import 'package:flutter/material.dart';
import 'package:hooks_riverpod/hooks_riverpod.dart';

import '../manager/analysis_chart_metric.dart';
import '../manager/analysis_range.dart';
import '../manager/analysis_ui_state.dart';
import '../manager/analysis_view_model.dart';
import '../widgets/analysis_line_chart.dart';

class AnalysisPage extends ConsumerWidget {
  const AnalysisPage({super.key});

  @override
  Widget build(BuildContext context, WidgetRef ref) {
    final theme = Theme.of(context);
    final rangePreset = ref.watch(analysisRangeNotifierProvider);
    final chartMetric = ref.watch(analysisChartMetricNotifierProvider);
    final stateAsync = ref.watch(analysisViewModelProvider);

    return Scaffold(
      backgroundColor: theme.scaffoldBackgroundColor,
      appBar: AppBar(
        title: const Text('Cashier Analysis'),
        backgroundColor: theme.scaffoldBackgroundColor,
        surfaceTintColor: theme.scaffoldBackgroundColor,
        elevation: 0,
        scrolledUnderElevation: 0,
      ),
      body: RefreshIndicator(
        onRefresh: () async => ref.invalidate(analysisViewModelProvider),
        child: ListView(
          physics: const AlwaysScrollableScrollPhysics(),
          padding: const EdgeInsets.fromLTRB(16, 8, 16, 96),
          children: [
            _RangeSelector(
              selected: rangePreset,
              onSelected: (preset) => ref
                  .read(analysisRangeNotifierProvider.notifier)
                  .setRange(preset),
            ),
            const SizedBox(height: 12),
            stateAsync.when(
              data: (state) => _AnalysisBody(
                state: state,
                chartMetric: chartMetric,
                onMetricSelected: (metric) => ref
                    .read(analysisChartMetricNotifierProvider.notifier)
                    .setMetric(metric),
              ),
              loading: () => const _LoadingBody(),
              error: (error, stackTrace) => _ErrorBody(
                onRetry: () => ref.invalidate(analysisViewModelProvider),
              ),
            ),
          ],
        ),
      ),
    );
  }
}

class _RangeSelector extends StatelessWidget {
  const _RangeSelector({required this.selected, required this.onSelected});

  final AnalysisRangePreset selected;
  final ValueChanged<AnalysisRangePreset> onSelected;

  @override
  Widget build(BuildContext context) {
    return SegmentedButton<AnalysisRangePreset>(
      showSelectedIcon: false,
      segments: AnalysisRangePreset.values
          .map(
            (preset) => ButtonSegment(value: preset, label: Text(preset.label)),
          )
          .toList(growable: false),
      selected: <AnalysisRangePreset>{selected},
      onSelectionChanged: (selection) {
        if (selection.isEmpty) return;
        onSelected(selection.first);
      },
    );
  }
}

class _AnalysisBody extends StatelessWidget {
  const _AnalysisBody({
    required this.state,
    required this.chartMetric,
    required this.onMetricSelected,
  });

  final AnalysisUiState state;
  final AnalysisChartMetric chartMetric;
  final ValueChanged<AnalysisChartMetric> onMetricSelected;

  @override
  Widget build(BuildContext context) {
    final summary = state.summary ?? AnalysisSummaryUiModel.empty;
    final series = state.series ?? const <AnalysisSeriesPointUiModel>[];
    final values = series
        .map(
          (p) => switch (chartMetric) {
            AnalysisChartMetric.scans => p.scanCount.toDouble(),
            AnalysisChartMetric.pointsUsed => p.pointsUsed.toDouble(),
          },
        )
        .toList(growable: false);
    final totalValue = switch (chartMetric) {
      AnalysisChartMetric.scans => summary.scans,
      AnalysisChartMetric.pointsUsed => summary.pointsUsed,
    };

    return Column(
      crossAxisAlignment: CrossAxisAlignment.start,
      children: [
        _ShiftSummaryCard(state: state),
        const SizedBox(height: 12),
        _CashierActionGrid(summary: summary, state: state),
        const SizedBox(height: 12),
        _ChartCard(
          selectedMetric: chartMetric,
          onMetricSelected: onMetricSelected,
          totalValue: totalValue,
          rangeLabel: state.rangeLabel ?? '',
          chart: AnalysisLineChart(values: values, height: 132),
          xLabels: series.map((p) => p.label).toList(growable: false),
        ),
        const SizedBox(height: 12),
        _OperationalNotes(state: state),
      ],
    );
  }
}

class _ShiftSummaryCard extends StatelessWidget {
  const _ShiftSummaryCard({required this.state});

  final AnalysisUiState state;

  @override
  Widget build(BuildContext context) {
    final colorScheme = Theme.of(context).colorScheme;
    final textTheme = Theme.of(context).textTheme;
    final summary = state.summary ?? AnalysisSummaryUiModel.empty;
    final pointsPerScan = state.pointsPerScan ?? 0;

    return Container(
      decoration: _cardDecoration(context),
      child: Padding(
        padding: const EdgeInsets.all(16),
        child: Column(
          crossAxisAlignment: CrossAxisAlignment.start,
          children: [
            Row(
              crossAxisAlignment: CrossAxisAlignment.start,
              children: [
                Container(
                  width: 44,
                  height: 44,
                  decoration: BoxDecoration(
                    color: colorScheme.primaryContainer,
                    borderRadius: BorderRadius.circular(8),
                  ),
                  alignment: Alignment.center,
                  child: Icon(
                    Icons.point_of_sale_rounded,
                    color: colorScheme.onPrimaryContainer,
                  ),
                ),
                const SizedBox(width: 12),
                Expanded(
                  child: Column(
                    crossAxisAlignment: CrossAxisAlignment.start,
                    children: [
                      Text(
                        'Loyalty counter',
                        style: textTheme.labelLarge?.copyWith(
                          color: colorScheme.onSurfaceVariant,
                          fontWeight: FontWeight.w700,
                        ),
                      ),
                      const SizedBox(height: 2),
                      Text(
                        state.rangeLabel ?? 'Selected range',
                        style: textTheme.titleLarge?.copyWith(
                          fontWeight: FontWeight.w900,
                        ),
                      ),
                    ],
                  ),
                ),
                _StatusPill(
                  label: '${summary.successRatePercent}% success',
                  icon: Icons.verified_rounded,
                ),
              ],
            ),
            const SizedBox(height: 18),
            Row(
              children: [
                Expanded(
                  child: _HeroMetric(
                    label: 'Member scans',
                    value: summary.scans.toString(),
                    icon: Icons.qr_code_scanner_rounded,
                  ),
                ),
                const SizedBox(width: 12),
                Expanded(
                  child: _HeroMetric(
                    label: 'Points redeemed',
                    value: summary.pointsUsed.toString(),
                    icon: Icons.redeem_rounded,
                  ),
                ),
              ],
            ),
            const SizedBox(height: 12),
            _InlineStatBar(
              items: [
                _InlineStatItem(
                  label: 'Active members',
                  value: summary.activeUsers.toString(),
                ),
                _InlineStatItem(
                  label: 'Coins/scan',
                  value: pointsPerScan.toStringAsFixed(1),
                ),
                _InlineStatItem(
                  label: 'Range users',
                  value: summary.users.toString(),
                ),
              ],
            ),
          ],
        ),
      ),
    );
  }
}

class _CashierActionGrid extends StatelessWidget {
  const _CashierActionGrid({required this.summary, required this.state});

  final AnalysisSummaryUiModel summary;
  final AnalysisUiState state;

  @override
  Widget build(BuildContext context) {
    final averageScansPerDay = state.averageScansPerDay ?? 0;
    final averagePointsPerDay = state.averagePointsPerDay ?? 0;
    final activeUserRatePercent = state.activeUserRatePercent ?? 0;

    return LayoutBuilder(
      builder: (context, constraints) {
        final tileWidth = (constraints.maxWidth - 10) / 2;

        return Wrap(
          spacing: 10,
          runSpacing: 10,
          children: [
            _ActionMetricTile(
              width: tileWidth,
              title: 'Avg scans/day',
              value: averageScansPerDay.toStringAsFixed(1),
              icon: Icons.timeline_rounded,
            ),
            _ActionMetricTile(
              width: tileWidth,
              title: 'Avg coins/day',
              value: averagePointsPerDay.toStringAsFixed(1),
              icon: Icons.savings_rounded,
            ),
            _ActionMetricTile(
              width: tileWidth,
              title: 'Active rate',
              value: '$activeUserRatePercent%',
              icon: Icons.people_alt_rounded,
            ),
            _ActionMetricTile(
              width: tileWidth,
              title: 'Scan issues',
              value: _failedScanCount(summary).toString(),
              icon: Icons.error_outline_rounded,
            ),
          ],
        );
      },
    );
  }

  int _failedScanCount(AnalysisSummaryUiModel summary) {
    final failed = summary.scans * (100 - summary.successRatePercent) / 100;
    return failed.round().clamp(0, summary.scans).toInt();
  }
}

class _ChartCard extends StatelessWidget {
  const _ChartCard({
    required this.selectedMetric,
    required this.onMetricSelected,
    required this.totalValue,
    required this.rangeLabel,
    required this.chart,
    required this.xLabels,
  });

  final AnalysisChartMetric selectedMetric;
  final ValueChanged<AnalysisChartMetric> onMetricSelected;
  final int totalValue;
  final String rangeLabel;
  final Widget chart;
  final List<String> xLabels;

  @override
  Widget build(BuildContext context) {
    final colorScheme = Theme.of(context).colorScheme;
    final textTheme = Theme.of(context).textTheme;

    return Container(
      decoration: _cardDecoration(context),
      child: Padding(
        padding: const EdgeInsets.fromLTRB(16, 14, 16, 14),
        child: Column(
          crossAxisAlignment: CrossAxisAlignment.start,
          children: [
            Row(
              crossAxisAlignment: CrossAxisAlignment.start,
              children: [
                Expanded(
                  child: Column(
                    crossAxisAlignment: CrossAxisAlignment.start,
                    children: [
                      Text(
                        'Counter trend',
                        style: textTheme.titleMedium?.copyWith(
                          fontWeight: FontWeight.w800,
                        ),
                      ),
                      const SizedBox(height: 2),
                      Text(
                        rangeLabel,
                        style: textTheme.bodySmall?.copyWith(
                          color: colorScheme.onSurfaceVariant,
                        ),
                      ),
                    ],
                  ),
                ),
                Text(
                  totalValue.toString(),
                  style: textTheme.headlineSmall?.copyWith(
                    fontWeight: FontWeight.w900,
                  ),
                ),
              ],
            ),
            const SizedBox(height: 12),
            _ChartMetricSelector(
              selected: selectedMetric,
              onSelected: onMetricSelected,
            ),
            const SizedBox(height: 14),
            chart,
            if (xLabels.isNotEmpty) ...[
              const SizedBox(height: 10),
              _XAxisLabels(labels: xLabels),
            ],
          ],
        ),
      ),
    );
  }
}

class _ChartMetricSelector extends StatelessWidget {
  const _ChartMetricSelector({
    required this.selected,
    required this.onSelected,
  });

  final AnalysisChartMetric selected;
  final ValueChanged<AnalysisChartMetric> onSelected;

  @override
  Widget build(BuildContext context) {
    return SegmentedButton<AnalysisChartMetric>(
      showSelectedIcon: false,
      segments: AnalysisChartMetric.values
          .map(
            (metric) => ButtonSegment(value: metric, label: Text(metric.label)),
          )
          .toList(growable: false),
      selected: <AnalysisChartMetric>{selected},
      onSelectionChanged: (selection) {
        if (selection.isEmpty) return;
        onSelected(selection.first);
      },
    );
  }
}

class _OperationalNotes extends StatelessWidget {
  const _OperationalNotes({required this.state});

  final AnalysisUiState state;

  @override
  Widget build(BuildContext context) {
    final summary = state.summary ?? AnalysisSummaryUiModel.empty;
    final colorScheme = Theme.of(context).colorScheme;
    final textTheme = Theme.of(context).textTheme;
    final pointsPerScan = state.pointsPerScan ?? 0;
    final successRate = summary.successRatePercent;
    final needsScanCheck = successRate < 98;
    final hasHighRedemption = pointsPerScan >= 1.2;

    return Container(
      decoration: _cardDecoration(context),
      child: Padding(
        padding: const EdgeInsets.all(16),
        child: Column(
          crossAxisAlignment: CrossAxisAlignment.start,
          children: [
            Text(
              'Cashier notes',
              style: textTheme.titleMedium?.copyWith(
                fontWeight: FontWeight.w800,
              ),
            ),
            const SizedBox(height: 12),
            _NoteRow(
              icon: needsScanCheck
                  ? Icons.build_circle_rounded
                  : Icons.check_circle_rounded,
              title: needsScanCheck ? 'Check QR retry flow' : 'QR scans stable',
              body: needsScanCheck
                  ? 'Success is below target. Confirm lighting and member QR focus at the counter.'
                  : 'Scan success is within the expected cashier range.',
            ),
            Divider(height: 24, color: colorScheme.outlineVariant),
            _NoteRow(
              icon: hasHighRedemption
                  ? Icons.local_offer_rounded
                  : Icons.payments_rounded,
              title: hasHighRedemption
                  ? 'Redemption demand is high'
                  : 'Redemption pace is normal',
              body: hasHighRedemption
                  ? 'Keep reward terms visible before checkout to reduce voids.'
                  : 'Coin use is tracking cleanly against member scans.',
            ),
          ],
        ),
      ),
    );
  }
}

class _HeroMetric extends StatelessWidget {
  const _HeroMetric({
    required this.label,
    required this.value,
    required this.icon,
  });

  final String label;
  final String value;
  final IconData icon;

  @override
  Widget build(BuildContext context) {
    final colorScheme = Theme.of(context).colorScheme;
    final textTheme = Theme.of(context).textTheme;

    return Container(
      constraints: const BoxConstraints(minHeight: 104),
      padding: const EdgeInsets.all(12),
      decoration: BoxDecoration(
        color: colorScheme.surfaceContainerHighest.withOpacity(0.42),
        borderRadius: BorderRadius.circular(8),
      ),
      child: Column(
        crossAxisAlignment: CrossAxisAlignment.start,
        children: [
          Icon(icon, color: colorScheme.primary, size: 22),
          const SizedBox(height: 10),
          Text(
            value,
            maxLines: 1,
            overflow: TextOverflow.ellipsis,
            style: textTheme.headlineSmall?.copyWith(
              fontWeight: FontWeight.w900,
            ),
          ),
          const SizedBox(height: 2),
          Text(
            label,
            maxLines: 2,
            overflow: TextOverflow.ellipsis,
            style: textTheme.bodySmall?.copyWith(
              color: colorScheme.onSurfaceVariant,
              fontWeight: FontWeight.w600,
            ),
          ),
        ],
      ),
    );
  }
}

class _ActionMetricTile extends StatelessWidget {
  const _ActionMetricTile({
    required this.width,
    required this.title,
    required this.value,
    required this.icon,
  });

  final double width;
  final String title;
  final String value;
  final IconData icon;

  @override
  Widget build(BuildContext context) {
    final colorScheme = Theme.of(context).colorScheme;
    final textTheme = Theme.of(context).textTheme;

    return SizedBox(
      width: width,
      child: Container(
        constraints: const BoxConstraints(minHeight: 96),
        decoration: _cardDecoration(context),
        child: Padding(
          padding: const EdgeInsets.all(12),
          child: Row(
            crossAxisAlignment: CrossAxisAlignment.start,
            children: [
              Container(
                width: 36,
                height: 36,
                decoration: BoxDecoration(
                  color: colorScheme.primaryContainer,
                  borderRadius: BorderRadius.circular(8),
                ),
                alignment: Alignment.center,
                child: Icon(
                  icon,
                  color: colorScheme.onPrimaryContainer,
                  size: 20,
                ),
              ),
              const SizedBox(width: 10),
              Expanded(
                child: Column(
                  crossAxisAlignment: CrossAxisAlignment.start,
                  children: [
                    Text(
                      value,
                      maxLines: 1,
                      overflow: TextOverflow.ellipsis,
                      style: textTheme.titleLarge?.copyWith(
                        fontWeight: FontWeight.w900,
                      ),
                    ),
                    const SizedBox(height: 2),
                    Text(
                      title,
                      maxLines: 2,
                      overflow: TextOverflow.ellipsis,
                      style: textTheme.bodySmall?.copyWith(
                        color: colorScheme.onSurfaceVariant,
                        fontWeight: FontWeight.w600,
                      ),
                    ),
                  ],
                ),
              ),
            ],
          ),
        ),
      ),
    );
  }
}

class _InlineStatBar extends StatelessWidget {
  const _InlineStatBar({required this.items});

  final List<_InlineStatItem> items;

  @override
  Widget build(BuildContext context) {
    final colorScheme = Theme.of(context).colorScheme;

    return Container(
      padding: const EdgeInsets.symmetric(vertical: 10),
      decoration: BoxDecoration(
        border: Border(
          top: BorderSide(color: colorScheme.outlineVariant.withOpacity(0.7)),
        ),
      ),
      child: Row(
        children: [
          for (var i = 0; i < items.length; i++) ...[
            if (i > 0)
              SizedBox(
                height: 34,
                child: VerticalDivider(
                  width: 16,
                  color: colorScheme.outlineVariant,
                ),
              ),
            Expanded(child: items[i]),
          ],
        ],
      ),
    );
  }
}

class _InlineStatItem extends StatelessWidget {
  const _InlineStatItem({required this.label, required this.value});

  final String label;
  final String value;

  @override
  Widget build(BuildContext context) {
    final colorScheme = Theme.of(context).colorScheme;
    final textTheme = Theme.of(context).textTheme;

    return Column(
      crossAxisAlignment: CrossAxisAlignment.start,
      children: [
        Text(
          value,
          maxLines: 1,
          overflow: TextOverflow.ellipsis,
          style: textTheme.titleSmall?.copyWith(fontWeight: FontWeight.w900),
        ),
        const SizedBox(height: 2),
        Text(
          label,
          maxLines: 2,
          overflow: TextOverflow.ellipsis,
          style: textTheme.labelSmall?.copyWith(
            color: colorScheme.onSurfaceVariant,
          ),
        ),
      ],
    );
  }
}

class _StatusPill extends StatelessWidget {
  const _StatusPill({required this.label, required this.icon});

  final String label;
  final IconData icon;

  @override
  Widget build(BuildContext context) {
    final colorScheme = Theme.of(context).colorScheme;
    final textTheme = Theme.of(context).textTheme;

    return Container(
      padding: const EdgeInsets.symmetric(horizontal: 10, vertical: 7),
      decoration: BoxDecoration(
        color: colorScheme.secondaryContainer.withOpacity(0.78),
        borderRadius: BorderRadius.circular(8),
      ),
      child: Row(
        mainAxisSize: MainAxisSize.min,
        children: [
          Icon(icon, size: 15, color: colorScheme.onSecondaryContainer),
          const SizedBox(width: 5),
          Text(
            label,
            style: textTheme.labelMedium?.copyWith(
              color: colorScheme.onSecondaryContainer,
              fontWeight: FontWeight.w800,
            ),
          ),
        ],
      ),
    );
  }
}

class _NoteRow extends StatelessWidget {
  const _NoteRow({required this.icon, required this.title, required this.body});

  final IconData icon;
  final String title;
  final String body;

  @override
  Widget build(BuildContext context) {
    final colorScheme = Theme.of(context).colorScheme;
    final textTheme = Theme.of(context).textTheme;

    return Row(
      crossAxisAlignment: CrossAxisAlignment.start,
      children: [
        Icon(icon, color: colorScheme.primary, size: 22),
        const SizedBox(width: 10),
        Expanded(
          child: Column(
            crossAxisAlignment: CrossAxisAlignment.start,
            children: [
              Text(
                title,
                style: textTheme.titleSmall?.copyWith(
                  fontWeight: FontWeight.w800,
                ),
              ),
              const SizedBox(height: 2),
              Text(
                body,
                style: textTheme.bodySmall?.copyWith(
                  color: colorScheme.onSurfaceVariant,
                  height: 1.35,
                ),
              ),
            ],
          ),
        ),
      ],
    );
  }
}

class _XAxisLabels extends StatelessWidget {
  const _XAxisLabels({required this.labels});

  final List<String> labels;

  @override
  Widget build(BuildContext context) {
    final textStyle = Theme.of(context).textTheme.labelSmall;
    final onSurfaceVariant = Theme.of(context).colorScheme.onSurfaceVariant;

    final count = labels.length;
    final desiredTicks = 4;
    final step = count <= desiredTicks ? 1 : (count - 1) ~/ (desiredTicks - 1);

    final ticks = <int>{0, count - 1};
    for (var i = 0; i < count; i += step) {
      ticks.add(i);
    }

    return Row(
      children: List.generate(count, (i) {
        final show = ticks.contains(i);
        return Expanded(
          child: Align(
            alignment: i == 0
                ? Alignment.centerLeft
                : i == count - 1
                ? Alignment.centerRight
                : Alignment.center,
            child: Text(
              show ? labels[i] : '',
              maxLines: 1,
              overflow: TextOverflow.ellipsis,
              style: textStyle?.copyWith(color: onSurfaceVariant),
            ),
          ),
        );
      }),
    );
  }
}

class _LoadingBody extends StatelessWidget {
  const _LoadingBody();

  @override
  Widget build(BuildContext context) {
    return const Padding(
      padding: EdgeInsets.only(top: 40),
      child: Center(
        child: Column(
          mainAxisSize: MainAxisSize.min,
          children: [
            CircularProgressIndicator(),
            SizedBox(height: 12),
            Text('Loading cashier loyalty analysis...'),
          ],
        ),
      ),
    );
  }
}

class _ErrorBody extends StatelessWidget {
  const _ErrorBody({required this.onRetry});

  final VoidCallback onRetry;

  @override
  Widget build(BuildContext context) {
    return Padding(
      padding: const EdgeInsets.only(top: 40),
      child: Center(
        child: Column(
          mainAxisSize: MainAxisSize.min,
          children: [
            const Text('Unable to load cashier analysis'),
            const SizedBox(height: 10),
            TextButton(onPressed: onRetry, child: const Text('Retry')),
          ],
        ),
      ),
    );
  }
}

BoxDecoration _cardDecoration(BuildContext context) {
  final colorScheme = Theme.of(context).colorScheme;

  return BoxDecoration(
    color: colorScheme.surface,
    borderRadius: BorderRadius.circular(8),
    border: Border.all(color: colorScheme.outlineVariant.withOpacity(0.55)),
    boxShadow: [
      BoxShadow(
        color: Colors.black.withOpacity(0.05),
        blurRadius: 12,
        offset: const Offset(0, 5),
      ),
    ],
  );
}