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

/// Individual service log entry for a motorcycle in the rider's garage.
class ServiceRecord {
  final String id;
  final DateTime date;
  final double odometer;
  final String serviceType;
  final String? notes;
  final double? cost;

  const ServiceRecord({
    required this.id,
    required this.date,
    required this.odometer,
    required this.serviceType,
    this.notes,
    this.cost,
  });

  Map<String, dynamic> toJson() => {
    'id': id,
    'date': date.toIso8601String(),
    'odometer': odometer,
    'serviceType': serviceType,
    if (notes != null && notes!.isNotEmpty) 'notes': notes,
    if (cost != null) 'cost': cost,
  };

  factory ServiceRecord.fromJson(Map<String, dynamic> json) {
    return ServiceRecord(
      id: json['id']?.toString() ?? 'srv_${DateTime.now().millisecondsSinceEpoch}',
      date: json['date'] != null
          ? DateTime.tryParse(json['date'].toString()) ?? DateTime.now()
          : DateTime.now(),
      odometer: (json['odometer'] as num?)?.toDouble() ?? 0.0,
      serviceType: json['serviceType']?.toString() ?? 'General Maintenance',
      notes: json['notes']?.toString(),
      cost: (json['cost'] as num?)?.toDouble(),
    );
  }
}

enum MaintenanceUrgency {
  ok,
  dueSoon,
  overdue,
}

/// Dynamic countdown status for a specific scheduled maintenance item.
class MaintenanceItemStatus {
  final String key;
  final String title;
  final IconData icon;
  final int intervalMiles;
  final double milesRemaining;
  final double lastServicedOdometer;
  final MaintenanceUrgency urgency;

  const MaintenanceItemStatus({
    required this.key,
    required this.title,
    required this.icon,
    required this.intervalMiles,
    required this.milesRemaining,
    required this.lastServicedOdometer,
    required this.urgency,
  });

  String get label {
    if (milesRemaining <= 0) {
      return 'OVERDUE (${(-milesRemaining).round()} mi)';
    } else if (urgency == MaintenanceUrgency.dueSoon) {
      return 'Due Soon (${milesRemaining.round()} mi)';
    } else {
      return '${milesRemaining.round()} mi remaining';
    }
  }

  Color getBadgeColor(BuildContext context) {
    switch (urgency) {
      case MaintenanceUrgency.overdue:
        return const Color(0xFFEF4444); // Red
      case MaintenanceUrgency.dueSoon:
        return const Color(0xFFF59E0B); // Amber
      case MaintenanceUrgency.ok:
        return const Color(0xFF10B981); // Emerald
    }
  }
}

/// Helper to parse and calculate maintenance intervals and logs from specificationJson.
class MaintenanceData {
  final double baseOdometer;
  final List<ServiceRecord> serviceRecords;
  final Map<String, int> customIntervals;

  const MaintenanceData({
    this.baseOdometer = 0.0,
    this.serviceRecords = const [],
    this.customIntervals = const {},
  });

  static const int defaultOilInterval = 3000;
  static const int defaultChainInterval = 600;
  static const int defaultTireInterval = 4000;
  static const int defaultBrakeInterval = 6000;

  static MaintenanceData fromSpecificationJson(String? specJson) {
    if (specJson == null || specJson.trim().isEmpty) {
      return const MaintenanceData();
    }
    try {
      final decoded = json.decode(specJson);
      if (decoded is! Map<String, dynamic>) return const MaintenanceData();

      final baseOdo = (decoded['baseOdometer'] as num?)?.toDouble() ?? 0.0;
      final rawRecords = decoded['serviceRecords'];
      final List<ServiceRecord> records = [];

      if (rawRecords is List) {
        for (final r in rawRecords) {
          if (r is Map<String, dynamic>) {
            records.add(ServiceRecord.fromJson(r));
          }
        }
      }

      // Sort service records descending by date and odometer
      records.sort((a, b) => b.odometer.compareTo(a.odometer));

      final rawIntervals = decoded['customIntervals'];
      final Map<String, int> intervals = {};
      if (rawIntervals is Map) {
        for (final entry in rawIntervals.entries) {
          if (entry.value is num) {
            intervals[entry.key.toString()] = (entry.value as num).toInt();
          }
        }
      }

      return MaintenanceData(
        baseOdometer: baseOdo,
        serviceRecords: records,
        customIntervals: intervals,
      );
    } catch (_) {
      return const MaintenanceData();
    }
  }

  /// Calculates real-time countdown pills for all standard maintenance categories.
  List<MaintenanceItemStatus> calculatePills(double totalRiddenMiles) {
    final currentOdometer = baseOdometer + totalRiddenMiles;

    final oilInterval = customIntervals['oil'] ?? defaultOilInterval;
    final chainInterval = customIntervals['chain'] ?? defaultChainInterval;
    final tireInterval = customIntervals['tire'] ?? defaultTireInterval;
    final brakeInterval = customIntervals['brake'] ?? defaultBrakeInterval;

    return [
      _calculateItem(
        key: 'oil',
        title: 'Engine Oil',
        icon: Icons.oil_barrel,
        interval: oilInterval,
        currentOdometer: currentOdometer,
        typeMatch: (t) => t.toLowerCase().contains('oil'),
        dueSoonThreshold: 350,
      ),
      _calculateItem(
        key: 'chain',
        title: 'Chain Service',
        icon: Icons.link,
        interval: chainInterval,
        currentOdometer: currentOdometer,
        typeMatch: (t) => t.toLowerCase().contains('chain'),
        dueSoonThreshold: 80,
      ),
      _calculateItem(
        key: 'tire',
        title: 'Tire Wear',
        icon: Icons.tire_repair,
        interval: tireInterval,
        currentOdometer: currentOdometer,
        typeMatch: (t) => t.toLowerCase().contains('tire') || t.toLowerCase().contains('tyre'),
        dueSoonThreshold: 450,
      ),
      _calculateItem(
        key: 'brake',
        title: 'Brake Fluid/Pads',
        icon: Icons.speed,
        interval: brakeInterval,
        currentOdometer: currentOdometer,
        typeMatch: (t) => t.toLowerCase().contains('brake'),
        dueSoonThreshold: 600,
      ),
    ];
  }

  MaintenanceItemStatus _calculateItem({
    required String key,
    required String title,
    required IconData icon,
    required int interval,
    required double currentOdometer,
    required bool Function(String) typeMatch,
    required int dueSoonThreshold,
  }) {
    // Find the latest service record for this category
    ServiceRecord? lastService;
    for (final r in serviceRecords) {
      if (typeMatch(r.serviceType)) {
        if (lastService == null || r.odometer > lastService.odometer) {
          lastService = r;
        }
      }
    }

    final lastServicedOdo = lastService?.odometer ?? baseOdometer;
    final milesSinceService = currentOdometer - lastServicedOdo;
    final milesRemaining = interval - milesSinceService;

    final urgency = milesRemaining <= 0
        ? MaintenanceUrgency.overdue
        : (milesRemaining <= dueSoonThreshold
            ? MaintenanceUrgency.dueSoon
            : MaintenanceUrgency.ok);

    return MaintenanceItemStatus(
      key: key,
      title: title,
      icon: icon,
      intervalMiles: interval,
      milesRemaining: milesRemaining,
      lastServicedOdometer: lastServicedOdo,
      urgency: urgency,
    );
  }

  /// Injects or updates maintenance records and base odometer into the existing specification JSON string.
  static String updateSpecJsonWithMaintenance({
    required String? originalSpecJson,
    double? baseOdometer,
    List<ServiceRecord>? serviceRecords,
    Map<String, int>? customIntervals,
  }) {
    Map<String, dynamic> map = {};
    if (originalSpecJson != null && originalSpecJson.trim().isNotEmpty) {
      try {
        final decoded = json.decode(originalSpecJson);
        if (decoded is Map<String, dynamic>) {
          map = Map<String, dynamic>.from(decoded);
        }
      } catch (_) {}
    }

    if (baseOdometer != null) {
      map['baseOdometer'] = baseOdometer;
    }
    if (serviceRecords != null) {
      map['serviceRecords'] = serviceRecords.map((s) => s.toJson()).toList();
    }
    if (customIntervals != null) {
      map['customIntervals'] = customIntervals;
    }

    return json.encode(map);
  }
}