From 01dd2a6d38885078d92f52845b9a58d34752fbbb Mon Sep 17 00:00:00 2001
From: Paul Mundt <paul.mundt@adaptant.io>
Date: Wed, 3 Mar 2021 21:05:19 +0100
Subject: [PATCH 1/8] Bump version to 0.2.0-nullsafety.

---
 CHANGELOG.md | 4 ++++
 pubspec.yaml | 2 +-
 2 files changed, 5 insertions(+), 1 deletion(-)

diff --git a/CHANGELOG.md b/CHANGELOG.md
index a17f02f..816f51d 100644
--- a/CHANGELOG.md
+++ b/CHANGELOG.md
@@ -1,3 +1,7 @@
+## 0.2.0-nullsafety
+
+- Migrate for null safety
+
 ## 0.1.3
 
 - Update dependencies
diff --git a/pubspec.yaml b/pubspec.yaml
index c59c682..49ce8dc 100644
--- a/pubspec.yaml
+++ b/pubspec.yaml
@@ -3,7 +3,7 @@ description:
   Dart library for working with Vehicle Identification Numbers (VINs) based on ISO 3779:2009 and
   World Manufacturer Identifiers (WMIs) based on ISO 3780:2009, enriched by NHTSA data.
 
-version: 0.1.3
+version: 0.2.0-nullsafety
 repository: https://github.com/adaptant-labs/vin-decoder-dart
 issue_tracker: https://github.com/adaptant-labs/vin-decoder-dart/issues
 

From 3763cf96600592d84abd7c1de3b0d2b40b1097c2 Mon Sep 17 00:00:00 2001
From: Paul Mundt <paul.mundt@adaptant.io>
Date: Sat, 29 May 2021 19:49:29 +0200
Subject: [PATCH 2/8] Add support for 2-character manufacturer codes in the WMI

Some manufacturers use the first 2 characters of the WMI as the
manufacturer ID, with the 3rd denoting the specific class of vehicle
specific to that manufacturer.

Fixes #7.
---
 CHANGELOG.md                  |  4 ++++
 lib/src/vin_decoder_base.dart | 10 +++++++++-
 test/vin_decoder_test.dart    | 22 ++++++++++++++++++++++
 3 files changed, 35 insertions(+), 1 deletion(-)

diff --git a/CHANGELOG.md b/CHANGELOG.md
index 816f51d..d6dbc94 100644
--- a/CHANGELOG.md
+++ b/CHANGELOG.md
@@ -1,3 +1,7 @@
+## 0.2.1
+
+- Support VINs with 2-character manufacturer IDs in their WMI (reported by @huangkaichang, issue #7)
+
 ## 0.2.0-nullsafety
 
 - Migrate for null safety
diff --git a/lib/src/vin_decoder_base.dart b/lib/src/vin_decoder_base.dart
index d0655c3..e95caff 100644
--- a/lib/src/vin_decoder_base.dart
+++ b/lib/src/vin_decoder_base.dart
@@ -65,10 +65,18 @@ class VIN {
 
   /// Get the full name of the vehicle manufacturer as defined by the [wmi].
   String? getManufacturer() {
+    // Check for the standard case - a 3 character WMI
     if (manufacturers.containsKey(this.wmi)) {
       return manufacturers[this.wmi];
     } else {
-      return "Unknown (WMI: ${this.wmi.toUpperCase()})";
+      // Some manufacturers only use the first 2 characters for manufacturer
+      // identification, and the third for the class of vehicle.
+      var id = this.wmi.substring(0, 2);
+      if (manufacturers.containsKey(id)) {
+        return manufacturers[id];
+      } else {
+        return "Unknown (WMI: ${this.wmi.toUpperCase()})";
+      }
     }
   }
 
diff --git a/test/vin_decoder_test.dart b/test/vin_decoder_test.dart
index 3089f96..9448418 100644
--- a/test/vin_decoder_test.dart
+++ b/test/vin_decoder_test.dart
@@ -37,4 +37,26 @@ void main() {
       expect(vin.getRegion(), 'AS');
     });
   });
+
+  group('2-character WMI Manufacturer Test', () {
+    late VIN vin;
+
+    setUp(() {
+      // Here the first 2 characters refer to the manufacturer, with the 3rd
+      // representing the class of vehicle specific to that manufacturer.
+      vin = VIN(number: '5TENL42N94Z436445');
+    });
+
+    test('Validity Test', () {
+      expect(vin.valid(), isTrue);
+    });
+
+    test('Region Test', () {
+      expect(vin.getRegion(), 'NA');
+    });
+
+    test('Manufacturer Test', () {
+      expect(vin.getManufacturer(), 'Toyota - trucks');
+    });
+  });
 }

From b416dbf461a7bbecb623944fec55ac51436db906 Mon Sep 17 00:00:00 2001
From: Paul Mundt <paul.mundt@adaptant.io>
Date: Sat, 29 May 2021 20:05:45 +0200
Subject: [PATCH 3/8] Update package dependencies

---
 pubspec.yaml | 6 +++---
 1 file changed, 3 insertions(+), 3 deletions(-)

diff --git a/pubspec.yaml b/pubspec.yaml
index 49ce8dc..189f249 100644
--- a/pubspec.yaml
+++ b/pubspec.yaml
@@ -11,9 +11,9 @@ environment:
   sdk: '>=2.12.0 <3.0.0'
 
 dependencies:
-  basic_utils: ^3.0.0-nullsafety.0
-  http: ^0.13.0
+  basic_utils: ^3.1.0
+  http: ^0.13.3
   random_string: ^2.2.0-nullsafety
 
 dev_dependencies:
-  test: ^1.16.5
+  test: ^1.17.5

From 431ee5046e0fd2f07345eb1306f73b25a0f91adc Mon Sep 17 00:00:00 2001
From: Paul Mundt <paul.mundt@adaptant.io>
Date: Sat, 29 May 2021 20:06:57 +0200
Subject: [PATCH 4/8] Bump release to 0.2.1

---
 pubspec.yaml | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/pubspec.yaml b/pubspec.yaml
index 189f249..4944499 100644
--- a/pubspec.yaml
+++ b/pubspec.yaml
@@ -3,7 +3,7 @@ description:
   Dart library for working with Vehicle Identification Numbers (VINs) based on ISO 3779:2009 and
   World Manufacturer Identifiers (WMIs) based on ISO 3780:2009, enriched by NHTSA data.
 
-version: 0.2.0-nullsafety
+version: 0.2.1
 repository: https://github.com/adaptant-labs/vin-decoder-dart
 issue_tracker: https://github.com/adaptant-labs/vin-decoder-dart/issues
 

From 5c74ef97acd18c9ea269a8b554772e963bb6fc7d Mon Sep 17 00:00:00 2001
From: Paul Mundt <paul.mundt@adaptant.io>
Date: Sat, 29 May 2021 20:12:12 +0200
Subject: [PATCH 5/8] Mark release version as pre-release, due to random_string
 dependency.

---
 pubspec.yaml | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/pubspec.yaml b/pubspec.yaml
index 4944499..ca7c13d 100644
--- a/pubspec.yaml
+++ b/pubspec.yaml
@@ -3,7 +3,7 @@ description:
   Dart library for working with Vehicle Identification Numbers (VINs) based on ISO 3779:2009 and
   World Manufacturer Identifiers (WMIs) based on ISO 3780:2009, enriched by NHTSA data.
 
-version: 0.2.1
+version: 0.2.1-nullsafety
 repository: https://github.com/adaptant-labs/vin-decoder-dart
 issue_tracker: https://github.com/adaptant-labs/vin-decoder-dart/issues
 

From ade3821c6a0bc37a7ef7c9cfea17f71ed6bff060 Mon Sep 17 00:00:00 2001
From: Paul Mundt <paul.mundt@adaptant.io>
Date: Sat, 29 May 2021 20:13:29 +0200
Subject: [PATCH 6/8] Update CHANGELOG for 0.2.1-nullsafety pre-release.

---
 CHANGELOG.md | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/CHANGELOG.md b/CHANGELOG.md
index d6dbc94..e52f7ed 100644
--- a/CHANGELOG.md
+++ b/CHANGELOG.md
@@ -1,4 +1,4 @@
-## 0.2.1
+## 0.2.1-nullsafety
 
 - Support VINs with 2-character manufacturer IDs in their WMI (reported by @huangkaichang, issue #7)
 

From 6ea3d4268338632c9c8c1eb4cce5a0c73e9c3de3 Mon Sep 17 00:00:00 2001
From: Bailie Livingston <rampion@mindspring.com>
Date: Fri, 2 Dec 2022 13:25:52 -0600
Subject: [PATCH 7/8] Nullsafety compliant

---
 AUTHORS                          |  3 +-
 CHANGELOG.md                     |  3 ++
 example/vin_decoder_example.dart | 10 ++---
 lib/nhtsa.dart                   |  1 -
 lib/src/nhtsa_model.dart         | 64 ++++++++++++++++++--------------
 lib/src/vin_decoder_base.dart    | 13 +++----
 lib/vin_decoder.dart             |  1 -
 pubspec.yaml                     |  9 ++---
 test/vin_decoder_test.dart       |  2 +-
 test/vin_generator_test.dart     |  4 +-
 10 files changed, 60 insertions(+), 50 deletions(-)

diff --git a/AUTHORS b/AUTHORS
index 7d248e8..580b1f6 100644
--- a/AUTHORS
+++ b/AUTHORS
@@ -3,4 +3,5 @@
 #
 #   Name/Organization <email address>
 
-Adaptant Labs <labs@adaptant.io>
\ No newline at end of file
+Adaptant Labs <labs@adaptant.io>
+Stemco
\ No newline at end of file
diff --git a/CHANGELOG.md b/CHANGELOG.md
index 9e725cc..d33e625 100644
--- a/CHANGELOG.md
+++ b/CHANGELOG.md
@@ -1,3 +1,6 @@
+## 0.2.1
+- Migrated completely to nullsafety
+
 ## 0.2.0
 
 - Expose helpers for querying NHTSA DB and accessing extended vehicle information (requested by @ride4sun, issue #8)
diff --git a/example/vin_decoder_example.dart b/example/vin_decoder_example.dart
index 96fe069..7471dc3 100644
--- a/example/vin_decoder_example.dart
+++ b/example/vin_decoder_example.dart
@@ -1,5 +1,5 @@
-import 'package:vin_decoder/nhtsa.dart';
-import 'package:vin_decoder/vin_decoder.dart';
+import 'package:custom_vin_decoder/nhtsa.dart';
+import 'package:custom_vin_decoder/vin_decoder.dart';
 
 void main() async {
   var vin = VIN(number: 'WP0ZZZ99ZTS392124', extended: true);
@@ -11,7 +11,7 @@ void main() async {
   print("Model year is " + vin.modelYear());
   print("Serial number is " + vin.serialNumber());
   print("Assembly plant is " + vin.assemblyPlant());
-  print("Manufacturer is " + vin.getManufacturer());
+  print("Manufacturer is " + (vin.getManufacturer() ?? ""));
   print("Year is " + vin.getYear().toString());
   print("Region is " + vin.getRegion());
   print("VIN string is " + vin.toString());
@@ -27,10 +27,10 @@ void main() async {
   print("Type is ${type}");
 
   var info = await NHTSA.decodeVin(vin.number);
-  print('Plant Country is ' + info.value('Plant Country'));
+  print('Plant Country is ' + (info?.value('Plant Country') ?? ""));
 
   var values = await NHTSA.decodeVinValues(vin.number);
-  print('Manufacturer from NHTSA DB is ' + values['Manufacturer']);
+  print('Manufacturer from NHTSA DB is ' + values?['Manufacturer']);
 
   var generated = VINGenerator().generate();
   print('Randomly Generated VIN is ${generated}');
diff --git a/lib/nhtsa.dart b/lib/nhtsa.dart
index 0bddffa..44fd877 100644
--- a/lib/nhtsa.dart
+++ b/lib/nhtsa.dart
@@ -1,5 +1,4 @@
 /// Support for querying NHTSA database by VIN.
-// @dart=2.1
 library nhtsa;
 
 export 'src/nhtsa_model.dart';
diff --git a/lib/src/nhtsa_model.dart b/lib/src/nhtsa_model.dart
index af28dfc..74c626d 100644
--- a/lib/src/nhtsa_model.dart
+++ b/lib/src/nhtsa_model.dart
@@ -5,24 +5,25 @@ import 'dart:convert';
 // NHTSA Results not relevant for a specific vehicle can be either null or N/A
 const String _RESULT_NOT_APPLICABLE = 'Not Applicable';
 
+// ignore: avoid_classes_with_only_static_members
 /// A wrapper for the NHTSA REST API
 class NHTSA {
   static const String _uriBase = 'https://vpic.nhtsa.dot.gov/api/vehicles';
 
   /// Obtain information about a given [vin] from the NHTSA DB.
-  static Future<NHTSAVehicleInfo> decodeVin(String vin) async {
+  static Future<NHTSAVehicleInfo?> decodeVin(String vin) async {
     var path = _uriBase + '/DecodeVin/' + vin + '?format=json';
     final response = await http.get(Uri.parse(path));
 
     if (response.statusCode == 200) {
-      return NHTSAVehicleInfo.fromJson(jsonDecode(response.body));
+      return NHTSAVehicleInfo.fromJson(jsonDecode(response.body) as Map<String, dynamic>);
     }
 
     return null;
   }
 
   /// Obtain a map of key/value pairs containing known values for a given [vin]
-  static Future<Map<String, dynamic>> decodeVinValues(String vin) async {
+  static Future<Map<String, dynamic>?> decodeVinValues(String vin) async {
     var path = _uriBase + '/DecodeVinValues/' + vin + '?format=json';
     final response = await http.get(Uri.parse(path));
 
@@ -30,8 +31,8 @@ class NHTSA {
     // variables and values as an array of encapsulated key/value pairs.
     // Manually unpack this in order to provide the caller a populated Dart map.
     if (response.statusCode == 200) {
-      Map<String, dynamic> data = jsonDecode(response.body);
-      Map<String, dynamic> map = data['Results'][0];
+      final Map<String, dynamic> data = jsonDecode(response.body) as Map<String, dynamic>;
+      final Map<String, dynamic> map = data['Results'][0] as Map<String, dynamic>;
       // Discard empty and not applicable entries from map
       map.removeWhere((key, value) =>
           value == null || value == _RESULT_NOT_APPLICABLE || value == '');
@@ -45,25 +46,27 @@ class NHTSA {
 /// The result of a single data point from the NHTSA DB for a specific variable.
 class NHTSAResult {
   /// The value associated with a given [variable] or [variableId]
-  String value;
+  String? value;
 
   /// The ID number associated with a given [value]
-  String valueId;
+  String? valueId;
 
   /// The variable name
-  String variable;
+  String? variable;
 
   /// The ID number of a given [variable]
-  int variableId;
+  int? variableId;
 
-  NHTSAResult({this.value, this.valueId, this.variable, this.variableId});
+  NHTSAResult({required this.value, required this.valueId, required this.variable, required this.variableId});
 
   /// Create a new [NHTSAResult] instance from a fixed JSON payload
-  NHTSAResult.fromJson(Map<String, dynamic> json) {
-    value = json['Value'];
-    valueId = json['ValueId'];
-    variable = json['Variable'];
-    variableId = json['VariableId'];
+  factory NHTSAResult.fromJson(Map<String, dynamic> json) {
+    return NHTSAResult(
+      value: json['Value'] as String?, 
+      valueId: json['ValueId'] as String?, 
+      variable: json['Variable'] as String?, 
+      variableId: json['VariableId'] as int?
+    );
   }
 
   @override
@@ -80,13 +83,11 @@ class NHTSAVehicleInfo {
   List<NHTSAResult> results = [];
 
   NHTSAVehicleInfo(
-      {this.count, this.message, this.searchCriteria, this.results});
+      {required this.count, required this.message, required this.searchCriteria, required this.results});
 
   /// Create a new [NHTSAVehicleInfo] instance from a fixed JSON payload
-  NHTSAVehicleInfo.fromJson(Map<String, dynamic> json) {
-    count = json['Count'];
-    message = json['Message'];
-    searchCriteria = json['SearchCriteria'];
+  factory NHTSAVehicleInfo.fromJson(Map<String, dynamic> json) {
+    List<NHTSAResult> results = [];
     if (json['Results'] != null) {
       json['Results'].forEach((v) {
         if (v['Value'] != null &&
@@ -96,25 +97,34 @@ class NHTSAVehicleInfo {
         }
       });
     }
+    return NHTSAVehicleInfo(
+      count: (json['Count'] as int?) ?? 0,
+      message: json['Message'] as String? ?? "",
+      searchCriteria: json['SearchCriteria'],
+      results: results
+    );
   }
 
-  static String _normalizeStringValue(String s) {
+  static String? _normalizeStringValue(String? s) {
+    if (s == null){
+      return null;
+    }
     return s.splitMapJoin(' ',
         onNonMatch: (m) => StringUtils.capitalize(m.toLowerCase()));
   }
 
   /// Lookup the value of a variable by its [variableId] in the NHTSA DB results
-  String valueFromId(int variableId) {
+  String? valueFromId(int? variableId) {
     var result = results.singleWhere((e) => e.variableId == variableId,
-        orElse: () => null);
-    return result != null ? _normalizeStringValue(result.value) : null;
+        orElse: () => NHTSAResult(value: null, valueId: null, variable: null, variableId: null));
+    return _normalizeStringValue(result.value);
   }
 
   /// Lookup the value of a named [variable] in the NHTSA DB results
-  String value(String variable) {
+  String? value(String variable) {
     var result =
-        results.singleWhere((e) => e.variable == variable, orElse: () => null);
-    return result != null ? _normalizeStringValue(result.value) : null;
+        results.singleWhere((e) => e.variable == variable, orElse: () => NHTSAResult(value: null, valueId: null, variable: null, variableId: null));
+    return _normalizeStringValue(result.value);
   }
 
   @override
diff --git a/lib/src/vin_decoder_base.dart b/lib/src/vin_decoder_base.dart
index e832b96..6e4ed98 100644
--- a/lib/src/vin_decoder_base.dart
+++ b/lib/src/vin_decoder_base.dart
@@ -2,8 +2,6 @@ import 'manufacturers.dart';
 import 'nhtsa_model.dart';
 import 'year_map.dart';
 
-import 'package:meta/meta.dart';
-
 class VIN {
   /// The VIN that the class was instantiated with.
   final String number;
@@ -21,14 +19,14 @@ class VIN {
   final bool extended;
   Map<String, dynamic> _vehicleInfo = {};
 
-  VIN({@required this.number, this.extended = false})
+  VIN({required this.number, this.extended = false})
       : wmi = normalize(number).substring(0, 3),
         vds = normalize(number).substring(3, 9),
         vis = normalize(number).substring(9, 17);
 
   /// Carry out VIN validation. A valid [number] must be 17 characters long
   /// and contain only valid alphanumeric characters.
-  bool valid([String number]) {
+  bool valid([String? number]) {
     String value = normalize(number != null ? number : this.number);
     return RegExp(r"^[a-zA-Z0-9]+$").hasMatch(value) && value.length == 17;
   }
@@ -39,7 +37,7 @@ class VIN {
 
   /// Obtain the encoded manufacturing year in YYYY format.
   int getYear() {
-    return yearMap[modelYear()];
+    return yearMap[modelYear()] ?? 2001;
   }
 
   /// Obtain the 2-character region code for the manufacturing region.
@@ -85,7 +83,7 @@ class VIN {
   /// Returns the checksum for the VIN. Note that in the case of the EU region
   /// checksums are not implemented, so this becomes a no-op. More information
   /// is provided in ISO 3779:2009.
-  String getChecksum() {
+  String? getChecksum() {
     return (getRegion() != "EU") ? normalize(this.number)[8] : null;
   }
 
@@ -98,9 +96,10 @@ class VIN {
   /// Extract the serial number from the [number].
   String serialNumber() => normalize(this.number).substring(12, 17);
 
+  /// Assigns the 
   Future<void> _fetchExtendedVehicleInfo() async {
     if (this._vehicleInfo.isEmpty && extended == true) {
-      this._vehicleInfo = await NHTSA.decodeVinValues(this.number);
+      this._vehicleInfo = await NHTSA.decodeVinValues(this.number) ?? {};
     }
   }
 
diff --git a/lib/vin_decoder.dart b/lib/vin_decoder.dart
index a596681..84467c7 100644
--- a/lib/vin_decoder.dart
+++ b/lib/vin_decoder.dart
@@ -1,5 +1,4 @@
 /// Support for VIN parsing, validation, and generation.
-// @dart=2.1
 
 library vin_decoder;
 
diff --git a/pubspec.yaml b/pubspec.yaml
index 1163387..dbdedb9 100644
--- a/pubspec.yaml
+++ b/pubspec.yaml
@@ -1,19 +1,18 @@
-name: vin_decoder
+name: custom_vin_decoder
 description:
   Dart library for working with Vehicle Identification Numbers (VINs) based on ISO 3779:2009 and
   World Manufacturer Identifiers (WMIs) based on ISO 3780:2009, enriched by NHTSA data.
 
-version: 0.2.1-nullsafety
+version: 0.2.1
 repository: https://github.com/adaptant-labs/vin-decoder-dart
 issue_tracker: https://github.com/adaptant-labs/vin-decoder-dart/issues
 
 environment:
-  sdk: '>=2.1.0 <3.0.0'
+  sdk: '>=2.12.0 < 3.0.0'
 
 dependencies:
-  meta: ^1.4.0
+  meta: ^1.8.0
   basic_utils: ^3.4.0
-  basic_utils: ^3.1.0
   http: ^0.13.3
   random_string: ^2.2.0-nullsafety
 
diff --git a/test/vin_decoder_test.dart b/test/vin_decoder_test.dart
index c913d7e..532f82f 100644
--- a/test/vin_decoder_test.dart
+++ b/test/vin_decoder_test.dart
@@ -1,4 +1,4 @@
-import 'package:vin_decoder/vin_decoder.dart';
+import 'package:custom_vin_decoder/vin_decoder.dart';
 import 'package:test/test.dart';
 
 void main() {
diff --git a/test/vin_generator_test.dart b/test/vin_generator_test.dart
index 9e4b067..e3a1cf5 100644
--- a/test/vin_generator_test.dart
+++ b/test/vin_generator_test.dart
@@ -1,10 +1,10 @@
-import 'package:vin_decoder/vin_decoder.dart';
+import 'package:custom_vin_decoder/vin_decoder.dart';
 import 'package:test/test.dart';
 
 void main() {
   group('VIN Generator Test', () {
     VINGenerator generator;
-    VIN vin;
+    late VIN vin;
 
     setUp(() {
       generator = VINGenerator();

From 2357c09d253e7dc4132251f571eca468175eb933 Mon Sep 17 00:00:00 2001
From: Bailie Livingston <rampion@mindspring.com>
Date: Wed, 7 Dec 2022 13:16:46 -0600
Subject: [PATCH 8/8] Added as submodule

---
 example/vin_decoder_example.dart |  2 +-
 lib/src/nhtsa_model.dart         |  2 +-
 lib/src/vin_decoder_base.dart    | 51 ++++++++++++++++++++-------
 lib/src/year_map.dart            | 60 ++++++++++++++++----------------
 test/vin_decoder_test.dart       |  6 ++--
 test/vin_generator_test.dart     |  2 +-
 6 files changed, 74 insertions(+), 49 deletions(-)

diff --git a/example/vin_decoder_example.dart b/example/vin_decoder_example.dart
index 7471dc3..6b0de2a 100644
--- a/example/vin_decoder_example.dart
+++ b/example/vin_decoder_example.dart
@@ -2,7 +2,7 @@ import 'package:custom_vin_decoder/nhtsa.dart';
 import 'package:custom_vin_decoder/vin_decoder.dart';
 
 void main() async {
-  var vin = VIN(number: 'WP0ZZZ99ZTS392124', extended: true);
+  var vin = VIN(vin: 'WP0ZZZ99ZTS392124', extended: true);
 
   print('WMI: ${vin.wmi}');
   print('VDS: ${vin.vds}');
diff --git a/lib/src/nhtsa_model.dart b/lib/src/nhtsa_model.dart
index 74c626d..7244959 100644
--- a/lib/src/nhtsa_model.dart
+++ b/lib/src/nhtsa_model.dart
@@ -85,7 +85,7 @@ class NHTSAVehicleInfo {
   NHTSAVehicleInfo(
       {required this.count, required this.message, required this.searchCriteria, required this.results});
 
-  /// Create a new [NHTSAVehicleInfo] instance from a fixed JSON payload
+  /// Create a new [NHTSAVehicleInfo] instance from a fixed JSON payload.
   factory NHTSAVehicleInfo.fromJson(Map<String, dynamic> json) {
     List<NHTSAResult> results = [];
     if (json['Results'] != null) {
diff --git a/lib/src/vin_decoder_base.dart b/lib/src/vin_decoder_base.dart
index 6e4ed98..5cd5cec 100644
--- a/lib/src/vin_decoder_base.dart
+++ b/lib/src/vin_decoder_base.dart
@@ -19,13 +19,25 @@ class VIN {
   final bool extended;
   Map<String, dynamic> _vehicleInfo = {};
 
-  VIN({required this.number, this.extended = false})
-      : wmi = normalize(number).substring(0, 3),
-        vds = normalize(number).substring(3, 9),
-        vis = normalize(number).substring(9, 17);
+  /// Private named constructor. Creates a new VIN. 
+  /// 
+  /// [wmi], [vds], and [vis] are populated based on [number]. 
+  VIN._({required this.number, required this.extended}) : 
+    wmi = number.substring(0, 3),
+    vds = number.substring(3, 9),
+    vis = number.substring(9, 17);
+
+  /// Creates a new VIN. 
+  /// 
+  /// This factory constructor makes sure the string is normallyed 
+  factory VIN({required String vin, bool extended = false}){
+    return VIN._(number: normalize(vin), extended: extended);
+  }
 
   /// Carry out VIN validation. A valid [number] must be 17 characters long
   /// and contain only valid alphanumeric characters.
+  /// 
+  /// If a number is provided, validates that number. Otherwise, it validates the number this object was initialized with.
   bool valid([String? number]) {
     String value = normalize(number != null ? number : this.number);
     return RegExp(r"^[a-zA-Z0-9]+$").hasMatch(value) && value.length == 17;
@@ -64,6 +76,8 @@ class VIN {
   }
 
   /// Get the full name of the vehicle manufacturer as defined by the [wmi].
+  /// 
+  /// If the full name cannot be found, returns null.
   String? getManufacturer() {
     // Check for the standard case - a 3 character WMI
     if (manufacturers.containsKey(this.wmi)) {
@@ -75,7 +89,7 @@ class VIN {
       if (manufacturers.containsKey(id)) {
         return manufacturers[id];
       } else {
-        return "Unknown (WMI: ${this.wmi.toUpperCase()})";
+        return null;
       }
     }
   }
@@ -83,18 +97,20 @@ class VIN {
   /// Returns the checksum for the VIN. Note that in the case of the EU region
   /// checksums are not implemented, so this becomes a no-op. More information
   /// is provided in ISO 3779:2009.
+  /// 
+  /// If the region is EU, returns null
   String? getChecksum() {
-    return (getRegion() != "EU") ? normalize(this.number)[8] : null;
+    return (getRegion() != "EU") ? this.number[8] : null;
   }
 
   /// Extract the single-character model year from the [number].
-  String modelYear() => normalize(this.number)[9];
+  String modelYear() => this.number[9];
 
   /// Extract the single-character assembly plant designator from the [number].
-  String assemblyPlant() => normalize(this.number)[10];
+  String assemblyPlant() => this.number[10];
 
   /// Extract the serial number from the [number].
-  String serialNumber() => normalize(this.number).substring(12, 17);
+  String serialNumber() => this.number.substring(12, 17);
 
   /// Assigns the 
   Future<void> _fetchExtendedVehicleInfo() async {
@@ -110,15 +126,24 @@ class VIN {
     return this._vehicleInfo['Make'];
   }
 
-  /// Get the Model of the vehicle from the NHTSA database if [extended] mode
-  /// is enabled.
+  /// Get the Make ID of a vehicle from the NHTSA database if the [extended] mode is enabled
+  Future<int> getMakeIdAsync() async {
+    await _fetchExtendedVehicleInfo();
+    return this._vehicleInfo["MakeID"];
+  }
+
+  /// Get the Model of the vehicle from the NHTSA database if [extended] mode is enabled.
   Future<String> getModelAsync() async {
     await _fetchExtendedVehicleInfo();
     return this._vehicleInfo['Model'];
   }
 
-  /// Get the Vehicle Type from the NHTSA database if [extended] mode is
-  /// enabled.
+  Future<String> getModelIdAsync() async {
+    await _fetchExtendedVehicleInfo();
+    return this._vehicleInfo['ModelID'];
+  }
+
+  /// Get the Vehicle Type from the NHTSA database if [extended] mode is enabled.
   Future<String> getVehicleTypeAsync() async {
     await _fetchExtendedVehicleInfo();
     return this._vehicleInfo['VehicleType'];
diff --git a/lib/src/year_map.dart b/lib/src/year_map.dart
index 075277a..3bbbebb 100644
--- a/lib/src/year_map.dart
+++ b/lib/src/year_map.dart
@@ -1,32 +1,32 @@
 const yearMap = <String, int>{
-  'N': 1992,
-  'P': 1993,
-  'R': 1994,
-  'S': 1995,
-  'T': 1996,
-  'V': 1997,
-  'W': 1998,
-  'X': 1999,
-  'Y': 2000,
-  '1': 2001,
-  '2': 2002,
-  '3': 2003,
-  '4': 2004,
-  '5': 2005,
-  '6': 2006,
-  '7': 2007,
-  '8': 2008,
-  '9': 2009,
-  'A': 2010,
-  'B': 2011,
-  'C': 2012,
-  'D': 2013,
-  'E': 2014,
-  'F': 2015,
-  'G': 2016,
-  'H': 2017,
-  'J': 2018,
-  'K': 2019,
-  'L': 2020,
-  'M': 2021,
+  "S": 1995,
+  "T": 1996,
+  "V": 1997,
+  "W": 1998,
+  "X": 1999,
+  "Y": 2000,
+  "1": 2001,
+  "2": 2002,
+  "3": 2003,
+  "4": 2004,
+  "5": 2005,
+  "6": 2006,
+  "7": 2007,
+  "8": 2008,
+  "9": 2009,
+  "A": 2010,
+  "B": 2011,
+  "C": 2012,
+  "D": 2013,
+  "E": 2014,
+  "F": 2015,
+  "G": 2016,
+  "H": 2017,
+  "J": 2018,
+  "K": 2019,
+  "L": 2020,
+  "M": 2021,
+  "N": 2022,
+  "P": 2023,
+  "R": 2024,
 };
diff --git a/test/vin_decoder_test.dart b/test/vin_decoder_test.dart
index 532f82f..e8a190e 100644
--- a/test/vin_decoder_test.dart
+++ b/test/vin_decoder_test.dart
@@ -3,7 +3,7 @@ import 'package:test/test.dart';
 
 void main() {
   group('EU VIN Test', () {
-    final vin = VIN(number: 'WP0ZZZ99ZTS392124');
+    final vin = VIN(vin: 'WP0ZZZ99ZTS392124');
 
     test('Validity Test', () {
       expect(vin.valid(), isTrue);
@@ -19,7 +19,7 @@ void main() {
   });
 
   group('AS VIN Test', () {
-    final vin = VIN(number: 'JS1VX51L7X2175460');
+    final vin = VIN(vin: 'JS1VX51L7X2175460');
 
     test('Validity Test', () {
       expect(vin.valid(), isTrue);
@@ -37,7 +37,7 @@ void main() {
     setUp(() {
       // Here the first 2 characters refer to the manufacturer, with the 3rd
       // representing the class of vehicle specific to that manufacturer.
-      vin = VIN(number: '5TENL42N94Z436445');
+      vin = VIN(vin: '5TENL42N94Z436445');
     });
 
     test('Validity Test', () {
diff --git a/test/vin_generator_test.dart b/test/vin_generator_test.dart
index e3a1cf5..420f3ac 100644
--- a/test/vin_generator_test.dart
+++ b/test/vin_generator_test.dart
@@ -8,7 +8,7 @@ void main() {
 
     setUp(() {
       generator = VINGenerator();
-      vin = VIN(number: generator.generate());
+      vin = VIN(vin: generator.generate());
     });
 
     test('Validity Test', () {