From 3039cd41c779fc5dbb7e743b5faf462f2e9e47ab Mon Sep 17 00:00:00 2001
From: talveg-1 <talveg_uk@proton.me>
Date: Sun, 17 May 2026 19:15:12 +0100
Subject: [PATCH] Add RU SNILS

---
 stdnum/ru/snils.py          | 75 +++++++++++++++++++++++++++++++++++++
 tests/test_ru_snils.doctest | 28 ++++++++++++++
 2 files changed, 103 insertions(+)
 create mode 100644 stdnum/ru/snils.py
 create mode 100644 tests/test_ru_snils.doctest

diff --git a/stdnum/ru/snils.py b/stdnum/ru/snils.py
new file mode 100644
index 00000000..c7035ac7
--- /dev/null
+++ b/stdnum/ru/snils.py
@@ -0,0 +1,75 @@
+"""СНИЛС (Страховой номер индивидуального лицевого счёта, Russian Individual insurance account number)
+
+More information:
+
+* https://en.wikipedia.org/wiki/SNILS_(Russia)
+* https://ru.wikipedia.org/wiki/Страховой_номер_индивидуального_лицевого_счёта
+
+>>> validate('11223344595')
+'112-233-445 95'
+>>> validate('010-242-368 77')
+'010-242-368 77'
+>>> validate('010-242-368 00')
+Traceback (most recent call last):
+    ...
+InvalidChecksum: ...
+"""
+
+from __future__ import annotations
+
+from stdnum.exceptions import *
+from stdnum.util import clean, isdigits
+
+
+def compact(number: str) -> str:
+    """Convert the number to the minimal representation. This strips the
+    number of any valid separators and removes surrounding whitespace."""
+    return clean(number, " -").strip()
+
+
+def calc_check_digit(number: str) -> str:
+    """Calculate the expected SNILS checksum digits"""
+    calculated_checksum: int = sum([int(c) * (9 - i) for i, c in enumerate(number[:9])])
+    if calculated_checksum > 101:
+        calculated_checksum %= 101
+    if calculated_checksum in [100, 101]:
+        calculated_checksum = 0
+    return f"{calculated_checksum:02d}"
+
+
+def _is_valid_checksum(number: str) -> bool:
+    """Determine if checksum is correct"""
+    checksum_digits: str = number[9:11]
+    if calc_check_digit(number) != checksum_digits:
+        return False
+    return True
+
+
+def validate(number: str) -> str:
+    """Determine if the given number is a valid SNILS."""
+    number = compact(number)
+    if not isdigits(number):
+        raise InvalidFormat()
+    if not len(number) == 11:
+        raise InvalidLength()
+    if not _is_valid_checksum(number):
+        raise InvalidChecksum()
+    return number
+
+
+def is_valid(number: str) -> bool:
+    """Check if the number is a valid SNILS."""
+    try:
+        return bool(validate(number))
+    except ValidationError:
+        return False
+
+
+def format(number: str) -> str:
+    """Format the number provided for output."""
+    number = validate(number)
+    return f"{number[0:3]}-{number[3:6]}-{number[6:9]} {number[9:11]}"
+
+
+if __name__ == "__main__":
+    print(format("148-481-255 85"))
diff --git a/tests/test_ru_snils.doctest b/tests/test_ru_snils.doctest
new file mode 100644
index 00000000..daeb1f8f
--- /dev/null
+++ b/tests/test_ru_snils.doctest
@@ -0,0 +1,28 @@
+>>> from stdnum.ru import snils
+>>> from stdnum.exceptions import *
+
+Checks a valid SNILS number and its formatting behavior:
+
+>>> snils.validate('148-481-255 85')
+'14848125585'
+>>> snils.format('14848125585')
+'148-481-255 85'
+>>> snils.compact(' 148 481 255 85 ')
+'14848125585'
+>>> snils.is_valid('148-481-255 85')
+True
+
+Invalid SNILS values raise the expected exceptions:
+
+>>> snils.validate('148-481-255')  # too short
+Traceback (most recent call last):
+    ...
+InvalidLength: ...
+>>> snils.validate('148-481-255 xx')  # invalid characters
+Traceback (most recent call last):
+    ...
+InvalidFormat: ...
+>>> snils.validate('148-481-255 00')  # invalid checksum
+Traceback (most recent call last):
+    ...
+InvalidChecksum: ...