lib.itmens/catalog/book/utils.py

63 lines
1.3 KiB
Python

import re
from .models import IdType
def check_digit_10(isbn):
assert len(isbn) == 9
sum = 0
for i in range(len(isbn)):
c = int(isbn[i])
w = i + 1
sum += w * c
r = sum % 11
return "X" if r == 10 else str(r)
def check_digit_13(isbn):
assert len(isbn) == 12
sum = 0
for i in range(len(isbn)):
c = int(isbn[i])
w = 3 if i % 2 else 1
sum += w * c
r = 10 - (sum % 10)
return "0" if r == 10 else str(r)
def isbn_10_to_13(isbn):
if not isbn or len(isbn) != 10:
return None
return "978" + isbn[:-1] + check_digit_13("978" + isbn[:-1])
def isbn_13_to_10(isbn):
if not isbn or len(isbn) != 13 or isbn[:3] != "978":
return None
else:
return isbn[3:12] + check_digit_10(isbn[3:12])
def is_isbn_13(isbn):
return re.match(r"^\d{13}$", isbn) is not None
def is_isbn_10(isbn):
return re.match(r"^\d{9}[X0-9]$", isbn) is not None
def is_asin(asin):
return re.match(r"^B[A-Z0-9]{9}$", asin) is not None
def detect_isbn_asin(s):
if not s:
return None, None
n = re.sub(r"[^0-9A-Z]", "", s.upper())
if is_isbn_13(n):
return IdType.ISBN, n
if is_isbn_10(n):
return IdType.ISBN, isbn_10_to_13(n)
if is_asin(n):
return IdType.ASIN, n
return None, None