1 files changed, 63 insertions, 0 deletions
diff --git a/stdnum/gr/vat.py b/stdnum/gr/vat.py
new file mode 100644
index 0000000..e37fe95
--- /dev/null
+++ b/stdnum/gr/vat.py
@@ -0,0 +1,63 @@
+# vat.py - functions for handling Greek VAT numbers
+# coding: utf-8
+#
+# Copyright (C) 2012 Arthur de Jong
+#
+# This library is free software; you can redistribute it and/or
+# modify it under the terms of the GNU Lesser General Public
+# License as published by the Free Software Foundation; either
+# version 2.1 of the License, or (at your option) any later version.
+#
+# This library is distributed in the hope that it will be useful,
+# but WITHOUT ANY WARRANTY; without even the implied warranty of
+# MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
+# Lesser General Public License for more details.
+#
+# You should have received a copy of the GNU Lesser General Public
+# License along with this library; if not, write to the Free Software
+# Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA
+# 02110-1301 USA
+
+"""Module for handling Greek VAT (Foros Prostithemenis Aksias, FPA, ΦΠΑ)
+numbers.
+
+>>> compact('GR 23456783')
+'023456783'
+>>> is_valid('EL 094259216 ')
+True
+>>> is_valid('EL 123456781')
+False
+"""
+
+from stdnum.util import clean
+
+
+def compact(number):
+    """Convert the number to the minimal representation. This strips the
+    number of any valid separators and removes surrounding whitespace."""
+    number = clean(number, ' -./').upper().strip()
+    if number.startswith('EL') or number.startswith('GR'):
+        number = number[2:]
+    if len(number) == 8:
+        number = '0' + number  # old format had 8 digits
+    return number
+
+
+def calc_check_digit(number):
+    """Calculate the check digit. The number passed should not have the
+    check digit included."""
+    checksum = 0
+    for n in number:
+        checksum = checksum * 2 + int(n)
+    return str(checksum * 2 % 11 % 10)
+
+
+def is_valid(number):
+    """Checks to see if the number provided is a valid VAT number. This
+    checks the length, formatting and check digit."""
+    try:
+        number = compact(number)
+    except:
+        return False
+    return len(number) == 9 and number.isdigit() and \
+           calc_check_digit(number[:-1]) == number[-1]