/// Transaction detail: label, recurring, notes, apply-to-similar.
library;

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

import '../models/bank.dart';
import '../models/transaction_meta.dart';
import '../providers/bank_provider.dart';
import '../providers/tx_meta_provider.dart';
import '../utils/helpers.dart';
import '../widgets/label_parent_picker.dart';
import '../widgets/responsive_body.dart';
import '../widgets/similar_match_dialog.dart';

class TransactionDetailScreen extends StatefulWidget {
  const TransactionDetailScreen({super.key, required this.tx});

  final BankTransaction tx;

  @override
  State<TransactionDetailScreen> createState() =>
      _TransactionDetailScreenState();
}

class _TransactionDetailScreenState extends State<TransactionDetailScreen> {
  late final TextEditingController _notesController;
  late SimilarMatchCriteria _matchCriteria;
  late Set<String> _draftLabelIds;
  var _dirty = false;
  var _labelsDirty = false;
  late bool _applyToSimilar;
  var _busy = false;
  String? _busyMessage;

  @override
  void initState() {
    super.initState();
    final meta = context.read<TxMetaController>();
    final notes = meta.metaFor(widget.tx).notes;
    _notesController = TextEditingController(text: notes);
    final tx = widget.tx;
    _matchCriteria = SimilarMatchCriteria(
      pattern: defaultSimilarPattern(tx.description),
      flow: tx.amount < 0
          ? TxFlowFilter.expense
          : tx.amount > 0
              ? TxFlowFilter.income
              : TxFlowFilter.all,
    );
    _draftLabelIds = meta.metaFor(tx).labelIds.toSet();
    final all = context.read<BankController>().transactions;
    final similarCount = meta.countSimilar(
      tx,
      all,
      criteria: _matchCriteria,
    );
    // Default on when there are peers — otherwise users never notice the toggle.
    _applyToSimilar = similarCount > 1;
  }

  @override
  void dispose() {
    _notesController.dispose();
    super.dispose();
  }

  String get _pattern => _matchCriteria.pattern;

  List<BankTransaction> _similarScope(TxMetaController meta) {
    final all = context.read<BankController>().transactions;
    if (!_applyToSimilar) return const [];
    return meta.similarTo(widget.tx, all, criteria: _matchCriteria);
  }

  Future<void> _editMatchCriteria() async {
    final all = context.read<BankController>().transactions;
    final result = await showSimilarMatchDialog(
      context,
      prototype: widget.tx,
      all: all,
      initial: _matchCriteria,
    );
    if (result == null || !mounted) return;
    setState(() {
      _matchCriteria = result;
      final count = context.read<TxMetaController>().countSimilar(
            widget.tx,
            all,
            criteria: result,
          );
      if (count > 1) _applyToSimilar = true;
    });
  }

  Future<void> _runBusy(
    Future<void> Function() action, {
    String? message,
  }) async {
    if (_busy) return;
    setState(() {
      _busy = true;
      _busyMessage = message;
    });
    // Let the progress bar paint before heavy similar-matching / rebuilds.
    await WidgetsBinding.instance.endOfFrame;
    try {
      await action();
    } finally {
      if (mounted) {
        setState(() {
          _busy = false;
          _busyMessage = null;
        });
      }
    }
  }

  Future<void> _saveNotes() async {
    await _runBusy(
      () async {
        final meta = context.read<TxMetaController>();
        final similar = _similarScope(meta);
        final count = similar.isEmpty ? 1 : similar.length;
        await meta.setNotes(
          widget.tx,
          _notesController.text,
          applyToSimilar: similar,
          matchPattern: _pattern,
        );
        if (!mounted) return;
        setState(() => _dirty = false);
        ScaffoldMessenger.of(context).showSnackBar(
          SnackBar(
            content: Text(
              count == 1
                  ? 'Notes saved'
                  : 'Notes saved on $count similar transactions',
            ),
          ),
        );
      },
      message: _applyToSimilar
          ? 'Saving notes on matching transactions…'
          : 'Saving notes…',
    );
  }

  Future<void> _toggleDraftLabel(String labelId) async {
    final meta = context.read<TxMetaController>();
    setState(() {
      if (_draftLabelIds.contains(labelId)) {
        final remove = {labelId, ...meta.descendantIdsOf(labelId)};
        _draftLabelIds.removeWhere(remove.contains);
      } else {
        _draftLabelIds.add(labelId);
        _draftLabelIds.addAll(meta.ancestorIdsOf(labelId));
      }
      _labelsDirty = true;
    });
  }

  Future<void> _applyLabels({required bool toMatched}) async {
    await _runBusy(
      () async {
        final meta = context.read<TxMetaController>();
        final similar = toMatched ? _similarScope(meta) : const <BankTransaction>[];
        final targets = similar.isEmpty ? [widget.tx] : similar;
        await meta.setLabelsForMany(
          targets,
          _draftLabelIds.toList(growable: false),
        );
        if (!mounted) return;
        setState(() {
          _labelsDirty = false;
          _draftLabelIds = meta.metaFor(widget.tx).labelIds.toSet();
        });
        final count = targets.length;
        ScaffoldMessenger.of(context).showSnackBar(
          SnackBar(
            content: Text(
              count == 1
                  ? 'Labels saved'
                  : 'Labels updated on $count transactions',
            ),
          ),
        );
      },
      message: toMatched
          ? 'Updating labels on matching transactions…'
          : 'Saving labels…',
    );
  }

  Future<void> _clearDraftLabels() async {
    setState(() {
      _draftLabelIds.clear();
      _labelsDirty = true;
    });
  }

  Future<void> _createLabel() async {
    final meta = context.read<TxMetaController>();
    final result = await showCreateLabelDialog(
      context,
      parents: meta.allLabels,
    );
    if (result == null || !mounted) return;
    final label = await meta.createLabel(
      result.name,
      parentId: result.parentId,
    );
    if (!mounted) return;
    await _toggleDraftLabel(label.id);
  }

  Future<void> _labelActions(TxLabel label) async {
    final action = await showModalBottomSheet<String>(
      context: context,
      showDragHandle: true,
      builder: (sheetContext) {
        return SafeArea(
          child: Column(
            mainAxisSize: MainAxisSize.min,
            children: [
              ListTile(
                leading: const Icon(Icons.account_tree_outlined),
                title: const Text('Move under…'),
                onTap: () => Navigator.pop(sheetContext, 'move'),
              ),
              if (label.custom)
                ListTile(
                  leading: Icon(
                    Icons.delete_outline,
                    color: Theme.of(sheetContext).colorScheme.error,
                  ),
                  title: const Text('Remove label'),
                  onTap: () => Navigator.pop(sheetContext, 'remove'),
                ),
            ],
          ),
        );
      },
    );
    if (!mounted || action == null) return;
    if (action == 'move') {
      await showMoveLabelDialog(context, label: label);
    } else if (action == 'remove') {
      await _confirmRemoveLabel(label);
    }
  }

  Future<void> _confirmRemoveLabel(TxLabel label) async {
    final ok = await showDialog<bool>(
      context: context,
      builder: (context) {
        return AlertDialog(
          title: Text('Remove “${label.name}”?'),
          content: const Text(
            'This deletes the label. Transactions keep any other labels.',
          ),
          actions: [
            TextButton(
              onPressed: () => Navigator.pop(context, false),
              child: const Text('Cancel'),
            ),
            FilledButton(
              onPressed: () => Navigator.pop(context, true),
              child: const Text('Remove'),
            ),
          ],
        );
      },
    );
    if (ok != true || !mounted) return;
    await context.read<TxMetaController>().removeLabel(label.id);
  }

  @override
  Widget build(BuildContext context) {
    final tx = widget.tx;
    final metaController = context.watch<TxMetaController>();
    final meta = metaController.metaFor(tx);
    // Prefer read: bank data rarely changes while editing labels.
    final all = context.read<BankController>().transactions;
    final similarCount = metaController.countSimilar(
      tx,
      all,
      criteria: _matchCriteria,
    );
    final theme = Theme.of(context);
    final colors = theme.colorScheme;
    final amountColor = tx.amount >= 0 ? colors.primary : colors.error;
    final labelEntries = metaController.labelsInTreeOrder();

    return Scaffold(
      appBar: AppBar(
        title: const Text('Transaction'),
        actions: [
          if (_dirty)
            TextButton(
              onPressed: _busy ? null : _saveNotes,
              child: const Text('Save'),
            ),
        ],
      ),
      body: ResponsiveBody(
        child: ListView(
          padding: const EdgeInsets.only(top: 8, bottom: 32),
          children: [
            if (_busy) ...[
              const LinearProgressIndicator(minHeight: 2),
              if (_busyMessage != null)
                Padding(
                  padding: const EdgeInsets.fromLTRB(0, 8, 0, 4),
                  child: Text(
                    _busyMessage!,
                    style: theme.textTheme.labelMedium?.copyWith(
                      color: colors.primary,
                    ),
                  ),
                ),
            ],
            AbsorbPointer(
              absorbing: _busy,
              child: Column(
                crossAxisAlignment: CrossAxisAlignment.stretch,
                children: [
            Text(
              formatMoney(tx.amount, tx.currency),
              style: theme.textTheme.headlineMedium?.copyWith(
                color: amountColor,
              ),
            ),
            const SizedBox(height: 8),
            Text(tx.description, style: theme.textTheme.titleMedium),
            const SizedBox(height: 4),
            Text(
              [
                formatIsoDate(tx.date),
                if (tx.pending) 'Pending',
              ].join(' · '),
              style: theme.textTheme.bodyMedium,
            ),
            const SizedBox(height: 16),
            Row(
              children: [
                Text('Match similar', style: theme.textTheme.titleSmall),
                const Spacer(),
                TextButton.icon(
                  onPressed: _busy ? null : _editMatchCriteria,
                  icon: const Icon(Icons.tune, size: 18),
                  label: const Text('Edit'),
                ),
              ],
            ),
            const SizedBox(height: 4),
            Text(
              '“${_matchCriteria.pattern}”',
              style: theme.textTheme.bodySmall?.copyWith(
                color: colors.onSurfaceVariant,
              ),
            ),
            SwitchListTile(
              contentPadding: EdgeInsets.zero,
              secondary: const Icon(Icons.copy_all_outlined),
              title: const Text('Include matched transactions'),
              subtitle: Text(
                similarCount <= 1
                    ? 'No other matches for this pattern'
                    : '$similarCount matching transactions',
              ),
              value: _applyToSimilar && similarCount > 1,
              onChanged: _busy || similarCount <= 1
                  ? null
                  : (value) => setState(() => _applyToSimilar = value),
            ),
            if (_applyToSimilar && similarCount > 1)
              Align(
                alignment: Alignment.centerLeft,
                child: TextButton(
                  onPressed: _busy ? null : _editMatchCriteria,
                  child: Text('Review $similarCount matches'),
                ),
              ),
            const SizedBox(height: 8),
            SwitchListTile(
              contentPadding: EdgeInsets.zero,
              secondary: const Icon(Icons.autorenew),
              title: const Text('Recurring'),
              subtitle: const Text('Salary, mortgage, subscriptions…'),
              value: meta.recurring,
              onChanged: _busy
                  ? null
                  : (value) {
                      context.read<TxMetaController>().setRecurring(tx, value);
                    },
            ),
            const SizedBox(height: 16),
            Row(
              children: [
                Text('Labels', style: theme.textTheme.titleSmall),
                const Spacer(),
                TextButton(
                  onPressed: _busy ? null : _createLabel,
                  child: const Text('New'),
                ),
                if (_draftLabelIds.isNotEmpty)
                  TextButton(
                    onPressed: _busy ? null : _clearDraftLabels,
                    child: const Text('Clear'),
                  ),
              ],
            ),
            const SizedBox(height: 8),
            DecoratedBox(
              decoration: BoxDecoration(
                color: colors.surfaceContainerHighest,
                borderRadius: BorderRadius.circular(12),
                border: Border.all(
                  color: colors.outlineVariant.withValues(alpha: 0.8),
                ),
              ),
              child: ClipRRect(
                borderRadius: BorderRadius.circular(12),
                child: Column(
                  children: [
                    for (final entry in labelEntries) ...[
                      if (entry != labelEntries.first)
                        Divider(
                          height: 1,
                          indent: 40,
                          color: colors.outlineVariant.withValues(alpha: 0.45),
                        ),
                      InkWell(
                        onTap:
                            _busy ? null : () => _toggleDraftLabel(entry.label.id),
                        onLongPress:
                            _busy ? null : () => _labelActions(entry.label),
                        child: Padding(
                          padding: EdgeInsets.fromLTRB(
                            8 + entry.depth * 16.0,
                            2,
                            4,
                            2,
                          ),
                          child: Row(
                            children: [
                              if (entry.depth > 0) ...[
                                Icon(
                                  Icons.subdirectory_arrow_right,
                                  size: 14,
                                  color: colors.onSurfaceVariant,
                                ),
                                const SizedBox(width: 4),
                              ],
                              Icon(
                                entry.label.icon,
                                size: 18,
                                color: entry.label.color,
                              ),
                              const SizedBox(width: 10),
                              Expanded(
                                child: Text(
                                  entry.label.name,
                                  style: theme.textTheme.bodyMedium,
                                  maxLines: 1,
                                  overflow: TextOverflow.ellipsis,
                                ),
                              ),
                              SizedBox(
                                height: 32,
                                width: 32,
                                child: Checkbox(
                                  materialTapTargetSize:
                                      MaterialTapTargetSize.shrinkWrap,
                                  visualDensity: VisualDensity.compact,
                                  value: _draftLabelIds.contains(entry.label.id),
                                  onChanged: _busy
                                      ? null
                                      : (_) =>
                                          _toggleDraftLabel(entry.label.id),
                                ),
                              ),
                            ],
                          ),
                        ),
                      ),
                    ],
                  ],
                ),
              ),
            ),
            const SizedBox(height: 10),
            Row(
              children: [
                Expanded(
                  child: FilledButton(
                    onPressed: _busy || !_labelsDirty
                        ? null
                        : () => _applyLabels(toMatched: false),
                    child: const Text('Apply'),
                  ),
                ),
                const SizedBox(width: 8),
                Expanded(
                  child: FilledButton.tonal(
                    onPressed: _busy ||
                            !_labelsDirty ||
                            !_applyToSimilar ||
                            similarCount <= 1
                        ? null
                        : () => _applyLabels(toMatched: true),
                    child: Text(
                      similarCount > 1
                          ? 'Apply to matched ($similarCount)'
                          : 'Apply to matched',
                    ),
                  ),
                ),
              ],
            ),
            const SizedBox(height: 24),
            Text('Notes', style: theme.textTheme.titleSmall),
            const SizedBox(height: 8),
            TextField(
              controller: _notesController,
              minLines: 3,
              maxLines: 6,
              enabled: !_busy,
              textInputAction: TextInputAction.newline,
              decoration: const InputDecoration(
                hintText: 'Add a private note…',
              ),
              onChanged: (_) {
                if (!_dirty) setState(() => _dirty = true);
              },
            ),
            const SizedBox(height: 12),
            FilledButton(
              onPressed: _dirty && !_busy ? _saveNotes : null,
              child: Text(
                _applyToSimilar && similarCount > 1
                    ? 'Save notes for $similarCount'
                    : 'Save notes',
              ),
            ),
            const SizedBox(height: 16),
            Text(
              'Sub-labels also select their parents. Unchecking a parent '
              'clears its sub-labels. Long-press a row to move or delete. '
              'Use Apply to save label changes.',
              style: theme.textTheme.labelMedium,
            ),
                ],
              ),
            ),
          ],
        ),
      ),
    );
  }
}