/// Banner, list markers, and merge sheet for name duplicates.
library;

import 'package:flutter/material.dart';

import '../models/product.dart';
import '../services/product_repository.dart';
import '../utils/money.dart';
import '../utils/product_names.dart';
import 'product_image.dart';

const IconData kProductNameConflictIcon = Icons.merge_type;

class ProductNameConflictBanner extends StatelessWidget {
  const ProductNameConflictBanner({
    super.key,
    required this.issues,
    required this.onTap,
  });

  final ProductNameIssues issues;
  final VoidCallback onTap;

  @override
  Widget build(BuildContext context) {
    final theme = Theme.of(context);
    final scheme = theme.colorScheme;
    final title = _bannerTitle(issues);
    final subtitle = _bannerSubtitle(issues);

    return Padding(
      padding: const EdgeInsets.fromLTRB(16, 0, 16, 8),
      child: Material(
        color: scheme.errorContainer.withValues(alpha: 0.65),
        borderRadius: BorderRadius.circular(12),
        child: InkWell(
          onTap: onTap,
          borderRadius: BorderRadius.circular(12),
          child: Padding(
            padding: const EdgeInsets.fromLTRB(12, 10, 8, 10),
            child: Row(
              children: [
                Icon(kProductNameConflictIcon, color: scheme.error),
                const SizedBox(width: 12),
                Expanded(
                  child: Column(
                    crossAxisAlignment: CrossAxisAlignment.start,
                    children: [
                      Text(title, style: theme.textTheme.titleSmall),
                      Text(
                        subtitle,
                        maxLines: 2,
                        overflow: TextOverflow.ellipsis,
                        style: theme.textTheme.bodySmall,
                      ),
                    ],
                  ),
                ),
                Icon(Icons.chevron_right, color: scheme.onSurfaceVariant),
              ],
            ),
          ),
        ),
      ),
    );
  }
}

String _bannerTitle(ProductNameIssues issues) {
  final count = issues.issueCount;
  if (count == 1 && issues.mergeGroups.length == 1) {
    return '1 duplicate product';
  }
  if (count == 1 && issues.spellingVariants.length == 1) {
    return '1 product, multiple spellings';
  }
  return '$count name issues';
}

String _bannerSubtitle(ProductNameIssues issues) {
  final examples = <String>[];
  for (final group in issues.mergeGroups.take(2)) {
    final store = group.supermarket == null ? '' : ' @ ${group.supermarket}';
    examples.add(
      '${group.products.map((product) => product.name).join(' / ')}$store',
    );
  }
  for (final variant in issues.spellingVariants.take(2)) {
    final store = variant.supermarket == null
        ? ''
        : ' @ ${variant.supermarket}';
    examples.add('${variant.variants.join(' / ')}$store');
  }
  return examples.join(', ');
}

class ProductNameConflictMarker extends StatelessWidget {
  const ProductNameConflictMarker({
    super.key,
    this.onTap,
    this.compact = false,
  });

  final VoidCallback? onTap;
  final bool compact;

  @override
  Widget build(BuildContext context) {
    final scheme = Theme.of(context).colorScheme;
    final icon = Icon(
      kProductNameConflictIcon,
      size: compact ? 14 : 20,
      color: scheme.error,
    );
    if (onTap == null) return icon;
    if (compact) {
      return Material(
        color: scheme.errorContainer,
        shape: const CircleBorder(),
        child: InkWell(
          onTap: onTap,
          customBorder: const CircleBorder(),
          child: Padding(padding: const EdgeInsets.all(2), child: icon),
        ),
      );
    }
    return IconButton(
      tooltip: 'Resolve name issues',
      visualDensity: VisualDensity.compact,
      padding: EdgeInsets.zero,
      constraints: const BoxConstraints(minWidth: 32, minHeight: 32),
      onPressed: onTap,
      icon: icon,
    );
  }
}

Future<bool> showProductNameConflictSheet(
  BuildContext context, {
  required ProductRepository repository,
  required ProductNameIssues issues,
  int? focusProductId,
}) {
  if (issues.isEmpty) return Future.value(false);

  return showModalBottomSheet<bool>(
    context: context,
    isScrollControlled: true,
    showDragHandle: true,
    useSafeArea: true,
    builder: (context) {
      final size = MediaQuery.sizeOf(context);
      return SizedBox(
        width: size.width,
        height: size.height * 0.85,
        child: _ProductNameConflictSheet(
          repository: repository,
          issues: issues,
          focusProductId: focusProductId,
        ),
      );
    },
  ).then((resolved) => resolved == true);
}

class _ProductNameConflictSheet extends StatefulWidget {
  const _ProductNameConflictSheet({
    required this.repository,
    required this.issues,
    this.focusProductId,
  });

  final ProductRepository repository;
  final ProductNameIssues issues;
  final int? focusProductId;

  @override
  State<_ProductNameConflictSheet> createState() =>
      _ProductNameConflictSheetState();
}

class _ProductNameConflictSheetState extends State<_ProductNameConflictSheet> {
  late List<ProductMergeGroup> _mergeGroups;
  late List<ProductSpellingVariant> _spellingVariants;
  late Map<int, int> _keepByMergeGroup;
  late Map<int, String> _spellingChoiceByIndex;
  final Set<int> _busyMergeGroups = {};
  final Set<int> _busySpellingGroups = {};
  bool _resolvedAny = false;

  @override
  void initState() {
    super.initState();
    _mergeGroups = [for (final group in widget.issues.mergeGroups) group];
    _spellingVariants = [
      for (final variant in widget.issues.spellingVariants) variant,
    ];
    _rebuildChoices();
  }

  void _rebuildChoices() {
    _keepByMergeGroup = {
      for (var i = 0; i < _mergeGroups.length; i++)
        i: _defaultKeep(_mergeGroups[i].products),
    };
    _spellingChoiceByIndex = {
      for (var i = 0; i < _spellingVariants.length; i++)
        i: _spellingVariants[i].variants.first,
    };
  }

  int _defaultKeep(List<Product> group) {
    final sorted = [...group]
      ..sort((a, b) {
        final seen = b.timesSeen.compareTo(a.timesSeen);
        if (seen != 0) return seen;
        return a.id.compareTo(b.id);
      });
    return sorted.first.id;
  }

  bool get _isEmpty => _mergeGroups.isEmpty && _spellingVariants.isEmpty;

  int? _focusedMergeIndex() {
    final focus = widget.focusProductId;
    if (focus == null) return null;
    for (var i = 0; i < _mergeGroups.length; i++) {
      if (_mergeGroups[i].products.any((product) => product.id == focus)) {
        return i;
      }
    }
    return null;
  }

  int? _focusedSpellingIndex() {
    final focus = widget.focusProductId;
    if (focus == null) return null;
    for (var i = 0; i < _spellingVariants.length; i++) {
      if (_spellingVariants[i].product.id == focus) return i;
    }
    return null;
  }

  void _maybeClose() {
    if (_isEmpty && mounted) {
      Navigator.of(context).pop(true);
    }
  }

  Future<void> _mergeGroup(int index) async {
    if (_busyMergeGroups.contains(index)) return;
    final group = _mergeGroups[index];
    final keepId = _keepByMergeGroup[index]!;
    setState(() => _busyMergeGroups.add(index));
    try {
      await widget.repository.mergeProducts(
        keepId: keepId,
        sourceIds: [for (final product in group.products) product.id],
      );
      if (!mounted) return;
      setState(() {
        _resolvedAny = true;
        _busyMergeGroups.remove(index);
        _mergeGroups.removeAt(index);
        _rebuildChoices();
      });
      _maybeClose();
    } catch (_) {
      if (!mounted) return;
      setState(() => _busyMergeGroups.remove(index));
      ScaffoldMessenger.of(context).showSnackBar(
        const SnackBar(content: Text('Could not merge these products.')),
      );
    }
  }

  Future<void> _leaveMergeAsIs(int index) async {
    final group = _mergeGroups[index];
    await widget.repository.dismissNameIssue(group.key);
    if (!mounted) return;
    setState(() {
      _resolvedAny = true;
      _mergeGroups.removeAt(index);
      _rebuildChoices();
    });
    _maybeClose();
  }

  Future<void> _applySpelling(int index) async {
    if (_busySpellingGroups.contains(index)) return;
    final variant = _spellingVariants[index];
    final chosen = _spellingChoiceByIndex[index]!;
    setState(() => _busySpellingGroups.add(index));
    try {
      await widget.repository.unifyProductSpelling(
        productId: variant.product.id,
        name: chosen,
        supermarket: variant.supermarket,
      );
      if (!mounted) return;
      setState(() {
        _resolvedAny = true;
        _busySpellingGroups.remove(index);
        _spellingVariants.removeAt(index);
        _rebuildChoices();
      });
      _maybeClose();
    } catch (_) {
      if (!mounted) return;
      setState(() => _busySpellingGroups.remove(index));
      ScaffoldMessenger.of(context).showSnackBar(
        const SnackBar(content: Text('Could not update this spelling.')),
      );
    }
  }

  Future<void> _leaveSpellingAsIs(int index) async {
    final variant = _spellingVariants[index];
    await widget.repository.dismissNameIssue(variant.key);
    if (!mounted) return;
    setState(() {
      _resolvedAny = true;
      _spellingVariants.removeAt(index);
      _rebuildChoices();
    });
    _maybeClose();
  }

  @override
  Widget build(BuildContext context) {
    final theme = Theme.of(context);
    final focusMergeIndex = _focusedMergeIndex();
    final focusSpellingIndex = _focusedSpellingIndex();

    return Column(
      crossAxisAlignment: CrossAxisAlignment.stretch,
      children: [
        Padding(
          padding: const EdgeInsets.fromLTRB(16, 0, 16, 0),
          child: Column(
            crossAxisAlignment: CrossAxisAlignment.stretch,
            children: [
              Text('Resolve name issues', style: theme.textTheme.titleLarge),
              const SizedBox(height: 4),
              Text(
                'Same name at the same store. Pick which entry to keep, '
                'then merge or leave as separate products.',
                style: theme.textTheme.bodyMedium,
              ),
            ],
          ),
        ),
        const SizedBox(height: 12),
        Expanded(
          child: _isEmpty
              ? Center(
                  child: Padding(
                    padding: const EdgeInsets.all(24),
                    child: Text(
                      _resolvedAny
                          ? 'All name issues resolved.'
                          : 'No name issues found.',
                      textAlign: TextAlign.center,
                      style: theme.textTheme.bodyLarge,
                    ),
                  ),
                )
              : ListView(
                  padding: const EdgeInsets.fromLTRB(16, 0, 16, 16),
                  children: [
                    if (_mergeGroups.isNotEmpty) ...[
                      Text(
                        'Separate products to merge',
                        style: theme.textTheme.titleSmall,
                      ),
                      const SizedBox(height: 8),
                      for (var i = 0; i < _mergeGroups.length; i++) ...[
                        if (i > 0) const SizedBox(height: 12),
                        _MergeGroupCard(
                          group: _mergeGroups[i],
                          keepId: _keepByMergeGroup[i]!,
                          busy: _busyMergeGroups.contains(i),
                          highlighted: focusMergeIndex == i,
                          onKeepChanged: (id) {
                            setState(() => _keepByMergeGroup[i] = id);
                          },
                          onMerge: () => _mergeGroup(i),
                          onLeaveAsIs: () => _leaveMergeAsIs(i),
                        ),
                      ],
                    ],
                    if (_spellingVariants.isNotEmpty) ...[
                      if (_mergeGroups.isNotEmpty) const SizedBox(height: 20),
                      Text(
                        'One product, multiple spellings',
                        style: theme.textTheme.titleSmall,
                      ),
                      const SizedBox(height: 8),
                      for (var i = 0; i < _spellingVariants.length; i++) ...[
                        if (i > 0) const SizedBox(height: 12),
                        _SpellingVariantCard(
                          variant: _spellingVariants[i],
                          chosen: _spellingChoiceByIndex[i]!,
                          busy: _busySpellingGroups.contains(i),
                          highlighted: focusSpellingIndex == i,
                          onChosen: (name) {
                            setState(() => _spellingChoiceByIndex[i] = name);
                          },
                          onApply: () => _applySpelling(i),
                          onLeaveAsIs: () => _leaveSpellingAsIs(i),
                        ),
                      ],
                    ],
                  ],
                ),
        ),
      ],
    );
  }
}

class _MergeGroupCard extends StatelessWidget {
  const _MergeGroupCard({
    required this.group,
    required this.keepId,
    required this.busy,
    required this.highlighted,
    required this.onKeepChanged,
    required this.onMerge,
    required this.onLeaveAsIs,
  });

  final ProductMergeGroup group;
  final int keepId;
  final bool busy;
  final bool highlighted;
  final ValueChanged<int> onKeepChanged;
  final VoidCallback onMerge;
  final VoidCallback onLeaveAsIs;

  @override
  Widget build(BuildContext context) {
    final theme = Theme.of(context);
    final products = group.products;

    return Card(
      color: highlighted
          ? theme.colorScheme.tertiaryContainer.withValues(alpha: 0.35)
          : null,
      child: Padding(
        padding: const EdgeInsets.fromLTRB(12, 12, 12, 8),
        child: Column(
          crossAxisAlignment: CrossAxisAlignment.stretch,
          children: [
            Row(
              children: [
                Icon(
                  kProductNameConflictIcon,
                  size: 18,
                  color: theme.colorScheme.tertiary,
                ),
                const SizedBox(width: 8),
                Expanded(
                  child: Text(
                    [
                      normalizeProductName(products.first.name),
                      if (group.supermarket != null) group.supermarket!,
                    ].join(' · '),
                    style: theme.textTheme.titleSmall,
                  ),
                ),
              ],
            ),
            const SizedBox(height: 8),
            for (final product in products)
              ListTile(
                contentPadding: EdgeInsets.zero,
                dense: true,
                leading: ProductImage(
                  name: product.name,
                  path: product.imagePath,
                  size: 36,
                ),
                title: Text(product.name),
                subtitle: Text(
                  [
                    formatEuro(product.lastPrice),
                    product.timesSeen == 1
                        ? '1 purchase'
                        : '${product.timesSeen} purchases',
                  ].join(' · '),
                ),
                trailing: Icon(
                  keepId == product.id
                      ? Icons.check_circle
                      : Icons.circle_outlined,
                  color: keepId == product.id
                      ? theme.colorScheme.primary
                      : theme.colorScheme.outline,
                ),
                onTap: busy ? null : () => onKeepChanged(product.id),
              ),
            Wrap(
              alignment: WrapAlignment.end,
              spacing: 8,
              runSpacing: 8,
              children: [
                TextButton(
                  onPressed: busy ? null : onLeaveAsIs,
                  child: const Text('Leave as is'),
                ),
                FilledButton(
                  onPressed: busy ? null : onMerge,
                  child: busy
                      ? const SizedBox(
                          width: 16,
                          height: 16,
                          child: CircularProgressIndicator(strokeWidth: 2),
                        )
                      : const Text('Merge'),
                ),
              ],
            ),
          ],
        ),
      ),
    );
  }
}

class _SpellingVariantCard extends StatelessWidget {
  const _SpellingVariantCard({
    required this.variant,
    required this.chosen,
    required this.busy,
    required this.highlighted,
    required this.onChosen,
    required this.onApply,
    required this.onLeaveAsIs,
  });

  final ProductSpellingVariant variant;
  final String chosen;
  final bool busy;
  final bool highlighted;
  final ValueChanged<String> onChosen;
  final VoidCallback onApply;
  final VoidCallback onLeaveAsIs;

  @override
  Widget build(BuildContext context) {
    final theme = Theme.of(context);
    final product = variant.product;

    return Card(
      color: highlighted
          ? theme.colorScheme.tertiaryContainer.withValues(alpha: 0.35)
          : null,
      child: Padding(
        padding: const EdgeInsets.fromLTRB(12, 12, 12, 8),
        child: Column(
          crossAxisAlignment: CrossAxisAlignment.stretch,
          children: [
            ListTile(
              contentPadding: EdgeInsets.zero,
              dense: true,
              leading: ProductImage(
                name: product.name,
                path: product.imagePath,
                size: 36,
              ),
              title: Text(product.name),
              subtitle: Text(
                [
                  if (variant.supermarket != null) variant.supermarket!,
                  product.timesSeen == 1
                      ? '1 purchase'
                      : '${product.timesSeen} purchases',
                ].join(' · '),
              ),
            ),
            const SizedBox(height: 4),
            Text('Recorded as:', style: theme.textTheme.labelLarge),
            const SizedBox(height: 4),
            for (final name in variant.variants)
              ListTile(
                contentPadding: EdgeInsets.zero,
                dense: true,
                title: Text(name),
                trailing: Icon(
                  chosen == name ? Icons.check_circle : Icons.circle_outlined,
                  color: chosen == name
                      ? theme.colorScheme.primary
                      : theme.colorScheme.outline,
                ),
                onTap: busy ? null : () => onChosen(name),
              ),
            Wrap(
              alignment: WrapAlignment.end,
              spacing: 8,
              runSpacing: 8,
              children: [
                TextButton(
                  onPressed: busy ? null : onLeaveAsIs,
                  child: const Text('Leave as is'),
                ),
                FilledButton(
                  onPressed: busy ? null : onApply,
                  child: Text(busy ? 'Saving…' : 'Use this spelling'),
                ),
              ],
            ),
          ],
        ),
      ),
    );
  }
}