From d23efeb4811c5aded10b547fc0f4c0fcc3fec8dc Mon Sep 17 00:00:00 2001
From: Sean H <50758691+cyanghsieh@users.noreply.github.com>
Date: Fri, 7 Jul 2023 22:19:15 +0800
Subject: [PATCH] Add fake automotive `vin` number function (#1879) (#1884)

---
 faker/providers/automotive/__init__.py | 41 ++++++++++++++++++++++++++
 tests/providers/test_automotive.py     | 14 +++++++++
 2 files changed, 55 insertions(+)

diff --git a/faker/providers/automotive/__init__.py b/faker/providers/automotive/__init__.py
index 4a3156e34c..1f89d37c2a 100644
--- a/faker/providers/automotive/__init__.py
+++ b/faker/providers/automotive/__init__.py
@@ -7,6 +7,36 @@
 localized = True
 
 
+def calculate_vin_str_weight(s: str, weight_factor: list) -> int:
+    """
+    multiply s(str) by weight_factor char by char
+    e.g.
+    input: s="ABCDE", weight_factor=[1, 2, 3, 4, 5]
+    return: A*1 + B*2 + C*3 + D*4 + E*5
+
+    will multiply 0 when len(weight_factor) less than len(s)
+    """
+
+    def _get_char_weight(c: str) -> int:
+        """A=1, B=2, ...., I=9,
+        J=1, K=2, ..., R=9,
+        S=2, T=3, ..., Z=9
+        """
+        if ord(c) <= 64:  # 0-9
+            return int(c)
+        if ord(c) <= 73:  # A-I
+            return ord(c) - 64
+        if ord(c) <= 82:  # J-R
+            return ord(c) - 73
+        # S-Z
+        return ord(c) - 81
+
+    res = 0
+    for i, c in enumerate(s):
+        res += _get_char_weight(c) * weight_factor[i] if i < len(weight_factor) else 0
+    return res
+
+
 class Provider(BaseProvider):
     """Implement default automotive provider for Faker."""
 
@@ -20,3 +50,14 @@ def license_plate(self) -> str:
             self.random_element(self.license_formats),
         )
         return self.numerify(temp)
+
+    def vin(self) -> str:
+        """Generate vin number."""
+        vin_chars = "1234567890ABCDEFGHJKLMNPRSTUVWXYZ"  # I, O, Q are restricted
+        front_part = self.bothify("????????", letters=vin_chars)
+        rear_part = self.bothify("????????", letters=vin_chars)
+        front_part_weight = calculate_vin_str_weight(front_part, [8, 7, 6, 5, 4, 3, 2, 10])
+        rear_part_weight = calculate_vin_str_weight(rear_part, [9, 8, 7, 6, 5, 4, 3, 2])
+        checksum = (front_part_weight + rear_part_weight) % 11
+        checksum_char = "X" if checksum == 10 else str(checksum)
+        return front_part + checksum_char + rear_part
diff --git a/tests/providers/test_automotive.py b/tests/providers/test_automotive.py
index 62f725b087..8373e79959 100644
--- a/tests/providers/test_automotive.py
+++ b/tests/providers/test_automotive.py
@@ -8,6 +8,7 @@
 from faker.providers.automotive.ru_RU import Provider as RuRuAutomotiveProvider
 from faker.providers.automotive.sk_SK import Provider as SkSkAutomotiveProvider
 from faker.providers.automotive.tr_TR import Provider as TrTrAutomotiveProvider
+from faker.providers.automotive import calculate_vin_str_weight
 
 
 class _SimpleAutomotiveTestMixin:
@@ -23,6 +24,19 @@ def test_license_plate(self, faker, num_samples):
             assert match is not None
             self.perform_extra_checks(license_plate, match)
 
+    def test_vin(self, faker, num_samples):
+        for _ in range(num_samples):
+            vin_number = faker.vin()
+            # length check: 17
+            assert len(vin_number) == 17
+
+            # verify checksum: vin_number[8]
+            front_part_weight = calculate_vin_str_weight(vin_number[:8], [8, 7, 6, 5, 4, 3, 2, 10])
+            rear_part_weight = calculate_vin_str_weight(vin_number[9:], [9, 8, 7, 6, 5, 4, 3, 2])
+            checksum = (front_part_weight + rear_part_weight) % 11
+            checksum_str = "X" if checksum == 10 else str(checksum)
+            assert vin_number[8] == checksum_str
+
 
 class TestArBh(_SimpleAutomotiveTestMixin):
     """Test ar_BH automotive provider methods"""