instanceName) {
    final date = '${_to.year}-${_to.month.toString().padLeft(2, '0')}-'
        '${_to.day.toString().padLeft(2, '0')}';
    final slug = '$instanceName ${l.statsAttendanceTitle} $date'
        .toLowerCase()
        .replaceAll(RegExp(r'[^a-z0-9]+'), '-')
        .replaceAll(RegExp(r'^-+|-+$'), '');
    return slug.isEmpty ? 'rapport' : slug;
  }

  int _peakIndex(List<_DayPoint> series) {
    var index = 0;
    for (var i = 1; i < series.length; i++) {
      if (series[i].visits > series[index].visits) index = i;
    }
    return index;
  }

  /// Arrondit le haut de l'axe pour que les deux graduations tombent sur des
  /// nombres ronds (0 / moitié / max).
  double _roundedAxisMax(int peak) {
    if (peak <= 4) return 4;
    final magnitude = math.pow(10, (math.log(peak) / math.ln10).floor()).toDouble();
    for (final step in const [1.0, 2.0, 4.0, 10.0]) {
      final candidate = magnitude * step;
      if (candidate >= peak) return candidate;
    }
    return magnitude * 10;
  }

  /// Contenus à gauche, canaux et langues à droite. Barres horizontales partout,
  /// une seule teinte : toutes mesurent un nombre de visites, c'est la longueur
  /// qui porte l'information.
  List<_Bar> _contentBars(StatsSummaryDTO stats) => [
        for (final section in stats.topSections.take(8))
          _Bar(_plainTitle(section.sectionTitle, section.sectionId), section.views),
      ];

  /// Un graphe à une seule barre à 100 % ne dit rien : ni en mono-canal, ni
  /// quand l'écran est déjà filtré sur un canal.
  List<_Bar> _channelBars(StatsSummaryDTO stats) {
    if (!_isMultiChannel || _selectedChannel != null) return const [];
    return [
      for (final channel in _channels)
        if ((stats.appTypeDistribution[channel.name] ?? 0) > 0)
          _Bar(_channelLabel(channel), stats.appTypeDistribution[channel.name]!),
    ];
  }

  List<_Bar> _languageBars(StatsSummaryDTO stats) => [
        for (final entry in _sortedEntries(stats.languageDistribution))
          _Bar(entry.key.toUpperCase(), entry.value),
      ];

  Widget _distributionRow(AppLocalizations l, StatsSummaryDTO stats, bool wide) {
    final contents = _card(
      title: l.statsTopContents,
      subtitle: l.statsTopContentsSub,
      child: _bars(_contentBars(stats)),
    );

    final channelBars = _channelBars(stats);
    final languageBars = _languageBars(stats);

    final side = <Widget>[
      if (channelBars.isNotEmpty)
        _card(
          title: l.statsChannels,
          subtitle: l.statsChannelsSub,
          child: _bars(channelBars),
        ),
      if (languageBars.isNotEmpty)
        _card(
          title: l.statsLanguages,
          subtitle: l.statsLanguagesSub,
          child: _bars(languageBars),
        ),
    ];

    if (stats.topSections.isEmpty && side.isEmpty) return const SizedBox();

    final sideColumn = Column(
      crossAxisAlignment: CrossAxisAlignment.stretch,
      children: [
        for (final card in side)
          Padding(
            padding: EdgeInsets.only(bottom: card == side.last ? 0 : 16),
            child: card,
          ),
      ],
    );

    if (!wide) {
      return Column(
        crossAxisAlignment: CrossAxisAlignment.stretch,
        children: [
          if (stats.topSections.isNotEmpty) ...[contents, const SizedBox(height: 16)],
          sideColumn,
        ],
      );
    }

    if (side.isEmpty) return contents;
    if (stats.topSections.isEmpty) return sideColumn;

    return Row(
      crossAxisAlignment: CrossAxisAlignment.start,
      children: [
        Expanded(flex: 135, child: contents),
        const SizedBox(width: 16),
        Expanded(flex: 100, child: sideColumn),
      ],
    );
  }

  List<MapEntry<String, int>> _sortedEntries(Map<String, int> data) {
    final entries = data.entries.toList()..sort((a, b) => b.value.compareTo(a.value));
    return entries;
  }

  Widget _bars(List<_Bar> bars) {
    if (bars.isEmpty) return const SizedBox();
    final max = bars.map((bar) => bar.value).reduce(math.max);

    return Column(
      crossAxisAlignment: CrossAxisAlignment.stretch,
      children: [
        for (final bar in bars)
          Padding(
            padding: EdgeInsets.only(bottom: bar == bars.last ? 0 : 11),
            child: Column(
              crossAxisAlignment: CrossAxisAlignment.stretch,
              children: [
                Row(
                  crossAxisAlignment: CrossAxisAlignment.end,
                  children: [
                    Expanded(
                      child: Text(
                        bar.label,
                        maxLines: 2,
                        overflow: TextOverflow.ellipsis,
                        style: TextStyle(fontSize: 13.5, color: kBodyTextColor),
                      ),
                    ),
                    const SizedBox(width: 10),
                    Text(
                      _count(bar.value),
                      style: TextStyle(
                        fontSize: 12.5,
                        fontWeight: FontWeight.w600,
                        color: kBodyTextColor.withValues(alpha: 0.8),
                      ),
                    ),
                  ],
                ),
                const SizedBox(height: 5),
                ClipRRect(
                  borderRadius: BorderRadius.circular(4),
                  child: LinearProgressIndicator(
                    value: max == 0 ? 0 : bar.value / max,
                    minHeight: 9,
                    backgroundColor: _kTrack,
                    color: kPrimaryColor,
                  ),
                ),
              ],
            ),
          ),
      ],
    );
  }

  List<_TableData> _advancedTables(AppLocalizations l, StatsSummaryDTO stats) {
    if (!_hasAdvancedStats) return const [];

    return [
      if (stats.topPois.isNotEmpty)
        _TableData(l.statsTopPOI, [l.statsPOI, l.statsTaps], [
          for (final poi in stats.topPois)
            [_plainTitle(poi.title, poi.geoPointId?.toString()), _count(poi.taps)],
        ]),
      if (stats.topAgendaEvents.isNotEmpty)
        _TableData(l.statsTopAgenda, [l.statsEvent, l.statsTaps], [
          for (final event in stats.topAgendaEvents)
            [_plainTitle(event.eventTitle, event.eventId), _count(event.taps)],
        ]),
      if (stats.quizStats.isNotEmpty)
        _TableData(l.statsQuiz, [l.statsSection, l.statsAvgScore, l.statsCompletions], [
          for (final quiz in stats.quizStats)
            [
              _plainTitle(quiz.sectionTitle, quiz.sectionId),
              '${_oneDecimal(quiz.avgScore)} / ${quiz.totalQuestions}',
              _count(quiz.completions),
            ],
        ]),
      if (stats.gameStats.isNotEmpty)
        _TableData(l.statsGames, [l.statsGameType, l.statsCompletions, l.statsAvgDuration], [
          for (final game in stats.gameStats)
            [
              game.gameType ?? '—',
              _count(game.completions),
              _formatDuration(game.avgDurationSeconds),
            ],
        ]),
      if (stats.topArticles.isNotEmpty)
        _TableData(l.statsArticles, [l.statsSection, l.statsReadings], [
          for (final article in stats.topArticles)
            [article.sectionId ?? '—', _count(article.reads)],
        ]),
      if (stats.topMenuItems.isNotEmpty)
        _TableData(l.statsMenuTitle, [l.statsMenuItem, l.statsTaps], [
          for (final item in stats.topMenuItems)
            [_plainTitle(item.menuItemTitle, item.targetSectionId), _count(item.taps)],
        ]),
      if (stats.qrScans.totalScans > 0)
        _TableData(l.statsQrScans, [l.statsTotal, l.statsViews], [
          [l.statsTotal, _count(stats.qrScans.totalScans)],
          [l.statsValid, _count(stats.qrScans.validScans)],
          [l.statsInvalid, _count(stats.qrScans.invalidScans)],
        ]),
    ];
  }

  Widget _advancedSection(AppLocalizations l, StatsSummaryDTO stats) {
    if (!_hasAdvancedStats) {
      return Padding(
        padding: const EdgeInsets.only(bottom: 16),
        child: _lockedCard(l),
      );
    }

    final tables = _advancedTables(l, stats);
    if (tables.isEmpty) return const SizedBox();

    return Padding(
      padding: const EdgeInsets.only(bottom: 16),
      child: Wrap(
        spacing: 16,
        runSpacing: 16,
        children: [
          for (final table in tables)
            SizedBox(width: 340, child: _tableCard(table.title, table.headers, table.rows)),
        ],
      ),
    );
  }

  /// Le rapport se montre comme le document qu'on va envoyer, pas comme un bouton :
  /// c'est ce qui transforme l'écran en livrable pour un dossier de subside.
  Widget _reportCard(AppLocalizations l, StatsSummaryDTO stats) {
    final bullets = [
      l.statsReportItemAttendance,
      l.statsReportItemContents,
      l.statsReportItemChannels,
      if (_hasAdvancedStats) l.statsReportItemAdvanced,
    ];

    return Container(
      padding: const EdgeInsets.all(20),
      decoration: BoxDecoration(
        color: kWhite,
        border: Border.all(color: kPrimaryColor),
        borderRadius: BorderRadius.circular(8),
      ),
      child: Row(
        crossAxisAlignment: CrossAxisAlignment.start,
        children: [
          _documentPreview(),
          const SizedBox(width: 20),
          Expanded(
            child: Column(
              crossAxisAlignment: CrossAxisAlignment.start,
              children: [
                Text(
                  l.statsReportTitle,
                  style: TextStyle(fontSize: 15, fontWeight: FontWeight.w700, color: kPrimaryColor),
                ),
                const SizedBox(height: 5),
                Text(
                  l.statsReportBody,
                  style: TextStyle(fontSize: 13.5, color: kBodyTextColor),
                ),
                const SizedBox(height: 12),
                for (final bullet in bullets)
                  Padding(
                    padding: const EdgeInsets.only(bottom: 3),
                    child: Row(
                      crossAxisAlignment: CrossAxisAlignment.start,
                      children: [
                        Text('•  ', style: _captionStyle),
                        Expanded(child: Text(bullet, style: _captionStyle)),
                      ],
                    ),
                  ),
                const SizedBox(height: 14),
                FilledButton.icon(
                  onPressed: _exporting ? null : () => _exportReport(l, stats),
                  icon: _exporting
                      ? const SizedBox(
                          width: 15,
                          height: 15,
                          child: CircularProgressIndicator(strokeWidth: 2, color: kWhite),
                        )
                      : const Icon(Icons.download_outlined, size: 17),
                  label: Text(l.statsReportDownload),
                  style: FilledButton.styleFrom(backgroundColor: kPrimaryColor),
                ),
              ],
            ),
          ),
        ],
      ),
    );
  }

  Widget _documentPreview() {
    Widget line(double widthFactor) => FractionallySizedBox(
          alignment: Alignment.centerLeft,
          widthFactor: widthFactor,
          child: Container(
            height: 4,
            margin: const EdgeInsets.only(bottom: 5),
            decoration: BoxDecoration(
              color: _kTrack,
              borderRadius: BorderRadius.circular(2),
            ),
          ),
        );

    return Container(
      width: 108,
      padding: const EdgeInsets.symmetric(horizontal: 11, vertical: 13),
      decoration: BoxDecoration(
        color: kWhite,
        border: Border.all(color: _kLine),
        borderRadius: BorderRadius.circular(4),
        boxShadow: const [
          BoxShadow(color: _kTrack, blurRadius: 8, offset: Offset(0, 2)),
        ],
      ),
      child: Column(
        crossAxisAlignment: CrossAxisAlignment.stretch,
        children: [
          Container(
            height: 16,
            margin: const EdgeInsets.only(bottom: 9),
            decoration: BoxDecoration(
              color: kPrimaryColor,
              borderRadius: BorderRadius.circular(2),
            ),
          ),
          line(0.84),
          line(1),
          line(0.62),
          Container(
            height: 26,
            margin: const EdgeInsets.only(top: 4, bottom: 7),
            decoration: BoxDecoration(
              color: kPrimaryColor.withValues(alpha: 0.14),
              borderRadius: BorderRadius.circular(3),
            ),
          ),
          line(1),
          line(0.84),
          line(0.62),
        ],
      ),
    );
  }

  Widget _lockedCard(AppLocalizations l) {
    return Container(
      padding: const EdgeInsets.all(20),
      decoration: BoxDecoration(
        color: _kMuted,
        border: Border.all(color: _kLine),
        borderRadius: BorderRadius.circular(8),
      ),
      child: Row(
        children: [
          Icon(Icons.lock_outline, color: kBodyTextColor.withValues(alpha: 0.5), size: 26),
          const SizedBox(width: 16),
          Expanded(
            child: Column(
              crossAxisAlignment: CrossAxisAlignment.start,
              children: [
                Text(
                  l.statsAdvancedTitle,
                  style: TextStyle(fontSize: 15, fontWeight: FontWeight.w600, color: kPrimaryColor),
                ),
                const SizedBox(height: 4),
                Text(l.statsAdvancedBody, style: TextStyle(fontSize: 13, color: kBodyTextColor)),
              ],
            ),
          ),
        ],
      ),
    );
  }

  Widget _card({required String title, String? subtitle, required Widget child}) {
    return Container(
      padding: const EdgeInsets.fromLTRB(19, 18, 19, 20),
      decoration: BoxDecoration(
        color: kWhite,
        border: Border.all(color: _kLine),
        borderRadius: BorderRadius.circular(8),
      ),
      child: Column(
        crossAxisAlignment: CrossAxisAlignment.start,
        children: [
          Text(
            title,
            style: TextStyle(fontSize: 14.5, fontWeight: FontWeight.w700, color: kPrimaryColor),
          ),
          if (subtitle != null) ...[
            const SizedBox(height: 2),
            Text(subtitle, style: _captionStyle),
          ],
          const SizedBox(height: 16),
          child,
        ],
      ),
    );
  }

  Widget _tableCard(String title, List<String> headers, List<List<String>> rows) {
    return _card(
      title: title,
      child: Table(
        columnWidths: const {0: FlexColumnWidth(2), 1: FlexColumnWidth(1)},
        children: [
          TableRow(
            decoration: const BoxDecoration(border: Border(bottom: BorderSide(color: _kLine))),
            children: headers
                .map((header) => Padding(
                      padding: const EdgeInsets.only(bottom: 8),
                      child: Text(
                        header,
                        style: TextStyle(
                          fontSize: 12,
                          fontWeight: FontWeight.w600,
                          color: kBodyTextColor.withValues(alpha: 0.7),
                        ),
                      ),
                    ))
                .toList(),
          ),
          for (final row in rows)
            TableRow(
              children: row
                  .map((cell) => Padding(
                        padding: const EdgeInsets.symmetric(vertical: 6),
                        child: Text(
                          cell,
                          maxLines: 1,
                          overflow: TextOverflow.ellipsis,
                          style: TextStyle(fontSize: 13, color: kBodyTextColor),
                        ),
                      ))
                  .toList(),
            ),
        ],
      ),
    );
  }

  Widget _emptyMessage(IconData icon, String title, String? detail) {
    return Center(
      child: Column(
        mainAxisAlignment: MainAxisAlignment.center,
        children: [
          Icon(icon, size: 52, color: kBodyTextColor.withValues(alpha: 0.4)),
          const SizedBox(height: 16),
          Text(title, style: TextStyle(fontSize: 15, color: kBodyTextColor)),
          if (detail != null) ...[
            const SizedBox(height: 8),
            Text(
              detail,
              textAlign: TextAlign.center,
              style: TextStyle(fontSize: 13, color: kBodyTextColor.withValues(alpha: 0.6)),
            ),
          ],
        ],
      ),
    );
  }

  TextStyle get _captionStyle =>
      TextStyle(fontSize: 12.5, color: kBodyTextColor.withValues(alpha: 0.65));
}

class _DayPoint {
  const _DayPoint(this.date, this.visits);

  final DateTime date;
  final int visits;

  bool get isWeekend =>
      date.weekday == DateTime.saturday || date.weekday == DateTime.sunday;
}

class _Bar {
  const _Bar(this.label, this.value);

  final String label;
  final int value;
}

class _Kpi {
  const _Kpi(this.label, this.value, {this.unit, this.trend});

  final String label;
  final String value;
  final String? unit;
  final _Trend? trend;
}

class _TableData {
  const _TableData(this.title, this.headers, this.rows);

  final String title;
  final List<String> headers;
  final List<List<String>> rows;
}

class _Trend {
  const _Trend(this.icon, this.label, this.color);

  final IconData icon;
  final String label;
  final Color color;
}