import 'dart:convert';

import 'package:flutter/material.dart';
import 'package:http/http.dart' as http;
import 'package:intl/intl.dart';
import 'package:manager_app/Components/common_loader.dart';
import 'package:manager_app/Models/managerContext.dart';
import 'package:manager_app/Screens/Audit/audit_entry.dart';
import 'package:manager_app/app_context.dart';
import 'package:manager_app/constants.dart';
import 'package:manager_app/l10n/app_localizations.dart';
import 'package:provider/provider.dart';

/// Les types journalisés par `MyInfoMateDbContext.AuditedTypes`. La liste est fixe :
/// l'endpoint ne rend pas les valeurs distinctes présentes en base, et un filtre
/// construit sur la page courante ne proposerait que ce qui y est déjà visible.
const _kAuditEntityTypes = ['Section', 'Resource', 'Configuration', 'Device', 'User', 'Instance'];

const _kAuditPageSize = 50;

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

  @override
  State<AuditScreen> createState() => _AuditScreenState();
}

class _AuditScreenState extends State<AuditScreen> {
  AuditPage? _page;
  bool _loading = true;
  bool _failed = false;

  int _pageNumber = 1;
  String? _instanceId;
  String? _entityType;
  String? _userId;
  DateTime? _from;
  DateTime? _to;

  /// Les deux annuaires servent à afficher un nom là où le journal ne garde qu'un id.
  /// Un id absent de l'annuaire (instance ou utilisateur supprimé depuis) reste affiché
  /// tel quel : le journal doit rester lisible après la disparition de ce qu'il décrit.
  Map<String, String> _instanceNames = {};
  Map<String, String> _userNames = {};

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

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

  Future<void> _loadDirectories() async {
    final ctx = _managerContext;
    if (ctx.clientAPI == null) return;
    try {
      final instances = await ctx.clientAPI!.instanceApi!.instanceGet();
      final users = await ctx.clientAPI!.userApi!.userGet();
      if (!mounted) return;
      setState(() {
        _instanceNames = {for (final i in instances ?? []) i.id: i.name};
        _userNames = {
          for (final u in users ?? [])
            if (u.id != null) u.id!: _fullName(u.firstName, u.lastName, u.email),
        };
      });
    } catch (_) {
      // Les filtres retombent sur les identifiants bruts, la consultation reste possible.
    }
  }

  static String _fullName(String? firstName, String? lastName, String? email) {
    final name = [firstName, lastName].where((p) => (p ?? '').isNotEmpty).join(' ');
    return name.isEmpty ? (email ?? '') : name;
  }

  Future<void> _load() async {
    final ctx = _managerContext;
    setState(() {
      _loading = true;
      _failed = false;
    });

    final query = <String, String>{
      'page': '$_pageNumber',
      'limit': '$_kAuditPageSize',
      if (_instanceId != null) 'instanceId': _instanceId!,
      if (_entityType != null) 'entityType': _entityType!,
      if (_userId != null) 'userId': _userId!,
      if (_from != null) 'from': _from!.toUtc().toIso8601String(),
      // Borne haute prise à la fin de la journée choisie : un `to` au 12/08 doit
      // inclure ce qui s'est passé le 12/08, pas s'arrêter à minuit.
      if (_to != null) 'to': _endOfDay(_to!).toUtc().toIso8601String(),
    };

    try {
      final response = await http.get(
        Uri.parse('${ctx.host}/api/Audit').replace(queryParameters: query),
        headers: {'Authorization': 'Bearer ${ctx.accessToken}'},
      );
      if (!mounted) return;
      if (response.statusCode != 200) {
        setState(() {
          _loading = false;
          _failed = true;
        });
        return;
      }
      setState(() {
        _page = AuditPage.fromJson(
            jsonDecode(utf8.decode(response.bodyBytes)) as Map<String, dynamic>);
        _loading = false;
      });
    } catch (_) {
      if (!mounted) return;
      setState(() {
        _loading = false;
        _failed = true;
      });
    }
  }

  static DateTime _endOfDay(DateTime day) =>
      DateTime(day.year, day.month, day.day, 23, 59, 59, 999);

  /// Tout changement de filtre ramène à la première page : rester en page 4 d'un
  /// résultat qui n'en compte plus qu'une afficherait une liste vide sans raison visible.
  void _applyFilter(VoidCallback change) {
    setState(() {
      change();
      _pageNumber = 1;
    });
    _load();
  }

  void _resetFilters() => _applyFilter(() {
        _instanceId = null;
        _entityType = null;
        _userId = null;
        _from = null;
        _to = null;
      });

  bool get _hasFilters =>
      _instanceId != null || _entityType != null || _userId != null || _from != null || _to != null;

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

    return Column(
      crossAxisAlignment: CrossAxisAlignment.start,
      children: [
        Text(l.auditTitle, style: kTitleScreen),
        const SizedBox(height: kSpace1),
        Text(l.auditSubtitle, style: kSubtitleCard),
        const SizedBox(height: kSpace5),
        _filters(l),
        const SizedBox(height: kSpace5),
        Expanded(child: _body(l)),
      ],
    );
  }

  Widget _filters(AppLocalizations l) {
    return Wrap(
      spacing: kSpace4,
      runSpacing: kSpace4,
      crossAxisAlignment: WrapCrossAlignment.center,
      children: [
        _dropdown<String>(
          label: l.auditFilterInstance,
          value: _instanceId,
          emptyLabel: l.auditAllInstances,
          entries: _instanceNames.entries.map((e) => MapEntry(e.key, e.value)).toList(),
          onChanged: (v) => _applyFilter(() => _instanceId = v),
        ),
        _dropdown<String>(
          label: l.auditFilterEntity,
          value: _entityType,
          emptyLabel: l.auditAllEntities,
          entries: _kAuditEntityTypes.map((t) => MapEntry(t, _entityLabel(l, t))).toList(),
          onChanged: (v) => _applyFilter(() => _entityType = v),
        ),
        _dropdown<String>(
          label: l.auditFilterUser,
          value: _userId,
          emptyLabel: l.auditAllUsers,
          entries: _userNames.entries.map((e) => MapEntry(e.key, e.value)).toList(),
          onChanged: (v) => _applyFilter(() => _userId = v),
        ),
        _dateField(l.auditFilterFrom, _from, (d) => _applyFilter(() => _from = d)),
        _dateField(l.auditFilterTo, _to, (d) => _applyFilter(() => _to = d)),
        if (_hasFilters)
          TextButton.icon(
            onPressed: _resetFilters,
            icon: const Icon(Icons.filter_alt_off_outlined, size: 18),
            label: Text(l.auditReset),
          ),
      ],
    );
  }

  Widget _dropdown<T>({
    required String label,
    required T? value,
    required String emptyLabel,
    required List<MapEntry<T, String>> entries,
    required ValueChanged<T?> onChanged,
  }) {
    return SizedBox(
      width: 220,
      child: Column(
        crossAxisAlignment: CrossAxisAlignment.start,
        children: [
          Text(label, style: kLabelField),
          const SizedBox(height: kSpace1),
          // `DropdownButton` piloté plutôt que `DropdownButtonFormField` : ce dernier
          // ne relit pas `initialValue` sur reconstruction, donc « Réinitialiser les
          // filtres » aurait vidé la requête sans vider l'affichage.
          Container(
            padding: const EdgeInsets.symmetric(horizontal: kSpace4),
            decoration: BoxDecoration(
              border: Border.all(color: kLine),
              borderRadius: BorderRadius.circular(kRadiusInput),
            ),
            child: DropdownButtonHideUnderline(
              child: DropdownButton<T?>(
                value: value,
                isExpanded: true,
                isDense: true,
                padding: const EdgeInsets.symmetric(vertical: 11),
                style: kTextSmall,
                items: [
                  DropdownMenuItem<T?>(value: null, child: Text(emptyLabel, style: kTextSmall)),
                  for (final entry in entries)
                    DropdownMenuItem<T?>(
                      value: entry.key,
                      child: Text(entry.value, style: kTextSmall, overflow: TextOverflow.ellipsis),
                    ),
                ],
                onChanged: onChanged,
              ),
            ),
          ),
        ],
      ),
    );
  }

  Widget _dateField(String label, DateTime? value, ValueChanged<DateTime?> onChanged) {
    return SizedBox(
      width: 170,
      child: Column(
        crossAxisAlignment: CrossAxisAlignment.start,
        children: [
          Text(label, style: kLabelField),
          const SizedBox(height: kSpace1),
          InkWell(
            borderRadius: BorderRadius.circular(kRadiusInput),
            onTap: () async {
              final picked = await showDatePicker(
                context: context,
                initialDate: value ?? DateTime.now(),
                firstDate: DateTime(2020),
                lastDate: DateTime.now().add(const Duration(days: 1)),
              );
              if (picked != null) onChanged(picked);
            },
            child: Container(
              padding: const EdgeInsets.symmetric(horizontal: kSpace4, vertical: 11),
              decoration: BoxDecoration(
                border: Border.all(color: kLine),
                borderRadius: BorderRadius.circular(kRadiusInput),
              ),
              child: Row(
                children: [
                  Expanded(
                    child: Text(
                      value == null ? '—' : DateFormat('dd/MM/yyyy').format(value),
                      style: kTextSmall,
                    ),
                  ),
                  if (value != null)
                    InkWell(
                      onTap: () => onChanged(null),
                      child: const Icon(Icons.close, size: 16, color: kInk3),
                    )
                  else
                    const Icon(Icons.calendar_today_outlined, size: 15, color: kInk3),
                ],
              ),
            ),
          ),
        ],
      ),
    );
  }

  Widget _body(AppLocalizations l) {
    if (_loading) return const CommonLoader();
    if (_failed) return Center(child: Text(l.auditLoadError, style: kTextBody));

    final page = _page;
    if (page == null || page.items.isEmpty) {
      return Center(child: Text(l.auditEmpty, style: kTextBody));
    }

    return Column(
      crossAxisAlignment: CrossAxisAlignment.start,
      children: [
        Expanded(
          child: Container(
            width: double.infinity,
            decoration: BoxDecoration(
              color: kSurface,
              border: Border.all(color: kLine),
              borderRadius: BorderRadius.circular(kRadiusCard),
            ),
            clipBehavior: Clip.antiAlias,
            child: SingleChildScrollView(
              child: DataTable(
                horizontalMargin: kSpace5,
                columnSpacing: kSpace7,
                headingRowColor: WidgetStateProperty.all(kSurface2),
                dividerThickness: 1,
                columns: [
                  DataColumn(label: Text(l.auditColDate, style: kLabelField)),
                  DataColumn(label: Text(l.auditColInstance, style: kLabelField)),
                  DataColumn(label: Text(l.auditColEntity, style: kLabelField)),
                  DataColumn(label: Text(l.auditColAction, style: kLabelField)),
                  DataColumn(label: Text(l.auditColUser, style: kLabelField)),
                  DataColumn(label: Text(l.auditColEntityId, style: kLabelField)),
                ],
                rows: page.items
                    .map((entry) => DataRow(
                          onSelectChanged: (_) => _showDetail(entry),
                          cells: [
                            DataCell(Text(
                              DateFormat('dd/MM/yyyy HH:mm').format(entry.timestamp),
                              style: kTextSmall.copyWith(fontFamily: kMonoFamily),
                            )),
                            DataCell(Text(_instanceLabel(entry.instanceId), style: kTextSmall)),
                            DataCell(Text(_entityLabel(l, entry.entityType), style: kTextSmall)),
                            DataCell(_actionChip(l, entry.action)),
                            DataCell(Text(_userLabel(entry.userId), style: kTextSmall)),
                            DataCell(Text(
                              entry.entityId,
                              style: kOverlineMono.copyWith(color: kInk2),
                            )),
                          ],
                        ))
                    .toList(),
              ),
            ),
          ),
        ),
        const SizedBox(height: kSpace4),
        _pagination(l, page),
      ],
    );
  }

  Widget _pagination(AppLocalizations l, AuditPage page) {
    final first = (page.page - 1) * page.limit + 1;
    final last = first + page.items.length - 1;

    return Row(
      children: [
        Text(l.auditRange(first, last, page.total), style: kTextHint),
        const Spacer(),
        IconButton(
          onPressed: page.page <= 1
              ? null
              : () {
                  setState(() => _pageNumber = page.page - 1);
                  _load();
                },
          icon: const Icon(Icons.chevron_left),
          tooltip: l.auditPrevious,
        ),
        Text('${page.page} / ${page.pageCount}', style: kTextSmall),
        IconButton(
          onPressed: page.page >= page.pageCount
              ? null
              : () {
                  setState(() => _pageNumber = page.page + 1);
                  _load();
                },
          icon: const Icon(Icons.chevron_right),
          tooltip: l.auditNext,
        ),
      ],
    );
  }

  Widget _actionChip(AppLocalizations l, String action) {
    final color = switch (action) {
      'Create' => kGood,
      'Delete' => kSerious,
      _ => kBrand,
    };
    return Container(
      padding: const EdgeInsets.symmetric(horizontal: kSpace3, vertical: 3),
      decoration: BoxDecoration(
        color: color.withValues(alpha: 0.08),
        border: Border.all(color: color.withValues(alpha: 0.3)),
        borderRadius: BorderRadius.circular(kRadiusPill),
      ),
      child: Text(_actionLabel(l, action), style: kTextHint.copyWith(color: color)),
    );
  }

  String _actionLabel(AppLocalizations l, String action) => switch (action) {
        'Create' => l.auditActionCreate,
        'Update' => l.auditActionUpdate,
        'Delete' => l.auditActionDelete,
        _ => action,
      };

  String _entityLabel(AppLocalizations l, String entityType) => switch (entityType) {
        'Section' => l.auditEntitySection,
        'Resource' => l.auditEntityResource,
        'Configuration' => l.auditEntityConfiguration,
        'Device' => l.auditEntityDevice,
        'User' => l.auditEntityUser,
        'Instance' => l.auditEntityInstance,
        _ => entityType,
      };

  String _instanceLabel(String? id) =>
      id == null ? '—' : (_instanceNames[id] ?? id);

  String _userLabel(String? id) => id == null ? '—' : (_userNames[id] ?? id);

  void _showDetail(AuditEntry entry) {
    final l = AppLocalizations.of(context)!;
    final changes = entry.changes;

    showDialog(
      context: context,
      builder: (dialogContext) => AlertDialog(
        title: Text(l.auditDetailTitle, style: kTitleCard),
        content: SizedBox(
          width: 720,
          child: SingleChildScrollView(
            child: Column(
              crossAxisAlignment: CrossAxisAlignment.start,
              mainAxisSize: MainAxisSize.min,
              children: [
                Text(
                  '${_entityLabel(l, entry.entityType)} · ${_actionLabel(l, entry.action)} · '
                  '${DateFormat('dd/MM/yyyy HH:mm:ss').format(entry.timestamp)}',
                  style: kSubtitleCard,
                ),
                const SizedBox(height: kSpace1),
                Text('${_instanceLabel(entry.instanceId)} · ${_userLabel(entry.userId)}',
                    style: kSubtitleCard),
                const SizedBox(height: kSpace5),
                if (changes.isEmpty)
                  Text(l.auditDetailNoValues, style: kTextBody)
                else
                  Table(
                    border: TableBorder.all(color: kLineSoft),
                    columnWidths: const {
                      0: FlexColumnWidth(2),
                      1: FlexColumnWidth(3),
                      2: FlexColumnWidth(3),
                    },
                    children: [
                      TableRow(
                        decoration: const BoxDecoration(color: kSurface2),
                        children: [
                          _detailCell(l.auditDetailField, kLabelField),
                          _detailCell(l.auditDetailBefore, kLabelField),
                          _detailCell(l.auditDetailAfter, kLabelField),
                        ],
                      ),
                      for (final change in changes)
                        TableRow(children: [
                          _detailCell(change.field, kTextSmall),
                          _detailCell(change.before ?? '—', kTextSmall.copyWith(color: kInk3)),
                          _detailCell(change.after ?? '—', kTextSmall),
                        ]),
                    ],
                  ),
              ],
            ),
          ),
        ),
        actions: [
          TextButton(
            onPressed: () => Navigator.pop(dialogContext),
            child: Text(l.close),
          ),
        ],
      ),
    );
  }

  Widget _detailCell(String text, TextStyle style) => Padding(
        padding: const EdgeInsets.symmetric(horizontal: kSpace3, vertical: kSpace2),
        child: SelectableText(text, style: style),
      );
}