/// Home: balance overview; tap balance to open transactions.
library;

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

import '../models/home_filter_widget.dart';
import '../providers/bank_provider.dart';
import '../providers/preferences_provider.dart';
import '../providers/tx_meta_provider.dart';
import '../utils/app_theme.dart';
import '../utils/connect_bank.dart';
import '../utils/helpers.dart';
import '../utils/navigation.dart';
import '../widgets/empty_state.dart';
import '../widgets/home_filter_widget_card.dart';
import '../widgets/home_widgets_sheet.dart';
import '../widgets/loading_view.dart';
import '../widgets/responsive_body.dart';
import '../widgets/shell_tab_scope.dart';
import '../widgets/skip_build_when_covered.dart';
import 'transaction_detail_screen.dart';
import 'transactions_screen.dart';

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

  static const tabIndex = 0;

  @override
  State<HomeScreen> createState() => _HomeScreenState();
}

class _HomeScreenState extends State<HomeScreen> {
  var _editingWidgets = false;

  @override
  Widget build(BuildContext context) {
    // Inactive IndexedStack tabs must not watch providers — otherwise every
    // annotation save rebuilds Home while the user is on another tab.
    if (ShellTabScope.of(context) != HomeScreen.tabIndex) {
      return const SizedBox.expand();
    }

    final bank = context.watch<BankController>();

    return Scaffold(
      appBar: AppBar(
        title: Text(_editingWidgets ? 'Edit Home' : 'Home'),
        actions: [
          if (bank.isLinked || bank.hasData)
            IconButton(
              tooltip: _editingWidgets ? 'Done' : 'Edit Home layout',
              onPressed: () =>
                  setState(() => _editingWidgets = !_editingWidgets),
              icon: Icon(
                _editingWidgets ? Icons.check : Icons.dashboard_customize_outlined,
              ),
            ),
          ...bankAppBarActions(
            context: context,
            onRefresh: bank.refresh,
            refreshing: bank.isLoading,
          ),
        ],
      ),
      body: RefreshIndicator(
        onRefresh: bank.refresh,
        child: ResponsiveBody(
          child: _HomeBody(
            bank: bank,
            editingWidgets: _editingWidgets,
          ),
        ),
      ),
    );
  }
}

class _HomeBody extends StatelessWidget {
  const _HomeBody({
    required this.bank,
    required this.editingWidgets,
  });

  final BankController bank;
  final bool editingWidgets;

  void _openTransactions(BuildContext context) {
    Navigator.of(context).push(
      MaterialPageRoute<void>(builder: (_) => const TransactionsScreen()),
    );
  }

  @override
  Widget build(BuildContext context) {
    // Stay subscribed, but skip heavy scans while covered by another route
    // (e.g. transaction detail applying labels to many similar txs).
    context.watch<TxMetaController>();
    final prefs = context.watch<PreferencesController>();

    if (bank.isLoading && bank.balance == null && !bank.hasData) {
      return const LoadingView(message: 'Checking bank link…');
    }

    if (!bank.isLinked && !bank.hasData) {
      return ListView(
        physics: const AlwaysScrollableScrollPhysics(),
        children: [
          EmptyState(
            icon: Icons.account_balance_outlined,
            title: 'Bank not linked',
            message: bank.error ??
                'Connect your bank to see balance and categorize spending.',
            actionLabel: bank.isConnecting ? 'Opening…' : 'Connect bank',
            onAction: () => runConnectBank(context, bank),
          ),
        ],
      );
    }

    if (bank.error != null && bank.balance == null && !bank.hasData) {
      return ListView(
        physics: const AlwaysScrollableScrollPhysics(),
        children: [
          EmptyState(
            icon: Icons.error_outline,
            title: 'Could not load balance',
            message: bank.error!,
            actionLabel: 'Retry',
            onAction: bank.refresh,
          ),
        ],
      );
    }

    return SkipBuildWhenCovered(
      builder: (context) {
        final balance = bank.balance;
        final theme = Theme.of(context);
        final colors = theme.colorScheme;
        final meta = context.watch<TxMetaController>();
        final recent = bank.transactions.take(5).toList(growable: false);
        final categorized =
            meta.labeledTransactionCount(bank.transactions);
        final widgets = editingWidgets
            ? prefs.homeFilterWidgets
            : prefs.displayedHomeFilterWidgets;

        return ListView(
          physics: const AlwaysScrollableScrollPhysics(),
          padding: const EdgeInsets.only(top: 8, bottom: 32),
          children: [
            Material(
              color: Colors.transparent,
              child: InkWell(
                borderRadius: BorderRadius.circular(20),
                onTap: () => _openTransactions(context),
                child: Ink(
                  width: double.infinity,
                  padding: const EdgeInsets.all(24),
                  decoration: BoxDecoration(
                    borderRadius: BorderRadius.circular(20),
                    gradient: LinearGradient(
                      colors: [colors.primary, colors.tertiary],
                    ),
                    boxShadow: [
                      BoxShadow(
                        color: colors.primary.withValues(alpha: 0.28),
                        blurRadius: 20,
                        offset: const Offset(0, 10),
                      ),
                    ],
                  ),
                  child: Column(
                    crossAxisAlignment: CrossAxisAlignment.start,
                    children: [
                      Text(
                        'Current balance',
                        style: theme.textTheme.labelMedium?.copyWith(
                          color: colors.onPrimary.withValues(alpha: 0.8),
                        ),
                      ),
                      const SizedBox(height: 8),
                      Text(
                        balance == null
                            ? '—'
                            : formatMoney(balance.amount, balance.currency),
                        style: theme.textTheme.headlineMedium?.copyWith(
                          color: colors.onPrimary,
                        ),
                      ),
                      const SizedBox(height: 12),
                      Row(
                        children: [
                          Icon(
                            Icons.receipt_long,
                            size: 16,
                            color: colors.onPrimary.withValues(alpha: 0.9),
                          ),
                          const SizedBox(width: 6),
                          Expanded(
                            child: Text(
                              'Tap to view transactions',
                              style: theme.textTheme.labelMedium?.copyWith(
                                color:
                                    colors.onPrimary.withValues(alpha: 0.9),
                              ),
                            ),
                          ),
                          Icon(
                            Icons.chevron_right,
                            color: colors.onPrimary.withValues(alpha: 0.9),
                          ),
                        ],
                      ),
                    ],
                  ),
                ),
              ),
            ),
            if (_showBuiltIn(
                  editing: editingWidgets,
                  enabled: prefs.homeBuiltInSections.showTransactions,
                ) ||
                _showBuiltIn(
                  editing: editingWidgets,
                  enabled: prefs.homeBuiltInSections.showCategorized,
                )) ...[
              const SizedBox(height: 20),
              Row(
                children: [
                  if (_showBuiltIn(
                    editing: editingWidgets,
                    enabled: prefs.homeBuiltInSections.showTransactions,
                  ))
                    Expanded(
                      child: _EditableHomeBlock(
                        editing: editingWidgets,
                        visible: prefs.homeBuiltInSections.showTransactions,
                        onToggleVisible: (value) =>
                            prefs.setHomeShowTransactions(value),
                        child: _StatChip(
                          label: 'Transactions',
                          value: '${bank.transactions.length}',
                          icon: Icons.list_alt,
                        ),
                      ),
                    ),
                  if (_showBuiltIn(
                        editing: editingWidgets,
                        enabled: prefs.homeBuiltInSections.showTransactions,
                      ) &&
                      _showBuiltIn(
                        editing: editingWidgets,
                        enabled: prefs.homeBuiltInSections.showCategorized,
                      ))
                    const SizedBox(width: 10),
                  if (_showBuiltIn(
                    editing: editingWidgets,
                    enabled: prefs.homeBuiltInSections.showCategorized,
                  ))
                    Expanded(
                      child: _EditableHomeBlock(
                        editing: editingWidgets,
                        visible: prefs.homeBuiltInSections.showCategorized,
                        onToggleVisible: (value) =>
                            prefs.setHomeShowCategorized(value),
                        child: _StatChip(
                          label: 'Categorized',
                          value: '$categorized',
                          icon: Icons.label_outline,
                        ),
                      ),
                    ),
                ],
              ),
            ],
            if (editingWidgets || widgets.isNotEmpty) ...[
              const SizedBox(height: 24),
              if (editingWidgets)
                Align(
                  alignment: Alignment.centerRight,
                  child: TextButton.icon(
                    onPressed: () => showHomeWidgetsSheet(context),
                    icon: const Icon(Icons.add, size: 18),
                    label: const Text('Add'),
                  ),
                ),
              if (widgets.isEmpty)
                Text(
                  'No widgets yet. Tap Add to pin a transaction filter.',
                  style: theme.textTheme.bodyMedium?.copyWith(
                    color: colors.onSurfaceVariant,
                  ),
                )
              else if (editingWidgets)
                ReorderableListView.builder(
                  shrinkWrap: true,
                  physics: const NeverScrollableScrollPhysics(),
                  buildDefaultDragHandles: false,
                  itemCount: widgets.length,
                  onReorderItem: prefs.reorderHomeFilterWidgets,
                  proxyDecorator: (child, index, animation) {
                    return Material(
                      elevation: 2,
                      color: Colors.transparent,
                      borderRadius: BorderRadius.circular(16),
                      child: child,
                    );
                  },
                  itemBuilder: (context, index) {
                    final widgetConfig = widgets[index];
                    return Padding(
                      key: ValueKey(widgetConfig.id),
                      padding: const EdgeInsets.only(bottom: 10),
                      child: _HomeWidgetSlot(
                        halfWidth: widgetConfig.halfWidth,
                        child: HomeFilterWidgetCard(
                          widgetConfig: widgetConfig,
                          editing: true,
                          onToggleDisplay: (display) =>
                              prefs.setHomeFilterWidgetDisplay(
                            widgetConfig.id,
                            display,
                          ),
                          onEdit: () async {
                            final preferences =
                                context.read<PreferencesController>();
                            final updated = await composeHomeFilterWidget(
                              context,
                              existing: widgetConfig,
                            );
                            if (updated == null) return;
                            await preferences.updateHomeFilterWidget(updated);
                          },
                          dragHandle: ReorderableDragStartListener(
                            index: index,
                            child: Icon(
                              Icons.drag_handle,
                              color: colors.onSurfaceVariant,
                            ),
                          ),
                        ),
                      ),
                    );
                  },
                )
              else
                ..._packedHomeWidgetRows(widgets),
            ],
            if (_showBuiltIn(
                  editing: editingWidgets,
                  enabled: prefs.homeBuiltInSections.showRecent,
                ) &&
                (recent.isNotEmpty || editingWidgets)) ...[
              const SizedBox(height: 24),
              _EditableHomeBlock(
                editing: editingWidgets,
                visible: prefs.homeBuiltInSections.showRecent,
                onToggleVisible: (value) => prefs.setHomeShowRecent(value),
                child: Column(
                  crossAxisAlignment: CrossAxisAlignment.stretch,
                  children: [
                    Row(
                      children: [
                        Text('Recent', style: theme.textTheme.titleMedium),
                        const Spacer(),
                        TextButton(
                          onPressed: () => _openTransactions(context),
                          child: const Text('See all'),
                        ),
                      ],
                    ),
                    const SizedBox(height: 4),
                    if (recent.isEmpty)
                      Text(
                        'No recent transactions yet.',
                        style: theme.textTheme.bodyMedium?.copyWith(
                          color: colors.onSurfaceVariant,
                        ),
                      )
                    else
                      for (final tx in recent)
                        ListTile(
                          contentPadding: EdgeInsets.zero,
                          dense: true,
                          leading: Builder(
                            builder: (context) {
                              final labels =
                                  meta.leafLabelsFor(meta.metaFor(tx));
                              final label =
                                  labels.isEmpty ? null : labels.first;
                              return Icon(
                                label?.icon ?? Icons.receipt_long_outlined,
                                color: label?.color,
                              );
                            },
                          ),
                          title: Text(
                            tx.description,
                            maxLines: 1,
                            overflow: TextOverflow.ellipsis,
                          ),
                          subtitle: Text(formatIsoDate(tx.date)),
                          trailing: Text(
                            formatMoney(tx.amount, tx.currency),
                            style: theme.textTheme.titleSmall?.copyWith(
                              color: tx.amount >= 0
                                  ? AppTheme.accent
                                  : AppTheme.expense,
                            ),
                          ),
                          onTap: editingWidgets
                              ? null
                              : () {
                                  Navigator.of(context).push(
                                    MaterialPageRoute<void>(
                                      builder: (_) =>
                                          TransactionDetailScreen(tx: tx),
                                    ),
                                  );
                                },
                        ),
                  ],
                ),
              ),
            ],
            if (bank.error != null) ...[
              const SizedBox(height: 12),
              Text(
                bank.error!,
                style: theme.textTheme.bodyMedium
                    ?.copyWith(color: colors.error),
              ),
            ],
          ],
        );
      },
    );
  }
}

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

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

  @override
  Widget build(BuildContext context) {
    final theme = Theme.of(context);
    final colors = theme.colorScheme;
    return Container(
      padding: const EdgeInsets.symmetric(horizontal: 14, vertical: 12),
      decoration: BoxDecoration(
        color: colors.surfaceContainerLow,
        borderRadius: BorderRadius.circular(14),
      ),
      child: Row(
        children: [
          Icon(icon, size: 18, color: colors.primary),
          const SizedBox(width: 10),
          Expanded(
            child: Column(
              crossAxisAlignment: CrossAxisAlignment.start,
              children: [
                Text(
                  label,
                  style: theme.textTheme.labelMedium?.copyWith(
                    color: colors.onSurfaceVariant,
                  ),
                ),
                Text(value, style: theme.textTheme.titleMedium),
              ],
            ),
          ),
        ],
      ),
    );
  }
}

bool _showBuiltIn({required bool editing, required bool enabled}) =>
    editing || enabled;

/// Wraps a built-in Home block with show/hide controls while editing.
class _EditableHomeBlock extends StatelessWidget {
  const _EditableHomeBlock({
    required this.editing,
    required this.visible,
    required this.onToggleVisible,
    required this.child,
  });

  final bool editing;
  final bool visible;
  final ValueChanged<bool> onToggleVisible;
  final Widget child;

  @override
  Widget build(BuildContext context) {
    final colors = Theme.of(context).colorScheme;
    final content = Opacity(
      opacity: editing && !visible ? 0.45 : 1,
      child: child,
    );
    if (!editing) return content;
    return Row(
      crossAxisAlignment: CrossAxisAlignment.start,
      children: [
        Expanded(child: content),
        IconButton(
          tooltip: visible ? 'Hide from Home' : 'Show on Home',
          onPressed: () => onToggleVisible(!visible),
          icon: Icon(
            visible ? Icons.visibility_outlined : Icons.visibility_off_outlined,
            color: visible ? colors.onSurfaceVariant : colors.primary,
          ),
        ),
      ],
    );
  }
}

/// Full- or half-width slot for a Home filter widget card.
class _HomeWidgetSlot extends StatelessWidget {
  const _HomeWidgetSlot({
    required this.halfWidth,
    required this.child,
  });

  final bool halfWidth;
  final Widget child;

  @override
  Widget build(BuildContext context) {
    if (!halfWidth) return child;
    return LayoutBuilder(
      builder: (context, constraints) {
        final width = (constraints.maxWidth - 10) / 2;
        return Align(
          alignment: Alignment.centerLeft,
          child: SizedBox(width: width, child: child),
        );
      },
    );
  }
}

List<Widget> _packedHomeWidgetRows(List<HomeFilterWidget> widgets) {
  final rows = <Widget>[];
  var i = 0;
  while (i < widgets.length) {
    final a = widgets[i];
    final canPair = a.halfWidth &&
        i + 1 < widgets.length &&
        widgets[i + 1].halfWidth;
    if (canPair) {
      final b = widgets[i + 1];
      rows.add(
        Padding(
          padding: const EdgeInsets.only(bottom: 10),
          child: IntrinsicHeight(
            child: Row(
              crossAxisAlignment: CrossAxisAlignment.stretch,
              children: [
                Expanded(
                  child: HomeFilterWidgetCard(widgetConfig: a),
                ),
                const SizedBox(width: 10),
                Expanded(
                  child: HomeFilterWidgetCard(widgetConfig: b),
                ),
              ],
            ),
          ),
        ),
      );
      i += 2;
      continue;
    }
    rows.add(
      Padding(
        padding: const EdgeInsets.only(bottom: 10),
        child: _HomeWidgetSlot(
          halfWidth: a.halfWidth,
          child: HomeFilterWidgetCard(widgetConfig: a),
        ),
      ),
    );
    i += 1;
  }
  return rows;
}