import 'dart:async';

import 'package:flutter/foundation.dart';
import '../models/agent_info.dart';
import '../models/log_entry.dart';
import '../services/jsonl_parser.dart';

class SessionProvider with ChangeNotifier {
  final JsonlParser _parser = JsonlParser();

  SessionLog? _session;
  bool _isLoading = false;
  String? _error;
  String? _filePath;
  List<ParseError> _parseErrors = const [];

  // Filter state
  String? _selectedAgentId;
  Set<String> _visibleTypes = {'user', 'assistant', 'system'};
  String _searchQuery = '';

  // Cached filtered results
  List<LogEntry> _cachedFilteredEntries = const [];
  // Cache key — tracks what was used to compute the cache
  _FilterKey? _cachedFilterKey;

  // Debounce timer for search
  Timer? _searchDebounce;

  SessionLog? get session => _session;
  bool get isLoading => _isLoading;
  String? get error => _error;
  String? get filePath => _filePath;
  String? get selectedAgentId => _selectedAgentId;
  Set<String> get visibleTypes => _visibleTypes;
  String get searchQuery => _searchQuery;
  List<ParseError> get parseErrors => _parseErrors;

  AgentInfo? get selectedAgent {
    if (_session == null || _selectedAgentId == null) return null;
    return _session!.agents.where((a) => a.id == _selectedAgentId).firstOrNull;
  }

  List<LogEntry> get filteredEntries {
    final key = _FilterKey(
      selectedAgentId: _selectedAgentId,
      visibleTypes: _visibleTypes,
      searchQuery: _searchQuery,
      hasSession: _session != null,
    );

    if (_cachedFilterKey == key) return _cachedFilteredEntries;

    // Recompute
    _cachedFilterKey = key;
    _cachedFilteredEntries = _computeFilteredEntries();
    return _cachedFilteredEntries;
  }

  List<LogEntry> _computeFilteredEntries() {
    if (_session == null) return [];

    List<LogEntry> entries;
    if (_selectedAgentId != null && _selectedAgentId != 'main') {
      final agent = selectedAgent;
      entries = agent?.messages ?? [];
    } else {
      entries = _session!.mainConversation;
    }

    return entries.where((e) {
      if (!_visibleTypes.contains(e.type)) return false;
      if (_searchQuery.isNotEmpty) {
        return _entryMatchesSearch(e, _searchQuery.toLowerCase());
      }
      return true;
    }).toList();
  }

  bool _entryMatchesSearch(LogEntry entry, String query) {
    if (entry is UserEntry) {
      return entry.promptText.toLowerCase().contains(query);
    }
    if (entry is AssistantEntry) {
      for (final block in entry.textBlocks) {
        if (block.text.toLowerCase().contains(query)) return true;
      }
      for (final block in entry.toolUseBlocks) {
        if (block.name.toLowerCase().contains(query)) return true;
        if (block.input.toString().toLowerCase().contains(query)) return true;
      }
    }
    return false;
  }

  Future<void> loadSession(String filePath) async {
    _isLoading = true;
    _error = null;
    _filePath = filePath;
    _selectedAgentId = null;
    _searchQuery = '';
    _parseErrors = const [];
    _invalidateCache();
    notifyListeners();

    try {
      final result = await _parser.parseFile(filePath);
      _session = result.sessionLog;
      _parseErrors = result.errors;
      _error = null;
    } catch (e) {
      _error = e.toString();
      _session = null;
    }

    _isLoading = false;
    notifyListeners();
  }

  void selectAgent(String? agentId) {
    _selectedAgentId = agentId;
    _invalidateCache();
    notifyListeners();
  }

  void toggleTypeFilter(String type) {
    if (_visibleTypes.contains(type)) {
      _visibleTypes = Set.from(_visibleTypes)..remove(type);
    } else {
      _visibleTypes = Set.from(_visibleTypes)..add(type);
    }
    _invalidateCache();
    notifyListeners();
  }

  void setSearchQuery(String query) {
    _searchQuery = query;
    // Update cache immediately but debounce notifyListeners
    _invalidateCache();
    _searchDebounce?.cancel();
    _searchDebounce = Timer(const Duration(milliseconds: 300), () {
      notifyListeners();
    });
  }

  void clearSession() {
    _session = null;
    _filePath = null;
    _error = null;
    _selectedAgentId = null;
    _searchQuery = '';
    _parseErrors = const [];
    _searchDebounce?.cancel();
    _invalidateCache();
    notifyListeners();
  }

  void _invalidateCache() {
    _cachedFilterKey = null;
  }

  @override
  void dispose() {
    _searchDebounce?.cancel();
    super.dispose();
  }
}

/// Immutable key to detect whether the filter result has changed.
class _FilterKey {
  final String? selectedAgentId;
  final Set<String> visibleTypes;
  final String searchQuery;
  final bool hasSession;

  const _FilterKey({
    required this.selectedAgentId,
    required this.visibleTypes,
    required this.searchQuery,
    required this.hasSession,
  });

  @override
  bool operator ==(Object other) =>
      identical(this, other) ||
      other is _FilterKey &&
          selectedAgentId == other.selectedAgentId &&
          _setEquals(visibleTypes, other.visibleTypes) &&
          searchQuery == other.searchQuery &&
          hasSession == other.hasSession;

  @override
  int get hashCode =>
      Object.hash(selectedAgentId, Object.hashAll(visibleTypes), searchQuery, hasSession);

  static bool _setEquals<T>(Set<T> a, Set<T> b) {
    if (a.length != b.length) return false;
    for (final v in a) {
      if (!b.contains(v)) return false;
    }
    return true;
  }
}