import 'dart:convert';

enum Intent { createEvent, searchEvent, unknown }

class AiDecisionEngine {
  /// 意图匹配规则（顺序敏感：searchEvent 优先级高于 createEvent）
  static final List<(RegExp, Intent)> _orderedPatterns = [
    (RegExp(r'^查看|^有什么|^今天.*日程|^明天.*安排|^查询'), Intent.searchEvent),
    (RegExp(r'提醒|开会|预约|安排.*时间|创建.*日程'), Intent.createEvent),
    (
      RegExp(r'明天.*\d|今天.*\d|后天.*\d|\d{1,2}点|\d{1,2}:\d{2}'),
      Intent.createEvent,
    ),
  ];

  Intent matchIntent(String text) {
    for (final (pattern, intent) in _orderedPatterns) {
      if (pattern.hasMatch(text)) return intent;
    }
    return Intent.unknown;
  }

  Map<String, dynamic>? tryExtractEventArgs(String text) {
    if (matchIntent(text) != Intent.createEvent) return null;

    final args = <String, dynamic>{};

    final titleMatch = RegExp(r'提醒(.+?)(?:明天|今天|几点|$)').firstMatch(text);
    if (titleMatch != null) {
      args['title'] = titleMatch.group(1)?.trim() ?? text;
    } else if (RegExp(r'\d{1,2}[:点]|\d{1,2}点').hasMatch(text)) {
      args['title'] = text
          .replaceAll(RegExp(r'\d{1,2}[:点]\d{0,2}|明天|今天|后天'), '')
          .trim();
    }

    if (args['title'] == null || (args['title'] as String).isEmpty) return null;

    final timeMatch = RegExp(
      r'(明天|今天|后天)?\s*(\d{1,2})[:点](\d{2})?',
    ).firstMatch(text);
    if (timeMatch != null) {
      final dayStr = timeMatch.group(1) ?? '今天';
      final hour = int.parse(timeMatch.group(2)!);
      final minute = int.parse(timeMatch.group(3) ?? '0');

      final now = DateTime.now();
      DateTime startAt;
      switch (dayStr) {
        case '明天':
          startAt = DateTime(now.year, now.month, now.day + 1, hour, minute);
          break;
        case '后天':
          startAt = DateTime(now.year, now.month, now.day + 2, hour, minute);
          break;
        default:
          startAt = DateTime(now.year, now.month, now.day, hour, minute);
      }

      args['startAt'] = startAt.toIso8601String();
      args['timezone'] = 'Asia/Shanghai';
    }

    if (!args.containsKey('startAt')) return null;
    return args;
  }

  bool shouldTriggerToolCall(String text) =>
      matchIntent(text) == Intent.createEvent;

  Map<String, dynamic>? getToolCallArgs(String text) {
    if (!shouldTriggerToolCall(text)) return null;
    return tryExtractEventArgs(text);
  }

  ForceTriggerResult? tryForceTrigger(String text) {
    final match = RegExp(r'#tool:(\w+)\s*(\{.*\})?').firstMatch(text);
    if (match == null) return null;

    final toolName = match.group(1)!;
    final argsJson = match.group(2);

    Map<String, dynamic>? args;
    if (argsJson != null) {
      try {
        args = jsonDecode(argsJson) as Map<String, dynamic>;
      } catch (_) {
        args = {};
      }
    }

    return ForceTriggerResult(toolName: toolName, args: args ?? {});
  }
}

class ForceTriggerResult {
  final String toolName;
  final Map<String, dynamic> args;
  ForceTriggerResult({required this.toolName, required this.args});
}