import 'package:meta/meta.dart';

import 'package:uto_manager/domain/entities/doctrinal_branch.dart';

/// Represents a validated Military Occupational Specialty (MOS) code.
///
/// MOS codes follow the U.S. Army standard format: 2 digits + 1 letter
/// (e.g., "11B", "68W", "13F"). Aviation warrant officer AOCs use a
/// 3-digit + 1-letter format (e.g., "153A"). Both formats are accepted.
/// This value object enforces that format and validates against the known
/// MOS dictionary.
@immutable
class DutyMos {
  /// Creates a [DutyMos] from a raw MOS code string.
  ///
  /// Throws [ArgumentError] if the code is not a valid 3-character MOS.
  factory DutyMos(String code) {
    final normalized = code.trim().toUpperCase();
    if (!_isValidFormat(normalized)) {
      throw ArgumentError(
        'Invalid MOS code format: "$code". '
        'Expected format: 2 digits + 1 letter (e.g., "11B", "68W") '
        'or 3 digits + 1 letter for aviation AOCs (e.g., "153A").',
      );
    }
    if (!_knownMosCodes.contains(normalized)) {
      throw ArgumentError(
        'Unknown MOS code: "$normalized". '
        'Code is not in the authorized MOS dictionary.',
      );
    }
    return DutyMos._(normalized);
  }

  /// Creates a [DutyMos] without dictionary validation (for testing/migration).
  factory DutyMos.unvalidated(String code) {
    final normalized = code.trim().toUpperCase();
    if (!_isValidFormat(normalized)) {
      throw ArgumentError(
        'Invalid MOS code format: "$code". '
        'Expected format: 2 digits + 1 letter (e.g., "11B", "68W") '
        'or 3 digits + 1 letter for aviation AOCs (e.g., "153A").',
      );
    }
    return DutyMos._(normalized);
  }

  const DutyMos._(this.code);

  /// The normalized MOS code string (e.g., "11B", "68W", "13F").
  final String code;

  /// Returns true if [code] matches a valid MOS format:
  /// - Standard: 2 digits + 1 letter (e.g., "11B", "68W")
  /// - Aviation AOC: 3 digits + 1 letter (e.g., "153A")
  static bool _isValidFormat(String code) {
    // Standard 3-char format: NNx
    if (code.length == 3) {
      final digits = code.substring(0, 2);
      final letter = code[2];
      return RegExp(r'^\d{2}$').hasMatch(digits) && RegExp(r'^[A-Z]$').hasMatch(letter);
    }
    // Aviation AOC 4-char format: NNNx
    if (code.length == 4) {
      final digits = code.substring(0, 3);
      final letter = code[3];
      return RegExp(r'^\d{3}$').hasMatch(digits) && RegExp(r'^[A-Z]$').hasMatch(letter);
    }
    return false;
  }

  /// Returns true if [code] is a known MOS in the authorized dictionary.
  static bool isKnown(String code) {
    return _knownMosCodes.contains(code.trim().toUpperCase());
  }

  /// Returns all known MOS codes as a sorted list.
  static List<String> get allCodes => _knownMosCodes.toList()..sort();

  /// Returns all MOS codes for a given [DoctrinalBranch].
  static Set<String> codesForBranch(DoctrinalBranch branch) {
    return _branchMosMap[branch] ?? {};
  }

  /// The complete set of authorized MOS codes.
  static const Set<String> _knownMosCodes = {
    // Infantry & Maneuver (CMF 11 / 15)
    '11A', '11B', '11C', '15W', '15A', '15T', '15B', '15D', '15G', '153A',
    // Medical (CMF 68)
    '68W', '68A', '68D', '68E', '68F', '68G', '68J',
    '68K', '68P', '68Q', '68R', '68S', '68T', '68X',
    // Field Artillery (CMF 13)
    '13A', '13B', '13D', '13F', '13J', '13M', '13P', '13R', '13T',
    // Signal (CMF 25)
    '25A', '25B', '25C', '25D', '25E', '25H', '25L', '25M',
    '25N', '25P', '25Q', '25R', '25S', '25U', '25V', '25W', '25X', '25Z',
    // Cyber/EW (CMF 17)
    '17A', '17C', '17E', '17S',
    // Aviation (CMF 15)
    '15Z',
    // Logistics (CMF 91/92)
    '91A', '91B', '91C', '91D', '91E', '91F', '91G', '91H',
    '91J', '91L', '91M', '91P', '91S', '91X', '91Z',
    '92A', '92F', '92G', '92L', '92M', '92R', '92S', '92W', '92Y', '92Z',
    // Engineer (CMF 12)
    '12A', '12B', '12C', '12D', '12G', '12H', '12K', '12M',
    '12N', '12P', '12Q', '12R', '12T', '12W', '12X', '12Y', '12Z',
  };

  /// Maps each [DoctrinalBranch] to its associated MOS codes.
  static const Map<DoctrinalBranch, Set<String>> _branchMosMap = {
    DoctrinalBranch.infantry: {
      '11A',
      '11B',
      '11C',
      '15W',
      '15A',
      '15T',
      '153A',
    },
    DoctrinalBranch.medical: {
      '68W',
      '68A',
      '68D',
      '68E',
      '68F',
      '68G',
      '68J',
      '68K',
      '68P',
      '68Q',
      '68R',
      '68S',
      '68T',
      '68X',
    },
    DoctrinalBranch.fires: {
      '13A',
      '13B',
      '13D',
      '13F',
      '13J',
      '13M',
      '13P',
      '13R',
      '13T',
    },
    DoctrinalBranch.signal: {
      '25A',
      '25B',
      '25C',
      '25D',
      '25E',
      '25H',
      '25L',
      '25M',
      '25N',
      '25P',
      '25Q',
      '25R',
      '25S',
      '25U',
      '25V',
      '25W',
      '25X',
      '25Z',
    },
    DoctrinalBranch.cyberEw: {'17A', '17C', '17E', '17S'},
    DoctrinalBranch.aviation: {
      '15A',
      '15B',
      '15D',
      '15G',
      '15T',
      '15W',
      '15Z',
      '153A',
    },
    DoctrinalBranch.logistics: {
      '91A',
      '91B',
      '91C',
      '91D',
      '91E',
      '91F',
      '91G',
      '91H',
      '91J',
      '91L',
      '91M',
      '91P',
      '91S',
      '91X',
      '91Z',
      '92A',
      '92F',
      '92G',
      '92L',
      '92M',
      '92R',
      '92S',
      '92W',
      '92Y',
      '92Z',
    },
    DoctrinalBranch.engineer: {
      '12A',
      '12B',
      '12C',
      '12D',
      '12G',
      '12H',
      '12K',
      '12M',
      '12N',
      '12P',
      '12Q',
      '12R',
      '12T',
      '12W',
      '12X',
      '12Y',
      '12Z',
    },
  };

  @override
  bool operator ==(Object other) =>
      identical(this, other) || (other is DutyMos && other.code == code);

  @override
  int get hashCode => code.hashCode;

  @override
  String toString() => code;
}